US1813024A - Production or recovery of lighter hydrocarbons - Google Patents

Description

July 7, 1931. A. CLARKE ET'AL 'PRODUCTION .OR RECOVERY OF LIGHTER `HYIROGAHBONS 3 Sheets-Sheet l Filed Aug. 7, 1926 July 7, 1931. A. CLARKE ET AL 1,813,024

PRODUCTION OR RECOVERY OF LIGHTER HYDROCARBONS Filed Aug. 7I 1926 3 Sheets-Sheet 2 Juve/MTM W0 1/ @5% Mal, @Hof/41e if M `.lu/ly 7; 1931. A. CLARKE ET AL PRODUCTION OR RECOVERY OF LIGHTER HYDROCARBONS Filed Aug. 7, 1926 3 Sheets-Sheet 3 Patented July 7, '1931 UNITED STATES PATENT OFFICE ALEXANDER CLARKE, OF EASTL'AND, TEXAS,`AND HORACE BUTLER, OF WEST CHESTER, PENNSYLVANIA, ASSIGNORS T UNITED HYDRO CARBONS COMPANY, OF WEST CHESTER, PENNSYLVANIA, A CORPORATION OF WEST VIRGINIA i PRODUCTION OR RECOVER-Y OF LIGHTER HYDROCARBONS Application led August 7, 1926. Serial No. 127,718.

This invention relates to the production or recovery of lighter hydrocarbons. It is directed to the production or recovery of lighter hydrocarbons in liquid form from vapors or I gases containing the vdesired hydrocarbons and perhaps other hydrocarbons regardless of whether such vapors or'gases occur naturally, or are produced by distillation of mineral oils or bituminous coal orsimilar substances rich in hydrocarbons, or are produced by distilling a mixture produced by absorbing liqueable or other hydrocarbons in a heavier liquid hydrocarbon or even a solid substance, or are produced as a by-product or intermediate product in refineries. This invention is also directed to the distillation of such lighter hydrocarbons from mixtures containing heavier hydrocarbons regardless of whether such mixtures occur naturally, as

f in petroleum, or are a product of distillation,

mixture or absorption, or an intermediate or by--product of oil refining. This invention is also directed to the production of mixtures that are to 4be distilled as by the `a-bsorption f' of desired lighter hydrocarbons in an absorption medium. It vis also directed to the achievement of any two or more of such objects or results by conjoint use of several features of our invention. Thus our invention comprises the'liquefaction by novel methods of lighter hydrocarbon vapors, and comprises the separation of lighter hydrocarbons from heavier hydrocarbons by distillation that involves novel features and also comprises the production by novel methods, preliminary to distillation, of mixtures of lighter hydrocarbons with heavier hydrocarbons by the absorption of the desired lighter hydrocarbons in heavier hydrocarbons.

An object of our invention is to provide a process and apparatus for the practice thereof which comprises features whereby lighter hydrocarbons are absorbed by an absorption medium or menstruum and whereby lighter hydrocarbons are separated to a high degree by distillation from mixtures containing heavier hydrocarbons regardless of whether such mixtures occur naturally or are artificially produced or constitute an intei-mediate or by-produ'ct, and whereby the desired hydrocarbons are liquefied from vapors or gases containing the same as by compression and cooling, and whereby such a resulting liquid product may be brought to a condition wherein it meets commercial `requirements as to stability under specified temperatures and pressures. It is a further object of our invention to provide a process and apparatus wherein the foregoing features contribute individually, but to a greater degree through cooperation and conjoint use, to the'attainment of the desired ends.

Our invention is particularly well adapted to the production or recovery from nat-- ural gas of gasoline that meets commercial requirements as. to stability under specified temperatures and pressures. Our invention will be described in connection with the production of such gasoline as that operation Well illustrates the features of our invention,

but the applicability of the features of our invention and of the whole. or various parts thereof in the recovery of other hydrocarbons in liquid form, and to the distillation of other hydrocarbons from mixtures of hydrocarbons, and to the absorption of other hydrocarbons will be apparent to those skilled in the art.

Accordingly it is a specific object of this invention to obtain or recover from natural gas a suitably stable gasoline comprising a high proportion of those hydrocarbons of the natural gas which are desirable constituents of such gasoline. To this end, it is a further object of this invention to recover or produce from natural gas, in the form lof a gross product comprising wild gasoline containing low-boiling hydrocarbons that are maintained in liquid form at atmospheric temperature only under pressure above atmospheric pressure, as high a proportion as possible of the total hydrocarbons present in the natural gas. Careless reduction of the pressure under produces refrigeration that is useful when carefully employed in preventing such loss of desirable hydrocarbons; and it is an object of this invention'to produce a gross product that contains a high proportion of low-boiling hydrocarbons and is thereby well suited to stabilization or weathering steps in which loss of desirable hydrocarbons is so prevented. The increase of gross product obtained hydrocarbons of the natural gas, which proor so called heavy ends of such vapors.

tained in the final or stable product when the hydrocarbons, particularly heavy hydrocarpgrtion includes a high percentage of lowiling hydrocarbons, and to the-production of a final product containing a high proportion of the hydrocarbons of natural gas that are suitable constituents of stable gasoline. We have found, in the ractice of our invention, that the proportion of hydrocarbons recovered from natural gas, both in the gross product and in the final or stable, product, is greatly increased if the vapors distilled from the absorption medium are -subjected to compression and condensation without previous removal therefrom of any part of such vapors and particularly without previousiremoval therefrom of the higher-boiling constituenIts n this connection we have found that a higher proportion of the hydrocarbons of the gas, including'low-boiling hydrocarbons, is not only carried into the gross product but is recondensation of the lower-boiling substances occurs simultaneously with the condensation of .thehigher-boiling substances. In other words, we have found that a higher proportion of the hydrocarbons of the gas is .condensed and brought into the gross product and retained in the final product if a high or the maximum, of higher-boilproportion,

ing substances 1s carried throughor treatedv in -the compressing and condensing operations together with the lower-boiling substances. To this end still vapors that include as large a proportion as possible ofthe ab` sorbed hydrocarbons are subjected simultaneously or in one operation to compression and subsequent condensation. Thus, if any bons, have been condensed from thestill vapors prior to com ression and condensation, itis withinthe splrit of our inventionto re-A turn such condensed hydrocarbons, preferably' in vapor form, to the vapors passing to the compression and condensation operations.

Such previously condensed hydrocarbons may be introduced into the compressed -va pors passing to the cooling operation in which case they will cool the compressed vapors, particularly if expanded into the compressed product.

The-more thoroughly the absorption medium is stripped of previously absorbed hydro. carbons of the natural gas prior to reuse in the absorption operation the greater will be the proportion of hydrocarbons absorbed by it from the gas and the greater will be the percentage of low-boiling hydrocarbons included in such absorbed hydrocarbons; and such thorough stripping brings into the distilling and condensing and stabilizing operations that greater proportion of absorbed hydrocarbons. We have found that in the practice of our invention such thorough stripping can be attained and that the advantages ldue thereto may be realized to a high degree in our process; and we have found that such thorough stripping may be economically practiced in our process and will augment the effectiveness of other parts thereof. Steam distillation of a liquid absorption medium is effective to strip the absorption medium to a high degree but in. separating the condensed steam some of the heavy -hydrocarbons are condensed and ditliculties are imposed upon that step of our invention wherein the lighter or lower-boiling hydrocarbons are condensed in the presence of, or in contact with, condensing heavier hydrocarbons, andthe removal of heavier hydrocarbons increases the partial` pressure of the remaining vapors, and losses occur in separating the Water fromv the condensed hydrocarbons. If the distillation is carried out without the use of steam as in a fire still, the vapors vmay all be passed together to the compressing and condensing operation. If complete strippingk without vthe subsequent steam distillation will thoroughly strip the absorption medium." lFurthermore, -particularly in the absorption 'of lll gasoline hydrocarbons-from natural gas from` certain sources, additional beneficial eli'ects of steam distillation are that the'vapor tension of the absorption -oil is greatly lowered and -unsaturated hydrocarbonsare distilled off so that they may be brought into the final product by other features of our invention, whereas they might otherwise produce undesirable sludge in the absorption oil as by polymerization there. In such double distillation the hydrocarbons distilled o by `the steam will constitute but a small quantity of the total hydrocarbons distilled oil' from the absorption medium and will inlclude but a small quantity of hydrocarbons that will condense with the steam. Such hydrocarbons as condense with the steam may even be discarded Without fatal impairment l ot the efliciencyof our processor they may be returned in vapor form to the vapors passing from the fire still to the compressor or in liquid form or vapor form to the product of the' lire still that is passing from the compressor to the condenser. Vapors evolved by thel 'steam distillation that do not condense when passing to the compressing and condensing' steps in the practice of our invention contain a large proportion of 10W-boiling hydrocarbons as Well as higher-boiling hydrocarbons, such vapors including both lowboiling and high-boiling hydrocarbons with perhaps a predominance of the former as are not condensed When first passed through the condensing and cooling operations and also such vapors as are evolved in the stabilizing` operation may be recirculated through the condensing and cooling operations and eventually liquefied and brought into the gross liquid product fand into the iinal product either entirely or to a very large degree. In the operation of our process either no venting or but little venting of such recirculation system is required. In our process pressure is not released until the stabilizing operation and there is no loss by weathering during the liquefying operationsor other operations and the vapors` evolved in stabilizing are returned to the condensing operation, unless vnecessarily vented.

IVe have further f und that the effectiveness of' complete stripping of he absorption medium is augmented by special precautions inthe absorption operation. In this connection we avoid inefficiency of absorption due to heating of the absorption medium by heat of absorption and due to saturation of the absorption medium and to dislodgment therefrom of lighter hydrocarbons by more readily absorbed heavy hydrocarbons, as by carrying out the absorption operation in a plurality of stages by successively contacting the oil with separate bodies of stripped absorption medium. And to attain the advantages of re- Irigeration in the absorption operation but to attain them economically the absorption medium passing to the last or latter stages of absorption may be refrigerated While medium passing to earlier stages is merely cooled. And to attain to a high degree the advantages of using highly stripped absorption lnedium and of carrying out the absorption in multiple stages, we have found that a mechanical agitation of the absorptionmedium producing intimate contact between the medium and the gas is of great value.

The use of thoroughly stripped absorption medium and the use of multistage absorption and the carrying out of such absorption under mechanical agitation, in accordance .With our invention, are all l'eatures acting to increase the eiiiciency of the absorption operation; and it is apparent that these features actually cooperate in that the advantages of each feature are retained and augmented by the effect of the other features. The use of 'these features not only diminishes the necesity of using excessive quantities of absorption medium and of using the extensive and unecononncal cooling apparatus that 1s required in conjunction with the use of such eX- cessive quantities of absorption medium, but these features render effective increases in the amount of absorption medium circulated. In prior practice increasing the amount of absorption medium circulated soon led to a condition at which large increases in the amount of absorption medium circulated produced but inconsequential increase in the efficiency of the gasoline producing plant but in the practice of our invention similar increases in the amount of absorption medium circulated produce increased etliciency. In other Words increase in circulation beyond the point Where such increase fails to produce an increase of eiiciency in prior practice nevertheless produces substantial increase of efficiency in the practice of our invention.

The ideal condensation or compression and condensation of all absorbed hydrocarbons in a single stage otcompression and condensation is not always practicable and in accordance with our invention still vapors that are not condensed in the first compressing and condensing operation are subjected to a second compression and condensation. Such multistage compression and condensation overcomes the practical difliculties and the principle of condensing lower-boiling hydrocarbons in the presence of higher-boiling hydrocarbons may be followed if necessary in such multistage compression and condensation by introducing-into the second stage of compression and condensation some heavier gasoline hydrocarbons, for example, some of the liquid product of the first stage of compression and condensation. It conditions are such that the addition of some higherboiling hydrocarbons to the second stage condensation Will-effect a'condensation of more of the low-boiling hydrocarbons in that stage of condensation there will then be available a greater quantity of refrigeration, produced by evaporation of such lowboiling constituents, for use inthe stabilizing operation. To a similar end, namely complete condensation ot the low-boiling consituents, and with a view to effecting condensation of as large a proportion of still vapors as possible in a single condensing operation, some or all of the condensed product of the second stage of condensation may be introduced, as by. expanding, into the products that are .under compression inthe first stage of compression and condensation. In such case it may be desirable to carry the first stage of compresthe purpose of producing the refrigeration necessary to economical inal stabilization of the grossproduct.

In the production of gasoline from natural gas in 4accordance with our invention, andy particularly by the employment of the several `features thereof in conjunction, it is lpossible to obtain from natural -gas much more gasoline that meets commercial requirements with respect to stability than the charcoal test and other well known tests indicate to be present in such natural gas.

In the practice of our invention as high a proportion as possible of the hydrocarbons of the natural gas is absorbed andadvanitageously. whatever part of the absorbed hydrocarbons is not condensed is maintained in circulation and recirculation within the system as long as possible. To this end the vapors evolved inthe stabilizing operation may be recirculated together with whatever vapors are not condensed in the-condensing operation.

In the production of gasoline from natural gas the character of the naturaly gas treated or the conditions of'operation of our invention may require that unsaturated hydrocarbons absorbed in the absorption medium from the "natural gas or otherwise introduced therein must be removed from the absorption medium in order thatsuch unsaturated hydrocarbons will not impair the absorptivep'ower of that medium as by producing sludge in the absorption medium, -In accordance with our invention such unsaturatedy hydrocarbons may be taken'into the products subjected to compression and condensationand recirculation to the end that the treatment applied to those products may effect such polymerization of the unsaturated compounds as will increase the gasoline output. Such unsaturated compounds may befdriven out of the absorption medium in any manner but if conditions are such that steam distillation must be employed in conjunction with fire distillation in order I.thatthe absorption'medium may be .sufli- Aciently stripped, then such steam distillation will contribute to the removal of suchlunsaturated compounds. If-conditions are such that more eliicient absorption of unsaturated compounds of thenatural gas is broughtl about by the presence of unsaturated"`com pounds in the absorption medium then absorption maybe carried out in part, as in one` of several stages of absorption, by the use of oil that contains unsaturated compounds but is otherwise sufficiently stripped to permit absorption of unsaturated hydrocarbons of the gas.

For the purpose of more fully disclosing our invention but as merely illustrative of the application thereof, the features of our process and of apparatus embodying and suitable to the practice of our invention are described in connection with the accompanying drawings in which; l

Fig. 1 is adiagrammatic illustration of apparatus embodying our invention and whereby our invention may be practiced.

Fig. 2 is an elevation, partly in section, of the absorption apparatus,

Fig. 3 is a diagrammatic illustration of apparatus embodying a modilication of our invention and `whereby a modilication of our invention may be practiced, and

Fig. 4 is a detailed View of the stabilizer.

Referring to thedrawings, natural gas is introduced to the absorber A that is supplied with an absorption medium, for eX- vample, mineral seal oil, and dry distillation of the absorption medium may be carried out by a dry or fire still B while steam distillation of the absorption medium may be carried out in the steam still C, a first stage of compression and condensation being carried out by the compressor and'condenser D, and a second stage of compression and condensation being carried out by the compressor and con-v denser E. Stabilization is carried out by the stabilizer F and recirculation is carried outv through. the recirculating system G.

The absorber A. comprises casing 1 into which natural gas is introduced through the inlet 3 and from which unabsorbed gas is discharged 'from the outlet 4. While the operation of the process and apparatus of our tion is carried o-ut in two stages in the absorber illustrated but any number of stages may be employed. The stripped oil is introduced through thepipes9 and 10, the oilentering through the pipe 9 being withdrawn ,through the pipe 11 and the o-il entering through the pipe l10 being withdrawn through the pipe 1.2. The oil entering through the pipe/5.9 and 10 discharges into pans 8 and eventually passes over the edges of those pans onto baies 2 that direct the oil into the next llower pan and the oil in each pan is acted upon by blades mounted on a shaft 6 that is driven by a motor 7 and thus dispersed inline particles so that the gas passing up through the absorber is brought into intimate contact with the absorption oil. Absorption oil entering through the pipe 10 first contacts with gas that has previously been in contact with absorption oil and from which heavierhydrocarbons which are more rcadily absorbed have thereby been removed. Thus the entering oil first absorbs lighter hydrocarbons but as it descends in the absorber some of such lighter hydrocarbons may be displaced by fresh quantities of heavier hydrocarbons coming in with the fresh gas; but the lighter hydrocarbons so displaced and any heavier hydrocarbons that are not absorbed by the oil entering through the pipe 10 are absorbed by the oil that enters through the pipe 9 and provides a second stage of absorption. Other stages of absorption including a stage in which the oil contains a relatively large proportion of unsaturated hydrocarbons may be similarly produced. f

Low temperature and high pressure within the absorber facilitate absorption but the pressure and temperature commercially emp-loyedaredependentuponpractical considerations such as the rate of circulation of the gas and oil and we have attained efficient results by maintaining about thirty pounds per square inch of pressure and atmospheric temperature within the absorber but lower temperature is desirable. Refrigeration of absorption medium passing to any' stage of absorption may be readily effected as by passingv it through refrigerating chamber 110 from which refrigerating medium passes through compressor 111, cooler 112, tank 113 and Valve 114 back to chamber 110.

The absorption oil from the several absorption stages is all brought together as by the i pipe 13 and if necessary may be passed to a vent tank 14 that is provided with a valve 15 that may be opened if the pressure becomes excessive. A pump 16 passes the saturated oil through a. heat exchanger 17, where it takes up heat from 'the distilling step or steps, to the absorber. The hydrocarbonbearing oil then passes to a preheater 18, the use of which is optional vand which may be heated by lire or by steam, as by means of the steam inlet and outlet pipes and 21.

jected to dr)7 or fire distillation in theI fire still B. The fire still l5 may be a pipe still99 of coinnion construction operating in con- `iunction with a chamber or tower 100, in which case the preheater is not indispensable. Pipe still 99 may be heated by burner 99a. When a pipe still is used the oil is maintained at suchv a velocity therein that it will not be injured by heat but will attain a desired final temperature, e. g. 400 F., and pass through the p-ipe 28a into chamber or tower 100 where it flows down over devices that will expose large surfaces for example balies 101 that are provided with upwardly extending tubes 102 over which are placed caps -103, the oil level being maintained on each baffle by drain tubes 104. Or, the fire still B maybe of the construction shown in Fig. 3 wherein an outer casing 22 encloses a cylindrical still 23 and a burner 24 that is arranged below the still so that the combustion gases pass uparound the still and out through Hue 25. One or more spray nozzles 26 within the still 23 direct hydrocarbon-bearing oil supplied through pipe. 19 against the heated upper portion thereof, the desired pressure being maintained by manually regulating the number of nozzles 26 in position.- Brief contact of hydrocarbon-bearing oil against an effective heat source and while in a divided state is thus effected. The burner 24 is so regulated that oil in the bottom of the still 23 will be at as high a. temperature as possible without injuring the oil, for example, 400 F.

The vapors produced in the fire-distilling operation will pass through the pipe 28, that leads from still 23 or tower 100, to a knockout 29 that returns to the fire-distilling operation, e. g. to still 23 or tower 100, through pipe 30 any of the absorption medium that may have been carried off with the vapors. Vapors pass from knockout 29 through the pipe 3l to the compressionand condensation operations, such vapors being then at a temperature of approximately 125 F. to 200 F.

The fire still may under favorable conditions, and particularly when a pipe still is used, suiiciently strip the absorption medium of absorbed hydrocarbons, or under less favorable conditions the absorbed hydrocarbons may thereby be reduced to yths of 1% or perhaps only to 1% or even 2%, these percentages being based upon standard distillation tests.

If ,the absorption medium is not or can not be sufliciently stripped in the fire still or if it be desired to remove unsaturated compounds from the absorption medium the absorption oil is passed from the fire-distilling operation, e. g. from still 23 or tower 100, through pipe 47 to a steam distillation operation in a steam still C.

The steam still C may consist of a casing 98 provided with-suitable bailies 98a and is The hydrocarbon-bearing oil is then subpreferably maintained at a temperature that will. prevent condensation that inight produce emulsions. Absorption medium is passed from pipe 47 through trap 105 into casing 98 and steam is supplied thereto through pipe l07a by boiler' 106, the steam being preferably but not necessarily superheated in superheater 107. 1Or, the steam still C may, as shown in Fig. 3, consist of casing 38 into which absorption medium is i passed directly from pipe 47 by means of Y still the valve 37 may be opened and the pump 36, being sprayed therein from spray-` heads 39. Casing 38 is supplied with` steam, i'

preferably superheated through pipe 107e and if necessary additional heat is supplied lthereto by burner 40.

Stripped oilis returned from the'steam distilling operation by pump 41 through heat exchanger 17 and cooling coils 42 to the supply pipes of the various stages of the absorber, foryexample, the supply pipes 9 and 10. If it be desired to eliminate the steam valve 37a closed.

Vapors are withdrawn from thefsteam distilling operation through pipe 42 that leads to the knockout 42a from which any collected liquid is returned to the steam still through pipe 42?). The knockout 42a is preferably maintained at a temperature that will not return water to thev steamA still.

Vapors pass from-the knockout 42a through the pipe 43 to cooler 43a and condensed steam and hydrocarbons in liquid and vapo-r form pass tolthe accumulator 44 which is pro vided with a water drain 44a and with a vapor line 45 that leads to-the vapor pipe 31 if the trolled in connection with-the operation of compressor 32 that the compressor is not overloaded and proper balance of pressure 'is maintained throughout the system. We have obtained good results when a vacuum of two inches of mercury is maintained in the lire distilling operation by such balancing of pressure.

Compression of the vapors in compressor 32 increases the temperature thereof to approximately 280 F. and they pass through pipe 33 to condenser 34 in which the temperature is reduced by good atmospheric or Water cooling and the resulting liquid and remaining vapors pass to accumulator tank 35. Vapors are Withdrawn from accumulator tank 35 through pipe 49a to the second stage compressor 49 in which the temperature of the vapors is raised and the vapors are passed through pipe 50a to condenser 50 in which the temperature of the vapors is reduced by good atmospheric or water coolingvaries in accumulator tank 35 but may be between 25 and 50 pounds per square inch.

Gasoline hydrocarbons collected in the accumulator `tank 44 as a result of the distillation may be withdrawn .from the system through the valve or may be passed to the pump 71 which delivers those condensed hydrocarbons into the pipe 33, if valve 72 is open, and thus into the vapors compressed in the first stage of compression. Or, those hydrocarbons may be passed, ifthe valve 73 is open, into the still or vaporizer 48a heated by the burner 48a from which the vaporized hydrocarbons are led by pipe 74 to the pipe 45 from ,which they may be passed either to the pipe 28 or the pipe 31` as above-described. If for any reason such as -preventing impairment of the color of the final product, a residue is retained in the still 48 it may be drained therefrom by the valve 7 5j If it be desired to bring into the vapors in the second stage of compression and condensation some of the hydrocarbonsr condensed -in the first stage of compression and condensation suchhydrocarbons may be withdrawn from the accumulator 35 by means of the pipe 76 and passed by means of pump 77 into the pipe 50a leading to the second stage condenser. If it be desired to conduct into the vapors undergoing the first stage of condensation and compression liquid hydrocarbons collected in accumulator tank 51, this may be done by` conducting liquid from the accumulator tank 51 through pipe 177 and eX- panding it into the chamber 78 in the pipe 33 or expanding it in the chamber 79. With this mode of operation the compressor 32 may be so designed and voperated that the pressure in the accumulator tank 35 may be maintained, with a view to condensing as much liquid therein as possible, at a pressure higher than the pressure occurring therein when liquidI from the second condensation is 4not so expanded.

Uncondensed vapor from accumulator tank 51 is conducted by pipe 52a through a preheate-r 52 where its temperature is raised to 450 F. to 500 F. and it is then returned to the system either through the pipe 27u/l to the hydrocarbon-bearing oil entering the fire still or through the pipe 27?) to the chamber or through the pipe 27 c to the vapor pipe 28 or through the pipe 27dto the vapor pipe 31. In the construction shown in Fig. 3 such recirculation vapor may be carried into the still 23 through the pipe 27a and discharged through nozzles 27 towardY the bottom of the still 23 so as to assist in agitation of the absorption medium therein. The point at which such recirculation vapors are returned to the system will depend upon the operating conditions, for, example, upon the character of the recirculation vapors or upon the extent to which it is necessary to keep such recirculation vapors out of contact with the 11 absorption medium in order to prevent an accumulation of unsaturated hydrocarbons therein. Knockouts 96 remove lubricating oil from compressed vapors. y

In order to remove from the liquid hydrocarbons collected in accumulators 35 vand 51 such hydrocarbons as will Anot remain therein at temperatures and pressures commercially required and in order to remove such hydrocarbons without loss of hydrocarbons that will remain liquid under such temperatures and pressures, the collected liquid hy drocarbons are stabilized in the stabilizer F. The stabilizer F comprises a casing 152 within which there are several pressure reduction chambers 54, 55 and 56 that are formed by tube-sheets 53 that are joined by tubes 53. Liquid hydrocarbons from high pressure accumulator tank 51 are introduced by pipe 51a into upper pressure reduction chamber 54 and conducted-from the bottom of chamber 54 to the next lower pressure reduction chamber 55 through a pipe 57 having a bend 58 that ensures that chamber 54 is kept substantially full. Any liquidithat is not evaporated by pressure reduction will pass from the lower portion of chamber 55 through the bend 58a and be discharged through pipe 59 lwithin the stabilizer casing 52. Vapors evolved in the chambers 54 and 55 pass through pipe 60 and are liberated at 61 in the vicinity of liquid passing out of pipe 59. Liquid hydrocarbons from accumulator tank 35 enter pressure reduction chamber 56 through pipe 35a, leave that ch amber through the bend 62 that maintains chamber 56 substantially full and are discharged through p ipe 63 within the casing 52. Vapors evolved in chamber 56 pass from the top thereof through pipe 64 and are discharged through pipe 65 within casing 52 in the vicinity of liquid passing from pipe 63. Vapors evolved by the reduction of pressure of the liquid hydrocarbons from high stage accumulator tank 5l are thus subjected to refrigeration produced by evolution of those vapors as those vapors pass up through the tubes 53 of the chamber 54 and 55. Vapors evolved by reduction of pressure on liquid hy drocarbons from low stage accumulatortank 35 are subjected to refrigeration produced by reduction of pressure on both yquantities of liquid.hydrocarbons, by passing up through tubes 53 ot chambers 54, 55 and 56. Any vapors that are not condensed by such refri geration are Vented from chamber 52 through pipe 525 and compressor 520 into recirculation pipe 52a. Excess recirculation vapors are vented when necessary to preserve proper pressure conditions throughout the syste-m as by vent valves 8() that should be so located and controlled as to vent the least desirable vapors.

do not provide sutficient refrigeration, for example, in the case where suchliquids are ex- Ifliquidscollected in accumulator tank 51 panded into the chamber 7 8 or 79 then vapors may be withdrawn from the top of the stabilizercasing 52 through the pipe 81 compressed by compressor 82, condensed in condenser 83 and returned to pressure reduction chamber 54 of stabilizer 52 through pipe 51a, uncondensed vapors being introduced into recirculation pipe 52a by pipe 515.

Liquid hydrocarbons collecting in the bottom of stabilizer 52 pass through pipe 67 to kettle 68 in which the temperature is raised to desired temperature and evolved gases are passed through pipe 68 back to the stabilizer 52 wherein they are again subjected to refrigeration. The finished product may be withdrawn'through the valve 90. Bae plates 69 of any suitable configuration may be positioned within the stabilizer casing 52. Briefly, the function of the stabilizer is to remove in vapor form from the hydrocarbons liquefied by compression and cooling, such light hydrocarbons'as are ordinarily in vapor form at atmospheric temperature and pressure, and to remove such light hydrocarbons in such a Way that their vapors will not carry away with them the vapors of hydrocarbons which are desired in the final liquid product, and to remove such light hydrocarbons to such an extent that the final liquid product will possess a vapor pressure low enough to permit them to be handled by usual methods without danger. In the stabilizer, vapors are evolved from the total liquid produced, which vapors consist of such undesirably light hydrocarbons.

From t-he foregoing it is apparent that we have described numerous lfeatures that each contribute to the eficiency of the absorption of gasoline trom natural gas and that cooperate with one another to retain and augment the advantages of each feature; and it is apparent that the several features described may be selected in accordance with conditions of operation to the end that the best results may be obtained. For example we have obtained much more gasoline from natural gas than is indicated by well known tests to be present in such gas, merelyby using a fire still and two stages of compression 'androndensation together Vwith 'either a twor stage mechanical absorption or mere static absorption and together with recirculation even though the stripped oil' contained as much.

rious stages in petroleum refineries and in the production and handling of crude oil generally. It is also apparent that the distilling steps of our invention are applicable to distilling operations generally where it is desired to effect a complete or substantially complete separation of the desired hydrocarbons from other hydrocarbons Without undesirably altering the residue, and also Where it is desired to free the residue entirely or to a high degree of lighter hydrocarbons. It is also apparent that the absorption and stabilizing steps of our processare susceptible of general application and are not limited to the treatment of natural gas and of products derived therefrom.

,What we claim and desire to secure by Letters Patent of the United States is:

1. In the production of gasoline from natural gas by a method wherein hydrocarbons are absorbed from natural gas by an'absorp- .tion medium, the steps comprising subjecting the medium charged with absorbed hydiocarbon vapors toy dry distillation vand then separately to steam distillation, separately withdrawing evolved hydrocarbon vapors from said distilling operations, admixing the hydrocarbon vapors so withdrawn, and subjecting the admixed vapors-to compression and cooling.

' 2. In the production of gasoline from nat-- ural gas by a method wherein hydrocarbons are absorbed from natura-l gas by an absorption medium, the steps comprising subjecting the medium charged with absorbed hydrocarbon vapors to dry distillation and thenseparately to steam distillation, separately withdrawing evolved hydrocarbon vapors from said distilling operations,` admixing the hydrocarbon vapors so withdrawn, subjecting the admixed vapors to compression while said vapors contain substantially all of the heavier constituents absorbed by lsaid Kmedium and.

expelled therefrom by said distillation, and cooling the compressed vapors.

3. In the production of gasoline from natural gas by amethod wherein hydrocarbons are absorbed from natural gas by an absorption medium, the steps comprising subjecting the medium charged with absorbed hydrocarbon vapors to dry distillation and then separately to steam distillation, separately' withdrawing' evolved hydrocarbon vapors from said distilling operations, admiXing the hydrocarbon vapors'so Withdrawn, compressing and cooling the adinixed vapors., and recirculating into contact with the absorption medium in the dry distilling operation vapors of lower boiling hydrocarbon constituents, that are normally invapor form under substantially atmospheric pressure and temperature, of hydrocarbons that have passed through said compressing and cooling operations.

14. In the production of gasoline from natural gas by a method wherein' hydrocarbons are absorbed from natural gas by an absorpe tion medium, the steps comprising subject-ing the medium charged with absorbe-d hydrocarbon vapors to drv .distillation and then separately to steam distillation, separately withdrawing evolved hydrocarbon vaporsural as by a method wherein hydrocarbons the admixed vapors,

are a soi-bed from natural gas by an abso-rption medium, the steps comprising subjecting the medium charged with absorbed hydrocarbon vapors to dry distillation and then separately to steam distillation, separately withdrawing evolved hydrocarbon vapors from said distilling operations, admixingthe hydrocarbon vapors so withdrawn,.compress ing and cooling the admixed vapors, stabilizing by rectification the resulting condensate, reheating hydrocarbon vapors evolved in the stabilizing operation, and passing the reheated vapors into contact with absorption incd'ium in the dry distilling operation.

6. In the production of gasoline from natural gas by a method wherein hydrocarbons are absorbed fromnatural gas by an absorption medium, `the steps comprising subjecting the medium charged with absorbed hydrocarbon vapors to 'dry distillation and then separately to steam distillation, separately withdrawing evolved hydrocarbon vapors from said distilling operations, admixing the hydrocarbon vapors so withdrawn, subjecting the admiXed vapors to compression and cooling, stabilizing by rectification the resulting condensate, and passing vapors evolved in thestabilizing operation into contact with the absorption medium in the dry distilling operation.

7. In the production of gasoline from natural gas by a method wherein hydrocarbons are absorbed from natural gas by an absorption medium, the steps comprising distilling absorbed hydrocarbons from Athe charged absorption medium, subjecting to compression all of the evolved hydrocarbon vapors while said vapors contain substantially all of the heavier constituents absorbed by said medium and expelled therefrom ,by said distillation, cooling the compressed vapors, stabilizing the condensate by rectification, reheating vapors evolved in the stabilization, and adding thel reheatedvapors to the vvapors passing to absorbed hydrocarbons from the charged 'absorption medium,

8.' In the production of gasoline from natural as by a method wherein hydrocarbons are a sorbed from natural gas by an absorption medium, the steps comprising distilling rom the charged abt1on and tion.

9. In the production of gasoline from natural as by a method wherein hydrocarbons are a sorbed from natural gas by an absorption medium, the steps comprising distilling condensing the vapors evolved in the distilling operation, stabilizing by rectication the condensate of the condensing operation, recirculating the vapors .evolved in the stabilizing operation into contact with absorption medium in the distilling operation.

10. In the production of gasoline from natural s by a method wherein hydrocarbons are a sorbed from natural gas by an absorption medium, the steps comprising subjecting the absorption medium charged with hydrocarbons of the natural gas to dry distillation to remove substantially all absorbed hydrocarbons that can be so removed without substantial injury-to the medium ,and then' separatelyto steam distillation, separately withdrawing from said distilling operations the hydrocarbon vapors evolved therein, admixing the hydrocarbon vapors so withdrawn, and subjecting the admixed hydrocarbon vapors, to compression and cooling.

11. In the production ofgasoline from natural gas by a method wherein hydrocarbons are absorbed from natural gas by an absorption medium, the steps comprising multiple absorption by dispersed absorption medium, subjecting the absorption medium to dry distillation and then to steam distillation, separately withdrawing and then admixing the vapors evolved in said distilling operations, compressing and coolin the admixed vapors prior to removal there om of a substantial quantity of heavier constituents, stabilizing-the condensate of the cooling operation, reheating uncondensed vapors of hydrocarbons that have passed through said cooling operation and said stabilizing operation, recirculating the heated vapors into contact with absorption medium in the dry distilling operation, ,and returning' stripped absorption medium from saidsteam distilling operation to each of said absorption ages.

12. In the production of gasoline rom'natural gas by a method wherein hydrocarbons are absorbed from natural gas by an absorption mediumrthe steps comprising distilling absorbed hy ocarbons from the absorption medium by the use of heat and light hydrocarbon vapor, then in a separate operation distilling unsaturated hydrocarbons from the absorption medium by use of steam, returning the stripped absorption medium to the absorption operation, and bringing together and compressing and then cooling all of the hydrocarbon vapors evolved from the charged absorption medium together with said light hydrocarbon vapors.

13. In the production of gasoline from natural as by a method wherein hydrocarbons are a sorbed from natural gas by an absorption medium, the steps comprising subjecting the charged absorption medium to steam distillation with superheated steam, and then subjecting to compression all of the hydro-Vl carbons so distilled off while said vapors contain substantially all of theheavier constituents absorbed by said medium and expelled therefrom by distillation, and then cooling the compressed vapors. n

14. In the production of gasoline from natural gas by a method wherein'hydrocarbons are absorbed from natural gas by an absorption medium, the steps com risin contacting the natural gas sucssive y wit separate parallel streams of absorption medium, stripping the charged absorption medium after its contact with the gas to a point at which it contains less than .6% of absorbed hydrocarbons, and feeding the stripped absorption medium to each of said separate streams.

15. In the production of gasoline from natural gas by a method wherein hydrocarbons are absorbed from natural gas by an absorption medium, the steps comprising maintaining separate parallel streams of absorption medium, .mechanically agitating the absorption medium of said streams to bring it to a finely divided state, successively contacting natural gas with finely divided absorption medium, and separately withdrawing the absorption medium of said streams from contact with the gas.

16. In the production of gasoline from the resulting bodies rof im natural gas by a method wherein hydrocarbons are absorbed from natural gas by an absorption medium, the steps comprislng contacting the natural gas successively with separate parallel streams of absorption medium,

bringing. together absorption medium from `|zo said streams aft-er contact with the gas, stripping the absorption medium of absorbed hydrocarbons to a.l point at which they contain less than 1% thereof, feeding stripped absorption medium to each of said streams, compressing and. cooling the vapors evolved in said stripping operation, and recirculating to the system at a point thereof between said absorbing operation and said compressing operation vapors of lower boiling hydrocarbon constituents, that are normally in vapor form under substantially atmospheric pressure and temperature, of hydrocarbons passing through'said compressing and cooling operations. f

17. In the production of gasoline from natural gas by a method wherein hydrocarbons are absorbed from natural gas by an absorption medium, the steps comprising multistage absorption by dispersed absorption medium, dry distillation of the charged absorption medium with separate withdrawal of hydrocarbon vapors evolved, followed by steam distillation of the absorption medium with separate withdrawal and subsequent admixture of vapors evolved, compression and cooling of the admixed hydrocarbons distilled otl' 'in said distilling operations, recirculation into contact with the oil in the dry distilling operation of vapors of lower boilrality of separate parallel streams of absorption medium, contacting the natural gas successively with said streams, separately withdrawing said streams -from contact with the gas, bringing togetherthe absorption medium flowing from said streams and subjecting it to dry distillation and then separately to steam distillation and thereby thoroughly stripping the medium of absorbed hydrocarbons, and then supplying each of said streams with stripped absorption medium from the steam distilling operation.

19.l In the production of gasoline from natural gas by a method wherein hydrocar-I bons are absorbed from natural gas by an absorptionmedium, the steps comprising dry distilling the absorption medium, then steam ldistilling the absorption medium after removal from contact therewith of hydrocarbon vapors evolved in the dry distilling operation, and compressing together while hot the hydrocarbons evolved in said distilling operation and condensing the resulting vapors.

20. In the production of gasoline from natural gas by a -method wherein hydrocarbons are absorbed from natural gas by an absorption medium, the steps comprising dry distilling the absorption medium, then steam distilling the absorption medium after rel moval from contact therewith of hydrocarbon vapors evolved in the dry distilling operation, compressing together while hot the hydrocarbons evolved in said distilling operations, cooling the compressed vapors, stabilizing the condensate by rectification,

reh'eating vapors evolved in the stabilization and recirculating them to the vapors passing the compressingl operation.

21. In the production of gasoline from naturalgas by a method wherein hydrocarbons are absorbed Jf'rom lnatural gas by an absorption medium, the steps comprising distilling of absorbed hydrocarbon vapors from the charged absorption medium, subjecting substantially all of the vaporsevolved in the distilling operation to high compression and temperature while said vapors contain substantially all of the heavier constituents absorbed by said medium and expelled therefrom by distillation, cooling the compressed vapors, stabilizing the/condensate, and reheating and returning to the system at a point between the absorption operation and the compressing operation vapors evolved in the stabilizing operation.

22.` In the production ural gas by a method wherein hydrocarbons are absorbed from natural gas by an absorption medium, the steps comprising contacting the gas successively with separate dispersed bodies of absorption medium, separately withdrawingsaid bodies from contact with the gas, subjecting the charged medium to dry distillation to remove substantially all absorbed hydrocarbons that can be so removed' without injury to the medium, thereafter thoroughly stripping the absorpof gasoline lfrom natf tion medium of absorbed hydrocarbons "including unsaturated hydrocarbons, and feeding stripped absorption medium to each of said bodies thereof;

23. In the production of gasoline from natural gas by a method wherein'hydrocarbons l are absorbed from natural gas by an absorp tion medium, the stepscomprising dry distilling the absorption medium, then steam distilling the absorption medium, condensing the steam from the vapors of the steam distilling operation, vaporizing hydrocarbons condensed in said condensing operatiomcombining saidlast named vapors and uncondensed vapors of said condensing operation andy vapors of said dry distillation, and com'- pressing and cooling said combined vapors.

24. In the production of gasoline from natural gas by la method wherein hydrocarbon vapors are absorbed from natural gas b an absorption medium and distilled there rom and condensed and the condensate is stabilized, the steps comprising combining in vapor phase under pressure hydrocarbon vapors evolved in the distilling operation and in the stabilizing operation, and passing the comwith natural gas, bon vapors distilled from the absorption mesorption medium char hydrocarbons as may be so distilled'without undesirable alteration of the absorption medium, then subjecting the absorption medium -to steam distillation after removal from contact therewith of h drocarbon vapors evolved in the dry distillatlon, then brin mg together the hydrocarbon vapors evolve in said distillations and compressing .and cooling said vapors stabilizing the condensate after removal from contact therewith of uncondensed vapors of said cooling operation, and reheating and recirculating to the dry distilling operation vapors evolved in the stabilizing operation.

26. Apparatus for obtaining hydrocarbons from natural gas which comprises a plurality y of absorption elements,

means for passing streams of absorption medium in parallel through said elements, means for passing natural gas through said elements in series, a dry still and a steam still connected in series and adapted to receive charged absorption medium from said elements, and means for returning stripped medium to each of said elements from said steam still, and means for separatel withdrawing from said stills hydrocar on vapors evolved therein and for bringing said vapors together.

27. In apparatus for the treatment of hydrocarbons recovered from absorption medium charged with hydrocarbons by contact a compressor for hydrocardium, a condenser receiving compressed vapors from said compressor, means for stabillzing by rectification condensate formed in saidcondenser and thereby liberating vapors from said condensate, a heater, means for passing hydrocarbon vapors liberated in said stabilizer into said heater, and means for conducting heated vapors from said heater and mixing them with vapors passing to said compressor.

28. In apparatus for the treatment of abd with hydrocarbons b contact with natura gas, a dry still for the c arged absorption medium and having an Youtlet lfor evolved hydrocarbon vapors, a

steam still having an outlet for evolved hydrocarbon vapors, means for conducting aby sorption medium from said dry still to said steam still, means for bringingtogetherhydrocarbon vapors from said outlets, means for condensin said vapors, means for stabilizing by rectication and in the absence of vapors not condensed `in said condensing means pondensate formed in said condens' hydrocarbon vapors evolved inf said stabi izing means, and means for conducting hydrocarbon va from said reheating means in contact with absorption medium in said dry still.

29. In apparatus for the treatment of absorption medium charged with hydrocarbons Pots' b contact with natural gas, a fire still for cllarged absorption medium and having an outlet for evolved hydrocarbon vapors, a steam still having an outlet for evolved hydrocarbon vapors, means for conducting absorption medlum from said first still to said steam still, a compressor, means for conduct- 1ng to said compressor all of the hydrocarbon vapors from both of said outlets, and a condenser receiving compressed vapors from said compressor.

30. In apparatus for the treatment of absorption medium charged with hydrocarbons b contact with natural gasp, a lire still for cllyarged absorption medium and having `an outlet for evolved hydrocarbon vapors, a steam still having an' outlet for evolved h drocarbon vapors, means for conducting a sorption medium from fsaid fire still to said steam still, a compreor, means for conducting to said compressor all of the hydrocarbon vapors from both of said outlets, a condenser receiving compressed vapors from said compressor, means for stabilizing by rectification and in the absence of ,uncondensed vapors from said condenser the condensate formed in said condenser, means for reheating hydrocarbon vapors evolved in said stabilizing means, and means for introducing hot vapors from said reheater into said compressor with vapors from said stills.`

31. In apparatus for the absorption of hydrocarbons in an absorption medium by contact thereof with natural gas, means for maintaining a lurality of separate bodies of absorption me ium in dispersed form, means for passing natural gas successively into contact with said bodies of absorption medium, means for separately' withdrawing said bodies from contactv with the meansfor subjectin to steam distillatlon absorption medium fgrom said bodies, and means for conducting absorption medium from saididistilling means separately. to each of said bodies of absorption medium. v

32. In apparatus for the absorption of hydrocarbons 1n an absorption medium by conv tact thereof Wik h natural gas, means for maintaining a plurality of separate streams of absorption medium, means for passing natural gas successive] into contact with said streams, means or bringing together absorpfeeding to said streams separately absorption f 'l medium from saidl distillmg means.;`

33. Inapparatus for the treatment of absorption medium charged with hydrocarbons by contact with natural gas, a still for absorption medium charged with hydrocarbons from natural gas, means for heating by fire charged absorption medium fed to said'still, a steam still, means for .conducting absorption medium from said fire still to said steam still, means for separately withdrawing from' said stills hydrocarbon vapors evolved theredrocarbons from said Condenser, and means for heating-lighter hydrocarbons from said condenser, and means for conducting hot hydrocarbon vapors from said heater 1nto contact with absorption medium in said first still. l

\ 34. In the production of gasoline from nat ural gas by a method wherein hydrocarbons sorbed from the gas by an absorption are a medium, the steps comprising subjecting vapors evolved in distillation of absorbed hyvdrocarbons `from the absorption medium to compression and condensation, compressing the uncondensed vapors of said rst condensmg operation, adding to the compressed `vapors liquid hydrocarbons produced in said irst condensing operation and cooling the resulting mixture.

35. In the production of gasoline from natural as by a method wherein hydrocarbons are a sorbed from the gas by an absorption medium, the steps comprising subjecting vapors evolved in distillation of absorbed hydrocarbons from the absorption medium to compression and condensation, compressing and cooling the remaining vapors and refluxing to the first cooling operation liquid hydrocarbons produced in said second cooling operation. y

36. In the production of gasoline from natural gas by a method wherein hydrocarbons are absorbed from the gas by an absorption medium, the steps comprising subjecting vapors evolved in distillation ofabsorbed hydrocarbons from the absorption medium to compression and cooling, compressin cooling the remaining vapors, reiiuxrng to the rst cooling operation liquid hydrocarbons produced 1n said second cooling operation, stabilizing the liquid product of the first compressing and cooling operation and recondensing and expanding in said stabilizing operation vapors evolved in said stabilizing operation.

37. In the production of gasoline from natand heated vapors evolved in the stabilizing operation andsteam, compressing and cooling the hydrocarbon vapors evolved in thedistilling operation, stabilizing the condensate, reheating hydrocarbon vapors evolved in the stabilizing operation and passing them to the distilling operation. f

38. 4Apparatus for the treatment of absorption medium charged with hydrocarbons by contact with natural gas comprising,

a still for separating absorbed vapors from the charged medium, means for subjecting to condensingconditions the vapors evolved in said still, stabilizing means for the resulting condensate, and means for conducting vapors evolved in saidstabilizing means into contact with charged absorption medium in said still. Y

39. In the production of gasoline from natj ural gas by a method wherein hydrocarbon vapors are absorbed from the' natural gas by an absorption'medium and distilled therefrom ,and condensed and the condensate is stabilized,'the steps comprising distillin absorbed'hydrocarbons from the charge absorption medium by distillation including vsteam distillation, substantially freeing of bilizing the resulting condensate, and recir' culating to the system at a point between the absorption operation and the compressing operation vapors of 'lower boiling hydrocarbon constituents, that are normally in vapor form under substantially atmospheric pressure and temperature, of hydrocarbons that have passed through said compressing and cooling operations. In testimony whereof, we have signed our names to this s ecification.v

l v H RACE BUTLER.

ALEXANDER CLARE.

` ural gas by a method wherein hydrocarbons are absorbed from natural gas by an absorp- -tion medium and distilled therefrom and the

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