MXPA06014200A - Liquefied natural gas processing - Google Patents

Abstract

A processand apparatus for the recovery of ethane, ethylene, propane, propylene, and heavier hydrocarbons from a liquefied natural gas (LNG) stream is disclosed. The LNG feed stream is divided into two portions. The first portion is supplied to a fractionation column at an upper mid-column feed point. The second portion is directed in heat exchange relation with a warmer distillation stream rising from the fractionation stages of the column, whereby this portion of the LNG feed stream is partially heated and the distillation stream is totally condensed. The condensed distillation stream is divided into a"lean"LNG product stream and a reflux stream, whereupon the reflux stream is supplied to the column at a top column feed position. The partially heated portion of the LNG feed stream is heated further to partially or totally vaporize it and thereafter supplied to the column at a lower mid-column feed position.

Description

PROCESS FOR LIQUEFIED NATURAL GAS DESCRIPTION OF THE INVENTION The present invention relates to a process for the separation of ethane and heavier hydrocarbons or propane and heavier hydrocarbons from liquefied natural gas, hereinafter referred to as LNG, to provide a methane-rich volatile stream of poor LNG and a less volatile flow of natural gas liquids (LNG) or liquefied petroleum gas (LPG). Applicants claim the benefits under Title 35 of the United States Code, Section 119 (e) of the previous Provisional Applications of U.S. Numbers 60 / 584,668, filed on July 1, 2004, 60 / 646,903 filed on January 24, 2005, 60 / 669,642 filed on April 8, 2005, and 60 / 671,930 filed on April 15, 2005. As an alternative When transported by gas pipelines, natural gas is sometimes liquefied in distant places and transported in special LNG tankers to appropriate terminals to receive and store the LNG. Then you can re-vaporize the LNG and use it as a gaseous fuel in the same way as natural gas. Although LNG usually has a majority proportion of methane, that is, at least 50 mole percent of the LNG is methane, and it also contains relatively large quantities. REF .: 175273 smaller than heavier hydrocarbons such as ethane, propane, butanes, etc., as well as nitrogen. Frequently, it is necessary to separate part of the heavier hydrocarbons or all of the methane present in the LNG in such a way that the gaseous fuel obtained from vaporizing the LNG meets the gas pipeline specifications with respect to its calorific value. In addition, it is often also desirable to separate the heavier hydrocarbons from methane because the hydrocarbons have greater value as liquid products (to be used as petrochemical feedstocks, as an example) than their value as fuel. Although there are many processes that can be used to separate ethane and heavier hydrocarbons from LNG, often these processes must find a compromise between high recovery, low cost of services, and simplicity of the process (and therefore low capital investment). The U.S. Patents Nos. 2,952,984; 3,837,172 and 5,114,451 and Co-pending Application no. 10 / 675,785 describe relevant LNG processes that are capable of recovering ethane or propane while producing the lean LNG as a vapor stream that is then compressed to the distribution pressure to enter the distribution network of gas. However, a lower cost of services can be achieved if poor LNG is produced in Instead, it is a liquid stream that can be pumped (instead of compressed) to the distribution pressure of the gas distribution network, subsequently vaporizing the lean LNG using an external source of low level heat or other means. U.S. Patent Application Publication Number US 2003/0158458 Al describes a process with these characteristics. The present invention relates in general to the recovery of ethylene, ethane, propylene, propane, and heavier hydrocarbons from the LNG streams. It uses a novel process arrangement to allow a high recovery of ethane or a high recovery of propane while keeping the process equipment simple and lowering the capital investment. In addition, the present invention offers a reduction of the services (energy and heat) that are required for the treatment of LNG to give a lower operating cost than the processes of the prior art. A typical analysis of an LNG stream to be treated in accordance with the present invention may be, in approximate percentages in moles, 86.7% methane, 8.9% ethane and other C2 components, 2.9% propane and other C3 components , and 1.0%) of butanes-f, where the rest is nitrogen. To better understand the present invention, reference is made to the following examples and figures. With reference to the figures: FIG. 1 is a flow chart of an LNG process plant of the prior art; FIG. 2 is a flow diagram of an LNG process plant of the prior art in accordance with U.S. Patent Application. Publication Number US 2003/0158458 Al; FIG. 3 is a flow chart of an LNG process plant according to the present invention; and FIGS. 4 to 13 are flow diagrams illustrating alternative means of applying the present invention to an LNG process plant. In the following explanation of the previous figures, tables summarizing the flow rates calculated for representative process conditions are provided. In the tables that appear in this description the values of the flows (in moles per hour) have been rounded for convenience to the nearest whole number. The flows of the total streams shown in the tables include all the different hydrocarbon components and therefore, are generally greater than the sum of the streamflows for the hydrocarbon components. The indicated temperatures are approximate values, rounded to the nearest degree value. It should also be noted that the process design calculations made with the purpose of comparing the processes shown in the Figures, are based on the assumption that there is no heat loss from (or towards) the surroundings of the process. The quality of commercially available insulating materials makes this a very reasonable assumption typically made by those skilled in the art. For convenience, the process parameters are reported in traditional English units and units of the International System (SI). The molar flow rates shown in the Tables can be interpreted either in pound-mole per hour or in kilogram-mole per hour. Power consumption is reported in HP and / or thousands of British Thermal Units per hour (MBTU / h) and corresponds to the molar flow rates established in pound-mole per hour. The power consumptions that are reported in kiloWatts (k) correspond to the molar flow rates established in kilograms moles per hour.

Now with reference to FIG. 1, for comparison purposes the inventors will start with an example of an LNG processing plant of the prior art adapted to produce an LNG product containing most of the C components and the heavier hydrocarbon components present in the feed stream. The LNG to be treated (stream 41) from the LNG tank 10 enters the pump 11 at -255 ° F [-159 ° C]. Pump 11 raises the pressure of LNG enough to be able to flow through the heat exchangers and from there to the separator 15. The current 41a leaving the pump is heated in the heat exchangers 12 and 13 by heat exchange with the gas stream 52 to -120 ° F [-84 ° C] and the liquid bottom product of the methane separator (stream 51) at 80 ° F [27 ° C]. The hot stream 41c enters the separator 15 at -163 ° F [-108 ° C] and 230 psia [1,586 kPa (a)] where the vapor (stream 46) is separated from the remaining liquid (stream 47). Stream 47 is pumped by pump 28 to a higher pressure, then expanded to operating pressure (about 430 psia [2,965 kPa (a)]) from the fractionation tower 21 via the control valve 20 and is supplied to the tower as the head feed of the column (stream 47b). The column or fractionation tower 21, is commonly referred to as a methane separator, is a conventional distillation column containing several vertically separated dishes, one or more packed beds, or some combination of dishes, and packing. The plates and / or the packing provide the necessary contact between the liquids that go down the column and the vapors that rise. The column also includes one or more kettles (such as kettle 25) that heat and vaporize a portion of the liquids that flow down the column to provide the distillation vapors that flow up the column. These vapors distill out the methane from the liquids, such that the bottom liquid product (stream 51) is substantially free of methane and comprises most of the C2 components and heavier hydrocarbons contained in the LNG feed stream. (Due to the level of temperature required in the column boiler, a high-level service heat source is usually required to provide the heat supply for the boiler, such as the heating medium which in the present example is used). The liquid product stream 51 exits the bottom of the tower at 80 ° F [27 ° C], based on the typical specifications of a methane fraction of 0.005 on a volume basis of the bottom product. After cooling to 43 ° F [6 ° C] in the heat exchanger 13 as described above, the liquid product (stream 51a) flows towards storage or further treatment. The steam stream 46 from the separator 15 enters the compressor 27 (driven by an external energy source) and is compressed to a higher pressure. The resulting stream 46a is combined with the overhead vapor from the methane separator, stream 48, which leaves the methane separator 21 at -130 ° F [-90 ° C] to produce a waste gas methane rich (stream 52) at -120 ° F [-84 ° C], which is then cooled to -143 ° F [-97 ° C] in heat exchanger 12 as described above to fully condense the stream. Then, the pump 32 pumps the condensed liquid (stream 52a) to 1365 psia [9,411 kPa (a)] (stream 52b) for subsequent vaporization and / or transport. The following table gives a summary of the flows of the currents and the energy consumption for the process illustrated in FIG. 1: Table I (FIG.l) Summary of stream flows - Lb Moles / h [kg Moles / h] Current Methane Ethane Propane Butane + Total 41 9,524 977 322 109 10,979 46 3,253 20 1 0 3,309 47 6,271 957 321 109 7,670 48 6,260 78 5 0 6,355 52 9,513 98 6 0 9,664 51 11 879 316 109 1,315 Recoveries * Ethane 90.00% Propane 98.33% Butane + 99.62% Power LNG Pump 123 HP [202 kW] 132 HP [217 kW] Methane Separator Pump 773 HP [1,271 kW] LNG Product Pump 527 HP [867 kW] Steam Compressor Totals 1,555 HP [2,557 kW] High-level service heat 23,871 methane separator [15,032 MBTU / h kW] * (Based on flows of a rounding) FIG. 2 shows an alternative process of the prior art in accordance with the US Patent Application, Publication Number US 2003/0158458 to which it can achieve slightly higher recovery levels with a lower consumption of services than the prior art process that is used in FIG. 1. The process of FIG. 2, adapted here to produce an LNG product that contains most of the C2 components and the heavier hydrocarbon components present in the feed stream, has been applied to the same LNG composition and conditions as described above for FIG. 1. In the simulation of the process of FIG. 2, the LNG to be treated (stream 41) from the LNG tank 10 enters the pump 11 at -255 ° F [-159 ° C]. The pump 11 raises the pressure of the LNG sufficiently so that it can flow through the heat exchangers and from there to the fractionation tower 21. The stream 41a leaving the pump is heated in the heat exchangers 12 and 13 by heat exchange with the vapor stream from the head of column 48 at -130 ° F [-90 ° C], compressed vapor stream 52a at -122 ° F [-86 ° C], and bottom liquid product from the methane separator (stream 51) at 85 ° F [29 ° C]. The partially heated stream 41c is then continued heating to -120 ° F [-84 ° C] (stream 41d) in the heat exchanger 14 using low level service heat. (Usually, the high level service heat is more expensive than the low level service heat, so that a lower operating cost is usually achieved when the use of low level heat is maximized, for example, in the present example it is used seawater, and the use of high level heat is minimized). After expansion at operating pressure (approximately 450 psia [3.103 kPa (a)]) of the fractionation tower 21 by control valve 20, stream 41e flows to a feed point at a midpoint of the column at -123 ° F [-86 ° C]. The methane separator in tower 21 is a conventional distillation column containing several vertically separated dishes, one or more packed beds, or some combination of dishes and packing. As is often the case in natural gas processing plants, the fractionating tower may consist of two sections. The upper absorption (rectification) section 21a contains the plates and / or packing to provide the necessary contact between the rising vapors and the cold liquid descending to condense and absorb the ethane and the heavier components; the lower distillation section (of methane separation) 21b contains the plates and / or a package to provide the necessary contact between the descending liquids and the vapors that rise. The methane separation section also includes one or more kettles (such as kettle 25) that heat and vaporize a portion of the liquids flowing down the column to provide the distillation vapors flowing up the column. These vapors distill the methane from the liquids, so that the bottom liquid product (stream 51) is substantially free of methane and comprises most of the C2 components and heavier hydrocarbons. contained in the LNG feed stream. The head stream 48 leaves the upper section of the fractionation tower 21 at -130 ° F [-90 ° C] and flows to the heat exchanger 12 where it is cooled to -135 ° F [-93 ° C] and it partially condenses by heat exchange with the cold LNG (stream 41a) described above. The partially condensed stream 48a enters the reflux separator 26 where the condensed liquid (stream 53) is separated from the uncondensed vapor (stream 52). The liquid stream 53 from the reflux separator 26 is pumped by the reflux pump 28 to a pressure slightly higher than the operating pressure of the methane separator 21 and the stream 53b is then supplied as a cold feed to the head of the column ( reflux) of a methane separator 21 by the control valve 30. This reflux of cold liquid absorbs and condenses the C2 components and the heavier hydrocarbon components of the vapors rising in the upper absorption (rectification) section 21 a methane separator 21. The liquid product stream 51 leaves the bottom of the fractionation tower 21 at 85 ° F [29 ° C], based on a methane fraction of 0.005 based on the volume of the bottom product. After cooling to 0 ° F [-18 ° C] in the heat exchanger 13 as described above, the liquid product (stream 51a) flows to the storage or to an additional treatment. The methane-rich waste gas (stream 52) leaving the reflux separator 26 is compressed to 493 psia [3400 kPa (a)] (stream 52a) by the compressor 27 (driven by an external power source), such so that the stream can be fully condensed while cooling to -136 ° F [-93 ° C] in the heat exchanger 12 as described above. Then, pump 32 pumps the condensed liquid (stream 52b) to 1365 psia [9,411 kPa (a)] (stream 52c) for subsequent vaporization and / or transport. The following table gives a summary of the flows of the currents and the energy consumption for the process illustrated in FIG. 2: Table II (FIG 2) Summary of stream flows - Lb Moles / h [Kg Moles / h] Current Methane Ethane Propane Butane + Total 41 9,524 977 322 109 10,979 48 10,540 177 0 0 10,766 53 1,027 79 0 0 1,108 52 9,513 98 0 0 9,658 51 11 879 322 109 1,321 Recoveries * Ethane 90.01% Propane 100.00% Butane + 100.00% Power LNG 298 HP [490 kW] Reflux pump 5 HP [8 kW] Pump product LNG 762 HP [1,253 kW] 226 HP steam compressor [371 kW] Total 1,291 HP [2,122 kW] Low level service heat LNG heater 6,460 [4,173 kW] MBTU / h High level service heat 17,968 methane separator kettle [11,606 MBTU / h kW] * (Based on flows of a rounding) The comparison of the recovery levels shown in Table II above for the prior art process of FIG. 2 with those of Table I for the prior art process of FIG. 1 shows that the process of FIG. 2 can essentially achieve the same recovery of ethane and slightly higher recoveries of propane and butanes +. The comparison of the consumptions of the services in Table II with those of Table I shows that the process of FIG. 2 requires less power and less high level service heat than the process of FIG. 1. The reduction of power is achieved by the use of the reflux for the methane separator 21 in the process of FIG. 2 to provide a more efficient recovery of ethane and the heavier components in the tower. In turn, this allows a higher temperature of the tower supply than the process of FIG. 1, reducing the heat requirements of the methane separator boiler 21 (which uses high level service heat) by using low level service heat in the heat exchanger 14 to heat the tower power. (Note that the process of FIG.1 cools the bottom product stream 51a to 43 ° F [6 ° C], against 0 ° F [-18 ° C] desired for the process of FIG. FIG. 1 process, attempting to cool the stream 51a at a lower temperature reduces the high-level heat requirement of the boiler 25, but the resulting higher temperature for the stream 41c entering the separator 15 causes the use of power of the steam compressor 27 is increased disproportionately, because the operating pressure of the separator 15 should be lowered if the same recovery efficiencies are to be maintained).

Example 1 FIG. 3 illustrates a flow diagram of a process according to the present invention. The composition of the LNG and the conditions that are considered in the process presented in FIG. 3 are the same as those of FIGS. 1 and 2. Therefore, the process of FIG. 3 with the processes of FIGS. 1 and 2 to illustrate the advantages of the present invention. In the simulation of the process of FIG. 3, the LNG to be treated (stream 41) from the LNG tank 10 enters the pump 11 at -255 ° F [-159 ° C]. The pump 11 raises the pressure of the LNG sufficiently so that it can flow through the heat exchangers and from there to the separator 15. The stream 41a leaving the pump is divided into two portions, streams 42 and 43. The first portion, stream 42, is expanded to the operating pressure (approximately 450 psia [3,103 kPa (a)]) of fractionation column 21 by expansion valve 17 and is supplied to the tower at a higher feed point in a intermediate point of the column. The second portion, stream 43, is heated before entering the separator 15 in such a manner that all or a portion of it vaporizes. In the example shown in FIG. 3, current 43 is first heated to -106 ° F [-77 ° C] in the exchangers of heat 12 and 13 by cooling the compressed-head steam stream 48a to -112 ° F [-80 ° C], the reflow stream 53 to -129 ° F [-90 ° C], and the liquid product from the column (stream 51) to 85 ° F [29 ° C]. The partially heated stream 43b (stream 43c) is then continued to heat in the heat exchanger 14 using low level service heat. Note that in all cases the exchangers 12, 13, and 14 are representative of either a multitude of individual heat exchangers or a single multi-stage heat exchanger, or any combination thereof. (The decision to use more than one heat exchanger and how to do so for the heating services indicated will depend on several factors including, but not limited to: LNG inlet flow rate, heat exchanger size, temperature currents, etc.) Hot stream 43c enters separator 15 at -62 ° F [-52 ° C] and 625 psia [4.309 kPa (a)] where steam (stream 46) is separated from all remaining liquid ( current 47). The steam coming from the separator 15 (stream 46) enters a machine with expansion work 18 where mechanical energy is extracted from the portion of the high pressure feed. The machine 18 expands the steam substantially isentropically to the operating pressure of the tower, and the expansion work cools the expanded stream 46a to a temperature of approximately -85 ° F [-65 ° C]. The typical expanders that can be obtained commercially are capable of recoveries of the order of 80-88% of the work theoretically available in an ideal isentropic expansion. The recovered work is often used to drive a centrifugal compressor (sas article 19) which can be used to recompress the head steam column (stream 48), for example. The condensed partially condensed stream 46a is then supplied as feed to the fractionation column 21 at a feed point at a midpoint of the column. The liquid from the separator (stream 47) is expanded to the operating pressure of the fractionation column 21 by expansion valve 20, cooling stream 47a at -77 ° F [-61 ° C] before being supplied to the tower. fractionation 21 at a lower feed point at an intermediate point of the column. The methane separator in the fractionation column 21 is a conventional distillation column containing several vertically separated plates, one or more packed beds, or some combination of plates and packing. Similar to the fractionation tower shown in FIG. 2, the fractionating tower in FIG. 3 can consist of two sections. The upper section of absorption (rectification) contains the plates and / or a packing for provide the necessary contact between the rising vapors and the cold liquid that descends to condense and absorb the ethane and the heavier components; the lower distillation section (of methane separation) contains the plates and / or a package to provide the necessary contact between the descending liquids and the vapors that rise. The methane separation section also includes one or more kettles (sas kettle 25) that heat and vaporize a portion of the liquids flowing down the column to provide the distillation vapors flowing up the column. The liquid product stream 51 leaves the bottom of the tower at 85 ° F [29 ° C], based on a methane fraction of 0.005 based on the volume of the bottom product. After cooling to 0 ° F [-18 ° C] in the heat exchanger 13 as described above, the liquid product (stream 51a) flows towards storage or further treatment. The overhead distillation stream 48 is withdrawn from the upper section of the fractionation tower 21 at -134 ° F [-92 ° C] and flows to a compressor 19 driven by the expansion machine 18, where it is compressed to 550 psia [3.799 kPa (a)] (stream 48a) sthat the stream can be fully condensed while cooling to -129 ° F [-90 ° C] in the heat exchanger 12 as described above. Then the condensed liquid is divided (stream 48b) in two portions, streams 52 and 53. The first portion (stream 52) is the lean LNG stream, rich in methane, which is then pumped by pump 32 to 1365 psia [9,411 kPa (a)] (stream 52a) for subsequent vaporization and / or transport. The remaining portion is the reflux stream 53, which flows into the heat exchanger 12 where it is subcooled to -166 ° F [-110 ° C] by heat exchange with a portion of the cold LNG (stream 43) as described above . The subcooled reflow stream 53a is expanded to the operation pressure of the methane separator 21 by the expansion valve 30 and the expanded stream 53b is then supplied as a cold feed to the column head (reflux) of a methane separator 21. This reflux of cold liquid absorbs and condenses the C2 components and the heavier hydrocarbon components of the vapors that rise in the upper rectification section of the methane separator 21. The following table gives a summary of the flow rates of the streams. and of the energy consumption for the process illustrated in FIG. 3: Table III (FIG.3) Summary of current flows - Lb Moles / h [kg moles / h] Current Methane Ethane Propane Butane * Total 41 9,524 977 322 109 10,979 42 1,743 179 59 20 2,009 43 7,781 798, 263 89 8,970 46 7,291 554 96 14 7,993 47 490 244 167 75 977 48 10,318 105 0 0 10,474 53 805 8 0 0 817 52 9,513 97 0 0 9,657 51 11 880 322 109 1,322 Recoveries * Ethane 90.05% Propane 99.89% Butane + 100.00% Power LNG 396 'HP Power Pump [651 kW] LNG product pump 756 HP [1,243 kW] 226 HP steam compressor [371 kW] Totals 1,152 HP [1,894 kW] Low level service heat LNG heater 18,077 [11,377 MBTU / h kW] High level service heat 8,441 [5,452 kW] methane separator MBTU / h * (Based on flows of a rounding) The comparison of the recovery levels shown in Table III above for the. process of FIG. 3 with those of Table I for the prior art process of FIG. 1 shows that the present invention equals the recovery of ethane and achieves a slightly higher propane recovery (99.89% vs. 98.33%) and a recovery of butanes + (100.00% vs. 99.62%) from the process of FIG. 1. However, the comparison of the consumptions of the services in Table III with those of Table I shows that both the power and the high level service heat required for the present invention are much lower than for the process of FIG. 1 (26% lower and 64% lower, respectively). The comparison of the recovery levels shown in Table III with those of Table II for the prior art process of FIG. 2 shows that the present invention essentially equals the recovery of liquids from the process of FIG. 2. (Only the recovery of propane is slightly lower, 99.89% against 100.00%). However, the comparison of the consumptions of the services in Table III with those of Table II shows that both the power and the high level service heat required for the present invention are significantly lower than for the process of the FIG. 2 (11% lower and 53% lower, respectively). There are three primary factors that are important for the greater efficiency of the present invention. First, compared to the prior art process of FIG. 1, the present invention does not depend on the feeding of LNG itself to directly serve as the reflux for the fractionation column 21. Instead, the cooling inherent in the cold LNG is used in the heat exchanger 12 to generate a liquid reflux stream (stream 53) containing very little of the C2 components and the heavier hydrocarbon components to be recovered, obtaining an efficient rectification in the upper absorption section of the fractionation tower 21 and avoiding the limitations of the equilibrium of the prior art process of FIG. 1. Second, compared to the processes of FIGS. 1 and 2 of the prior art, the division of the LNG feed into two portions before feeding it the fractionation column 21 allows a more efficient use of low level service heat, thereby reducing the amount of high level service heat consumed by the kettle 25. The relatively cooler LNG feed portion (stream 42a in FIG 3) it serves as a supplementary reflux current for the fractionation tower 21, to provide partial rectification of the vapors in the expanded vapor and the liquid stream (streams 46a and 47a in FIG. This portion (stream 43) of the LNG feed is partially vaporized and partially vaporized without unduly increasing the condensation load in the heat exchanger 12. Third, compared to the prior art process of FIG. 2, the use of a portion of the cold LNG feed (stream 42a in FIG.3) as a supplementary reflow stream allows to use less head reflow for the fractionating tower 21, as can be seen by comparing stream 53 in the Table III with stream 53 in Table II. In addition to the higher degree of heating using low level service heat in the heat exchanger 14 (as can be seen comparing table III with table II), the lower reflux of the head flow results in a lower total liquid feed to the fractionation column 21, reducing the effort required from the kettle 25 and minimizing the heat quantity of service high level required to achieve the specification for the liquid bottom product from the methane separator.

Example 2 In FIG. 4 an alternative embodiment of the present invention is shown. The composition of the LNG and the conditions that are considered in the process presented in FIG. 4 are the same as those in FIG. 3, as well as those described above for FIGS. 1 and 2. Therefore, the process of the present invention of FIG. 4 can be compared with the modality shown in FIG. 3 and with the prior art processes shown in FIGS. 1 and 2. In the simulation of the process of FIG. 4, the LNG to be treated (stream 41) from the LNG tank 10 enters the pump 11 at -255 ° F [-159 ° C]. The pump 11 raises the pressure of the LNG sufficiently so that it can flow through the heat exchangers and from there to the separator 15. The stream 41a leaving the pump is heated before entering the separator 15 in such a way that it is vaporizes all or a portion of it. In the example shown in FIG. 4, the stream 41a is first heated to -99 ° F [-73 ° C] in the heat exchangers 12 and 13 by cooling the compressed head steam stream 48b to - 63 ° F [-53 ° C], reflux current 53 to -135 ° F [-93 ° C], and liquid product from the column (stream 51) at 85 ° F [29 ° C]. Then the partially heated stream 41c (stream 41d) in the heat exchanger 14 is continued to be heated using low level service heat. The hot stream 41d enters the separator 15 at -63 ° F [-53 ° C] and 658 psia [4,537 kPa (a)] where the vapor (stream 44) is separated from all the remaining liquid (stream 47). The separator liquid (stream 47) is expanded to the operating pressure (approximately 450 psia [3,103 kPa (a)]) from the fractionation column 21 by the expansion valve 20, cooling stream 47a to -82 ° F [ -63 ° C] before supplying it to the fractionation tower 21 at a lower feed point at an intermediate point of the column. The vapor (stream 44) from the separator 15 is divided into two streams, 45 and 46. The stream 45, which contains approximately 30% of the total steam, passes through the heat exchanger 16 in a heat exchange relationship with the cold steam from the head of the methane separator at -134 ° F [-92 ° C] (stream 48) where it cools until it is substantially condensed. Then the substantially condensed stream 45a which is obtained at -129 ° F [-89 ° C] through the control valve is rapidly expanded. expansion 17 to the operating pressure of the fractionation tower 21. During the expansion, a portion of the current is vaporized, resulting in the cooling of the total current. In the process illustrated in FIG. 4, the expanded stream 45b leaving the expansion valve 17 reaches a temperature of -133 ° F [-92 ° C] and is supplied to the fractionation tower 21 at a higher feed point at an intermediate point of the column . The remaining 70% of the vapor from the separator 15 (stream 46) enters a machine with expansion work 18 where mechanical energy is extracted from the high pressure feed portion. The machine 18 expands the vapor substantially isentropically to the operating pressure of the tower, and the expansion work cools the expanded stream 46a to a temperature of about -90 ° F [-68 ° C]. The partially condensed expanded stream 46a is then fed as a feed to the fractionation column 21 at a feed point at a midpoint of the column. The liquid product stream 51 leaves the bottom of the tower at 85 ° F [29 ° C], based on a methane fraction of 0.005 based on the volume of the bottom product. After cooling to 0 ° F [-18 ° C] in the heat exchanger 13 as described above, the liquid product (stream 51a) flows to storage or to additional treatment. The overhead distillation stream 48 is withdrawn from the upper section of the fractionation tower 21 at -134 ° F [-92 ° C] and passes countercurrently with respect to the incoming feed gas in the heat exchanger 16 where it is warms to -78 ° F [-61 ° C]. The hot stream 48a flows to a compressor 19 driven by the expansion machine 18, where it is compressed to 498 psia [3430 kPa (a)] (current 48b) such that the stream can be fully condensed while cooling to -135 ° F [-93 ° C] in heat exchanger 12 as described above. Then the condensed liquid (stream 48c) is divided into two portions, streams 52 and 53. The first portion (stream 52) is the lean LNG stream, rich in methane, which is then pumped by pump 32 to 1365 psia [9,411]. kPa (a)] (stream 52a) for the subsequent vaporization and / or transport. The remaining portion is the reflux stream 53, which flows into the heat exchanger 12 where it is subcooled to -166 ° F [-110 ° C] by heat exchange with the cold LNG (stream 41a) as described above. The subcooled reflow stream 53a is expanded to the operating pressure of the methane separator 21 by the expansion valve 30 and the expanded stream 53b is supplied then as cold feed at the head of the column (reflux) of a methane separator 21. The reflux of cold liquid absorbs and condenses the C2 components and the heavier hydrocarbon components of the vapors that rise in the upper rectification section of the methane separator 21. The following table gives a summary of the flow rates and energy consumption for the process illustrated in FIG. 4: Table IV Summary of current flows - Lb Moles / h [kg moles / h] Current Methane Ethane Propane Butans-t- Total 41 9,524 977 322 109 10,979 44 8,789 647 111 16 9,609 47 735 330 211 93 1,370 45 2,663 196 34 5 2,911 46 6,126 451 77 11 6,698 48 10,547 108 0 0 10,706 53 1,034 11 0 0 1,049 52 9,513 97 0 0 6,657 51 11 880 322 109 1,322 Recoveries * Ethane 90.06% Propane 99.96% Butane + 100.00% Power LNG Fuel Pump 419 HP [688 kW] LNG 761 HP [1,252 kW] product pump Total 1,180 HP [1,940 kW] Low level service heat LNG heater 16,119 [10,412 MBTU / h kW] High level service heat Methane separator boiler 8,738 [5,644 kW] MBTU / h * (Based on flows of a rounding] The comparison of table IV above for the modality of FIG. 4 of the present invention with Table III for the embodiment of FIG. 3 of the present invention shows that the recovery of liquids is essentially the same for the embodiment of FIG. 4. As the embodiment of FIG. 4 uses the head of the tower (stream 48) to generate the supplementary reflux (stream 45b) for the column of fractionation 21 by condensing and subcooling a portion of the vapor from the separator 15 (stream 45) in the heat exchanger 16, the gas entering the compressor 19 (stream 48a) is considerably hotter than the corresponding stream in the embodiment of FIG. 3 (stream 48). Depending on the type of compression equipment used in such a service, the higher temperature may offer advantages in terms of metallurgy, etc. However, since the supplemental reflux stream 45b that is supplied to the fractionation column 21 is not as cold as the stream 42a in the embodiment of FIG. 3, more head reflux (stream 53b) is necessary and less heat of low level service can be used in heat exchanger 14. This increases the load on the kettle 25 and increases the amount of high level service heat required by the embodiment of FIG. 4 of the present invention compared to the embodiment of FIG. 3. The higher reflux rate of the head flow also slightly increases the power requirements of the FIG modality. 4 (in approximately 2%) compared to the embodiment of FIG. 3. The selection of which mode should be used for a particular application will be dictated in general by the relative costs of high-level power and heat of service and the relative capital costs of pumps, heat exchangers, and compressors.

Example 3 In FIG. 5 a simpler alternative embodiment of the present invention is shown. The composition of the LNG and the conditions that are considered in the process presented in FIG. 5 are the same as those of FIGS. 3 and 4, as well as those described above for FIGS. 1 and 2. Therefore, the process of FIG. 5 of the present invention can be compared with the modalities shown in FIGS. 3 and 4 and with the prior art processes shown in FIGS. 1 and 2. In the simulation of the process of FIG. 5, the LNG to be treated (stream 41) from the LNG tank 10 enters the pump 11 at -255 ° F [-159 ° C]. The pump 11 raises the pressure of the LNG sufficiently so that it can flow through the heat exchangers and from there to the separator 15. The stream 41a leaving the pump is heated before entering the separator 15 in such a way that it is vaporizes all or a portion of it. In the example shown in FIG. 5, stream 41a is first heated to -102 ° F [-75 ° C] in heat exchangers 12 and 13 by cooling the compressed head steam stream 48a to -110 ° F [-79 ° C], reflux 53 to -128 ° F [-89 ° C], and the liquid product from the column (stream 51) at 85 ° F [29 ° C]. Then the partially heated stream 41c (stream 41d) in the 14 heat exchanger using low level service heat. The hot stream 41d enters the separator 15 at -74 ° F [-59 ° C] and 715 psia [4.930 kPa (a)] where the vapor (stream 46) is separated from all the remaining liquid (stream 47). The steam from the separator (stream 46) enters a machine with expansion work 18 where mechanical energy is extracted from the portion of the high pressure feed. The machine 18 expands the steam in a substantially isentropic manner to the tower operating pressure (approximately 450 psia [3,103 kPa (a)]), and the expansion work cools the expanded stream 46a to a temperature of approximately -106 ° F. [-77 ° C]. Then the partially condensed expanded stream 46a is supplied as feed to the fractionation column 21 at a feed point at a midpoint of the column. The liquid from the separator (stream 47) is expanded to the operating pressure of the fractionation tower 21 by the expansion valve 20, cooling stream 47a at -99 ° F [-73 ° C] before being supplied to the column of fractionation 21 at a lower feed point at an intermediate point of the column. The liquid product stream 51 leaves the bottom of the tower at 85 ° F [29 ° C], based on a methane fraction of 0.005 based on the volume of the bottom product. After cooling to 0 ° F [-18 ° C] in the heat exchanger 13 as described above, the liquid product (stream 51 a) flows into storage or further treatment. The overhead distillation stream 48 is withdrawn from the upper section of the fractionation tower 21 at -134 ° F [-92 ° C] and flows to a compressor 19 driven by the expansion machine 18, where it is compressed to 563 psia [3.882 kPa (a)] (current 48a). In such a manner that the stream can be fully condensed while cooling to -128 ° F [-89 ° C] in the heat exchanger 12 as described above. The condensed liquid (stream 48b) is then divided into two portions, streams 52 and 53. The first portion (stream 52) is the lean LNG stream, rich in methane, which is then pumped by pump 32 to 1365 psia [9,411]. kPa (a)] (stream 52a) for the subsequent vaporization and / or transport. The remaining portion is the reflux stream 53, which flows into the heat exchanger 12 where it is subcooled to -184 ° F [-120 ° C] by heat exchange with the cold LNG (stream 41a) as described above. The subcooled reflow stream 53a is expanded to the operating pressure of the methane separator 21 via the expansion valve 30 and the expanded stream 53b is then supplied as a cold feed to the head of the column (reflux) of a methane separator 21. The reflux of cold liquid absorbs and condenses the C2 components and the heavier hydrocarbon components of the vapors that rise in the upper rectification section of the methane separator 21. The following table shows gives a summary of the flows of the currents and of the energy consumption for the process illustrated in FIG. 5: Table V Summary of current flow - Lb moles / h [kg moles / h] Current Methane Ethane Propane Butane + Total 41 9,524 977 322 109 10,979 46 7,891 475 72 10 8,493 47 1,633 502 250 99 2,486 48 11,861 121 0 0 12,042 53 2,348 24 0 0 2,385 52 9,513 97 0 0 9,657 51 11 880 322 109 1,322 Recoveries * Ethane 90.02% Propane 100.00% Butane + 100.00% Power LNG 457 HP [752 kW] Power Pump LNG product pump 756 HP [1,242 kW] Total 1,213 HP [1,242 kW] Low level service heat LNG 16,394 heater [10,590 MBTU / h kW] High level service heat 10,415 [6,728 kW] methane separator boiler MBTU / h * (Based on flows of a rounding) The comparison of table V above for the embodiment of FIG. 5 of the present invention with Table III for the embodiment of FIG. 3 and table IV for the embodiment of FIG. 4 of the present invention shows that the recovery of liquids is essentially the same for the embodiment of FIG. 5. As the embodiment of FIG. 5 does not use a supplementary reflux for the fractionation column 21 as the modalities of FIGS do. 3 and 4 (streams 42a and 45b, respectively), more head reflow is required (stream 53b) and less low level service heating can be used in the heat exchanger 14. This increases the charge on the kettle 25 and increases the amount of high level service heat which requires the embodiment of FIG. 5 of the present invention compared to the embodiments of FIGS. 3 and 4. The higher reflux rate of the head flow also slightly increases the power requirements of the FIG modality. 5 (in approximately 5% and 3%, respectively) compared to the modalities of FIGS. 3 and 4. The selection of which modality should be used for a particular application will be dictated in general by the relative costs of high-level power and heat of service and the relative capital costs of columns, pumps, heat exchangers, and compressors.

Example 4 A slightly more complex design can be achieved which maintains the same recovery of C2 components with lower power consumption if another embodiment of the present invention is used according to the process illustrated in FIG. 6. The composition of the LNG and the conditions that are considered in the process presented in FIG. 6 are the same as those of FIGS. 3 to 5, as well as those described previously for FIGS. 1 and 2. Therefore, the process of the present invention of FIG. 6 can be compared with the modalities shown in FIGS. 3 through 5 and with the prior art processes shown in FIGS. 1 and 2. In the simulation of the process of FIG. 6, the LNG to be treated (stream 41) from the LNG tank 10 enters the pump 11 at -255 ° F [-159 ° C]. The pump 11 raises the pressure of the LNG sufficiently so that it can flow through the heat exchangers and from there into the absorption column 21. In the example shown in FIG. 6, the stream 41a leaving the pump is first heated to -120 ° F [-84 ° C] in the heat exchanger 12 by cooling the overhead steam (distillation stream 48) which is withdrawn from the absorption column with contact and separation device 21 at -129 ° F [-90 ° C] and head steam (distillation stream 50) which is extracted from the fractional distillation column 24 at -83 ° F [-63 ° C]. The partially heated liquid stream 41b is then divided into two portions, streams 42 and 43. The first portion, stream 42, expands at the operating pressure (approximately 495 psia [3,413 kPa (a)]) of the absorption column. 21 by means of the expansion valve 17 and is supplied to the tower at a lower feed point at an intermediate point of the column.

The second portion, stream 43, is heated before entering the absorption column 21 such that all or a portion of it vaporizes. In the example shown in FIG. 6, stream 43 is first heated to -112 ° F [-80 ° C] in heat exchanger 13 by cooling the liquid product from the fractional distillation column 24 (stream 51) to 88 ° F [31 ° C] . Then the partially heated stream 43a (stream 43b) in the heat exchanger 14 is continued to be heated using low level service heat. The partially vaporized stream 43b is expanded to the operating pressure of the absorption column 21 by the expansion valve 20, cooling stream 43c at -61 ° F [-55 ° C] before being supplied to the absorption column 21 in a lower feed point of the column. The liquid portion (if any) of the expanded stream 43c is mixed with the liquids descending from the upper section of the absorption column 21 and the stream of combined liquids 49 leaves the bottom of the absorption column 21 to -79 ° F [-62 ° C]. The vapor portion of the expanded stream 43c rises through the absorption column 21 and is brought into contact with the cold liquid descending to condense and absorb the C2 components and the heavier hydrocarbon components. The combined liquid stream 49 from the bottom of the absorption column with contact device 21 expands rapidly to a pressure slightly higher than the operating pressure (465 psia [3,206 kPa (a)]) of the distillation column 24 by the expansion valve 22, stream of cooling 49 to -83 ° F [-64 ° C] (stream 49a) before entering the fractional distillation column 24 at a feed point at the head of the column. In the distillation column 24, the vapors that are generated in the kettle 25 distill the methane from stream 49a by distillation to achieve the specification of a methane fraction of 0.005 on a volumetric basis. The resulting liquid product stream 51 exits the bottom of the distillation column 24 to 88 ° F [31 ° C], cooled to 0 ° F [-18 ° C] in the heat exchanger 13 (stream 51a) as described above, and then flows to storage or to additional treatment. The overhead vapor (stream 50) from the distillation column 24 leaves the column at -83 ° F [-63 ° C] and flows to the heat exchanger 12 where it is cooled to -132 ° F [-91 ° C] C] as described above, fully condensing the current. The condensed liquid stream 50a then enters the head pump 33, which raises the pressure of the stream 50b to a pressure slightly higher than the operating pressure of the absorption column 21. After expansion to the pressure of operation of the absorption column 21 by the control valve 35, the current 50c at -130 ° F [-90 ° C] is supplied to the absorption column 21 at a higher feed point at an intermediate point of the column where it mixes with the liquids that descend from the upper section of the absorption column 21 and becomes part of the liquids that are used to capture the C2 and heavier components that are present in the vapors that rise from the lower section of the absorption column 21. The overhead distillation stream 48 is withdrawn from the upper section of the absorption column 21 at -129 ° F [-90 ° C], flows into the heat exchanger 12 and is cooled to - 135 ° F [-93 ° C] as described above, fully condensing the current. The condensed liquid (stream 48a) is pumped to a pressure a little above the operating pressure of the absorption column 21 by the pump 31 (stream 48b), then divided into two portions, streams 52 and 53. The first portion (stream 52) is the lean, methane-rich LNG stream, which is then pumped by pump 32 to 1365 psia [9,411 kPa (a)] (stream 52a) for subsequent vaporization and / or transport. The remaining portion is the reflux stream 53, which expands to the operating pressure of the column of absorption 21 by control valve 30. Expanded stream 53a is then supplied at -135 ° F [-93 ° C] as cold feed to the head of the column (reflux) of the absorption column 21. This reflux of liquid cold absorbs and condenses the C2 components and the heavier hydrocarbon components of the vapors that rise in the upper section of the absorption column 21. The following table gives a summary of the flows of the currents and of the energy consumption. for the process illustrated in FIG. 6: Table VI (FIG 6) Summary of flow current - Lb moles / h [kg moles / h] Current Methane Ethane Propane Butane * Total 41 9,524 977 322 109 10,979 42 2,769 284 94 32 3,192 43 6,755 693 228 77 7,787 48 10,546 108 0 0 10,706 49 1,373 994 329 109 2,808 50 1,362 114 7 0 1,486 53 1,033 11 0 0 1,049 52 9,513 97 0 0 9,657 51 11 880 322 109 1,322 Recoveries * Ethane 90.04% Propane 99.88% Butane * 100.00% Power LNG feed pump 359 HP [590 kW] Pump head absorber 48 HP [79 kW] Pump head distiller 11 HP [18 kW] (drag separator) LNG product pump 717 HP [1,179 kW] Total 1,135 HP [1,866 kW] Low-level service heat LNG heater 16,514 [10,667 MBTU / h kW] High-level service heat Disposal methane separator 8,358 [5,399 kW] MBTU / h * (Based on the flows of a rounding) The comparison of table VI above for the embodiment of FIG. 6 of the present invention with tables 111 through V for the embodiments of FIGS. 3 through 5 of the present invention shows that the recovery of liquids it is essentially the same for the embodiment of FIG. 6. However, the comparison of the consumptions of the services in Table VI with those in Tables III through V shows that both the power and the high level service heat required for the FIG modality. 6 of the present invention are smaller than for the embodiments of FIGS. 3 through 5. The power requirement for the FIG mode. 6 is 1%, 4%, and 6% lower, respectively, and the high-level service heat requirement is 1%, 4%, and 20% lower, respectively. The reductions in service requirements for the FIG modality. 6 of the present invention in relation to the embodiments of FIGS. 3 through 5 can be attributed mainly to two factors. First, by dividing the fractionation column 21 in the FIGS modalities. 3 to 5 in the absorption column 21 and the distillation column 24 separated, the operating pressures of the two columns can be optimized independently for their respective services. The operating pressure of fractionation column 21 in the embodiments of FIGS. 3 through 5 can not be raised much above the values shown without incurring the detrimental effect on the distillation performance that could result from the higher operating pressure. This effect is manifested by a poor mass transfer in the column of fractionation 21 due to the behavior of the phases of its vapor currents and liquids. The physical properties that affect the efficiency of the vapor-liquid separation, ie the surface tension of the liquid and the density differential of the two phases represent a particular concern. As the operating pressures of the rectification operation (absorption column 21) and the distillation operation (distillation column 24) are no longer coupled as in the embodiments of FIGS. 3 to 5, the distillation operation can be carried out at a reasonable operating pressure while enhancing the rectification operation at a higher pressure that facilitates the condensation of its head stream (stream 48 in the mode of operation). 6) in the heat exchanger 12. Second, in addition to the portion of the LNG feed stream that is used as a supplemental reflux stream in the embodiments of FIGS. 3 and 4 (stream 42a in FIG 3 and stream 45b in FIG 4), the embodiment of FIG. 6 of the present invention uses a second supplementary reflux stream (stream 50c) for the absorption column 21 to help rectify the vapors in the stream 43c entering the lower section of the absorption column 21. This allows optimal use of the low level service heat in the heat exchanger 14 to reduce the load on the kettle 25, reducing the requirement of high level service heat. The selection of which mode should be used for a particular application will be dictated in general by the relative costs of high-level power and heat of service and the relative capital costs of columns, pumps, heat exchangers, and compressors.

Example 5 The present invention can also be adapted to produce an LPG product containing most of the C3 components and the heavier hydrocarbon components that are present in the feed stream as shown in FIG. 7. The composition of the LNG and the conditions that are considered in the process presented in FIG. 7 are the same as described above for FIGS. 1 to 6. Therefore, the process of the present invention of FIG. 7 can be compared to the prior art processes shown in FIGS. 1 and 2 as well as with the other embodiments of the present invention shown in FIGS. 3 to 6. In the simulation of the process of FIG. 7, the LNG to be treated (stream 41) from the LNG tank 10 enters the pump 11 at -255 ° F [-159 ° C]. The pump 11 raises the pressure of the LNG sufficiently so that it can flow through the heat exchangers and from there to the absorption column 21. In the example shown in FIG. 7, the stream 41 leaving the pump is first heated to -99 ° F [-73 ° C] in the heat exchangers 12 and 13 by cooling the overhead steam (distillation stream 48) which is extracted from the column absorption with contact and separation device 21 at -90 ° F [-68 ° C], the compressed-head steam (stream 50a) at 57 ° F [14 ° C] which was extracted from the fractional distillation column 24, and the liquid product from the fractional distillation column 24 (stream 51) at 190 ° F [88 ° C]. The partially heated stream 41c (stream 41d) is then continued heating to -43 ° F [-42 ° C] in the heat exchanger 14 using low level service heat. The partially vaporized stream 41d is expanded to the operating pressure (approximately 465 psia [3,206 kPa (a)]) of the absorption column 21 by the expansion valve 20, cooling stream 41e at -48 ° F [-44 °] C] before supplying it to the absorption column 21 at a lower feed point of the column. The liquid portion (if any) of the expanded stream 4 a is mixed with the liquids descending from the upper section of the absorption column 21 and the stream of combined liquids 49 leaves the bottom of the absorption column 21 to -50 ° F [-46 ° C]. The vapor portion of the expanded stream 41e rises through the column of absorption 21 and it is brought into contact with the cold liquid that descends to condense and absorb the C3 components and the heavier hydrocarbon components. The combined liquid stream 49 from the bottom of the absorption column with contact device 21 rapidly expands to a pressure slightly above the operating pressure (430 psia [2,965 kPa (a)]) of the distillation column 24 by the expansion valve 22, cooling stream 49 at -53 ° F [-47 ° C] (stream 49a) before entering the fractional distillation column 24 at a feed point at the head of the column. In the distillation column 24, the vapors that are generated in the kettle 25 distill out the methane and the C2 components of the stream 49a to achieve the specification of an ethane to propane ratio of 0.020: 1 on a molar basis. The resulting liquid product stream 51 exits the bottom of the distillation column 24 at 190 ° F [88 ° C], it is cooled to 0 ° F [-18 ° C] in the heat exchanger 13 (stream 51a) as described above, and then flows towards storage or further treatment. The overhead steam (stream 50) from the distillation column 24 leaves the column at 30 ° F [-1 ° C] and flows to the overhead compressor 34 (driven by a supplemental energy source), which raises the pressure of the stream 50a to a pressure slightly higher than the operating pressure of the absorption column 21. Current 50a enters heat exchanger 12 where it is cooled to -78 ° F [-61 ° C] as described above, totally condensing the current. The condensed liquid stream 50b is expanded to the operating pressure of the absorption column 21 by the control valve 35, and the stream 50c obtained at -84 ° F [-64 ° C] is then supplied to the column of absorption 21 at a feed point at a midpoint of the column where it is mixed with the liquids that descend from the upper section of the absorption column 21 and becomes part of the liquids used to capture the C3 components and heavier particles that are present in the vapors rising from the lower section of the absorption column 21. The overhead distillation stream 48 is extracted from the upper section of the absorption column 21 at -90 ° F [-68] ° C], flows into heat exchanger 12 and cools down to -132 ° F [-91 ° C] as described above, fully condensing the current. The condensed liquid (stream 48a) is pumped to a pressure a little above the operating pressure of the absorption column 21 by the pump 31 (stream 48b), then divided into two portions, streams 52 and 53. The first portion (stream 52) is the poor LNG stream, rich in methane, which then is pumped by pump 32 to 1365 psia [9,411 kPa (a)] (stream 52a) for subsequent vaporization and / or transport. The remaining portion is the reflux stream 53, which is expanded to the operating pressure of the absorption column 21 by the control valve 30. The expanded stream 53a is then supplied at -131 ° F [-91 ° C] as cold feed at the head of the column (reflux) of the absorption column 21. The reflux of cold liquid absorbs and condenses the C3 components and the heavier hydrocarbon components of the vapors that rise in the upper section of the absorption column 2Í. The following table gives a summary of the flows of the currents and the energy consumption for the process illustrated in FIG. 7: Table VII (FIG 7) Summary of flow stream - Lb moles / h [kg moles / h] Current Methane Ethane Propane Butane * Total 41 9,524 977 322 109 10,979 48 11,475 1,170 4 0 12,705 49 426 326 396 116 1,266 50 426 320 77 7 832 Current Methane Ethane Propane Butane * Total 53 1,951 199 1 0 2,160 52 9,524 971 3 0 10,545 51 0 6 319 109 434 Recoveries * Propane 99.00% Butane * 100.00% Power LNG Feeding Pump 325 HP [535 kW] Absorber head pump 54 HP [89 kW] LNG product pump 775 HP [1,274 kW] Head Compressor 67 HP [110 kW] Distiller Total 1,221 HP [2,008 kW] Low level service heat LNG heater 15,139 [9,779 kW] MBTU / h High level service heat Ethane separator kettle 6,857 [4,429 kW] MBTU / h * (Based on the flows of a rounding) The comparison of the consumptions of the services in Table VII above for the process of FIG. 7 with those of Tables III through VI shows that the power requirement for this embodiment of the present invention is slightly greater than that of the embodiments of FIGS. 3 to 6. However, the high level service heat required for the embodiment of FIG. 7 of the present invention is significantly less than the one required for the FIGS modalities. 3 to 6 because in the heat exchanger 14, more low level service heat can be used when the recovery of the C2 components is not desired.

Example 6 The increase of the power requirement of the embodiment of FIG. 7 with respect to the modalities of FIGS. 3 to 6 of the present invention is mainly due to a compressor 34 in FIG. 7 which provides the driving force necessary to direct the overhead steam (stream 50) from the distillation column 24 through the heat exchanger 12 and thence into the absorption column 21. FIG.8 illustrates a alternative embodiment of the present invention that eliminates the compressor and reduces the power requirement. The composition of the LNG and the conditions that are considered in the process that presented in FIG. 8 are the same as those in FIG. 7, as well as those described above for FIGS. 1 to 6. Therefore, the process of FIG. 8 of the present invention can be compared with the embodiment of the present invention shown in FIG. 7, with the prior art processes shown in FIGS. 1 and 2, and with the other embodiments of the present invention shown in FIGS. 3 through 6. In the simulation of the process of FIG. 8, the LNG to be treated (stream 41) from the LNG tank 10 enters the pump 11 at -255 ° F [-159 ° C]. The pump 11 raises the pressure of the LNG sufficiently for it to flow through the heat exchangers and from there to the absorption column 21. The current 41a leaving the pump is first heated to -101 ° F [- 74 ° C] in the heat exchangers 12 and 13 as it provides cooling to the overhead steam (distillation stream 48) which is extracted from the absorption column with contact and separation device 21 at -90 ° F [-68 ° C], to the overhead steam (distillation stream 50) which is extracted from the fractional distillation column 24 at 20 ° F [-7 ° C], and to the liquid product (stream 51) from the fractional distillation column 21 to 190 ° F [88 ° C]. Then the partially heated stream 41c (stream 41d) in the heat exchanger continues to be heated 14 to -54 ° F [-48 ° C] using low level service heat. After expansion at the operating pressure (approximately 465 psia [3,206 kPa (a)]) of the absorption column 21 by the expansion valve 20, the stream 41e flows to a lower feed point of the column in the column at -58 ° F [-50 ° C]. The liquid portion (if any) of the expanded stream 41e is mixed with the liquids descending from the upper section of the absorption column 21 and the stream of combined liquids 49 leaves the bottom of the absorption column with device of contact 21 at -61 ° F [-52 ° C]. The vapor portion of the expanded stream 41e rises through the absorption column 21 and is brought into contact with the cold liquid that descends to condense and absorb the C3 components and the heavier hydrocarbon components. The combined liquid stream 49 from the bottom of the absorption column 21 rapidly expands to a pressure slightly higher than the operating pressure (430 psia [2,965 kPa (a)]) of the distillation column 24 by the expansion valve 22, cooling stream 49 at -64 ° F [-53 ° C] (stream 49a) before entering the fractional distillation column 24 at a feed point at the head of the column. In the distillation column 24, the vapors that are generated in the kettle 25 distillate methane and C2 components from stream 49a to achieve the specification of an ethane to propane ratio of 0.020: 1 on a molar basis. The resulting liquid product stream 51 exits the bottom of the distillation column 24 at 190 ° F [88 ° C] and is cooled to 0 ° F [-18 ° C] in the heat exchanger 13 (stream 51a) as described above, before flowing into storage or additional treatment. The overhead vapor (stream 50) from the distillation column 24 leaves the column at 20 ° F [-7 ° C] and flows to the heat exchanger 12 where it is cooled to -98 ° F [-72 ° C] ] as described above, totally condensing the current. Then, the condensed liquid stream 50a enters head pump 33, which raises the pressure of the stream 50b to a pressure slightly higher than the operating pressure of the absorption column 21, after which it re-enters the heat exchanger 12 to partially vaporize as it is heated to -70 ° F [-57 ° C] (current 50c) supplying part of the total cooling service in such an exchanger. After expansion to the operating pressure of the absorption column 21 by the control valve 35, the current 50d at -75 ° F [-60 ° C] is then supplied to the absorption column 21 at a feed point at a midpoint of the column where you mix with the liquids that descend from the upper section of the absorption column 21 and becomes part of the liquids that are used to capture the C3 and heavier components that are present in the vapors that rise from the lower section of the column of absorption 21. The overhead distillation stream 48 is extracted from the absorption column with contact device 21 at -90 ° F [-68 ° C] and flows to the heat exchanger 12 where it is cooled to -132 ° F [ -91 ° C] and is completely condensed by heat exchange with the cold LNG (stream 41a) as described above. The condensed liquid (stream 48a) is pumped to a pressure a little above the operating pressure of the absorption column 21 by the pump 31 (stream 48b), then divided into two portions, streams 52 and 53. The first portion (stream 52) is the lean LNG stream, rich in methane, which is then pumped by pump 32 to 1365 psia [9,411 kPa ( a)] (stream 52a) for the subsequent vaporization and / or transport. The remaining portion is the reflux stream 53, which is expanded to the operating pressure of the absorption column 21 by the control valve 30. The expanded stream 53a is then supplied at -131 ° F [-91 ° C] as cold feed at the head of the column (reflux) of the absorption column 21. The reflux of cold liquid absorbs and condenses the C3 components and the hydrocarbon components heavier than the vapors that rise in the upper section of the absorption column 21. The following table gives a summary of the flow rates and energy consumption for the process illustrated in FIG. 8: Table VIII (FIG 8) Summary of current flow - Lb moles / h [kg moles / h] Current Methane Ethane Propane Butane * Total 41 9,524 977 322 109 10,979 48 10,934 1,115 4 0 12,107 49 582 458 396 116 1,552 50 582 452 77 7 1,118 53 1,410 144 1 0 1,562 52 9,524 971 3 0 10,545 51 0 6 319 109 434 Recoveries * Propane 99.03% Butane * 100.00% Power LNG Power Pump 325 HP [534 kW] Absorber head pump 67 HP [110 kW] Pump head distiller 11 HP [18 kW] LNG 761 HP [1,251 kW] product pump Total 1,164 HP [1,913 kW] Low level service heat LNG heater 13,949 [9,010 kW] MBTU / h High level service heat Ethane separator kettle 8,192 [5,292 kW] MBTU / h * (Based on the flow rates of a rounding) The comparison of Table VIII above for the modality of FIG. 8 of the present invention with table VII for the embodiment of FIG. 7 of the present invention shows that the recovery of liquids is essentially the same for the embodiment of FIG. 8. As the embodiment of FIG. 8 used to pump (head pump 33 in FIG 8) more than one compressor (head compressor 34 in FIG 7) to directing the head steam from the fractional distillation column 24 to the absorption column with contact device 21, the embodiment of FIG. 8 requires less power. However, the high level service heat that is required for the embodiment of FIG. 8 is higher (by approximately 19%). The selection of which mode should be used for a particular application will be dictated in general by the relative costs of high-level power and heat of service and the relative costs of the pumps compared to the compressors.

Example 7 A slightly more complex design can be achieved which maintains the same recovery of C3 components with lower consumption of high level service heat using another embodiment of the present invention as illustrated in the process of FIG. 9. The composition of the LNG and the conditions that are considered in the process presented in FIG. 9 are the same as those of FIGS. 7 and 8, as well as those described above for FIGS. 1 to 6. Therefore, the process of FIG. 9 of the present invention can be compared with the embodiments of the present invention shown in FIGS. 7 and 8, with the prior art processes shown in FIGS. 1 and 2, and with the other embodiments of the present invention that they are shown in FIGS. 3 to 6. In the simulation of the process of FIG. 9, the LNG to be treated (stream 41) from the LNG tank 10 enters the pump 11 at 255 ° F [-159 ° C]. The pump 11 raises the pressure of the LNG sufficiently so that it can flow through the heat exchangers and from there to the separator 15. The stream 41a leaving the pump is heated before entering the separator 15 in such a way that it is vaporizes all or a portion of it. In the example shown in FIG. 9, stream 41a is first heated to -88 ° F [-66 ° C] in heat exchangers 12 and 13 by cooling the compressed head steam stream 48a to -70 ° F [-57 ° C], compressed head steam 50a at 67 ° F [19 ° C], and the liquid product from the fractional distillation column 24 (stream 51) at 161 ° F [72 ° C]. Then the partially heated stream 41c (stream 41d) in the heat exchanger 14 is continued to be heated using low level service heat. The hot stream 41d enters the separator 15 at -16 ° F [-27 ° C] and 596 psia [4.109 kPa (a)] where the vapor (stream 46) is separated from all the remaining liquid (stream 47). The steam from the separator (stream 46) enters a machine with expansion work 18 where mechanical energy is extracted from the portion of the high pressure feed. The machine 18 expands the steam substantially isentropic to the operating pressure of the tower (approximately 415 psia [2,861 kPa (a)]), and the expansion work cools the expanded current 46a to a temperature of approximately -42 ° F [-41 ° C]. The partially condensed expanded stream 46a is then supplied as feed to the absorption column 21 at a feed point at a midpoint of the column. If there is some liquid from the separator (stream 47), it expands to the operating pressure of the absorption column 21 via the expansion valve 20 before supplying it to the absorption column 21 at a lower feed point of the column. In the example shown in FIG. 9, stream 41d is completely vaporized in the heat exchanger 14, so that the separator 15 and the expansion valve 20 are not necessary, and instead the expanded stream 46a is supplied to the absorption column 21 in a lower feed point of the column. The liquid portion (if any) of the expanded stream 46a (and the expanded stream 47a if present) are mixed with the liquids descending from the upper section of the absorption column 21 and the stream of combined liquids 49 leaves the bottom of the absorption column 21 at -45 ° F [-43 ° C]. The vapor portion of the expanded stream 46a (and the expanded stream 47a if present) rises through the absorption column 21 and it comes into contact with the cold liquid that descends to condense and absorb the C3 components and the heavier hydrocarbon components. The flow of combined liquids 49 from the bottom of the absorption column with contact and separation device 21 rapidly expands to a pressure slightly higher than the operating pressure (320 psia). [2.206 kPa (a))) from the fractional distillation column 24 by expansion valve 22, cooling stream 49 to -54 ° F [-48 ° C] (stream 49a) before entering the fractional distillation column 24 at a feeding point at the head of the column. In the distillation column 24, the vapors that are generated in the kettle 25 distill out the methane and the C2 components of the stream 49a to achieve the specification of an ethane to propane ratio of 0.020: 1 on a molar basis. The resulting liquid product stream 51 exits the bottom of the distillation column 24 to 161 ° F [72 ° C] and is cooled to 0 ° F [-18 ° C] in the heat exchanger 13 (stream 51a) as described above, before flowing into storage or additional treatment. The overhead vapor (stream 50) from the distillation column 24 leaves the column at 20 ° F [-6 ° C] flows into the overhead compressor 34 (driven by a portion of the power generated by the expansion machine 18), which raises the pressure of the stream 50a to a pressure slightly higher than the operating pressure of the absorption column 21. The stream 50a enters the heat exchanger 12 where it is cooled to -87 ° F [-66 ° C ] as described above, totally condensing the current. The condensed liquid stream 50b is expanded to the operating pressure of the absorption column 21 by the control valve 35, and the resulting flow 50c at -91 ° F [-68 ° C] is then supplied to the column of absorption 21 at a feed point at a midpoint of the column where it is mixed with the liquids that descend from the upper section of the absorption column 21 and becomes part of the liquids used to capture the C3 components and heavier than are present in the vapors rising from the lower section of the absorption column 21. The overhead distillation stream 48 is drawn from the upper section of the absorption column 21 to -94 ° F [-70 °] C] and flows to a compressor 19 (driven by the remaining portion of the power generated by the expansion machine 18), where it is compressed to 508 psia [current 3.501 kPa (a)] (current 48a) in such a way that the current can conden tota While cooling to -126 ° F [-88 ° C] in the heat exchanger 12 as described above. Then the condensed liquid is divided (stream 48b) in two portions, streams 52 and 53. The first portion (stream 52) is the lean LNG stream, rich in methane, which is then pumped by pump 32 to 1365 psia [9,411 kPa (a)] (stream 52a) to the subsequent vaporization and / or transport. The remaining portion is the reflux stream 53, which is expanded to the operating pressure of the absorption column 21 by the expansion valve 30. The expanded stream 53a is then supplied at -136 ° F [-93 ° C] as cold feed at the head of the column (reflux) of the absorption column 21. The reflux of cold liquid absorbs and condenses the C3 components and the heavier hydrocarbon components of the vapors that rise in the upper section of the absorption column 21. The following table gives a summary of the flow rates and energy consumption for the process illustrated in FIG. 9: Table IX (FIG.9) Summary of current flow - Lb moles / h [kg moles / h] Current Methane Ethane Propane Butane * Total 41 9,524 977 322 109 10,979 46 9,524 977 322 109 10,979 Current Methane Ethane Propane Butane * Total 48 12,056 1,229 4 0 13,348 49 304 254 384 115 1,057 50 304 248 65 6 623 53 2,532 258 1 0 2,803 52 9,524 971 3 0 10,545 51 0 6 319 109 434 Recoveries * Propane 98.99% Butane * 100.00% Power LNG 377 HP [620 kW] LNG product pump 806 HP [1,325 kW] Total 1,183 HP [1,945 kW] Low-level service heat LNG heater 17,940 [11,588 MBTU / h kW] High-level service heat Evaporator separator for ethane 5,432 [3,509 kW] MBTU / h * (Based on the flows of a rounding] The comparison of table IX above for the embodiment of FIG. 9 of the present invention with tables VII and VIII for the embodiments of FIGS. 7 and 8 of the present invention shows that the recovery of liquids is essentially the same as for the embodiment of FIG. 9. The power requirement for the FIG modality. 9 is less than that of the embodiment of FIG. 7 at approximately 3% and greater than that of the FIG modality. 8 in approximately 2%. However, the high level service heat required by the embodiment of FIG. 9 of the present invention is significantly less than any of the embodiments of FIG. 7 (in approximately 21%) or FIG. 8 (in approximately 34%). The selection of which mode should be used for a particular application will be dictated in general by the relative costs of power versus high-level service heat and the relative capital costs of pumps and heat exchangers against compressors and expansion machines.

Example 8 A slightly simpler embodiment of the present invention maintaining the same recovery of C3 components than the embodiment of FIG. 9 using another embodiment of the present invention as illustrated in the process of FIG. 10. The composition of LNG and conditions that are considered in the process presented in FIG. 10 are the same as those of FIGS. 7 to 9, as well as those described above for FIGS. 1 to 6. Therefore, the process of FIG. 10 of the present invention can be compared with the embodiments of the present invention shown in FIGS. 7 to 9, with the prior art processes shown in FIGS. 1 and 2, and with the other embodiments of the present invention shown in FIGS. 3 to 6. In the simulation of the process of FIG. 10, the LNG to be treated (stream 41) from the LNG tank 10 enters the pump 11 at -255 ° F [-159 ° C]. The pump 11 raises the pressure of the LNG sufficiently so that it can flow through the heat exchangers and from there to the separator 15. The stream 41a leaving the pump is heated before entering the separator 15 in such a way that it is vaporizes all or a portion of it. In the example shown in FIG. 10, the stream 41a is first heated to -83 ° F [-64 ° C] in the heat exchangers 12 and 13 by cooling the compressed head steam stream 48a to -61 ° F [-52 ° C], head steam 50 to 40 ° F [4 ° C], and the liquid product from the fractional distillation column 24 (stream 51) at 190 ° F [88 ° C]. Then the partially heated stream 41c (stream 41d) in the heat exchanger 14 continues to be heated using heat of low level service. The hot stream 41d enters the separator 15 at -16 ° F [-26 ° C] and 621 psia [4,282 kPa (a)] where the vapor (stream 46) is separated from all the remaining liquid (stream 47). The steam from the separator (stream 46) enters a machine with expansion work 18 where mechanical energy is extracted from the portion of the high pressure feed. The machine 18 expands the vapor in a substantially isentropic manner to the operating pressure of the tower (approximately 380 psia [2,620 kPa (a)]), and the expansion work cools the expanded current 46a to a temperature of approximately -50 ° F. [-46 ° C]. The partially condensed expanded stream 46a is then supplied as feed to the absorption column 21 at a feed point at a midpoint of the column. If there is some liquid from the separator (stream 47), it expands to the operating pressure of the absorption column 21 via the expansion valve 20 before supplying it to the absorption column 21 at a lower feed point of the column. In the example shown in FIG. 10, the stream 41d is completely vaporized in the heat exchanger 14, so that the separator 15 and the expansion valve 20 are not necessary, and instead the expanded stream 46a is supplied to the absorption column 21 in a lower feed point of the column. The liquid portion (if any) of the expanded stream 46a (and the expanded stream 47a if present) is mixed with the liquids descending from the upper section of the absorption column 21 and the combined liquid stream 49 leaves the bottom of the absorption column 21 at -53 ° F [-47 ° C]. The vapor portion of the expanded stream 46a (and the expanded stream 47a if present) rises through the absorption column 21 and contacts the cold liquid descending to condense and absorb the C3 components and components heavier hydrocarbons. The flow of combined liquids 49 from the bottom of the absorption column with contact and separation device 21 enters the pump 23 and is pumped to a pressure slightly higher than the operating pressure (430 psia [2]., 965 kPa (a)]) of the distillation column 24. The resulting stream 49a at -52 ° F [-47 ° C] then enters the fractional distillation column 24 at a feed point at the head of the spine. In the distillation column 24, the vapors that are generated in the kettle 25 distill out the methane and the C2 components of the stream 49a to achieve the specification of an ethane to propane ratio of 0.020: 1 on a molar basis. The resulting liquid product stream 51 exits the bottom of the distillation column 24 at 190 ° F [88 ° C] and cooled to 0 ° F [-18 ° C] in the heat exchanger 13 (stream 51a) as described above, before flowing to storage or further treatment. The overhead steam (stream 50) from distillation column 24 leaves the column at 40 ° F [4 ° C] and enters heat exchanger 12 where it is cooled to -89 ° F [-67 ° C] according to described above, fully condensing the current. The condensed liquid stream 50a is expanded to the operating pressure of the absorption column 21 by the expansion valve 35, and the resulting 50 b current to -94 ° F [-70 ° C] is then supplied to the column of absorption 21 at a feed point at a midpoint of the column where it is mixed with the liquids that descend from the upper section of the absorption column 21 and becomes part of the liquids used to capture the C3 components and heavier particles that are present in the vapors rising from the lower section of the absorption column 21. The overhead distillation stream 48 is extracted from the upper section of the absorption column 21 at -97 ° F [-72 °] C] and flows to a compressor 19 driven by the expansion machine 18, where it is compressed to 507 psia [3496 kPa (a)] (current 48a). At this pressure, the stream can be fully condensed while cooling to -126 ° F [-88 ° C] in the heat exchanger 12 as described earlier. The condensed liquid (stream 48b) is then divided into two portions, streams 52 and 53. The first portion (stream 52) is the lean LNG stream, rich in methane, which is then pumped by pump 32 to 1365 psia [9,411]. kPa (a)] (stream 52a) for the subsequent vaporization and / or transport. The remaining portion is the reflux stream 53, which is expanded to the operating pressure of the absorption column 21 by the expansion valve 30. The expanded stream 53a is then supplied at -141 ° F [-96 ° C] as cold feed at the head of the column (reflux) of the absorption column 21. The reflux of cold liquid absorbs and condenses the C3 components and the heavier hydrocarbon components of the vapors that rise in the upper section of the absorption column 21. The following table gives a summary of the flow rates and energy consumption for the process illustrated in FIG. 10: Table X (FIG 10) Summary of current flow - Lb moles / h [kg moles / h] Current Methane Ethane Propane Butane * Total 41 9,524 977 322 109 10,979 46 9,524 977 322 109 10,979 48 11,631 1,186 4 0 12,879 49 309 275 395 117 1,096 50 309 269 76 8 662 53 2,107 215 1 0 2,334 52 9,524 971 3 0 10,545 51 0 6 319 109 434 Recoveries * Propane 99.02% Butane * 100.00% Power LNG 394 HP [648 kW] LNG Pump Pump [14 kW] LNG product pump 806 HP [1,325 kW] Total. 1,209 HP [1,987 kW] Low level service heat LNG heater 16,912 [10,924 MBTU / h kW] High level service heat Ethanol separator kettle 6,390 [4, 121 kW] MBTU / h * (Based on the flows of a rounding) The comparison of table X above for the mode of FIG. 10 of the present invention with tables VII to IX for the embodiments of FIGS. 7-9 of the present invention shows that the recovery of liquids is essentially the same for the embodiment of FIG. 10. The power requirement for the FIG mode. 10 is less than that required by the embodiment of FIG. 7 in approximately 1% and greater than that in the FIGS modalities. 8 and 9 in approximately 4% and 2%, respectively. The high level service heat required by the embodiment of FIG. 10 of the present invention is significantly less than both embodiments of FIGS. 7 and 8 (in approximately 7% and 22%, respectively), but greater than the modality of FIG. 9 at approximately 18%. The selection of which mode should be used for a particular application will be dictated in general by the relative costs of power versus high-level service heat and the relative capital costs of pumps, heat exchangers, compressors, and expansion machines .

Other Modes Some circumstances may favor subcooling of the reflux stream 53 with another process stream, instead of using the cold LNG stream entering the heat exchanger 12. Under these circumstances, alternative embodiments of the present invention may be employed. as for example those shown in FIGS. 11 to 13. In the modalities of FIGS. 11 and 12, a portion (stream 42) of the partially heated LNG stream 41b leaving the heat exchanger 12 expands to a pressure slightly higher than the operating pressure of the fractionation tower 21 (FIG. 11) or column of absorption 21 (FIG. 12) by the expansion valve 17 and the expanded stream 42a is directed into the interior of the heat exchanger 29 to heat it as the reflow current 53 is subcooled. A subcooling reflow stream 53a then expands at the operating pressure of the fractionation tower 21 (FIG: 11) or absorption column with contact and separation device 21 (FIG.12) by the expansion valve 30 and the expanded stream 53b is supplied as a cold feed to the head of the column (reflux) of the fractionation tower 21 (FIG 11) or absorption column 21 (FIG 12). The hot stream 42b leaving the heat exchanger 29 is supplied to the tower at a feed point at a midpoint of the column where it serves as a supplemental reflux stream. Alternatively, as shown by dotted lines in FIGS. 11 and 12, the stream 42 can be withdrawn from the LNG stream 41a before entering the heat exchanger 12. In the embodiment of FIG. 13, the supplementary reflux stream which is produced by condensing the overhead steam stream 50 from the fractional distillation column 24 is used to subcool the reflux stream 53 in the heat exchanger 29 by expanding the stream 50b to a slightly higher pressure to the operating pressure of the absorption column 21 with the control valve 17 and directing the expanded stream 50c within the heat exchanger 29. The hot stream 50d is then supplied to the tower at a feed point at a midpoint of the spine. The decision as to whether or not to sub-cool the reflux stream 53 before expanding it to the operating pressure of the column will depend on many factors, including the composition of the LNG, the level of recovery desired, etc. As shown by dotted lines in FIGS. 3 to 10, the stream 53 can be directed towards the heat exchanger 12 if subcooling is desired, or it can be directed directly towards the expansion valve 30 if subcooling is not desired. Of the In the same way, the heating of the supplementary reflux stream 42 before expanding it to the operating pressure of the column should be evaluated for each application. As shown by dotted lines in FIGS. 3, 6, and 13, the stream 42 can be withdrawn before heating the LNG stream 41a and can be directed directly to the expansion valve 17 if heating is not desired, or is drawn from the partially heated stream of LNG 41b and it can be directed towards the expansion valve 17 if heating is desired. On the other hand, heating and partial vaporization of the supplemental reflux stream 50b as shown in FIG. 8 may not be advantageous, since this reduces the amount of liquid entering the absorption column 21 which is used to capture the C2 components and / or the C3 components and the heavier hydrocarbon components in the vapors that rise from the lower section of the absorption column 21. Instead, as shown by the dotted line in FIG. 8, the stream 50b can be directed directly to the expansion valve 35 and thence to the interior of the absorption column 21. When the LNG to be treated is poorer or when full vaporization of the LNG is contemplated in the heat exchangers 12, 13, and 14, the spacer 15 may not be justified in FIGS. 3 to 5 and 9 to 11.

Depending on the amount of heavier hydrocarbons in the LNG of the inlet and the pressure of the LNG stream leaving the feed pump 11, the hot LNG stream leaving the heat exchanger 14 may not contain any liquid (because it is on its dew point, or because it is on its cricondenbara). In these cases, the separator 15 and the expansion valve 20 can be eliminated as shown by dotted lines. In the examples shown, the total condensation of the stream 48a in FIGS. 3, 5, and 9 through 11, stream 48b in FIG. 4, stream 48 in FIGS. 6 to 8, 12, and 13, stream 50 in FIGS. 6, 8, 10, 12, and 13, and stream 50a in FIGS. 7 and 9. Some circumstances may favor the subcooling of one or both of these currents, while other circumstances may favor only partial condensation. If partial condensation of one or both of these streams is to be used, it may be necessary to treat the uncondensed steam, using a compressor or other means to raise the vapor pressure in such a way that it can be attached to the pumped condensed liquid. As an alternative, uncondensed steam could be directed to the plant fuel system or other similar use. LNG conditions, plant size, equipment available or other factors may indicate that it is feasible to suppress the machine with expansion work 18 in FIGS. 3 to 5 and 9 to 11, or replace it with an alternate expansion device (such as an expansion valve). Although expansion devices in particular show the expansion of individual currents, alternative means of expansion can be used where appropriate. It should also be noted that the expansion valves 17, 20, 22, 30, and / or 35 can be replaced by expansion motors (turboexpanders) by which work could be extracted from the pressure reduction of the current 42 in FIGS. . 3, 6, and 11 through 13, the current 45a in FIG. 4, the stream 47 in FIGS. 3 to 5 and 9 to 11, the current 43b in FIGS. 6, 12, and 13, the stream 41d in FIGS. 7 and 8, the stream 49 in FIGS. 6 to 9, 12, and 13, the stream 53a in FIGS. 3 to 5 and 11 to 13, current 53 in FIGS. 6 to 10, the stream 50b in FIGS. 6, 7, 9, 12, and 13, the stream 50c in FIG. 8, and / or the stream 50a in FIG. 10. In these cases, it may be necessary to pump the LNG (stream 41) and / or another stream of liquids up to a higher pressure so that the extraction of work is feasible. This work could be used to provide power to pump the LNG feed stream, to pump the product stream of Poor LNG, for the compression of head steam streams, or to generate electricity. The choice between the use of valves or expansion engines will depend on the particular circumstances of each LNG process project. In FIGS. 3 to 13, individual heat exchangers are shown for most services. However, it is possible to combine two or more heat exchange services in a heat exchanger in common, such as by combining the heat exchangers 12, 13, and 14 in FIGS. 3 to 13 in a heat exchanger in common. In some cases, circumstances may favor the division of a heat exchange service into several exchangers. The decision as to whether heat exchange services should be combined or whether more than one heat exchanger should be used for the service indicated will depend on several factors including, but not limited to: LNG flow, size of the heat exchanger heat, current temperatures, etc. It will be recognized that the relative amount of feed found in each branch of the divided LNG feed to the fractionation column 21 or to the absorption column 21 will depend on several factors, including the composition of the LNG, the amount of heat that is can be extracted economically from food, and the amount of available power. More feeding to the top of the column can increase the recovery while increasing the work required of the boiler 25 and therefore increasing the heat requirement of high level services. Increasing the power in the lower part of the column reduces the consumption of high level service heat but can also reduce product recovery. The relative positions of the feeds at intermediate points in the column may vary depending on the composition of the LNG or other factors such as, for example, the level of recovery desired and the amount of vapor formed during the heating of the feed streams. In addition, two or more of the feed currents, or portions thereof, may be combined, depending on the relationship between the temperatures and quantities of the individual currents, and then the combined current may be fed to a feed position at a point middle of the column. In the examples given for the modalities of FIGS. 3 to 6, the recovery of C2 components and heavier hydrocarbon components is illustrated, while the recovery of C3 components and heavier hydrocarbon components is illustrated in the examples given for the embodiments of FIGS. 7 to 10. However, it is believed that the modalities of FIGS. 3 to 6 are also advantageous when only the recovery of the C3 components and the heavier hydrocarbon components is desired, and that the embodiments of FIGS. 7 to 10 are also advantageous when the recovery of C2 components and heavier hydrocarbon components is desired. In the same way, it is believed that the modalities of FIGS. 11 to 13 are advantageous both for the recovery of C2 components and heavier hydrocarbon components and for the recovery of C3 components and heavier hydrocarbon components. The present invention provides a better recovery of C2 components and heavier hydrocarbon components or of C3 components and heavier hydrocarbon components depending on the consumption of the services required to operate the process. An improvement in the consumption of the services required to operate the process can be manifested in the form of a reduction of the power requirements for compression or pumping, lower energy requirements for the boilers of the tower, or a combination of the same. As an alternative, the advantages of the present invention can be realized by achieving higher levels of recovery for a certain service consumption, or through some combination of a greater recovery and an improvement in the consumption of services. While what is believed to be preferred embodiments of the invention have been described, those experienced in The art will recognize that other modifications and additional modifications may be made thereto, for example to adapt the invention to different conditions, types of feeding, or other requirements without departing from the spirit of the present invention as defined by the following claims. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (67)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. A process for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a majority portion of the methane and a relatively minor volatile liquid fraction containing a major portion of the heavier hydrocarbon components, characteriin that it comprises the steps of: (a) dividing the liquefied natural gas into at least a first stream and a second stream; (b) expanding the first stream at lower pressure and then supplying it to the fractionation column at a higher feed position at an intermediate point of the column; (c) heating the second stream sufficiently to vaporize it partially, thereby forming a vapor stream and a liquid stream; (d) expanding the vapor stream at lower pressure and supplying it to the fractionation column in a first lower feed position at a midpoint of the column; (e) expand the liquid stream to the lowest pressure and supplying it to the fractionation column in a second lower feeding position at a midpoint of the column; (f) extracting a distillation steam stream from an upper region of the fractionation column and compressing it; (g) cooling the compressed distillation steam stream sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a heating portion of the second stream; (h) dividing the condensate stream into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream; (i) supplying the reflux stream to the fractionation column in a feed position at the head of the column; and (j) the amount and temperature of the reflux stream and the temperatures of the feeds to the fractionating column are effective to maintain the temperature at the head of the fractionation column at a value by which the majority portion is recovered of the heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
2. 2. A process for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a majority portion of the heavier hydrocarbon components, characteriin that it comprises the steps of: (a) heating liquefied natural gas and then dividing it into at least a first stream and a second stream; (b) expanding the first stream at lower pressure and then supplying it to the fractionation column at a higher feed position at an intermediate point of the column; (c) heating the second stream sufficiently to vaporize it partially, thereby forming a vapor stream and a liquid stream; (d) expanding the vapor stream at lower pressure and supplying it to the fractionation column in a first lower feed position at a midpoint of the column; (e) expanding the liquid stream to the lowest pressure and supplying it to the fractionating column in a second lower feed position at a midpoint of the column; (f) extracting a distillation steam stream from an upper region of the fractionation column and compress it; (g) cooling the compressed distillation steam stream sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a portion of the heating of the liquefied natural gas; (h) dividing the condensate stream into at least the volatile liquid fraction containing a majority portion of the methane and a reflux stream; (i) supplying the reflux stream to the fractionation column in a feed position at the head of the column; and j) the amount and temperature of the reflux stream and the temperatures of the feeds to the fractionating column are effective to maintain the temperature at the head of the fractionation column at a value by which the majority portion of the fraction is recovered. heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
3. 3. A process for the separation of liquefied natural gas containing methane and heavier hydrocarbon components into a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a major portion of the heavier hydrocarbon components, characterized in that it comprises the steps of: (a) dividing the liquefied natural gas into at least a first stream and a second stream; (b) expanding the first stream at lower pressure and then supplying it to the fractionation column at a higher fposition at an intermediate point of the column; (c) heating the second stream. enough to vaporize it, thus forming a vapor stream; (d) expanding the vapor stream at lower pressure and supplying it to the fractionation column in a lower fposition at a midpoint of the column; (e) extracting a distillation steam stream from a top region of the fractionation column and compressing it; (f) cooling the compressed distillation steam stream sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a heating portion of the second stream; (g) dividing the condensate stream into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream; (h) supplying the reflux stream to the column of fractionation in a fng position at the head of the column; and (i) the amount and temperature of the reflux stream and the temperatures of the f to the fractionating column are effective to maintain the temperature at the head of the fractionation column at a value by which the majority portion is recovered of the heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
4. 4. A process for the separation of liquefied natural gas containing methane and heavier hydrocarbon components into a volatile liquid fraction containing a majority portion of the methane and a relatively minor volatile liquid fraction containing a major portion of the heavier hydrocarbon components, characterized in that it comprises the steps of: (a) heating the liquefied natural gas and then dividing it into at least a first stream and a second stream; (b) expanding the first stream at lower pressure and then supplying it to the fractionation column at a higher fposition at an intermediate point of the column; (c) heating the second stream sufficiently to vaporize it, thereby forming a vapor stream; (d) expanding the vapor stream at lower pressure and supplying it to the fractionation column in a lower fposition at a midpoint of the column; (e) extracting a distillation steam stream from a top region of the fractionation column and compressing it; (f) cooling the compressed distillation steam stream sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a portion of the heating of the liquefied natural gas; (g) dividing the condensate stream into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream; (h) supplying the reflux stream to the fractionation column in a fposition at the head of the column; and (i) the amount and temperature of the reflux stream and the temperatures of the f to the fractionating column are effective to maintain the temperature at the head of the fractionation column at a value by which the majority portion is recovered of the heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
5. 5. A process for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a majority portion of the heavier hydrocarbon components, characterized in that it comprises the steps of: (a) heating the liquefied natural gas enough to vaporize it partially, thus forming a vapor stream and a liquid stream; (b) dividing the vapor stream into at least a first stream and a second stream; (c) cooling the first stream to substantially all of the condensate and then expanding it to a lower pressure thereby further cooling it; (d) supplying the first expanded stream cooled to the fractionation column in a higher feed position at an intermediate point of the column; (e) expanding the second stream at lower pressure and supplying it to the fractionation column in a first lower feed position at a midpoint of the column; (f) expanding the liquid stream to lower pressure and supplying it to the fractionating column in a second lower feed position at a midpoint of the column; (g) extracting a stream of distillation steam from an upper region of the fractionation column and heating it, where the heating provides at least a portion of the cooling of the first stream; (h) compressing the heated distillation steam stream; (i) cooling the heated, compressed distillation vapor stream, enough to at least partially condense it and thereby form a condensate stream, where the cooling provides at least a portion of the heating of the liquefied natural gas; j) dividing the condensate stream into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream; (k) supplying the reflux stream to the fractionation column in a feed position at the head of the column; and (1) the amount and temperature of the reflux stream and the temperatures of the feeds to the fractionation column are effective to maintain the temperature at the head of the fractionation column at a value by which the majority portion is recovered of the heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
6. 6. A process for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a majority portion of the heavier hydrocarbon components, characterized in that it comprises the steps of: (a) heating the liquefied natural gas enough to vaporize it, thus forming a vapor stream; (b) dividing the vapor stream into at least a first stream and a second stream; (c) cooling the first stream to substantially all of the condensate and then expanding it to a lower pressure thereby further cooling it; (d) supplying the first expanded stream cooled to the fractionation column in a higher feed position at an intermediate point of the column; (e) expanding the second stream at lower pressure and supplying it to the fractionation column in a lower feed position at a midpoint of the column; (f) extracting a stream of distillation steam from an upper region of the fractionation column and heating it, where the heating provides at least a portion of the cooling of the first stream; (g) compress the distillation steam stream heated (h) cooling the heated and compressed distillation steam stream, enough to at least partially condense it and thereby form a condensate stream, where the cooling provides at least a portion of the heating of the liquefied natural gas; (i) dividing the condensate stream into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream; j) supplying the reflux stream to the fractionation column in a feed position at the head of the column; and (k) the amount and temperature of the reflux stream and the temperatures of the feeds to the fractionating column are effective to maintain the temperature at the head of the fractionation column at a value by which the majority portion is recovered of the heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
7. 7. A process for the separation of liquefied natural gas containing methane and heavier hydrocarbon components into a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a majority portion of the heavier hydrocarbon components, characterized in that it comprises the steps of: (a) heating the liquefied natural gas sufficiently to vaporize it partially, thereby forming a vapor stream and a liquid stream; (b) expanding the vapor stream at lower pressure and then supplying it to the fractionation column in a first feed position at a midpoint of the column; (c) expanding the liquid stream at lower pressure and supplying it to the fractionation column in a second feed position at a midpoint of the column; (d) extracting a distillation steam stream from an upper region of the fractionation column and compressing it; (e) cooling the compressed distillation steam stream sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a portion of the heating of the liquefied natural gas; (f) dividing the condensate stream into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream; (g) supplying the reflux stream to the fractionation column in a feed position at the head of the column; Y (h) the amount and temperature of the reflux stream and the temperatures of the feeds to the fractionating column are effective to maintain the temperature at the head of the fractionation column at a value by which the majority portion of the fraction is recovered. the heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
8. 8. A process for the separation of liquefied natural gas containing methane and heavier hydrocarbon components into a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a majority portion of the heavier hydrocarbon components, characterized in that it comprises the steps of: (a) heating the liquefied natural gas sufficiently to vaporize it, thereby forming a vapor stream; (b) expanding the vapor stream at lower pressure and then supplying it to the fractionation column at a feed position at a midpoint of the column; (c) extracting a distillation steam stream from an upper region of the fractionation column and compressing it; (d) cooling the compressed distillation steam stream sufficiently to condense at least partially and to thereby form a condensate stream, wherein the cooling provides at least a portion of the heating of the liquefied natural gas; (e) dividing the condensate stream into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream; (f) supplying the reflux stream to the fractionation column in a feed position at the head of the column; and (g) the amount and temperature of the reflux stream and the feed temperature to the fractionation column are effective to maintain the temperature at the head of the fractionation column at a value by which the majority portion of the fraction is recovered. the heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
9. 9. A process for the separation of liquefied natural gas containing methane and heavier hydrocarbon components into a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a majority portion of the heavier hydrocarbon components, characterized in that it comprises the steps of: (a) dividing the liquefied natural gas into at least a first stream and a second stream; (b) expanding the first stream at lower pressure and then supplying it in a first feed position at a midpoint of the column to an absorption column that produces a head steam stream and a bottom liquid stream; (c) heating the second stream sufficiently to vaporize it at least partially; (d) expanding the second stream heated to lower pressure and supplying it to the absorption column in a lower feed position; (e) supplying the liquid stream from the bottom to the fractional distillation column in a feed position at the head of the column; (f) extracting a stream of distillation steam from an upper region of the fractional distillation column and cooling it to substantially complete condensation, where cooling provides at least a portion of the heating of the second stream; (g) pumping the substantially condensed stream and then supplying it to the absorption column in a second feed position at a midpoint of the column; (h) the overhead steam stream is cooled sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a portion of the heating of the second current; (i) pumping the condensate stream and then dividing it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream; j) supplying the reflux stream to the absorption column in a feed position at the head of the column; and (k) the amount and temperature of the reflux stream and the temperatures of the feeds to the absorption column and the fractional distillation column are effective to maintain the temperature at the head of the absorption column and the distillation column fractionated in values by which the majority portion of the heavier hydrocarbon components is recovered by fractionation in the relatively less volatile liquid fraction.
10. 10. A process for the separation of liquefied natural gas containing methane and heavier hydrocarbon components into a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a majority portion of the heavier hydrocarbon components, characterized in that it comprises the steps of: (a) heating the liquefied natural gas and then dividing it into at least a first stream and a second stream; (b) expanding the first stream at lower pressure and then supplying it in a first feed position at a midpoint of the column to an absorption column that produces a head steam stream and a bottom liquid stream; (c) heating the second stream sufficiently to vaporize it at least partially; (d) expanding the second stream heated to lower pressure and supplying it to the absorption column in a lower feed position; (e) supplying the liquid stream from the bottom to the fractional distillation column in a feed position at the head of the column; (f) extracting a stream of distillation steam from an upper region of the fractional distillation column and cooling it to substantially complete condensation, where cooling provides at least a portion of the heating of the liquefied natural gas; (g) pumping the substantially condensed stream and then supplying it to the absorption column in a second feed position at a midpoint of the column; (h) cooling the head steam stream sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a portion of the heating of liquefied natural gas; (i) pumping the condensate stream and then dividing it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream; (j) supplying the reflux stream to the absorption column in a feed position at the head of the column; and (k) the amount and temperature of the reflux stream and the temperatures of the feeds to the absorption column and the fractional distillation column are effective to maintain the temperature at the head of the absorption column and the distillation column fractionated in values by which the majority portion of the heavier hydrocarbon components is recovered by fractionation in the relatively less volatile liquid fraction.
11. 11. A process for the separation of liquefied natural gas containing methane and heavier hydrocarbon components into a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a majority portion of the heavier hydrocarbon components, characterized in that it comprises the steps of: (a) heating the liquefied natural gas sufficiently to vaporize it at least partially; (b) expanding the liquefied natural gas heated to a lower pressure and then supplying it in a feed position lower than an absorption column that produces a head steam stream and a bottom liquid stream; (c) supplying the bottom liquid stream to the fractional distillation column at a feed position at the head of the column; (d) extracting a stream of distillation steam from an upper region of the fractional distillation column and compressing it; (e) cooling the compressed distillation steam stream sufficiently to condense it at least partially, where the cooling provides at least a portion of the heating of the liquefied natural gas; (f) supplying the cooled and compressed stream to the absorption column in a feed position at a midpoint of the column; (g) cooling the head steam stream sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a heating portion of the liquefied natural gas; (h) pumping the condensate stream and then dividing it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream; (i) supplying the flow of -reflux to the absorption column in a feeding position at the head of the column; and j) the amount and temperature of the reflux stream and the temperatures of the feeds to the absorption column and the fractional distillation column are effective to maintain the temperature at the head of the absorption column and the fractional distillation column at values by which the majority portion of the heavier hydrocarbon components is recovered by fractionation in the relatively less volatile liquid fraction.
12. 12. A process for the separation of liquefied natural gas containing methane and heavier hydrocarbon components into a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a majority portion of the heavier hydrocarbon components, characterized in that it comprises the steps of: (a) heating the liquefied natural gas sufficiently to vaporize it at least partially; (b) expanding the liquefied natural gas heated to a lower pressure and then supplying it in a feed position lower than an absorption column that produces a head steam stream and a bottom liquid stream; (c) supplying the bottom liquid stream to the fractional distillation column at a feed position at the head of the column; (d) extracting a distillation steam stream from an upper region of the fractional distillation column and cooling it to substantially complete condensation, where the cooling provides at least a heating portion of the liquefied natural gas; (e) pumping the substantially condensed stream and then supplying it to the absorption column in a feed position at a midpoint of the column; (f) cooling the head steam stream sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a heating portion of the liquefied natural gas; (g) pumping the condensate stream and then dividing it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream; h) supplying the reflux stream to the absorption column in a feed position at the head of the column; and (i) the amount and temperature of the reflux stream and the temperatures of the feeds to the absorption column and the fractional distillation column are effective to maintain the temperature at the head of the absorption column and the fractional distillation column at values by which the majority portion of the heavier hydrocarbon components is recovered by fractionation in the relatively less volatile liquid fraction.
13. 13. A process for the separation of liquefied natural gas containing methane and heavier hydrocarbon components into a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a majority portion of the heavier hydrocarbon components, characterized in that it comprises the steps of: (a) heating the liquefied natural gas sufficiently to vaporize it partially, thereby forming a vapor stream and a liquid stream; (b) expanding the vapor stream at lower pressure and then supplying it in a first lower feed position, to an absorption column which produces a head steam stream and a bottom liquid stream; (e) expanding the liquid stream to the lowest pressure and supplying it to the absorption column in a second lower feed position; (d) supply the liquid stream from the bottom to the fractional distillation column in a feeding position at the head of the column; (e) extracting a stream of distillation steam from an upper region of the fractional distillation column and compressing it; (f) cooling the compressed distillation steam stream sufficiently to condense it at least partially, where the cooling provides at least a heating portion of the liquefied natural gas; (g) supplying the cooled and compressed stream to the absorption column in a feeding position at a midpoint of the column; (h) compressing the head steam stream; (i) cooling the compressed head steam stream sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a heating portion of the liquefied natural gas; j) dividing the condensate stream into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream; (k) supplying the reflux stream to the absorption column in a feed position at the head of the column; and (1) the quantity and temperature of the stream of reflux and the temperatures of the feeds to the absorption column and the fractional distillation column are effective to maintain the temperature at the head of the absorption column and the fractional distillation column at values by which the majority portion of the heavier hydrocarbon components is recovered by fractionation in the relatively less volatile liquid fraction.
14. 14. A process for the separation of liquefied natural gas containing methane and heavier hydrocarbon components into a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a major portion of the heavier hydrocarbon components, characterized in that it comprises the steps of: (a) heating the liquefied natural gas sufficiently to vaporize it at least partially; (b) expanding the liquefied natural gas heated to a lower pressure and then supplying it in a feed position lower than an absorption column which produces a head steam stream and a bottom liquid stream; (c) supplying the bottom liquid stream to the fractional distillation column at a feed position at the head of the column; (d) extracting a distillation steam stream from an upper region of the fractional distillation column and compress it; (e) cooling the compressed distillation steam stream sufficiently to condense it at least partially, where the cooling provides at least a heating portion of the liquefied natural gas; (f) supplying the cooled and compressed stream to the absorption column in a feed position at a midpoint of the column; (g) compressing the head steam stream; (h) cool the. compressed head steam stream sufficient to at least partially condense and thereby form a condensate stream, where the cooling provides at least a heating portion of the liquefied natural gas; (i) dividing the condensate stream into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream; j) supplying the reflux stream to the absorption column in a feed position at the head of the column; and (k) the amount and temperature of the reflux stream and the temperatures of the feeds to the absorption column and the fractional distillation column are effective to maintain the temperature at the head of the absorption column and the fractional distillation column in values by which the majority portion of the heavier hydrocarbon components is recovered by fractionation in the relatively less volatile liquid fraction.
15. 15. A process for the separation of liquefied natural gas containing methane and heavier hydrocarbon components into a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a major portion of the heavier hydrocarbon components, characterized in that it comprises the steps of: (a) heating the liquefied natural gas sufficiently to vaporize it partially, thereby forming a vapor stream and a liquid stream; (b) expanding the vapor stream at lower pressure and then supplying it in a first lower feed position, to an absorption column which produces a head steam stream and a bottom liquid stream; (c) expanding the liquid stream to the lowest pressure and supplying it to the absorption column in a second lower feed position; (d) pumping the liquid stream from the bottom and then supplying it to the fractional distillation column in a feeding position at the head of the column; (e) extracting a distillation steam stream from an upper region of the fractional distillation column and cooling it sufficiently to condense it at least partially, where the cooling provides at least a heating portion of the liquefied natural gas; (f) supplying the cooled distillation stream to the absorption column in a feed position at a midpoint of the column; (g) compressing the head steam stream; (h) cooling the compressed head steam stream sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a heating portion of the liquefied natural gas; (i) dividing the condensate stream into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream; j) supplying the reflux stream to the absorption column in a feed position at the head of the column; and (k) where the process is characterized in that the amount and temperature of the reflux stream and the temperatures of the feeds to the absorption column and the fractional distillation column are effective to maintain the temperature at the head of the absorption column and the fractional distillation column in values by which the majority portion of the heavier hydrocarbon components is recovered by fractionation in the relatively less volatile liquid fraction.
16. 16. A process for the separation of liquefied natural gas containing methane and heavier hydrocarbon components into a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a major portion of the heavier hydrocarbon components, characterized in that it comprises the steps of: (a) heating the liquefied natural gas sufficiently to vaporize it at least partially; (b) expanding the liquefied natural gas heated to a lower pressure and then supplying it in a feed position lower than an absorption column which produces a head steam stream and a bottom liquid stream; (c) pumping the liquid stream from the bottom and then supplying it to the fractional distillation column in a feed position at the head of the column; (d) drawing a distillation steam stream from an upper region of the fractional distillation column and cooling it sufficiently to condense it at least partially, where cooling provides at least one heating portion of liquefied natural gas; (e) supplying the cooled distillation stream to the absorption column in a feed position at a midpoint of the column; (f) compressing the head steam stream; (g) cooling the compressed head steam stream sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a heating portion of the liquefied natural gas; (h) dividing the condensate stream into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream; (i) supplying the reflux stream to the absorption column in a feed position at the head of the column; and j) the amount and temperature of the reflux stream and the temperatures of the feeds to the absorption column and the fractional distillation column are effective to maintain the temperature at the head of the absorption column and the fractional distillation column at values by which the majority portion of the heavier hydrocarbon components is recovered by fractionation in the relatively less volatile liquid fraction.
17. 17. The process according to claim 1 or 3, characterized in that the reflux stream is further cooled and then supplied to the fractionating column in the feed position at the head of the column, where the cooling provides at least a heating portion of the second stream.
18. 18. The process according to claim 2, 4, 5, 6, 7, or 8, characterized in that the reflux stream is further cooled and then fed to the fractionation column in the feed position at the head of the column, where cooling provides at least a portion of heating of liquefied natural gas.
19. The process according to claim 9, characterized in that the reflux stream is further cooled and then supplied to the absorption column in the feed position at the head of the column, where the cooling provides at least a portion of heating of the second current.
20. 20. The process according to claim 10, 11, 12, 13, 14, 15, or 16, characterized in that the reflux stream is further cooled and then supplied to the absorption column in the feed position in the head of the column, where the cooling provides at least a portion of heating of the liquefied natural gas.
21. 21. The process according to claim 12, characterized in that the substantially condensed pumped stream is heated and then supplied to the absorption column in the feed position at a midpoint of the column, where heating provides at least a cooling portion of the distillation steam stream or head steam stream.
22. 22. The process according to claim 21, characterized in that the reflux stream is further cooled and then supplied to the absorption column in the feed position at the head of the column, where cooling provides at least a portion of heating of liquefied natural gas.
23. 23. The process according to claim 1, 2, 3, or 4, characterized in that it comprises the steps of: (a) further cooling the reflux stream and then supplying it to the fractionation column in the feed position in the head from the column; (b) expanding the first stream to the lowest pressure and then heating it, where heating provides at least a portion of the additional cooling of the reflux stream; and (c) supplying the first heated and expanded stream to the fractionation column in the upper feed position at an intermediate point of the column.
24. 24. The process according to claim 9 or 10, characterized in that it comprises the steps of: (a) further cooling the reflux stream and then supplying it to the absorption column in the feed position at the head of the column; (b) expanding the first stream to the lowest pressure and then heating it, where heating provides at least a portion of additional cooling of the reflux stream; and (c) supplying the first heated and expanded stream to the absorption column in the first feed position at a midpoint of the column.
25. 25. The process according to claim 9 or 10, characterized in that it comprises the steps of: (a) further cooling the reflux stream and then supplying it to the absorption column in the feed position at the head of the column; (b) pumping the substantially condensed stream and then heating it, where heating provides at least a portion of the additional cooling of the reflow stream; and (c) supplying the pumped and heated stream, substantially condensed to the absorption column in the second feed position at a midpoint of the column.
26. 26. An apparatus for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a major portion of the heavier hydrocarbon components, characterized in that it comprises: (a) first connected half splitter to receive the liquefied natural gas and divide it into at least a first stream and a second stream; (b) first expansion means connected to the first dividing means for receiving the first stream and expanding it at a lower pressure, where the first expansion means is also connected to the fractionation column for supplying the first expanded stream at a higher feed position in an intermediate point of the column; (c) heat exchange means connected to the first divider means for receiving the second stream and heating it sufficiently to vaporize it partially; (d) separation means connected to the heat exchange means for receiving the second partially vaporized and heated stream and separating it into a vapor stream and a liquid stream; (e) second expansion means connected to the separation means to receive the steam stream and expand it at the lowest pressure, where the second expansion medium is further connected to the fractionation column for supplying the expanded steam stream in a first lower feed position at a midpoint of the column; (f) third expansion means connected to the separation means to receive the liquid stream and expand it to the lowest pressure, where the third expansion medium is further connected to the fractionation column to supply the expanded liquid stream in a second lower feeding position at a midpoint of the column; (g) extraction medium connected to an upper region of the fractionation column for extracting a steam distillation stream; (h) compression means connected to the extraction means for receiving the distillation steam stream and compressing it; (i) the heat exchange medium is further connected to the compression means to receive the compressed distillation steam stream and to cool it sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a portion of the heating of the second stream; j) second divider half connected to the middle of heat exchange to receive the condensate stream and divide it into at least the volatile liquid fraction containing a majority portion of the methane and a reflux stream, where the second divider is further connected to the fractionating column to supply the reflux to the fractionation column in a feeding position at the head of the column; and (k) control means adapted to regulate the amount and temperature of the reflux stream and the temperatures of the feed streams to the fractionation column to maintain the temperature at the head of the fractionation column at a value by the which recovers the majority portion of the heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
27. 27. An apparatus for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a major portion of methane and a relatively minor volatile liquid fraction containing a major portion of the heavier hydrocarbon components, characterized in that it comprises: (a) heat exchange medium connected to receive the liquefied natural gas and heat it; (b) first divider half connected to the middle of exchanging heat to receive the heated liquefied natural gas and dividing it into at least a first stream and a second stream; (c) first expansion means connected to the first dividing means for receiving the first stream and expanding it at a lower pressure, where the first expansion means is also connected to the fractionating column for supplying the first expanded stream at a higher feed position in an intermediate point of the column; (d) heating means connected to the first dividing means for receiving the second stream and heating it sufficiently to vaporize it partially; (e) separation means connected to the heating means for receiving the second partially vaporized and heated stream and separating it into a vapor stream and a liquid stream; (f) second expansion means connected to the separation means to receive the vapor stream and expand it to the lowest pressure, where the second expansion means is further connected to the fractionation column to supply the expanded vapor stream in a first position of lower feed at a midpoint of the column; (g) third expansion medium connected to the separation medium to receive the liquid stream and expand it at the lowest pressure, where the third expansion means is further connected to the fractionation column to supply the expanded liquid stream in a second lower supply position at a midpoint of the column; (h) extraction medium connected to an upper region of the fractionation column to extract a steam distillation stream; (i) compression means connected to the extraction means for receiving the distillation steam stream and compressing it; j) the heat exchange medium is further connected to the compression means to receive the compressed distillation steam stream and to cool it sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a portion of the heating of liquefied natural gas; (k) second divider means connected to the heat exchange means for receiving the condensate stream and dividing it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream, where the second divider means is further connected to the fractionation column to supply the reflux stream to the fractionation column in a position of feeding at the head of the spine; and (1) control means adapted to regulate the amount and temperature of the reflux stream and the temperatures of the feed streams to the fractionation column to maintain the temperature at the head of the fractionation column at a value by the which recovers the majority portion of the heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
28. 28. An apparatus for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a major portion of the heavier hydrocarbon components, characterized in that it comprises: (a) first divider means connected to receive the liquefied natural gas and dividing it into at least a first stream and a second stream; (b) first expansion means connected to the first dividing means for receiving the first stream and expanding it at a lower pressure, where the first expansion means is also connected to the fractionation column for supplying the first expanded stream at a higher feed position in an intermediate point of the column; (c) heat exchange means connected to the first divider means to receive the second stream and heat it sufficiently to vaporize it, thereby forming a vapor stream; (d) second expansion means connected to the heat exchange means to receive the vapor stream and expand it to the lowest pressure, where the second expansion medium is further connected to the fractionation column to supply the expanded vapor stream in a lower feeding position at a midpoint of the column; (e) extraction medium connected to an upper region of the fractionation column for extracting a steam distillation stream; (f) compression means connected to the extraction means for receiving the distillation vapor stream and compressing it; (g) the heat exchange medium is further connected to the compression means to receive the compressed distillation steam stream and to cool it sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a heating portion of said second stream; (h) second divider half connected to the middle of heat exchange to receive the condensate stream and divide it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream, where the second divider is further connected to the fractionation column to supply the flow of reflux to the fractionation column in a feeding position at the head of the column; and (i) control means adapted to regulate the amount and temperature of the reflux stream and the temperatures of the feed streams to the fractionation column to maintain the temperature at the head of the fractionation column at a value by the which recovers the majority portion of the heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
29. 29. An apparatus for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a major portion of methane and a relatively minor volatile liquid fraction containing a major portion of the heavier hydrocarbon components, characterized in that it comprises: (a) heat exchange medium connected to receive the liquefied natural gas and heat it; (b) first divider half connected to the middle of exchanging heat to receive the heated liquefied natural gas and dividing it into at least a first stream and a second stream; (c) first expansion means connected to the first dividing means for receiving the first stream and expanding it at a lower pressure, where the first expansion means is also connected to the fractionating column for supplying the first expanded stream at a higher feed position in an intermediate point of the column; (d) heating means connected to the first dividing means for receiving the second stream and heating it sufficiently to vaporize it, thereby forming a vapor stream; (e) second expansion means connected to the heating means to receive the vapor stream and expand it to the lowest pressure, where the second expansion means is further connected to the fractionation column to supply the expanded steam stream in a supply position lower at a midpoint of the column; (f) extraction medium connected to an upper region of the fractionation column for extracting a steam distillation stream; (g) compression means connected to the extraction means for receiving the distillation vapor stream and compressing it; (h) the heat exchange medium is further connected to the compression means to receive the compressed distillation steam stream and to cool it sufficiently to condense it - at least partially and to thereby form a condensate stream, where the cooling provides at least a heating portion of the liquefied natural gas; (i) second divider means connected to the heat exchange medium for receiving the condensate stream and dividing it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream, where the second divider means is further connected to the fractionation column for supplying the reflux stream to the fractionation column in a feed position at the head of the column; and j) control means adapted to regulate the amount and temperature of the reflux stream and the temperatures of the feed streams to the fractionation column to maintain the temperature at the head of the fractionation column at a value by which it recovers the majority portion of the heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
30. 30. An apparatus for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a majority portion of the heavier hydrocarbon components, characterized in that it comprises: (a) first heat exchange medium connected to receive the natural gas liquefied and heat it enough to vaporize it partially; (b) separation means connected to the first heat exchange means for receiving the partially vaporized heated stream and separating it into a vapor stream and a liquid stream; (c) first dividing means connected to the separating means for receiving the vapor stream and dividing it into at least a first stream and a second stream; (d) second heat exchange means connected to the first divider means to receive the first current and to cool it sufficiently to substantially condense it; (e) first expansion means connected to the second heat exchange means for receiving the first substantially condensed stream and expanding it at a lower pressure, where the first expansion medium is also connected to the fractionating column for supplying the first expanded stream in a upper feeding position at an intermediate point in the column; (f) second expansion means connected to the first dividing means for receiving the second stream and expanding it to the lower pressure, where the second expansion means is further connected to the fractionating column for supplying the expanded vapor stream in a first position of lower feeding at a midpoint of the spine; (g) third expansion means connected to the separation means to receive the liquid stream and expand it to the lowest pressure, where the third expansion means is further connected to the fractionation column to supply the expanded liquid stream in a second position of lower feed at a midpoint of the column; (h) extraction medium connected to an upper region of the fractionation column to extract a steam distillation stream; ^ > (i) the second heat exchange means is further connected to the extraction means for receiving the distillation steam stream and heating it, where heating provides at least a cooling portion of the first stream; j) compression means connected to the second heat exchange means for receiving the steam stream from heated distillation and compress; (k) the first heat exchange means is further connected to the compression means to receive the compressed and heated distillation steam stream, and to cool it sufficiently to condense it at least partially and to thereby form a condensate stream , where the cooling provides at least a heating portion of the liquefied natural gas; (1) second divider means connected to the first heat exchange means for receiving the condensate stream and dividing it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream, where the second divider is connected further to the fractionation column for supplying the reflux stream to the fractionation column in a feed position at the head of the column; and (m) control means adapted to regulate the amount and temperature of the reflux stream and the temperatures of the feed streams to the fractionation column to maintain the temperature at the head of the fractionation column at a value by the which recovers the majority portion of the heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
31. 31. An apparatus for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a majority portion of the heavier hydrocarbon components, characterized in that it comprises: (a) first exchange medium of heat connected to receive the liquefied natural gas and heat it enough to vaporize it, thus forming a vapor current; (b) first dividing means connected to the first heat exchange means for receiving the vapor stream and dividing it into at least a first stream and a second stream; (c) second heat exchange means connected to the first divider means to receive the first current and to cool it sufficiently to substantially condense it; (d) first expansion means connected to the second heat exchange means for receiving the first substantially condensed stream and expanding it at a lower pressure, where the first expansion medium is also connected to the fractionating column for supplying the first expanded stream in a upper feeding position at an intermediate point of the column; (e) second expansion means connected to the first divider means for receiving the second stream and expanding it to the lowest pressure, where the second expansion medium is further connected to the fractionating column to supply the expanded vapor stream in a feed position lower at a midpoint of the column; (f) extraction medium connected to an upper region of the fractionation column for extracting a steam distillation stream; (g) the second heat exchange means is further connected to the extraction means for receiving the distillation steam stream and heating it, where the heating provides at least a cooling portion of the first stream; (h) compression means connected to the second heat exchange means for receiving the heated distillation vapor stream and compressing it; (i) the first heat exchange means is further connected to the compression means to receive the compressed and heated distillation steam stream, and to cool it sufficiently to condense it at least partially and to thereby form a condensate stream , where the cooling provides at least a heating portion of the liquefied natural gas; j) second divider means connected to the first means of heat exchange to receive the condensate stream and divide it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream, where the second divider is further connected to the fractionation column to supply the flow of reflux to the fractionation column in a feeding position at the head of the column; and (k) control means adapted to regulate the amount and temperature of the reflux stream and the temperatures of the feed streams to the fractionation column to maintain the temperature at the head of the fractionation column at a value by the which recovers the majority portion of the heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
32. 32. An apparatus for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a major portion of the heavier hydrocarbon components, characterized in that it comprises: (a) heat exchange medium connected to receive the liquefied natural gas and heat it sufficiently to vaporize it partially; (b) separation means connected to the heat exchange means for receiving the partially vaporized heated stream and separating it into a vapor stream and a liquid stream; (c) first expansion means connected to the separation means to receive the vapor stream and expand it at a lower pressure, where the first expansion means is also connected to the fractionation column to supply the expanded vapor stream in a first position of feeding at a midpoint of the column; (d) second expansion means connected to the separation means to receive the liquid stream and expand it to the lowest pressure, where the second expansion means is further connected to the fractionation column to supply the expanded liquid stream in a second position of feeding at a midpoint of the column; (e) extraction medium connected to an upper region of the fractionation column for extracting a steam distillation stream; (f) compression means connected to the extraction means for receiving the distillation vapor stream and compressing it; (g) the heat exchange medium is further connected to the compression means to receive the compressed distillation steam stream and to cool it sufficiently as to at least partially condense and thereby form a condensate stream, where the cooling provides at least a heating portion of the liquefied natural gas; (h) dividing means connected to the heat exchange means for receiving the condensate stream and dividing it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream, where the dividing means is further connected to the fractionation column for supplying the reflux stream to the fractionation column in a feed position at the head of the column; and (i) control means adapted to regulate the amount and temperature of the reflux stream and the temperatures of the feed streams to the fractionation column to maintain the temperature at the head of the fractionation column at a value by the which recovers the majority portion of the heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
33. 33. An apparatus for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a portion majority of the heavier hydrocarbon components, characterized in that it comprises: (a) heat exchange medium connected to receive the liquefied natural gas and heat it sufficiently to vaporize it, thereby forming a vapor stream; (b) expansion means connected to the heat exchange medium to receive the vapor stream and expand it at a lower pressure, where the expansion medium is further connected to the fractionation column to supply the expanded vapor stream in a supply position at a midpoint of the column; (c) extraction medium connected to an upper region of the fractionation column to extract a steam distillation stream; (d) compression means connected to the extraction means for receiving the distillation vapor stream and compressing it; (e) the heat exchange medium is further connected to the compression means to receive the compressed distillation steam stream and to cool it sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a portion of heating of liquefied natural gas; (f) half divisor connected to the means of exchange of heat to receive the condensate stream and divide it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream, where the dividing means is further connected to the fractionation column to supply the reflux stream to the fractionation column in a feeding position at the head of the column; and (g) control means adapted to regulate the amount and temperature of the reflux stream and the temperature of the feed stream to the fractionation column to maintain the temperature at the head of the fractionation column at a value by the which recovers the majority portion of the heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
34. 34. An apparatus for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a major portion of the heavier hydrocarbon components, characterized in that it comprises: (a) first divider means connected to receive the liquefied natural gas and dividing it into at least a first stream and a second stream; (b) first expansion means connected to the first divider means to receive the first stream and expand it at a lower pressure, where the first expansion means is also connected to supply the first expanded stream in a first feed position at a midpoint of the column in an absorption column that produces a head steam stream and a bottom liquid stream; (c) heat exchange means connected to the first divider means for receiving the second stream and heating it sufficiently to vaporize it at least partially; (d) second expansion means connected to the heat exchange medium to receive the second heated stream and expand it to the lower pressure, where the second expansion medium is further connected to the absorption column to supply the second stream expanded and heated in a lower feeding position; (e) a fractional distillation column connected to the absorption column to receive the liquid stream from the bottom in a feed position at the head of the column; (f) first extraction means connected to an upper region of the fractional distillation column to extract a steam distillation stream; (g) the heat exchange medium is further connected to the first extraction means to receive the distillation steam stream and to cool it to substantially condense it, where the cooling provides at least a heating portion of the second stream; (h) first pumping means connected to the heat exchange means for receiving the substantially condensed stream and pumping it, wherein the first pumping means is further connected to the absorption column to supply the pumped stream substantially condensed in a second supply position at a midpoint of the column; (i) second extraction means connected to an upper region of the absorption column to extract the overhead steam stream; j) the heat exchange medium is further connected to the second extraction means to receive the head steam stream and to cool it sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a heating portion of the second stream; (k) second pumping means connected to the heat exchange medium to receive the condensate stream and pump it; (1) second divider means connected to the second pump means to receive the pumped stream of condensate and divide it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream, where the second divider means is further connected to the absorption column for supplying the reflux stream to the absorption column in a feed position at the head of the column; and (m) control means adapted to regulate the amount and temperature of the reflux stream and the temperatures of the feed streams to the absorption column and the fractional distillation column to maintain the temperature at the head of the column of absorption and the fractional distillation column at a value by which the majority portion of the heavier hydrocarbon components is recovered by fractionation in the relatively less volatile liquid fraction.
35. 35. An apparatus for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a majority portion of the heavier hydrocarbon components, characterized because it comprises: (a) heat exchange medium connected to receive the liquefied natural gas and heat it; (b) first divider means connected to the heat exchange medium for receiving the heated liquefied natural gas and dividing it into at least a first stream and a second stream; (c) first expansion means connected to the first divider means for receiving the first current and expanding it at a lower pressure, where the first expansion means is also connected to supply the first expanded current in a first supply position at a mid-point of the column in an absorption column that produces a head steam stream and a bottom liquid stream; (d) heating means connected to the first dividing means for receiving the second stream and heating it sufficiently to vaporize it at least partially; (e) second expansion means connected to the heating means to receive the second heated stream and expand it to the lower pressure, where the second expansion means is further connected to the absorption column to supply the second expanded and heated stream in a position of lower feed; (f) a fractional distillation column connected to the absorption column to receive the liquid stream from the bottom in a feeding position at the head of the column; (g) first extraction means connected to an upper region of the fractional distillation column to extract a steam distillation stream; (h) the heat exchange medium is further connected to the first extraction means to receive the distillation steam stream and to cool it to substantially condense it, where the cooling provides at least a heating portion of the liquefied natural gas; (i) first pumping means connected to the heat exchange means for receiving the substantially condensed stream and pumping it, wherein the first pumping means is further connected to the absorption column for supplying the substantially condensed pumped stream in a second supply position at a midpoint of the column; j) second extraction means connected to an upper region of the absorption column to extract the overhead steam stream; (k) the heat exchange medium is further connected to the second extraction means to receive the head steam stream and to cool it sufficiently to condense it at least partially and to form this way a condensate stream, where the cooling, provides at least a portion of the liquefied natural gas heating; (1) second pumping means connected to the heat exchange medium for receiving the condensate stream and pumping it; (m) second divider means connected to the second pumping means to receive the pumped stream of condensate and divide it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream, where the second divider means is further connected to the absorption column for supplying the reflux stream to the absorption column in a feed position at the head of the column; and (n) control means adapted to regulate the amount and temperature of the reflux stream and the temperatures of said feed streams to the absorption column and the fractional distillation column to maintain the temperature at the head of the column of absorption and the fractional distillation column at a value by which the majority portion of the heavier hydrocarbon components is recovered by fractionation in the relatively less volatile liquid fraction.
36. 36. An apparatus for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a majority portion of the heavier hydrocarbon components, characterized in that it comprises: (a) heat exchange medium connected to receive liquefied natural gas and heat it enough to vaporize it at least partially; (b) expansion medium connected to the heat exchange medium for receiving the heated liquefied natural gas and expanding it to a lower pressure, where the expansion medium is further connected to supply the liquefied natural gas expanded and heated in a lower supply position in an absorption column that produces a head steam stream and a bottom liquid stream; (c) a fractional distillation column connected to the absorption column to receive the liquid stream from the bottom in a feed position at the head of the column; (d) first extraction means connected to an upper region of the fractional distillation column to extract a steam distillation stream; (e) compression means connected to the first extraction means to receive the distillation steam stream and compress it; (f) the heat exchange medium is further connected to the compression means to receive the compressed distillation steam stream and to cool it sufficiently to condense it at least partially, where the cooling provides at least a portion of gas heating liquefied natural, wherein the heat exchange medium is further connected to the absorption column to supply the cooled and compressed stream in a feed position at a midpoint of the column; (g) second extraction means connected to an upper region of the absorption column to extract the overhead steam stream; (h) the heat exchange medium is further connected to the second extraction means to receive the head steam stream and to cool it sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a portion of heating of liquefied natural gas; (i) pumping means connected to the heat exchange means for receiving the condensate stream and pumping it; j) second divider means connected to the pumping medium to receive the pumped condensate current and divide it into at least the volatile liquid fraction containing a a majority portion of methane and a reflux stream, wherein the second divider means is further connected to the absorption column to supply the reflux stream to the absorption column at a feed position at the head of the column; and (k) control means adapted to regulate the amount and temperature of the reflux stream and the temperatures of the feed streams to the absorption column and the fractional distillation column to maintain the temperature at the head of the column of absorption and the fractional distillation column at a value by which the majority portion of the heavier hydrocarbon components is recovered by fractionation in the relatively less volatile liquid fraction.
37. 37. An apparatus for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a major portion of the heavier hydrocarbon components, characterized in that it comprises: (a) heat exchange means connected to receive the liquefied natural gas and heating it sufficiently to vaporize it at least partially; (b) expansion medium connected to the exchange medium heat to receive the heated liquefied natural gas and expand it to a lower pressure, where the expansion medium is further connected to supply the liquefied natural gas expanded and heated in a lower feed position in an absorption column that produces a steam stream of head and a bottom liquid stream; (c) a fractional distillation column connected to the absorption column to receive the liquid stream from the bottom in a feed position at the head of the column; (d) first extraction means connected to an upper region of the fractional distillation column to extract a steam distillation stream; (e) the heat exchange means is further connected to the first extraction means to receive the distillation steam stream and to cool it to substantially condense it, where the cooling provides at least a heating portion of the liquefied natural gas; (f) first pumping means connected to the heat exchange means for receiving the substantially condensed stream and pumping it, where the first pumping means is further connected to the absorption column to supply the pumped current substantially condensed in a feeding position at a midpoint of the column; (g) second extraction means connected to an upper region of the absorption column to extract the overhead steam stream; "(h) the heat exchange medium is further connected to the second extraction means to receive the overhead steam stream and to cool it sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a portion of the heating of liquefied natural gas, (i) second pumping means connected to the heat exchange medium to receive the condensate stream and pump it, j) divider half connected to the second pumping means to receive the current pumped out of condensate and dividing it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream, where the dividing medium is further connected to the absorption column to supply the reflux stream to the absorption column in a feeding position at the head of the column, and (k) control means adapted to regulate the amount and reflux current temperature and temperatures of the feed streams to the absorption column and the fractional distillation column to maintain the temperature at the head of the absorption column and the fractionated distillation column at a value by which the majority portion of the heavier hydrocarbon components is recovered by fractionation in the relatively less volatile liquid fraction.
38. 38. An apparatus for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a major portion of methane and a relatively minor volatile liquid fraction containing a major portion of the heavier hydrocarbon components, characterized in that it comprises: (a) heat exchange medium connected to receive the liquefied natural gas and heat it sufficiently to vaporize it partially; (b) separation means connected to the heat exchange means for receiving the partially vaporized heated stream and separating it into a vapor stream and a liquid stream; (c) first expansion means connected to the separation means to receive the vapor stream and expand it at a lower pressure, where the first expansion medium is also connected to supply the vapor current expanded in a first lower feed position in an absorption column that produces a head steam stream and a bottom liquid stream; (d) second expansion means connected to the separation means to receive the liquid stream and expand it to the lowest pressure, where the second expansion means is further connected to the absorption column to supply the expanded liquid stream in a second position of lower feeding; (e) a fractional distillation column connected to the absorption column to receive the liquid stream from the bottom in a feed position at the head of the column; (f) first extraction means connected to an upper region of the fractional distillation column to extract a steam distillation stream; (g) first compression means connected to the first extraction means for receiving the distillation vapor stream and compressing it; (h) the heat exchange medium is further connected to the first compression means to receive the compressed distillation steam stream and to cool it sufficiently to condense it at least partially, where the cooling provides at least a portion of heating of the liquefied natural gas, where the means of heat exchange is further connected to the absorption column to supply the cooled and compressed stream in a feeding position at a midpoint of the column; (i) second extraction means connected to an upper region of the absorption column to extract the overhead steam stream; j) second compression means connected to the second extraction means for receiving the head steam stream and compressing it; (k) the heat exchange medium is further connected to the second compression means to receive the compressed head steam stream and to cool it sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a heating portion of the liquefied natural gas; (1) half splitter connected to the heat exchange means for receiving the condensate stream and dividing it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream, where the dividing means is further connected to the absorption column for supplying the reflux stream to the absorption column in a feed position at the head of the column; Y (m) control means adapted to regulate the amount and temperature of the reflux stream and the temperatures of the feed streams to the absorption column and the fractional distillation column to maintain the temperature at the head of the absorption column and the fractional distillation column at a value by which the majority portion of the heavier hydrocarbon components is recovered by fractionation in the relatively less volatile liquid fraction.
39. 39. An apparatus for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a major portion of the heavier hydrocarbon components, characterized in that it comprises: (a) heat exchange means connected to receive the liquefied natural gas and heating it sufficiently to vaporize it at least partially; (b) expansion medium connected to the heat exchange medium for receiving the heated liquefied natural gas and expanding it to a lower pressure, where the expansion medium is further connected to supply said expanded and heated liquefied natural gas in a lower supply position in an absorption column that produces a head steam stream and a bottom liquid stream; (c) a fractional distillation column connected to the absorption column to receive the liquid stream from the bottom in a feed position at the head of the column; (d) first extraction means connected to an upper region of the fractional distillation column to extract a steam distillation stream; (e) first compression means connected to the first extraction means to receive the distillation steam stream and compressing it; (f) the heat exchange medium is her connected to the first compression means to receive the compressed distillation steam stream and to cool it sufficiently to condense it at least partially, where the cooling provides at least a portion of heating the liquefied natural gas, wherein the heat exchange medium is her connected to the absorption column to supply the cooled and compressed stream in a feed position at a midpoint of the column; (g) second extraction means connected to the an upper region of the absorption column for extracting the head steam stream; (h) second compression means connected to the second extraction means for receiving the head steam stream and compressing it; (i) the heat exchange medium is further connected to the second compression means to receive the compressed head steam stream and to cool it sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a portion of the heating of liquefied natural gas; j) dividing means connected to the heat exchange medium for receiving the condensate stream and dividing it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream, where the dividing medium is further connected to the column of absorption to supply the reflux stream to the absorption column in a feeding position at the head of the column; and (k) control means adapted to regulate the amount and temperature of the reflux stream and the temperatures of the feed streams to the absorption column and the fractional distillation column to maintain the temperature at the top of the column of absorption and the fractional distillation column in a value through which the majority portion of the components is recovered heavier hydrocarbons by fractionation in the relatively less volatile liquid fraction.
40. 40. An apparatus for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a major portion of methane and a relatively minor volatile liquid fraction containing a major portion of the heavier hydrocarbon components, characterized in that it comprises: (a) heat exchange medium connected to receive the liquefied natural gas and heat it sufficiently to vaporize it partially; (b) separation means connected to the heat exchange means for receiving the partially vaporized heated stream and separating it into a vapor stream and a liquid stream; (c) first expansion means connected to the separation means to receive the vapor stream and expand it at a lower pressure, where the first expansion means is also connected to supply the expanded vapor stream in a first lower supply position in a column absorption that produces a head steam stream and a bottom liquid stream; (d) second expansion means connected to the separation means to receive the liquid stream and expand it at the lowest pressure, where the second expansion means is further connected to the absorption column to supply the expanded liquid stream in a second lower supply position; (e) pumping means connected to the absorption column to receive the liquid stream from the bottom and pump it; (f) a fractional distillation column connected to the pumping means for receiving the pumped stream of liquid from the bottom in a feed position at the head of the column; (g) first extraction means connected to an upper region of the fractional distillation column to extract a steam distillation stream; (h) the heat exchange medium is further connected to the first extraction means to receive the distillation steam stream and to cool it sufficiently to condense it at least partially, where the cooling provides at least a portion of the gas heating liquefied natural, wherein the heat exchange medium is further connected to the absorption column to supply the cooled distillation stream at a feed position at a midpoint of the column; (i) Second extraction medium connected to an upper region of the absorption column to extract the current steam head; j) compression means connected to the second extraction means to receive the head steam stream and compress it; (k) the heat exchange medium is further connected to the compression means to receive the compressed head steam stream and to cool it sufficiently to condense it at least partially and to thereby form a condensate stream, where the cooling provides at least a portion of heating of liquefied natural gas; (1) half splitter connected to the heat exchange means for receiving the condensate stream and dividing it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream, where the dividing means is further connected to the absorption column for supplying the reflux stream to the absorption column in a feed position at the head of the column; and (m) control means adapted to regulate the amount and temperature of the reflux stream and the temperatures of the feed streams to the absorption column and the fractional distillation column to maintain the temperature at the head of the column of absorption and the fractional distillation column in a value by the which recovers the majority portion of the heavier hydrocarbon components by fractionation in the relatively less volatile liquid fraction.
41. 41. An apparatus for the separation of liquefied natural gas containing methane and heavier hydrocarbon components in a volatile liquid fraction containing a majority portion of methane and a relatively minor volatile liquid fraction containing a majority portion of the heavier hydrocarbon components, characterized in that it comprises: (a) heat exchange means connected to receive the liquefied natural gas and heating it sufficiently to vaporize it at least partially; (b) expansion medium connected to the heat exchange medium for receiving the heated liquefied natural gas and expanding it to a lower pressure, where the expansion medium is further connected to supply the liquefied natural gas expanded and heated in a lower supply position in an absorption column that produces a head steam stream and a bottom liquid stream; (c) pumping means connected to the absorption column to receive the liquid stream from the bottom and pump it; (d) a fractional distillation column connected to the pumping medium to receive the pumped stream of liquid from the bottom in a feeding position at the head of the column; (e) first extraction means connected to an upper region of the fractional distillation column to extract a steam distillation stream; (f) the heat exchange medium is further connected to the first extraction means to receive the distillation steam stream and to cool it sufficiently to condense it at least partially, where the cooling provides at least a portion of the gas heating liquefied natural, wherein the heat exchange medium is further connected to the absorption column to supply the cooled distillation stream at a feed position at a midpoint of the column; (g) second extraction means connected to an upper region of the absorption column to extract the overhead steam stream; (h) compression means connected to the second extraction means for receiving the head steam stream and compressing it; (i) the heat exchange medium is further connected to the compression means to receive the compressed head steam stream and to cool it sufficiently to condense it at least partially and to form this way a condensate stream, where the cooling provides at least a heating portion of the liquefied natural gas; j) dividing means connected to the heat exchange medium for receiving the condensate stream and dividing it into at least the volatile liquid fraction containing a majority portion of methane and a reflux stream, where the dividing medium is further connected to the column of absorption to supply the reflux stream to the absorption column in a feeding position at the head of the column; and (k) control means adapted to regulate the amount and temperature of the reflux stream and the temperatures of the feed streams to the absorption column and the fractional distillation column to maintain the temperature at the head of the column of absorption and the fractional distillation column at a value by which the majority portion of the heavier hydrocarbon components is recovered by fractionation in the relatively less volatile liquid fraction.
42. 42. The apparatus according to claim 26 or 28, characterized in that the heat exchange medium is further connected to the second divider means for receiving the reflux current and continuing to cool it, where the heat exchange medium is further connected to the column of fractionation to supply the reflux stream further cooled in the feed position at the head of the column, wherein the cooling provides at least a heating portion of the second stream.
43. 43. The apparatus according to claim 27, 29, 30, or 31, characterized in that the heat exchange means is further connected to the second divider means for receiving the reflux current and continuing to cool it, wherein said heat exchange means it is further connected to the fractionation column for supplying the reflux stream further cooled in the feed position at the head of the column, where the cooling provides at least a heating portion of the liquefied natural gas.
44. 44. The apparatus according to claim 32 or 33 characterized in that the heat exchange medium is further connected to the dividing means for receiving the reflux current and continuing to cool it, where the heat exchange medium is further connected to the column of fractionation to supply the reflux stream further cooled in the feed position at the head of the column, where the cooling provides at least a heating portion of the liquefied natural gas.
45. 45. The apparatus according to claim 34, characterized in that the heat exchange medium is further connected to the second divider means for receiving the reflux stream and continuing to cool it, where the heat exchange medium is further connected to the absorption column to supply the reflux stream further cooled in the feed position at the head of the column , wherein the cooling provides at least a heating portion of the second stream.
46. 46. The apparatus according to claim 35, characterized in that the heat exchange medium is further connected to the second divider means for receiving the reflux current and continuing to cool it, where the heat exchange medium is further connected to the column of absorption to supply the reflux stream further cooled in the feed position at the head of the column, where the cooling provides at least a heating portion of the liquefied natural gas.
47. 47. The apparatus according to claim 36, 37, 38, 39, 40, or 41, characterized in that the heat exchange means is further connected to the dividing means for receiving the reflux current and continuing to cool it, wherein the medium Heat exchange is further connected to the absorption column to supply the reflux stream further cooled in the feed position at the head of the column, where cooling provides at least a portion of heating of liquefied natural gas.
48. 48. The apparatus according to claim 37, characterized in that the heat exchange means is further connected to the first pumping means to receive the substantially condensed pumped stream and to heat it, where the heat exchange medium is further connected to the column of absorption to supply the heated and pumped stream in the feed position at a midpoint of the column, where the heating provides at least a portion of the cooling of the distillation steam stream or the overhead steam stream.
49. 49. The apparatus according to claim 48, characterized in that the heat exchange medium is further connected to the dividing means for receiving the reflux current and continuing to cool it, where the heat exchange medium is further connected to the absorption column. for supplying the reflux stream further cooled in the feed position at the head of the column, where the cooling provides at least a heating portion of the liquefied natural gas.
50. 50. The apparatus according to claim 26, 27, 28, or 29, characterized in that: (a) a second heat exchange means is connected to the second divider means to receive the reflux current and continue to cool it, where the second exchange medium of heat is further connected to the fractionation column to supply the reflux stream further cooled in the feed position at the head of the column; and (b) the second heat exchange means is further connected to the first expansion means for receiving the first expanded stream and heating it, wherein the second heat exchange medium is further connected to the fractionation column for supplying the first heated stream. and expanded in the upper feed position at an intermediate point of the column, where heating provides at least a portion of the additional cooling of the reflux stream.
51. 51. The compliance apparatus according to claim 34 or 35, characterized in that: (a) a second heat exchange means is connected to the second divider means to receive the reflux current and continue to cool it, wherein the second exchange medium of heat is further connected to the absorption column to supply the reflux stream further cooled in the feed position at the head of the column; Y (b) the second heat exchange means is further connected to the first expansion means for receiving the first expanded current and heating it, wherein the second heat exchange means is further connected to the absorption column for supplying the first heated and expanded stream in the first feed position at a midpoint of the column, where heating provides at least a portion of the additional cooling of the reflux stream.
52. 52. The apparatus according to claim 34 or 35, characterized in that (a) there is a second heat exchange means connected to the second divider means for receiving the reflux current and continuing to cool it, where the second heat exchange means is further connected to the absorption column to supply the reflux stream further cooled in the feed position at the head of the column; and (b) the second heat exchange means is further connected to the first pumping means for receiving the substantially condensed pumped stream and heating it, wherein the second heat exchange medium is further connected to the absorption column for supplying the heated stream. and pumped, substantially condensed, in the second feeding position at a midpoint of the column, where heating provides at least a portion of additional cooling of the reflux stream.
53. 53. The process according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 19, 21, or 22, characterized in that a major portion of methane and of the C components present in the volatile liquid fraction are recovered and a major portion of the C3 components and of the heavier hydrocarbon components present in the relatively less volatile liquid fraction are recovered.
54. 54. The process according to claim 17, characterized in that a major portion of methane and the C2 components present in the volatile liquid fraction are recovered and a major portion of the C3 components and of the heavier hydrocarbon components present in the fraction are recovered. relatively less volatile liquid.
55. 55. The process according to claim 18, characterized in that a major portion of methane and the C2 components present in the volatile liquid fraction are recovered and a major portion of the C3 components and the heavier hydrocarbon components present in the fraction are recovered. relatively less volatile liquid.
56. 56. The process according to claim 20, characterized in that a major portion of methane and the C2 components present in the volatile liquid fraction are recovered and a major portion of the C3 components and the heavier hydrocarbon components present in the fraction are recovered. relatively less volatile liquid.
57. 57. The process according to claim 23, characterized in that a majority portion of methane and the C2 components present in the volatile liquid fraction and a major portion of the C3 components and the heavier hydrocarbon components present in the relatively less volatile liquid fraction are recovered.
58. 58. The process according to claim 24, characterized in that a major portion of methane and the C2 components present in the volatile liquid fraction are recovered and a major portion of the C3 components and of the heavier hydrocarbon components present in the liquid are recovered. the relatively less volatile liquid fraction.
59. 59. The process according to claim 25, characterized in that a major portion of methane and the C2 components present in the volatile liquid fraction are recovered and a major portion of the C3 components and the heavier hydrocarbon components present in the fraction are recovered. relatively less volatile liquid.
60. 60. The apparatus according to claim 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 45, 46, 48, or 49, characterized in that a major portion of methane and the C2 components present in the volatile liquid fraction are recovered and a major portion of the C3 components and of the heavier hydrocarbon components present in the relatively less volatile liquid fraction are recovered.
61. 61. The apparatus according to claim 42, characterized in that a major portion of methane and the C2 components present in the volatile liquid fraction are recovered and a major portion of the C3 components and of the heavier hydrocarbon components present in the relatively less volatile liquid fraction are recovered.
62. 62. The apparatus according to claim 43, characterized in that a major portion of methane and the C2 components present in the volatile liquid fraction are recovered and a major portion of the C3 components and the heavier hydrocarbon components present in the fraction are recovered. relatively less volatile liquid.
63. 63. The apparatus according to claim 44, characterized in that a major portion of methane and the C2 components present in the volatile liquid fraction are recovered and a major portion of the C3 components and of the heavier hydrocarbon components present in the fraction are recovered. relatively less volatile liquid.
64. 64. The apparatus according to claim 47, characterized in that a major portion of methane and the C2 components present in the volatile liquid fraction are recovered and a major portion of the C3 components and the heavier hydrocarbon components present in the fraction are recovered. relatively less volatile liquid.
65. 65. The apparatus according to claim 50, characterized in that a majority portion of methane and the C2 components present in the volatile liquid fraction and a major portion of the C3 components and the heavier hydrocarbon components present in the relatively less volatile liquid fraction are recovered.
66. 66. The apparatus according to claim 51, characterized in that a major portion of methane and the C2 components present in the volatile liquid fraction are recovered and a major portion of the C3 components and the heavier hydrocarbon components present in the liquid are recovered. the relatively less volatile liquid fraction.
67. 67. The apparatus according to claim 52, characterized in that a major portion of methane and C2 components present in the volatile liquid fraction are recovered and a major portion of the C3 components and the heavier hydrocarbon components present in the fraction are recovered. relatively less volatile liquid.