JP6931070B2 - Increased efficiency within the LNG generation system by precooling the natural gas feed stream - Google Patents

Description

[Cross-reference to related applications]
This application is a U.S. patent entitled "Increasing Efficiency in an LNG Generation System by Precooling a Natural Gas Feed Stream" filed February 13, 2017, which is incorporated herein by reference in its entirety. It claims the priority interests of Application Nos. 62 / 458, 131.

This application has a common inventor and assignee, the entire disclosure of which is incorporated herein by reference, in an application dated equivalent to this specification, "High Pressure Compression and" filed on February 13, 2017. It is related to US Provisional Patent Application No. 62 / 458,127, entitled "Precooling Natural Gas by Expansion".

The present invention relates to the liquefaction of natural gas to form liquefied natural gas (LNG), more specifically when the construction and / or maintenance of major facilities and / or the environmental impact of conventional LNG plants is harmful. With respect to the production of LNG in some remote or sensitive areas.

LNG production is a rapidly growing means of supplying natural gas from locations with abundant supply of natural gas to distant locations with strong demand for natural gas. Traditional LNG cycles include a) initial treatment of natural gas resources to remove contaminants such as water, sulfur compounds, and carbon dioxide, and b) self-freezing, external freezing, dilute oils, and more. Separation of some heavy hydrocarbon gases such as propane, butane, pentane, etc. by possible methods and c) Natural gas by substantially external refrigeration to form LNG at about -160 ° C at near atmospheric pressure. Freezing and d) transporting LNG products to market locations on ships or tankers designed for this purpose, and e) reusing LNG into pressurized natural gas that can be distributed to natural gas consumers. Includes pressurization and regassing. Conventionally, stage (c) of the LNG cycle usually requires the use of a large refrigerating compressor, often powered by a large gas turbine driver that emits substantial carbon and other emissions. Large capital investments of billions of US dollars and extensive infrastructure are needed as part of the liquefaction plant. Conventionally, step (e) of the LNG cycle is a step of repressurizing LNG to the required pressure using a low temperature pump, and then through an intermediate fluid, but finally by heat exchange with seawater. Alternatively, it generally comprises the step of regasifying LNG into pressurized natural gas by burning a portion of natural gas to heat and evaporate the LNG. Generally, the available energy of cryogenic LNG is not utilized.

Cold refrigerants produced in different locations, such as liquefied nitrogen gas (“LIN”), can be used to liquefy natural gas. A step known as the LNG-LIN concept is that at least step (c) described above is replaced by a natural gas liquefaction step that substantially uses liquid nitrogen (LIN) as an open loop source for freezing, and step (e) described above. ) Is modified to utilize the energy of cryogenic LNG to promote liquefaction of nitrogen gas and then to form a LIN that can be transported to a resource location and used as a refrigeration source for the production of LNG. Related to non-conventional LNG cycles. U.S. Pat. No. 3,400,547 describes the shipping of liquid nitrogen or liquid air from the market to the field where it is used to liquefy natural gas. U.S. Pat. No. 3,878,689 describes the process of producing LNG using LIN as a freezing source. U.S. Pat. No. 5,139,547 describes the use of LNG as a refrigerant to produce LIN.

The LNG-LIN concept further includes the transport of LNG by ship or tanker from the resource location to the market location and the reverse transport of LIN from the market location to the resource location. The use of the same vessel or tanker and perhaps the use of a common onshore tank capacity is expected to minimize costs and required infrastructure. As a result, some contamination of LNG by LIN and some contamination of LIN by LNG may be expected. Contamination of LNG by LIN is a major concern as natural gas specifications for pipelines and similar distribution means (such as those promulgated by the US Federal Energy Regulatory Commission) take into account the presence of some inert gas. Is unlikely. However, since LINs will eventually be ventilated to the atmosphere at resource sites, LNG pollution of LINs (greenhouse gases that have more than 20 times the impact of carbon dioxide) is subject to such aeration. Must be reduced to acceptable levels. Techniques for removing residual contents of tanks are known, but they achieve the low levels of contamination required to avoid LIN or evaporative nitrogen treatment at resource sites before venting gaseous nitrogen (GAS). However, it may not be economical or environmentally acceptable.

US Provisional Patent Application No. 62 / 458,127 U.S. Pat. No. 3,400,547 U.S. Pat. No. 3,878,689 U.S. Pat. No. 5,139,547 U.S. Patent Application Publication No. 2010/0251763

U.S. Patent Application Publication No. 2010/0251763 describes a variant of the LNG liquefaction process that uses both LIN and liquefied carbon dioxide (CO _{2) as the refrigerant.} Although CO ₂ is a greenhouse gas in its own right, _{it is unlikely that liquefied CO 2} will share storage or transport facilities with LNG or other greenhouse gases, and therefore the potential for contamination is low. However, the LIN can also be contaminated as described above and must be decontaminated before the resulting GAN stream is aerated. In addition to this, the LNG liquefaction system can be supplemented by precooling the natural gas with propane, mixed components, or other closed freezing cycles in addition to the once-through freezing provided by evaporation of the LIN. In these cases, decontamination of gaseous nitrogen is still considered necessary before aerating the GAN. What is needed is a method of producing LNG using LIN as a coolant, which can efficiently remove any greenhouse gas present in the LIN when LIN and LNG use a common storage facility. be.

The present invention provides a liquefied natural gas generation system according to the disclosed aspects. Natural gas streams are sourced from natural gas supplies. The liquid nitrogen stream is supplied from the liquid nitrogen supply. The natural gas compressor compresses the natural gas stream to a pressure of at least 135 bara to form a compressed natural gas stream. The natural gas cooler cools the compressed natural gas stream by indirect heat exchange with the ambient fluid to form a cooled compressed natural gas stream. The first heat exchanger exchanges heat between at least a partially evaporated nitrogen stream and a cooled compressed natural gas stream to form an additional cooled compressed natural gas stream. The work-generated natural gas expander expands the additional cooled compressed natural gas stream to a pressure less than 200 bara but not higher than the pressure at which the natural gas compressor compresses the natural gas stream, thereby forming a cooled natural gas stream. do. The second heat exchanger condenses the chilled natural gas stream at least partially by heat exchange between the chilled natural gas stream and the liquid nitrogen stream to form at least a partially evaporated nitrogen stream, at least. The partially evaporated nitrogen passes through the first heat exchanger.

The present invention also provides a method of producing LNG according to the disclosed aspects. Natural gas streams are provided by natural gas supplies and liquid nitrogen streams are provided by liquid nitrogen supplies. The natural gas stream is compressed in a natural gas compressor to a pressure of at least 135 bara to form a compressed natural gas stream. The compressed natural gas stream is cooled in the natural gas cooler through indirect heat exchange with the ambient fluid to form a cooled compressed natural gas stream. The cooled compressed natural gas stream and at least the partially evaporated nitrogen stream pass through the first heat exchanger. The first heat exchanger exchanges heat between at least a partially evaporated nitrogen stream and a cooled compressed natural gas stream to additionally cool the cooled compressed natural gas stream to form an additional cooled compressed natural gas stream. The additional cooling compressed natural gas stream is expanded to a pressure less than 200 bara in the work-producing natural gas expander but not higher than the pressure at which the natural gas compressor compresses the natural gas stream, thereby cooling the natural gas stream. Generate. The chilled natural gas stream is liquefied by passing the chilled natural gas stream and the liquefied nitrogen stream through a second heat exchanger that exchanges heat between them, and the liquefied nitrogen stream passes through the second heat exchanger. To form at least a partially evaporated nitrogen stream.

The present invention also provides a method of removing greenhouse gas pollutants in a liquid nitrogen stream used to liquefy a natural gas stream. The natural gas stream is compressed in a natural gas compressor to a pressure of at least 135 bara to form a compressed natural gas stream. The compressed natural gas stream is cooled in a natural gas cooler. The cooled compressed natural gas stream and at least the partially evaporated nitrogen stream are passed through the first heat exchanger. The first heat exchanger exchanges heat between at least a partially evaporated nitrogen stream and a cooled compressed natural gas stream and additionally cools the cooled compressed natural gas stream to form an additional cooled compressed natural gas stream. The additional cooled compressed natural gas stream is expanded in the natural gas expander to a pressure less than 200 bara but not higher than the pressure at which the natural gas compressor compresses the natural gas stream, thereby forming a cooled natural gas stream. .. Cooled compressed natural gas streams and liquefied nitrogen streams are passed through a second heat exchanger that exchanges heat between the liquefied and chilled natural gas streams, forming at least a partially evaporated nitrogen stream and cooling. The natural gas stream is at least partially liquefied. The liquefied nitrogen stream is circulated at least three times through the second heat exchanger. The nitrogen stream, at least partially evaporated, passes through the first heat exchanger. The pressure of the at least partially evaporated nitrogen stream can preferably be reduced using at least one inflator service. A greenhouse gas removal unit including a distillation column and a thermal pump condenser and reboiler system will be provided. The pressure and condensation temperature of the overhead stream of the distillation column increase. The overhead stream of the distillation column overhead stream and the bottom stream of the distillation column are cross-exchanged to affect both the overhead condenser load and the bottom reboiler load of the distillation column. The pressure of the distillation column overhead stream is reduced after the unknotting stage to produce a vacuum distillation column overhead stream. The vacuum distillation column overhead stream is separated to produce a first separator overhead stream of gaseous nitrogen from which the greenhouse gases are removed leaving the greenhouse gas removal unit. The first separator overhead stream is ventilated to the atmosphere.

It is a schematic diagram of the system which forms LNG by liquefying natural gas and using liquid nitrogen as only one refrigerant. It is a schematic diagram of the system which forms LNG by liquefying natural gas and using liquid nitrogen as only one refrigerant. It is a schematic diagram of the system which forms LNG by liquefying natural gas and using liquid nitrogen as only one refrigerant. It is a schematic diagram of the system which forms LNG by liquefying natural gas and using liquid nitrogen as only one refrigerant. It is a schematic diagram of the system which forms LNG by liquefying natural gas and using liquid nitrogen as only one refrigerant. It is a schematic diagram of the system which forms LNG by liquefying natural gas and using liquid nitrogen as only one refrigerant. It is a schematic diagram of the system which forms LNG by liquefying natural gas and using liquid nitrogen as only one refrigerant. It is a schematic diagram of the system which forms LNG by liquefying natural gas and using liquid nitrogen as only one refrigerant. It is a schematic diagram of a supplementary freezing system. It is a flow chart of the method of liquefying natural gas to form LNG. It is a flow chart of a method of removing greenhouse gas pollutants in a liquid nitrogen stream used to liquefy a natural gas stream. It is a schematic diagram of the system which forms LNG by liquefying natural gas and using liquid nitrogen as only one refrigerant. It is a schematic diagram of the system which forms LNG by liquefying natural gas and using liquid nitrogen as only one refrigerant. It is a flow chart of the method of generating LNG. It is a flow chart of a method of removing greenhouse gas pollutants in a liquid nitrogen stream used to liquefy a natural gas stream.

Various specific embodiments and versions of the invention, including preferred embodiments and definitions adopted herein, are described herein below. Although the following detailed description illustrates certain preferred embodiments, one of ordinary skill in the art will appreciate that these embodiments are merely exemplary and that the present invention can be practiced using other methods. Any reference to the "invention" may refer to one or more of embodiments defined by the claims, but not all. The use of the title is for convenience purposes only and does not limit the scope of the invention. For clarity and simplification, similar reference numbers in some figures represent similar items, stages, or structures and may not be described in detail in all figures.

All numerical values in the detailed description and claims of the present specification are modified by display values of "about" or "almost" and take into account experimental errors and variations that will be expected by those skilled in the art. ..

As used herein, the term "compressor" means a machine that increases the pressure of a gas by applying work. A "compressor" or "freezing compressor" includes any unit, device, or device capable of increasing the pressure of a gas stream. This includes compressors with a single compression step or stage, or compressors with multi-stage compression or stages, or especially multi-stage compressors in a single casing or shell. The compressed evaporated stream can be provided to the compressor at various pressures. Some stages or stages of the cooling process may involve two or three or more compressors in parallel, in series, or both. The present invention is not particularly limited by the type or arrangement or layout of one or more compressors in any refrigeration circuit.

As used herein, "cooling" broadly refers to lowering and / or reducing the temperature and / or internal energy of a substance by any suitable, desirable, or required amount. Cooling is at least about 1 ° C, at least about 5 ° C, at least about 10 ° C, at least about 15 ° C, at least about 25 ° C, at least about 35 ° C, or at least about 50 ° C, or at least about 75 ° C, or at least about 85 ° C. , Or at least about 95 ° C., or at least about 100 ° C. Cooling can use any suitable heat sink such as steam generator, hot water heating, cooling water, air, refrigerant, other processing streams (integration), and combinations thereof. One or more sources of cooling can be combined and / or cascaded to reach the desired outlet temperature. For the cooling stage, a cooling unit equipped with any suitable device and / or equipment can be used. Depending on some embodiments, cooling can include indirect heat exchange with one or more heat exchangers and the like. In an alternative form, cooling can use evaporation (heat of vaporization) cooling and / or direct heat exchange such as spraying the liquid directly into the processing stream.

As used herein, the term "expansion device" is suitable for reducing the pressure of a row of fluids (eg, a liquid stream, a vapor stream, or a polyphase stream containing both liquid and vapor). Refers to one or more devices. Unless specifically defining a particular type of inflatable device, the inflatable device may be (1) at least partially by isentropic means, or (2) at least partially by isentropic means. Or it can be a combination of both (3) isentropic means and isentropic means. Suitable devices for enthalpy expansion of natural gas are known in the art and are generally not limited to, for example, valves, control valves, "Jule Thomson (J-T)" valves, or Venturi. Includes manual or self-actuated throttle devices such as devices. Suitable devices for isentropic expansion of natural gas are known in the art and generally include equipment such as expanders or turbo expanders that extract or drive work from such expansions. Suitable devices for isentropic expansion of liquid streams are known in the art and are generally of the inflator, hydraulic inflator, liquid turbine, or turbo inflator that extracts or drives work from such expansion. Including equipment such as. Examples of combinations of both isentropic and isoenthalpy means can be parallel "Jule Thomson" valves and turbo expanders, which can be used alone or with J-T valves and turbo expansion. Provides the ability to use both vessels at the same time. Equal enthalpy or isotropic expansion can be performed in any liquid phase, all vapor phase, or mixed phase, from a vapor stream or liquid stream to a polyphase stream (a stream having both vapor and liquid phases), or. It can be done to facilitate a phase change to a single phase stream different from its initial phase. In the description of the drawings herein, more than one reference to an inflatable device in every drawing does not necessarily mean that each inflatable device is of the same type or size.

The term "gas" is used synonymously with "vapor" and is defined as a substance or mixture of substances in a gaseous state to distinguish it from a liquid or solid state. Similarly, the term "liquid" means a substance or mixture of substances in a liquid state to distinguish it from a gas or solid state.

"Heat exchanger" broadly means any device capable of transferring thermal or cold energy from one medium to another, such as between at least two different fluids. Heat exchangers include "direct heat exchange" and "indirect heat exchange". Therefore, the heat exchangers are parallel or countercurrent heat exchangers, indirect heat exchangers (eg, spiral wound heat exchangers or plate fin heat exchangers such as braided aluminum plate fin types), direct contact heat exchangers. Can be of any suitable design, such as shell and tube heat exchangers, spiral, hairpins, cores, core and kettles, printed circuits, double pipes, or any other type of known heat exchanger. can. A "heat exchanger" also allows the passage of one or more streams through it, affecting direct or indirect heat exchange between one or more lines of refrigerant and one or more feed streams. It may refer to any column, tower, unit, or other arrangement that is intended to exert. Heat exchangers as disclosed herein can include multiple heat exchangers as needed or desired.

As used herein, the term "indirect heat exchange" means bringing two fluids into a heat exchange relationship without any physical contact or mixing of the fluids with each other. Core inkettle heat exchangers and brazed aluminum plate fin heat exchangers are examples of equipment that facilitates indirect heat exchange.

As used herein, the term "natural gas" refers to a multi-component gas obtained from a crude oil field (accompanying gas) or from an underground gas-carrying formation (non-accompanying gas). The composition and pressure of natural gas can vary significantly. A typical natural gas stream contains methane (C ₁ ) as a significant component. Natural gas streams may also contain ethane (C ₂ ), higher molecular weight hydrocarbons, and one or more acid gases. Natural gas may also contain small amounts of contaminants such as water, nitrogen, iron sulfide, waxes, and crude oil.

Certain embodiments and features are described using a set of numerical upper bounds and a set of numerical lower bounds. It must be acknowledged that the range from any lower limit to any upper limit is considered unless otherwise instructed. All numbers are displayed as "about" or "almost" and take into account experimental errors and variations that would be expected by those skilled in the art.

All patents, test procedures, and other documents cited in this application are fully incorporated by citation to the extent that such disclosure does not contradict this application and all jurisdictions that allow such incorporation.

Described herein are systems and steps relating to a natural gas liquefaction process using once-through LIN as the primary refrigerant to remove most of the residual LNG contaminants in the LIN prior to aeration of gaseous hydrogen. .. Specific embodiments of the present invention include those shown in the following paragraphs, which are described with reference to the figures. Some features are described with particular reference to just one figure (such as FIGS. 1, 2, or 3), but these can be equally applicable to other figures and other figures. Alternatively, it can be used in combination with the above considerations.

FIG. 1 shows a system 10 that liquefies natural gas so as to produce LNG using liquid nitrogen (LIN) as the only external refrigerant. The system 10 can be called an LNG generation system. The LIN system 12 is accepted from the LIN supply system 14, which can include one or more tankers, tanks, pipelines, or a combination thereof. The LIN supply system 14 can be an alternating service between the LIN storage location and the LNG storage location. The LIN stream 12 may be contaminated with methane, ethane, propane, or other greenhouse gases such as alkanes or alkenes. The LIN stream 12 may be contaminated with greenhouse gases by about 1% by volume, but the level of contamination is to empty and purge the LIN supply system before switching between LIN and LNG storage locations. May vary depending on the method used for. The LIN stream 12 is supplied at or near atmospheric pressure at a temperature of about -196 ° C., which is close to the atmospheric pressure boiling point of pure nitrogen. The LIN stream 12 is sent through a LIN pump 16 that raises the pressure of the LIN from about 20 bara to 200 bara at a preferred pressure of about 90 bara. This pumping step may increase the temperature of the LIN in the LIN stream 12, but it is expected that the LIN will remain substantially in liquid form. The pressurized LIN stream 18 then flows through a series of heat exchangers and expanders to remove heat from the inflowing natural gas supply 20 and condense the natural gas into LNG. Further referring to FIG. 1, the pressurized LNG stream 18 flows through a first heat exchanger 22 in which it cools the natural gas stream 24. The pressurized LIN stream 18 then flows for the first time through a second heat exchanger 26, which again cools the natural gas stream.

After the LIN has passed through the first heat exchanger 22 and the second heat exchanger 26, the LIN and any greenhouse gas pollutants will be completely evaporated to form a polluted gaseous nitrogen (cGAN) stream 27. It is expected to be. When gaseous nitrogen is processed as described further, it may not evaporate completely, even if it is described herein as gaseous nitrogen or cGAN. For simplicity, any mixture of gaseous and partially condensed nitrogen is still referred to as cGAN or gaseous nitrogen.

The cGAN stream 27 is directed to the first inflator 28. The output stream of the first inflator 28, which is the expansion cGAN stream 29, is directed to the greenhouse gas removal unit 30. The pressure of the expanded cGAN stream 29 typically ranges from 5 bara to 30 bara, largely based on the phase envelope of the cGAN mixture, which is a mixture of nitrogen, methane, ethane, propane, and other potential greenhouse gases. In some cases. In one aspect, the pressure of the inflated cGAN stream 29 is 19-20 bara and the temperature of the inflated cGAN stream 29 is about -153 degrees Celsius. However, the temperature of the expanded cGAN stream can be reduced to 1 bara when alternative removal techniques such as adsorption, absorption, or catalytic steps are used.

The greenhouse gas removal unit 30 may be required to generate a GAN stream with a greenhouse gas content of less than 500 ppm, or less than 200 ppm, or less than 100 ppm, or less than 50 ppm, or less than 20 ppm. The greenhouse gas removal unit 30 is required to produce a greenhouse gas production stream with a nitrogen content of less than 80%, or less than 50%, or less than 20%, or less than 10%, or less than 5%. In some cases.

The greenhouse gas removal unit 30 can include a partially refluxed and partially reboiled distillation column 32. The distillation column 32 separates gaseous nitrogen from greenhouse gas pollutants based on the difference in evaporation temperature between nitrogen and greenhouse gases. The output of the distillation column is an overhead stream 34, which is a decontamination gas nitrogen stream, and a bottom product, which is a greenhouse gas production stream 36. Side reboilers, side condensers, and intermediate draws (not shown) can be included to remove the product elsewhere in the distillation column 32.

The greenhouse gas removal unit 30 is supplied by heat exchange with a LIN, GAN, cGAN, natural gas, or LNG source associated with the distillation column 32 and from other parts of the LNG production system or from a supplemental refrigeration system. An overhead condenser with a cooling load can be included. Similarly, the greenhouse gas removal unit is with LIN, GAN, cGAN, natural gas, or LNG associated with the distillation column 32 and from another part of the LNG production system or from another step outside the LNG generation system. It can include a bottom reboiler with a heating load supplied by the heat exchange of. Disadvantages of these types of arrangements are the adverse effects of most condensation and mostly boiling type heating requirements on the entire heating and cooling curve to condense natural gas into LNG. .. These effects can result in a temperature pinch in the heat exchanger that reduces the effectiveness of the available LIN supplies. According to the present invention, the condenser and reboiler cooling and heating loads are cross-exchanged to meet the high temperature load required by the condenser using the cold load available from the reboiler. To achieve this, the pressure of the column overhead stream 34 is increased using a heat pump condenser and reboiler system so that the temperature of the compressed overhead stream is higher than the temperature of the greenhouse gas production stream 36. Let me. Specifically, the heat pump condenser and re-boiling system includes an overhead compressor 38 that compresses and heats the overhead stream 34, and a heat pump heat exchanger 40 that cools the overhead stream and heats the greenhouse gas production stream. Includes, a pressure drop device 42 that reduces the pressure of the cooling overhead stream to reduce that pressure. The pressure drop device 42 can be a Jules Thomson valve or a turbo expander. At this point, the overhead stream is a partially condensed overhead stream 43. If desired, a first separator 44 can be used to separate the partially condensed overhead stream 43 to form the overhead generation stream 45 and the column reflux stream 46. The overhead generation stream 45, which is the overhead product of both the distillation column 32 and the first separator 44, is composed of a substantially decontaminated GAN of greenhouse gases such as methane, ethane, etc. Exit the greenhouse gas removal unit 30 for yet another heat exchange operation and aeration as described in. Since the column reflux stream 46 may contain some greenhouse gases, the column reflux stream is sent back to the distillation column 32 for yet another separation step.

Other parts of the heat pump condenser and reboiler system include a bottom pump 48, which can pump the greenhouse gas production stream 36 to the heat pump heat exchanger 40 at increased pressure. After being heated by the heat pump heat exchanger 40, the greenhouse gas production stream 36 is here partially evaporated, separating the partially evaporated greenhouse gas production stream into separate greenhouse gas production streams 54 and towers. It can be sent to a second separator 50 that forms the reboiler steam stream 56. The greenhouse gas pump 58 can be used to deliver the separated greenhouse gas production stream 54 to another location in the system 10 at the required pressure. In the embodiment shown in FIG. 1, the separated greenhouse gas production stream 54 mixes with the natural gas stream 24 after passing through the second heat exchanger 26 so that the natural gas stream 24 is included in the LNG generation stream of the system 10. Will be done. The column reboiler stream 56, which can contain a portion of the GAN, is returned to the distillation column 32 for yet another separation step.

The overhead generation stream 45, which is a substantially decontaminated GAN, exits the greenhouse gas removal unit 30 and repeatedly passes through the second heat exchanger 26 and the second and third expanders 60, 62. The natural gas stream 24 is further cooled. FIG. 1 shows three inflators acting as high pressure inflator (28), medium pressure inflator (60), and low pressure inflator (62), each of which passes through it. Reduce the pressure of the nitrogen stream. In some embodiments, the first, second, and third inflators 28, 60, 62 are turbo inflators. The expander can be a radial inflow turbine, a partially intake axial flow turbine, a fully open intake axial flow turbine, a reciprocating engine, a spiral screw turbine, or a similar expansion device. The inflator can be a separate machine or can be combined with one or more machines with a common output. The inflator can be designed to drive a generator, compressor, pump, water brake, or any similar power consuming device to remove energy from the system 10. Inflators can be used to directly drive (or drive through gearboxes or other transmission devices) pumps, compressors, and other machines used within the system 10. In some embodiments, each inflator is an inflator service, and expansion can be performed by one or more individual inflator devices operating in parallel or in series or a combination of parallel and series operations. One or more inflator or inflator services need to operate the system 10 economically, and generally at least two inflator services are provided. More than 3 inflator services can also be used in this system and the available LIN supplies can potentially further improve the effectiveness of freezing.

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After passing through the final third inflator 62 and the second heat exchanger 26, the overhead generation stream 45 passes through a third heat exchanger 64 that cools the natural gas stream 24 once more. The overhead generation stream, which is GAN as described above, is ventilated to the atmosphere at the GAN vent 66 or otherwise disposed of. When the GAN is aerated, the GAN plume is widely distributed and diluted by the atmosphere before any significant portion of the plume returns to near basal levels, which can result in potentially harmful oxygen deficiency. Must be sufficiently buoyant to be. The GAN is likely to have an essentially zero relative humidity and specific density slightly lower than the ambient air, and embodiments ensure a GAN aeration temperature higher than the local ambient temperature, improving buoyancy and GAN. The plume should be dissipated easily. Those skilled in the art of ventilated and vented stack designs will, for example, improve plume dissipation, including stack height modifications and the provision of faster stack outlets that can be provided by Venturi features as part of the stack design. Know alternatives to temperature.

The path of natural gas through the system 10 is now described below. The natural gas supply 20 is accepted through a variety of heat exchangers in series, in parallel, or in series and in parallel, which are accepted at a certain pressure or compressed to the desired pressure and then cooled by one or more refrigerants. It flows. The natural gas pressure provided to the system 10 is typically 20 to 100 bara, the upper pressure of which is generally limited by the economic choice of heat exchange equipment. Further advances in heat exchanger design allow supply pressures of 200 bara or higher. In a preferred embodiment, the natural gas supply pressure is selected at about 90 bara. Those skilled in the art know that increasing the natural gas supply pressure generally improves the heat exchange effectiveness within the LNG liquefaction process. As shown in FIG. 1, the natural gas from the natural gas supply 20 first flows through the third heat exchanger 64. The third heat exchanger precools the natural gas before entering the second heat exchanger 26, which is the main heat exchanger of the system 10. The third heat exchanger also warms the GAN in the overhead generation stream 45 to near the inflow temperature of the natural gas stream. The third heat exchanger 64 can be removed from the system 10 if desired.

After leaving the first heat exchanger, the natural gas stream 24 is cooled and condensed by the pressure of the second heat exchanger 26, where the natural gas stream is some of the GANs in the overhead generation stream 45. It is cooled by the path of. The natural gas stream 24 is fused with a separated greenhouse gas producing stream 54, which is a greenhouse gas from which substantially all GAN has been removed, as described above. The natural gas stream 24 then passes through a first heat exchanger 22 that cools the natural gas stream 24 using the LIN from the LIN supply system 14. The first heat exchanger 22 can be removed from the system 10 if necessary. At this point, the natural gas in the natural gas stream 24 is substantially completely liquefied to form LNG. Compressed high pressure LNG is reduced to near atmospheric pressure through a decompression device 68, which can include single-phase or multi-phase hydraulic turbines, Jules Thomson valves, or similar decompression devices. FIG. 1 shows the use of a hydraulic turbine. The LNG stream 70 exiting the decompression device 68 is then stored in a tank and delivered to a land or water tanker, eventually into a cold pipeline or similar means of transportation suitable for delivering LNG to a market location. Can be sent.

The distillation tower 32 of the greenhouse gas removal unit 30 meets the specifications required for the greenhouse gas content of the overhead production stream 45 and the nitrogen content of the greenhouse gas production stream 36 and / or the separated greenhouse gas production stream 54. May be controlled by. In general, the temperature and evaporated fraction of the expanded cGAN stream 29 will affect the relative condenser and reboiler loads, and higher evaporated or higher temperatures of the expanded cGAN stream 29 will affect the relative condenser and reboiler loads. Increase the condenser load while reducing the reboiler load in the same product specifications. Lower evaporative fractions or lower temperatures of the expanded cGAN stream 29 have the opposite effect. In addition, an increase (or decrease) in heat transfer coefficient within the heat pump heat exchanger 40 tends to increase (or decrease) both the condenser and reboiler loads, affecting product specifications. Condenser and reboiler loads (added by overhead compressor 38) using controller 72 to regulate both the temperature and / or evaporation fraction of the expanding cGAN stream 29 and the heat transfer coefficient of the heat pump heat exchanger 40. It is possible to balance both the product specifications of the distillation column 32) and the extra energy that is adjusted. In fact, these controls can be achieved by adjusting the inlet temperature of the first turbo expander 28 and by controlling the pressure rise of the tower overhead compressor 38. Alternatively, other components of the system 10 can be controlled to achieve the same result.

Having described aspects of the invention, additional aspects will now be described below. FIG. 2 shows an LNG generation system 200 similar to the system 10 of FIG. The LNG generation system 200 is a natural gas compressor used to pressurize and cool natural gas to an optimum temperature and to temperatures before entering the third, second, and first heat exchangers 64, 26, 22. 202 and natural gas cooler 204 are further included. The natural gas compressor 202 and the natural gas cooler 204 can be a plurality of individual compressors and coolers or a single compressor stage and cooler. The natural gas compressor 202 can be selected from compressor types generally known to those of skill in the art, including centrifugal, axial, screw, and reciprocating type compressors. Natural gas cooler 204 can be selected from cooler types generally known to those of skill in the art, including fins, double pipes, shells and tubes, plates and frames, spirals, and printed circuit type heat exchangers. can. The natural gas supply pressure following the natural gas compressor 202 and the natural gas cooler 204 should be similar to the above range (eg, up to 20-100 bara, and 200 bara, or more as heat exchanger design advances. Up to high).

FIG. 3 shows an LNG generation system 300 similar to the LNG generation system 200. The LNG generation system 300 adds a natural gas expander 302 following the natural gas compressor 202 and the natural gas cooler 204. The natural gas inflator 302 can be any type of inflator, such as a turbo inflator or another type of decompression device such as a J-T valve. In the LNG generation system 300, the discharge pressure of the natural gas compressor 202 may rise beyond the range indicated by the economical choice of heat exchange equipment and the extra pressure reduced through the natural gas expander 302. The combination of compression, cooling, and expansion further precools the natural gas supply before entering the third heat exchanger 64 or the second heat exchanger 26. For example, the natural gas compressor 202 can compress the natural gas supply to a pressure higher than 135 bara, and the natural gas expander has a natural gas pressure of less than 200 bara, in which case the natural gas is natural. It can be reduced to a point where it does not exceed the pressure at which the gas is compressed. In some embodiments, the natural gas stream is compressed by a natural gas compressor to a pressure higher than 200 bara. In another embodiment, the natural gas expander expands the natural gas stream to a pressure of less than 135 bara. However, the location of the third heat exchanger 64 downstream of the natural gas expander 302 (as shown in FIG. 3) significantly lowers the temperature of the GAN passing through the third heat exchanger 64. The temperature of the GAN thus cooled can be well below the local ambient temperature, thereby making efforts to reliably and / or efficiently ventilate the GAN into the atmosphere.

FIG. 4 shows an LNG generation system 400 similar to the LNG generation system 300. In the LNG generation system 400, the third heat exchanger 64 is positioned to enter the third heat exchanger before the natural gas from the natural gas supply 20 passes through the natural gas compressor 202. By arranging the third heat exchanger 64 as shown in FIG. 4, the temperature of the natural gas exiting the natural gas compressor 202 is reduced, and thus the pressure and power required by the natural gas compressor 202 is reduced. do. Further, the GAN aeration 66 temperature is restored to be similar to the embodiment shown in FIG.

FIG. 5 shows an LNG generation system 500 similar to the LNG generation systems 300 and 400. In the LNG generation system 500, the third heat exchanger 64 is positioned between the natural gas compressor 202 and the natural gas cooler 204. This arrangement sacrifices the potential power reduction of the natural gas compressor 202 provided by the LNG generation system (FIG. 4), but results in a significant increase in GAN aeration temperature, significantly increasing GAN plume buoyancy and dissipation. To improve. This arrangement also reduces the cooling load on the natural gas cooler 204, thus reducing the size, cost of capital, and operation of the natural gas cooler 204 and its associated support systems (eg, cooling water, air fin power supplies, etc.). Reduce costs.

FIG. 6 shows an LNG generation system 600 similar to the LNG generation system 400. In the LNG generation system 600, the GAN in the overhead generation stream 45 is an additional heat pump in the heat pump system as the overhead generation stream circulates through the second heat exchanger 26 and the second and third expanders 60, 62. Exposed to freezing. As shown in FIG. 6, the thermal pump system includes a nitrogen compressor 602, a nitrogen cooler 604, and a feed-outflow heat exchanger 606 is added upstream of the third expander 62. The addition of this combination of nitrogen compressor 602, nitrogen cooler 604, and feed-outflow heat exchanger 606 at the inlet of the third inflator 62 has a slight increase to the inlet temperature of the third inflator 62. Increase the available pressure. This combination of nitrogen compressor 602, nitrogen cooler 604, and feed-outflow heat exchanger 606 increases the power generated by the third inflator 62 and flows through this portion of the LNG generation system 600. Increases the heat removed from the GAN in the overhead generation stream 45. This combination also results in a lower GAN temperature that re-enters the second heat exchanger 26 compared to FIG. 4, resulting in increased effectiveness of the LIN supply available in the LNG generation system 600.

FIG. 7 shows an LNG generation system 700 similar to the LNG generation system 10, where alternative uses of the separated greenhouse gas generation stream 54 are shown. As shown in FIG. 1, instead of mixing the separated greenhouse gas producing stream 54 with the natural gas stream 24, the separated greenhouse gas producing stream 54 is compressed to the required pressure in the greenhouse gas pump 58 and exchanges heat. It can be used as a fuel gas supply 702 after being re-evaporated through one or more of the vessels. As an example, FIG. 7 shows a separated greenhouse gas production stream 54 passing through a third heat exchanger 64. Other uses of the separated greenhouse gas production stream are possible and are generally known to those of skill in the art.

FIG. 8 shows an LNG generation system 800 similar to the LNG generation systems 10, 200, 400, and 600. In the LNG generation system 800, a very dry composition of GAN in the overhead generation stream 45 is used to achieve yet another cooling in the LNG generation system 800. Humidity measurement cooling of the GAN in the overhead generation stream 45 is within a few degrees Celsius of the freezing temperature of the water or the overhead generation stream after the overhead generation stream 45 has passed through the third heat exchanger 64, as shown in FIG. The temperature of the stream can be reduced to about 2-5 degrees Celsius by adding and saturating water 802 relative to 45. The GAN stream 804, which is currently wet and saturated at that low temperature, can be rerouted through a third heat exchanger 64 (or any other suitable heat exchanger) to further precool the inflow natural gas stream. .. Those skilled in the art will appreciate many techniques for spraying water into a flowing GAN stream through cloud fog or other nozzles, or in water, filling materials, or towers, towers, or cooling tower-like devices on GANs and trays. It will be acknowledged that it is available to achieve this humidity measurement cooling, including the passage of other heat and mass transport devices. Alternatively, the cooling water or another heat transfer fluid can be further cooled through such humidity measurement cooling by passing a very dry GAN through a cooling tower-like device. This yet another cold cooling water can then be used to precool the other streams in the LNG generation stream 800 to increase the effectiveness of the available LIN supply. Finally, adding water vapor to the otherwise very dry gaseous nitrogen reduces the specific gravity of the GAN to improve GAN plume flotation and dissipation when the GAN is aerated at 806.

Each of the included figures shows the greenhouse gas removal unit 30 as part of the LNG generation system 10, 200, 300, 400, 500, 600, 700, 800, where the greenhouse gas removal unit is a distillation technique or It is shown based on the method. Alternative systems and methods can be used to remove greenhouse gas pollutants from LIN Supply 14. Although these alternative methods are not specifically shown, they may include a pressure swing, a temperature swing, or an adsorption step involving pressure and temperature swing adsorption, bulk adsorption or absorption by an activated carbon layer or the like, or a catalytic step.

The heat exchangers of the disclosed embodiments are described as being cooled solely by LIN, GAN, or a combination thereof originating from the LIN supply 14. However, it is possible to enhance the cooler capacity of any of the disclosed heat exchangers by using a supplemental refrigeration system that is not fluid connected to natural gas or nitrogen in the LNG generation system 10. Supplement Refrigerants used by refrigeration systems are any suitable hydrocarbon gas (eg, alkanes or alkanes such as methane, ethane, ethylene, propane, etc.), inert gases (eg, nitrogen, helium, argon, etc.) ), Or other refrigerants known to those skilled in the art. FIG. 9 shows a supplementary refrigeration system 900 that provides additional cooling functionality to the heat pump heat exchanger 40 of the greenhouse gas removal unit 30 that uses argon stream 902 as the refrigerant. The freezing system 900 includes an auxiliary compressor 904 that compresses the argon stream 902 to a favorable pressure. The argon stream 902 then passes through the supplemental heat exchanger shown in FIG. 9 as the cooler 906. The argon stream 902 then passes through a supplemental decompression device 908 such as a Jules Thomson valve or inflator. The argon stream 902 then passes through the heat pump heat exchanger 40 to supplement the cooling efforts of the GAN in the column overhead stream 34 and cool the greenhouse gases in the greenhouse gas production stream 36. The argon stream 902 is then recirculated through the auxiliary compressor 904 as described above.

Using a supplementary refrigeration system similar to the supplementary refrigeration system 900, a first heat exchanger 22, a second heat exchanger 26, a third heat exchanger 64, and / or a feed-outflow heat exchanger 606. The cooling effect of other heat exchangers disclosed herein, such as, can be enhanced. Further, the refrigerant of the supplementary refrigeration system 900 is not fluidly connected to the LNG generation system 10, but in some embodiments the refrigerant may originate from the natural gas stream and / or nitrogen stream of the LNG generation system. can. In addition, the supplemental heat exchanger 904 heat exchanges with the gaseous and / or liquid stream of the LNG generation system 10 such as the LIN stream 12, the natural gas stream 24, the cGAN stream 27, or the greenhouse gas production stream 36 ( Or it can be cooled).

FIG. 10 shows a method 1000 for producing LNG according to the disclosed aspects. At block 1002, the natural gas stream is provided by the natural gas supply. At block 1004, a refrigerant stream, such as a LIN stream, is provided by the refrigerant supply. In block 1006, the natural gas stream and the liquefied nitrogen stream are heat exchanged between the refrigerant stream and the natural gas stream to at least partially evaporate the refrigerant stream and at least partially condense the natural gas stream in a first heat exchange. Can be passed through the vessel. At block 1008, the natural gas stream is compressed in a natural gas compressor to a pressure of at least 135 bara to form a compressed natural gas stream. At block 1010, the compressed natural gas stream is cooled in a natural gas cooler. After being cooled by the natural gas cooler, at block 1012, the compressed natural gas stream expands to a pressure in the natural gas expander that is less than 200 bara but not higher than the pressure at which the natural gas compressor compresses the natural gas stream. Will be done. At block 1014, the natural gas from the natural gas cooler is supplied to at least one heat exchanger so that it is at least partially condensed therein.

FIG. 11 shows a method 1100 for removing greenhouse gas contaminants in a liquid nitrogen stream used to liquefy a natural gas stream. At block 1102, the natural gas stream is compressed in the natural gas compressor to a pressure of at least 135 bara to form a compressed natural gas stream. At block 1104, the compressed natural gas stream is cooled in a natural gas cooler. After being cooled by the natural gas cooler, at block 1106, the compressed natural gas stream expands to a pressure in the natural gas expander that is less than 200 bara but not higher than the pressure at which the natural gas compressor compresses the natural gas stream. Will be done. At block 1108, the natural gas stream and the liquefied nitrogen stream are first heat-exchanged between the liquefied nitrogen stream and the natural gas stream to at least partially evaporate the liquefied nitrogen stream and at least partially condense the natural gas stream. Passed through a heat exchanger. The liquefied nitrogen stream is circulated through the first heat exchanger at least once, and preferably at least three times. At block 1110, the pressure of the at least partially evaporated nitrogen stream can preferably be reduced using at least one inflator service. At block 1112, a greenhouse gas removal unit is provided that includes a distillation column and a heat pump condenser and reboiler system. At block 1114, the pressure and condensation temperature of the overhead stream of the distillation column rises. At block 1116, the overhead stream of the distilling tower overhead stream and the bottom stream of the distilling tower are cross-exchanged to affect both the overhead condenser load and the bottom reboiler load of the distilling tower. At block 1118, the pressure of the distillation column overhead stream drops after the unknotting step, creating a vacuum distillation column overhead stream. At block 1120, the vacuum distillation column overhead stream is separated to create a first separator overhead stream of gaseous nitrogen from which the greenhouse gases are removed leaving the greenhouse gas removal unit. At block 1122, the first separator overhead stream is ventilated to the atmosphere.

12 and 13 show LNG generation systems 1200 and 1300 similar to the LNG generation system 600 shown in FIG. However, the LNG generation system 1200 does not include the greenhouse gas removal unit 30 of the system 600. The elements of FIGS. 12 and 13 having the same reference numbers as the elements of the previous figure are the same as or similar to the respective above-mentioned elements. With respect to the LNG generation system 1200, instead of the overhead generation stream 45 of the greenhouse gas removal unit 30 entering the second heat exchanger 26, the expanding cGAN stream 29 is guided through the second heat exchanger 26 and the stream is second. Additional refrigeration is performed as it circulates through the heat exchanger 26 of 2 and the second and third expanders 60, 62. The LNG generation systems 1200 and 1300 further add to the natural gas compressor 1202 and natural gas cooler 1204 used to pressurize and cool the natural gas to optimum pressure and temperature before entering the third heat exchanger 64. include. The natural gas compressor 1202 and the natural gas cooler 1204 are similar to the natural gas compressor 202 and the natural gas cooler 204 described above. The natural gas supply pressure after the natural gas compressor 1202 and the natural gas cooler 1204 should be similar to the above range (eg, from 20 to 100 bara, and up to 200 bara, or as heat exchanger design advances. Up to higher). The natural gas exiting the natural gas cooler 1204 enters the third heat exchanger 64, where it is natural in the high pressure natural gas expander 302 using the evaporated low pressure nitrogen exiting the second heat exchanger 26. Cool the natural gas just before expanding the gas stream. By using the available coldness of the evaporated low pressure nitrogen to further cool the natural gas stream, the amount of precooling provided by the high pressure compression and expansion steps is increased. For the configurations shown in FIGS. 12 and 13, the required liquid nitrogen to LNG ratio is, as shown in FIG. 6, the liquid nitrogen to LNG ratio of the configuration having a natural gas compressor, a natural gas cooler, and a high pressure natural gas expander. It can be reduced to 2.5% compared to.

FIG. 14 shows a method 1400 for producing LNG according to the disclosed aspects. At block 1402, the natural gas stream is provided by the natural gas supply. At block 1404, the liquid nitrogen stream is provided by the liquid nitrogen supply. At block 1406, the natural gas stream is compressed to at least 135 bara in the natural gas compressor to form a compressed natural gas stream. At block 1408, the compressed natural gas stream is cooled through indirect heat exchange with the ambient fluid in the natural gas cooler to form a cooled compressed natural gas stream. At block 1410, the cooled compressed natural gas stream and at least the partially evaporated nitrogen stream are passed through the first heat exchanger. The first heat exchanger exchanges heat between at least a partially evaporated nitrogen stream and a cooled compressed natural gas stream and additionally cools the cooled compressed natural gas stream to form an additional cooled compressed natural gas stream. At block 1412, the additional cooled compressed natural gas stream was expanded in the work-generated natural gas expander to a pressure of less than 200 bara, but not higher than the pressure at which the natural gas compressor compresses the natural gas stream, thereby cooling. Produces a natural gas stream. At block 1414, the chilled natural gas stream is liquefied by passing the chilled natural gas stream and the liquefied nitrogen stream through a second heat exchanger that exchanges heat between them, and the liquefied nitrogen stream is the second heat. It passes through the exchanger to form a stream of nitrogen that is at least partially evaporated.

FIG. 15 shows a method 1500 for removing greenhouse gas contaminants in a liquid nitrogen stream used to liquefy a natural gas stream. At block 1502, the natural gas stream is compressed in the natural gas compressor to a pressure of at least 135 bara to form a compressed natural gas stream. At block 1504, the compressed natural gas stream is cooled in a natural gas cooler. At block 1506, the cooled compressed natural gas stream and at least the partially evaporated nitrogen stream are passed through the first heat exchanger. The first heat exchanger exchanges heat between at least a partially evaporated nitrogen stream and a cooled compressed natural gas stream and additionally cools the cooled compressed natural gas stream to form an additional cooled compressed natural gas stream. At block 1508, the additional cooled compressed natural gas stream is expanded to a pressure in the natural gas expander that is less than 200 bar, but not higher than the pressure at which the natural gas compressor compresses the natural gas stream, thereby cooling the natural gas. Form a stream. At block 1510, the cooled compressed natural gas stream and the liquefied nitrogen stream are passed through a second heat exchanger that exchanges heat between the liquefied and chilled natural gas stream, forming at least a partially evaporated nitrogen stream. The chilled natural gas stream is at least partially liquefied. The liquefied nitrogen stream is circulated at least three times through the second heat exchanger. The nitrogen stream, at least partially evaporated, passes through the first heat exchanger. At block 1512, the pressure of the at least partially evaporated nitrogen stream can preferably be reduced using at least one inflator service. At block 1514, a greenhouse gas removal unit is provided that includes a distillation column and a heat pump condenser and reboiler system. At block 1516, the pressure and condensation temperature of the overhead stream of the distillation column increase. At block 1518, the overhead stream of the distilling tower overhead stream and the bottom stream of the distilling tower are cross-exchanged to affect both the overhead condenser load and the bottom reboiler load of the distilling tower. At block 1520, the pressure of the distillation column overhead stream drops after the unknotting step, creating a vacuum distillation column overhead stream. At block 1522, the vacuum distillation column overhead stream is separated to produce a first separator overhead stream of gaseous nitrogen leaving the greenhouse gas removal unit from which the greenhouse gases have been removed. At block 1524, the first separator overhead stream is ventilated to the atmosphere.

Embodiments and embodiments provide an effective method of removing greenhouse gas pollutants from LIN streams used to liquefy natural gas. An advantage of the present invention is that the heat pump system within the greenhouse gas removal unit 30 eliminates the need for an external heating or cooling source to separate the greenhouse gases from nitrogen.

Another advantage of efficient removal of greenhouse gases from LIN is that the LIN storage facility can be used more economically as an LNG storage facility, thereby increasing the footprint of the liquid natural gas production facility. to shrink.

Yet another advantage is the ability to aerate gaseous nitrogen without the unwanted release of greenhouse gases into the atmosphere.

The exemplary embodiments discussed herein in connection with FIGS. 1-11 relate to generated LNG using LIN as the primary coolant, but those skilled in the art will appreciate that this principle is based on other cooling methods and cooling. You will understand that it applies to the agent. For example, the disclosed methods and systems can be used when there is no common storage for LNG and LIN and it is desirable to simply purify the coolant used for LNG or other liquefaction methods.

Embodiments of the invention can include any combination of methods and systems shown in the numbered paragraphs below. This is not considered to be a complete list of all possible embodiments, as any number of variants can be envisioned from the above description.
1. 1. Indirect of the natural gas stream from the natural gas supply, the liquid nitrogen stream from the liquid nitrogen supply, the natural gas compressor that compresses the natural gas stream to a pressure of at least 135 bara to form a compressed natural gas stream, and the ambient fluid. Additional cooling compressed natural gas by heat exchange between a natural gas cooler that cools the compressed natural gas stream by heat exchange to form a cooled compressed natural gas stream and at least a partially evaporated nitrogen stream and a cooled compressed natural gas stream. The first heat exchanger forming the stream and the additional cooling compressed natural gas stream are expanded to a pressure less than 200 bara but not higher than the pressure at which the natural gas compressor compresses the natural gas stream, thereby cooling the natural gas stream. The work-generated natural gas expander that forms the gas stream and the chilled natural gas stream by heat exchange between the chilled natural gas stream and the liquid nitrogen stream are at least partially condensed and passed through the first heat exchanger. A liquefied natural gas production system that includes a second heat exchanger that forms at least a partially evaporated nitrogen stream.
2. The liquefied natural gas generation system of paragraph 1 in which the natural gas compressor compresses the natural gas stream to a pressure higher than 200 bara.
3. 3. The liquefied natural gas production system of either paragraph 1 or 2 in which the natural gas expander expands the additional cooling compressed natural gas stream to a pressure of less than 135 bara.
4. The liquefied natural gas production system of any of paragraphs 1 to 3, wherein the liquid nitrogen supply is produced at different locations in the liquefied natural gas production system and transported as a liquid to the liquefied natural gas production system.
5. The liquefied natural gas generation system according to any one of paragraphs 1 to 4, wherein at least a partially evaporated nitrogen stream is released into the environment as vapor after passing through a first heat exchanger.
6. The liquefied natural gas generation system of paragraph 1 in which the first heat exchanger comprises at least one printing circuit heat exchanger.
7. The liquefied natural gas production system of paragraph 1 further comprising a greenhouse gas removal unit configured to remove greenhouse gases from at least a partially evaporated nitrogen stream.
8. The greenhouse gas removal unit includes a distillation column with a thermal pump condenser and re-boiling system, and further includes at least one expander service that reduces the pressure of the partially evaporated nitrogen stream of the distillation column. The liquefied natural gas generation system of paragraph 7, wherein the inlet stream is the outlet stream of the first of at least one expander service.
9. The liquefied natural gas production system of paragraph 8 further comprising a thermal pump system in which at least a partially evaporated nitrogen stream flows after flowing through the first of at least one inflator service.
10. The liquefied natural gas generation system of paragraph 9, wherein the heat pump system includes a heat pump compressor, a heat pump cooler, and a feed-outflow heat exchanger.
11. Any one of paragraphs 1-8, further comprising a humidity measuring heat exchanger that precools the natural gas stream before it enters the first heat exchanger using at least a partially evaporated nitrogen stream. Liquefied natural gas generation system.
12. The liquefied natural gas production system of any one of paragraphs 1-11, wherein the natural gas cooler is configured to cool the compressed natural gas stream to approximately ambient temperature after being compressed by the natural gas compressor.
13. It further comprises a first nitrogen expander that expands at least a partially evaporated nitrogen stream to form a first cold nitrogen gas stream, allowing the first cold nitrogen gas stream to pass through a second heat exchanger. A liquefied natural gas producing system according to any one of paragraphs 1-12, which condenses at least a partially cooled natural gas stream to form a first warm nitrogen gas stream.
14. It further comprises a second nitrogen expander that expands the first warm nitrogen gas stream to form a second cold nitrogen gas stream, and the second cold nitrogen gas stream is passed through the second heat exchanger. The liquefied natural gas generation system of paragraph 13, which condenses at least a partially cooled natural gas stream to form a second warm nitrogen gas stream.
15. Nitrogen cooling that compresses a second warm nitrogen gas stream to form a compressed nitrogen gas stream and cools the compressed nitrogen gas stream by indirect heat exchange with an ambient temperature fluid to form a cold compressed nitrogen gas stream. A third cold nitrogen gas stream is allowed to pass through a second heat exchanger, including a vessel and a third nitrogen expander that expands the cold compressed nitrogen gas stream to form a third cold nitrogen gas stream. The liquefied natural gas generation system of paragraph 14, which condenses at least a partially cooled natural gas stream to form a third warm nitrogen gas stream.
16. Liquefied paragraph 15 where the third warm nitrogen gas stream is at least partially evaporated nitrogen stream which is heat exchanged with the cooled compressed natural gas stream in the first heat exchanger to form an additional cooled compressed natural gas stream. Natural gas generation system.
17. The liquefied natural gas generation system according to any one of paragraphs 1 to 16, wherein the first heat exchanger comprises at least two heat exchangers and the second heat exchanger comprises at least two heat exchangers.
18. The steps of supplying a natural gas stream from a natural gas supply, the steps of supplying a liquid nitrogen stream from a liquid nitrogen supply, and the natural gas stream in a natural gas compressor to a temperature of at least 135 bara to form a compressed natural gas stream. The stage of compression, the stage of cooling the compressed natural gas stream to form a cooled compressed natural gas stream by indirect heat exchange with the ambient fluid in the natural gas cooler, and the cooling compressed natural gas stream and at least partially evaporating. A first heat exchanger that exchanges heat between the nitrogen stream that has at least partially evaporated and the cooled compressed natural gas stream and additionally cools the cooled compressed natural gas stream to form an additional cooled compressed natural gas stream. Passing and additional cooling in the work-generated natural gas expander The compressed natural gas stream was expanded to a pressure of less than 200 bara but not higher than the pressure at which the natural gas compressor compresses the natural gas stream, thereby cooling. A second step of producing a natural gas stream and a second heat exchange between the cold natural gas stream and a liquid nitrogen stream that passes through a second heat exchanger to form at least a partially evaporated nitrogen stream. A method of producing liquefied natural gas (LNG), which comprises the steps of liquefying a cooled natural gas stream by passing it through a heat exchanger.
19. The method of paragraph 18 in which the natural gas compressor compresses the natural gas stream to a pressure higher than 200 bara and the natural gas expander expands the additional cooling compressed natural gas stream to a pressure less than 135 bara.
20. A step of expanding at least a partially evaporated nitrogen stream in a first nitrogen expander to form a first cold nitrogen gas stream and a first condensing of at least a partially cooled natural gas stream. A step of passing a second heat exchanger through a first cold nitrogen gas stream to form a warm nitrogen gas stream and a second in a second nitrogen expander to form a second cold nitrogen gas stream. A second heat exchange to the second cold nitrogen gas stream to form a second warm nitrogen gas stream by condensing at least a partially cooled natural gas stream with the step of expanding one warm nitrogen gas stream. The step of passing through the vessel, the step of compressing the second warm nitrogen gas stream in the nitrogen compressor to form a compressed natural gas stream, and the surroundings in the nitrogen cooler to form a cold compressed nitrogen gas stream. A step of cooling the compressed nitrogen gas stream by indirect heat exchange with a thermal fluid and a step of expanding the cold compressed nitrogen gas stream in a third nitrogen expander to form a third cold nitrogen gas stream, at least. Paragraph 18 or paragraph further comprising the step of passing a second heat exchanger through a third cold nitrogen gas stream to condense the partially cooled natural gas stream to form a third warm nitrogen gas stream. 19 methods.
21. The method of paragraph 20 in which the third warm nitrogen gas stream is at least a partially evaporated nitrogen stream that exchanges heat with the cooled compressed natural gas stream in the first heat exchanger to form an additional cooled compressed natural gas stream. ..
22. The method of paragraph 20 further comprising removing greenhouse gases from at least partially evaporated nitrogen streams using a greenhouse gas removal unit.
23. A greenhouse gas removal unit includes a distillation column and a thermal pump condenser and reboiler system, in which the method raises the pressure and condensation temperature of the overhead stream of the distillation column, and the overhead stream and distillation of the distillation column. Distillation column overhead after the cross-exchange stage to cross-exchange the bottom stream of the column to affect both the overhead condenser load and the bottom re-boiling load of the distillation column and to generate the decompression distillation column overhead stream. The step of reducing the pressure of the stream and the step of separating the vacuum distillation column overhead stream to produce a first separator overhead stream that is gaseous nitrogen leaving the greenhouse gas removal unit from which the greenhouse gas has been removed. The method of paragraph 22 further comprising.
24. The method of paragraph 23 further comprising the step of flowing at least a partially evaporated nitrogen stream through a thermal pump system after flowing through the first of at least one inflator service.
25. The method of any one of paragraphs 18-24, wherein the natural gas cooler cools the compressed natural gas stream to approximately ambient temperature after being compressed by the natural gas compressor.
26. The method of any of paragraphs 18-25, wherein the first heat exchanger comprises at least two heat exchangers and the second heat exchanger comprises at least two heat exchangers.
27. A method of removing greenhouse gas contaminants in a liquid nitrogen stream used to liquefy a natural gas stream, naturally in a natural gas compressor up to a pressure of at least 135 bara to form a compressed natural gas stream. At least the steps of compressing the gas stream, cooling the compressed natural gas stream to form a cooled compressed natural gas stream in the natural gas cooler, and cooling the compressed natural gas stream and at least a partially evaporated nitrogen stream. The step of passing a first heat exchanger through which heat is exchanged between the partially evaporated nitrogen stream and the cooled compressed natural gas stream to form an additional cooled compressed natural gas stream and the additional cooled compressed natural gas stream is formed. Additional cooling compression in the natural gas expander The stage of expanding the natural gas stream to a pressure less than 200 bara but not higher than the pressure at which the natural gas compressor compresses the natural gas stream, thereby forming a cooled natural gas stream. And at least the liquefied nitrogen stream circulated at least three times through the cooled compressed natural gas stream and the second heat exchanger exchanges heat between the liquefied nitrogen stream and the cooled natural gas stream and passes through the first heat exchanger. The step of forming a partially evaporated nitrogen stream and passing the cooled natural gas stream through a second heat exchanger that at least partially liquefies, and at least partially evaporating using at least one inflator service. A step of reducing the pressure of the nitrogen stream, a step of providing a greenhouse gas removal unit including a distillation column and a heat pump condenser and a reboiler system, and a step of increasing the pressure and condensation temperature of the overhead stream of the distillation tower. The stage and the stage where the overhead stream of the distillation column overhead stream and the bottom stream of the distillation column are cross-exchanged to affect both the overhead condenser load and the bottom reboiler load of the distillation column, and the vacuum distillation column overhead stream are generated. After the cross-exchange stage, the pressure of the distillation tower overhead stream is reduced, and a first separator overhead stream is generated, which is gaseous nitrogen from which the greenhouse gas is removed from the greenhouse gas removal unit. A method comprising a step of separating the vacuum distillation column overhead stream so as to be performed and a step of ventilating the first separator overhead stream to the atmosphere.

Although the above relates to an embodiment of the present invention, other and yet another embodiments of the present invention can be devised without departing from its basic scope, and the scope of the invention is the following claims. Determined by claims.

20 Natural Gas Supply 22 First Heat Exchanger 45 Overhead Generation Stream 606 Feed-Outflow Heat Exchanger 1200 LNG Generation System

Claims (20)

Natural gas streams from natural gas supplies and
With a liquid nitrogen stream from a liquid nitrogen supply,
A natural gas compressor that compresses the natural gas stream to a pressure of at least 135 bara to form a compressed natural gas stream.
A natural gas cooler that cools the compressed natural gas stream by indirect heat exchange with the surrounding fluid to form a cooled compressed natural gas stream.
A first heat exchanger that exchanges heat between at least a partially evaporated nitrogen stream and the cooled compressed natural gas stream to form an additional cooled compressed natural gas stream.
Work-generated natural that expands the additional cooled compressed natural gas stream to a pressure less than 200 bara but not higher than the pressure at which the natural gas compressor compresses the natural gas stream, thereby forming a cooled natural gas stream. With a gas expander
The cold natural gas stream is at least partially condensed by heat exchange between the cold natural gas stream and the liquid nitrogen stream, and the at least partially evaporated nitrogen passes through the first heat exchanger. Equipped with a second heat exchanger, which forms a stream,
A liquefied natural gas generation system characterized by this. The liquefied natural gas generation system according to claim 1, wherein the natural gas compressor compresses the natural gas stream to a pressure higher than 200 bara. The natural gas expander expands the additional cooling compressed natural gas stream to a pressure of less than 135 bara.
The liquefied natural gas generation system according to claim 1 or 2. The liquid nitrogen supply is produced at different locations in the liquefied natural gas production system and is delivered as a liquid to the liquefied natural gas production system.
The liquefied natural gas generation system according to any one of claims 1 to 3. The at least partially evaporated nitrogen stream is released into the environment as vapor after passing through the first heat exchanger.
The liquefied natural gas generation system according to any one of claims 1 to 4. The first heat exchanger comprises at least one printing circuit heat exchanger.
The liquefied natural gas generation system according to claim 1. The liquefied natural gas production system further comprises a greenhouse gas removal unit configured to remove greenhouse gases from the at least partially evaporated nitrogen stream.
The greenhouse gas removal unit includes a distillation column with a heat pump condenser and a reboiler system, and further comprises at least one expander service that reduces the pressure of the at least partially evaporated nitrogen stream.
The inlet stream of the distillation column is the exit stream of the first of the at least one inflator services.
The liquefied natural gas production system further comprises a thermal pump system in which the at least partially evaporated nitrogen stream flows through the first of the at least one inflator services and then flows through it.
The heat pump system comprises a heat pump compressor, a heat pump cooler, and a feed-outflow heat exchanger.
The liquefied natural gas generation system according to claim 1. Further comprising a humidity measuring heat exchanger that precools the natural gas stream using the at least partially evaporated nitrogen stream before the natural gas stream enters the first heat exchanger.
The liquefied natural gas generation system according to any one of claims 1 to 7. The natural gas cooler is configured to cool the compressed natural gas stream to approximately ambient temperature after being compressed by the natural gas compressor.
The liquefied natural gas generation system according to any one of claims 1 to 8. Further comprising a first nitrogen expander to expand the at least partially evaporated nitrogen stream to form a first cold nitrogen gas stream.
The first cold nitrogen gas stream is passed through the second heat exchanger to at least partially condense the cold natural gas stream to form a first warm nitrogen gas stream.
The liquefied natural gas generation system according to any one of claims 1 to 9. Further comprising a second nitrogen expander to expand the first warm nitrogen gas stream to form a second cold nitrogen gas stream.
The second cold nitrogen gas stream is passed through the second heat exchanger to at least partially condense the cold natural gas stream to form a second warm nitrogen gas stream.
The liquefied natural gas generation system according to claim 10. A nitrogen compressor that compresses the second warm nitrogen gas stream to form a compressed nitrogen gas stream.
A nitrogen cooler that cools the compressed nitrogen gas stream by indirect heat exchange with an ambient temperature fluid to form a cold compressed nitrogen gas stream.
A third nitrogen expander, which expands the cold compressed nitrogen gas stream to form a third cold nitrogen gas stream, is further provided.
The third cold nitrogen gas stream is passed through the second heat exchanger to at least partially condense the cold natural gas stream to form a third warm nitrogen gas stream.
The third warm nitrogen gas stream is the at least partially evaporated nitrogen stream that exchanges heat with the cooled compressed natural gas stream in the first heat exchanger to form the additional cooled compressed natural gas stream. be,
The liquefied natural gas generation system according to claim 11. The first heat exchanger comprises at least two heat exchangers.
The second heat exchanger comprises at least two heat exchangers.
The liquefied natural gas generation system according to any one of claims 1 to 12. A method of producing liquefied natural gas (LNG)
The stage of supplying a natural gas stream from a natural gas supply,
The stage of supplying a liquid nitrogen stream from a liquid nitrogen supply and
A step of compressing the natural gas stream in a natural gas compressor to a temperature of at least 135 bara to form a compressed natural gas stream.
The stage of cooling the compressed natural gas stream through indirect heat exchange with the ambient fluid in the natural gas cooler to form a cooled compressed natural gas stream, and
Heat exchange between the at least partially evaporated nitrogen stream and the cooled compressed natural gas stream to the cooled compressed natural gas stream and at least the partially evaporated nitrogen stream to additionally cool and add the cooled compressed natural gas stream. The stage of passing through the first heat exchanger that forms the cooled compressed natural gas stream,
The additional cooling compressed natural gas stream is expanded in a work-generated natural gas inflator to a pressure less than 200 bara but not higher than the pressure at which the natural gas compressor compresses the natural gas stream, thereby cooling the natural gas stream. The stage of generating a gas stream and
A step of liquefying the chilled natural gas stream by passing the chilled natural gas stream and the liquefied nitrogen stream through a second heat exchanger that exchanges heat between them. Includes said liquefaction step of passing through the second heat exchanger to form the at least partially evaporated nitrogen stream.
A method characterized by that. The natural gas compressor compresses the natural gas stream to a pressure higher than 200 bara.
The natural gas expander expands the additional cooling compressed natural gas stream to a pressure of less than 135 bara.
14. The method of claim 14. A step of expanding the at least partially evaporated nitrogen stream in a first nitrogen expander to form a first cold nitrogen gas stream.
A step of passing the first cold nitrogen gas stream through the second heat exchanger to form a first warm nitrogen gas stream by at least partially condensing the cold natural gas stream.
A step of expanding the first warm nitrogen gas stream in a second nitrogen expander to form a second cold nitrogen gas stream.
A step of passing the second heat exchanger through the second cold nitrogen gas stream to at least partially condense the cold natural gas stream to form a second warm nitrogen gas stream.
The step of compressing the second warm nitrogen gas stream in a nitrogen compressor to form a compressed nitrogen gas stream, and
The step of cooling the compressed nitrogen gas stream by indirect heat exchange with the ambient temperature fluid in the nitrogen cooler to form a cold compressed nitrogen gas stream, and
A step of expanding the cold compressed nitrogen gas stream in a third nitrogen expander to form a third cold nitrogen gas stream.
Further, a step of passing the second heat exchanger through the third cold nitrogen gas stream to at least partially condense the cold natural gas stream to form a third warm nitrogen gas stream. include,
The method of claim 14 or 15. The third warm nitrogen gas stream is the at least partially evaporated nitrogen stream that exchanges heat with the cooled compressed natural gas stream in the first heat exchanger to form the additional cooled compressed natural gas stream. be,
16. The method of claim 16. It further comprises the step of removing greenhouse gases from the at least partially evaporated nitrogen stream using a greenhouse gas removal unit.
The greenhouse gas removal unit includes a distillation column and a heat pump condenser and reboiler system.
The above method
Steps to increase the pressure and condensation temperature of the overhead stream of the distillation column,
A step in which the overhead stream of the distillation column and the bottom stream of the distillation column are cross-exchanged to affect both the overhead condenser load and the bottom reboiler load of the distillation column.
After the cross-exchange step, the pressure of the distillation column overhead stream is reduced to generate a vacuum distillation column overhead stream, and
A step of separating the vacuum distillation column overhead stream to generate a first separator overhead stream which is gaseous nitrogen from which the greenhouse gases are removed and exits the greenhouse gas removal unit.
Further comprising the step of flowing the at least partially evaporated nitrogen stream through the first of the at least one inflator services and then through a thermal pump system.
16. The method of claim 16. The natural gas cooler cools the compressed natural gas stream to approximately ambient temperature after being compressed by the natural gas compressor.
The method according to any one of claims 14 to 18. A method of removing greenhouse gas pollutants in liquid nitrogen streams used to liquefy natural gas streams.
The step of compressing the natural gas stream in a natural gas compressor to a pressure of at least 135 bara to form a compressed natural gas stream.
The stage of cooling the compressed natural gas stream in a natural gas cooler to form a cooled compressed natural gas stream, and
Heat exchange between the at least partially evaporated nitrogen stream and the cooled compressed natural gas stream to the cooled compressed natural gas stream and at least the partially evaporated nitrogen stream to additionally cool and add the cooled compressed natural gas stream. The stage of passing through the first heat exchanger that forms the cooled compressed natural gas stream,
The additional cooled compressed natural gas stream is expanded in the natural gas inflator to a pressure less than 200 bara but not higher than the pressure at which the natural gas compressor compresses the natural gas stream, thereby cooling the natural gas stream. And the stage of forming
The cooled compressed natural gas stream and the liquefied nitrogen stream exchange heat between the liquefied nitrogen stream and the cold natural gas stream to form the at least partially evaporated nitrogen stream, and at least the cooled natural gas stream is formed. In the step of passing through a second heat exchanger that is partially liquefied, the liquefied nitrogen stream is circulated through the second heat exchanger at least three times, and the nitrogen stream that is at least partially evaporated is circulated. The step of passing through the first heat exchanger and the step of passing through the first heat exchanger
The step of reducing the pressure of the at least partially evaporated nitrogen stream using at least one inflator service, and
The stage of installing a greenhouse gas removal unit including a distillation column and a heat pump condenser and re-boiling system, and
Steps to increase the pressure and condensation temperature of the overhead stream of the distillation column,
A step in which the overhead stream of the distillation column overhead stream and the bottom stream of the distillation column are cross-exchanged to affect both the overhead condenser load and the bottom reboiler load of the distillation column.
After the cross-exchange step, the pressure of the distillation column overhead stream is reduced to generate a vacuum distillation column overhead stream, and
A step of separating the vacuum distillation column overhead stream to generate a first separator overhead stream which is gaseous nitrogen from which the greenhouse gases are removed and exits the greenhouse gas removal unit.
Including a step of ventilating the first separator overhead stream to the atmosphere.
A method characterized by that.

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