Патент USA US2117464код для вставки
‘May 17, 1938. J. w. THROCKM'ORTON 2,117,464 THERMOLYTIC CONVERSION OF HYDROCARBON GASES TO LIQUID Filed July 23, 1937 ‘ INVENTOR _ “John WBYThrac/rmorton 2 F ATTORNEY 2,117,464 Patented May 17, 1938 ‘v , UNITED STATES PATENT OFFICE 2,117,484 THERMOLYTIC CONVERSION OF HYDRO CARBON GASES LIQUID John W. Throckmorton, New York, N. Y., as si‘gnor to The Pure 01! Company, Chicago, 111.,‘ a corporation of Ohio Application July 23, 1937, Serial No. 155,152 12 Claims. (Cl. 196-10) In order to more fully comprehend the nature Y ‘This‘invention‘relates to method and apparatus and scope of the invention, reference, should be for‘ converting hydrocarbon gas to liquid hydro carbons and is‘ more particularly concerned with had to the following description together with method and ‘apparatus for efficiently converting 5 hydrocarbongas mixtures into gasoline type hy drocarbons.‘ f“ i ' ' “ In the‘operation of thermolytic gas polymeriza tionprocesses it is difficult to obtain complete conversion of the‘reactable constituents in a one 10 stepsystem without the necessity of high recycle ratios. ‘ But‘ v‘high recycle ratios mean low throughput lwithv‘vresultan't low output and high operating cost. “ ‘In accordance with this invention the charging gas is fractionated so as to separate the C2 hydro carbons and vlighter gas from a fraction contain mg C: and heavier hydrocarbons. The latter fraction is charged through suitable heating and reaction zones‘iseparate from the light fraction, wherein it is subjected to suitable conditions of time,‘ temperature ‘and pressure to convert a sub stantial portion togasoline boiling hydrocarbons. W'I‘he‘light fractionjmay or may not be further fractionated to remove the lightest constituents 25 suchas hydrogen and methane, and then charged ‘toaseparatecracking coil preferably operated at higher temperatures and lower pressures than we coil to whichjtheh'eavy fraction is charged. the accompanying drawing of which - The single ?gure is a diagrammatic elevational 5 view of apparatus suitable for carrying out the in vention. _ Referring to the drawing, the numeral l indi cates a line through which fresh gas is charged to the system by means of pump or compressor 10 3. The charging gas may be natural or cracked gas, gas from a liquid or vapor phase 011 crack ing operation, or other gas containing a. substan tial amountlof Cs and. C4 hydrocarbons. The charging gas is ‘then pumped through line 5 and 15 cooler ‘l to gas and liquid separator 9. If the charge is gaseous it may be compressed in com pressor 3 to a’ pressure of approximately 150-350 pounds per square inch and cooled to a tem perature of 80°-100° F. before entering the gas separator. ‘If the charge is liquid, the samecon dltions of temperature and pressure should be maintained. The liquid fraction consisting chie?y of C: and C4 hydrocarbons is withdrawn from the lower part of the gas separator through line I I by means of pump l3, and may be charged through line I 5 controlled by valve II, to the inlet of coil l9 In ‘t e'cracking'co conversion of gas to liquids' located in furnace 2| at a pressure ranging from and, to‘ olefins‘vtakesffplace. The desirable por tion’s ,ofjthereajcte gas are absorbed in a liquid ‘oil mén‘scmumfap "the rich oil used to chill the reaction‘produets‘f-froin the high pressure coil. Thefcombined, prtxluct'sv are then fractionated mixed with the fresh 35 and“ the resultinglgas 30 charge.‘ ‘In this‘lma‘nnerg the desirable portions of‘the gases‘from‘th‘ereaction zone are recovered and mixed ‘withfthe fresh gas after elimination 40 46 The pressure, under which the charge to the. coil I9 is maintained, will depend largely upon the composition of the charge and upon the product desired. If the charge contains sub 39 stantially only saturated hydrocarbons, pressures 35 of approximately atmospheric to 250 pounds per square inch and temperatures of approximately l200°-1300° F. will be preferably maintained with ?nished gasoline'is “obt "tied all in a single op a short reaction period in order to convert the saturated hydrocarbons to unsaturates. In such 4.0 case the products, after leaving the heating coil, el‘iti?n‘By ., . ajjtw‘o ._ "step‘op'eration of the type fresh charge which is by-passed through line 26 above ’described'the‘recycle “in the high pressure coil ‘may be“ maintained ‘between the limits of !/2 controlled by valve 21 to a temperature of ap proximately 10'75°—1200° F. and then passed to a reaction coil or chamber 29 maintained under substantially the same pressure as‘ the cracking of the ‘iixed gas‘, ,lowin polymerizable constitu ents,‘,_ifrom‘ the ,syste‘nigiandf a] uniform blend of ‘ ' " _ 50 200-3000 or more pounds per square inch. ‘ H ' i ‘ lefg‘astolf part of fresh gas, recycle ratio in the low pres surefc‘oil: 1‘ Moreovergthejyse of the two step sys tem‘enable‘s" the‘maintenance of optimum condi tions’forlthe productscharged to each coil, re may be chilled at 23 by means of a portion of the coil, wherein the products are given su?icient time to polymerize to hydrocarbons boiling within the gasoline range. ~ The reaction coil 29 is pref greatlylau‘gmentemand ‘operating costs are cor erably provided. with means for controlling tem perature. For this purpose the coil’ or chamber may be enclosed in a suitable vessel through respondingly‘lideci'eased ‘beleause of lower over which a draft of air, combustion gases, or other sulting‘in‘ longe'frim'sTwitheutexcessive coke for mation.“ The‘ throughputiandjgasoline yield are head“- i - 50 heat exchange or cooling means ‘may be passed. 55 2 2,117,464 If the charge to the coil I9 contains approxi mately 20% or more of oleflnic hydrocarbons, it may be heated in the coil I9 to a temperature between approximately 800°-l050° F. under pres sure of 500-3000 or more pounds per square inch, and these temperature and pressure conditions maintained in the reaction coil; or if it is de sired to produce primarily aromatic hydrocar bons, the charge may be maintained under a 10 pressure of approximately atmospheric to 250 pounds per square inch and at temperatures of 1075°-12oo° F. The products issuing from the reaction coil 29 may be suddenly chilled to a temperature of 15 approximately 600° F. or lower by direct contact with an intermediate oil fraction formed in the system and which is injected into the issuing products at the point 3I. Depending upon the pressure maintained in the reaction coil, the 20 pressure on the reaction products may or may not be reduced at the valve 33 and the products then passed into the lower portion of fractionat ing tower 35., The temperature of the reaction products, after chilling, should be high enough 25 to permit fractionation thereof without addition al heating. The reaction products are separated in the fractionating tower 35 into residual oil, an inter mediate fraction boiling above the gasoline range, which is collected on the plate 31, gasoline boil ing hydrocarbons which are collected on the plates 39 and ‘I, and residual gas which comes over the top of the tower through line 43. The residuum is withdrawn from the bottom of the 35 fractionating tower through line 45 controlled by valve 41, at which the pressure is reduced to ap rator 93 is recycled through line 95 by means of pump 91, as re?ux, to the upper portion of the fractionating tower 35. The gases which remain uncondensed are withdrawn from the upper por tion of the separator 93, through line 99, and join the fresh gas in the line 5, to be reprocessed. The gases which are not lique?ed in the sepa rator 9 are withdrawn from the top thereof through line IOI controlled by valve I03 and charged to the inlet of the cracking coil I05 lo cated in the furnace I0‘I. If desired, the gases withdrawn through the line I0l may be further fractionated by being by-passed through line I09, compressed by compressor III, and charged to separator I I3. In this manner the hydrogen and methane may be eliminated from the gas prior to charging to the cracking coil. The gases will be compressed in compressor III su?iciently to liquefy the C2 fractions in order to separate them from the hydrogen and methane which are elimi nated from the system through line II5 con trolled by valve II'I. The lique?ed C2 fractions may be withdrawn from the separator II3, through line II9 controlled by valve I2I, and charged to the inlet of the cracking coil I05. When the gases charged to the cracking coil I05 are not further fractionated they are pref erably charged thereto in the gaseousstate under pressure of from 50-100 pounds per square inch. The gases may be heated in the cracking coil to 30 temperatures of l200°-1600° F. The temperature and pressure conditions maintained in this coil I05 will be those most suitable for obtaining maximum yield of gasoline boiling hydrocarbons. If the fraction removed from separator 9 through 35 line IN is low in ole?nic hydrocarbons, high proximately atmospheric pressure, and the oil is temperatures and low pressures, such as those ?ashed in flash tower 49 into vapors and tar. The residual tar is withdrawn from the ?ash 40 tower through line 5|, by means of pump 53, the coil I05. If the ole?nic content of these gases through cooling coil 55, to-any suitable place of storage. The vapors are withdrawn from the ?ash tower through line 51 and condenser 59 into separator 6|. Any uncondensed material is 45 withdrawn from the separator 5|‘, through line 53, and eliminated from the system. The con densate is recycled through line 55, by means of pump 51, to an intermediate portion of the frac tionating tower 35, as reflux. This re?ux pref 60 erably enters the tower at a point intermediate the trays 31 and 39. v The gasoline boiling constituents are with drawn from the fractionating tower through line 59 controlled by valve ‘II and line ‘I3 controlled a GI by valve ‘I5 and pass through a common line 11 into a stripper ‘I9. In the stripper light hydro carbons, such as C: and a portion of the C4 hydrocarbons, are vaporized and taken overhead through the line 8|. The stripper ‘I9 is prefer ably provided with suitable fractionating plates and heating means in order to stabilize the gaso line. The stabilized gasoline may be withdrawn from the stripper through lines 53 and 85 and passed to storage through line 91 controlled by valve 99. The pressure in the fractionating tower 35 is preferably maintained at approximately 175-250 pounds per square inch and the temperature at the top of the tower is‘ maintained su?iclently 70 low to condense the major portion of the gasoline fraction. vThe incondensible gases together with a small amount of uncondensed gasoline va'pors leave the fractionating tower 35 through line 53, then pass through condenser 9|, into gas and 75 liquid separator 93. 'The condensate from sepa above mentioned, are preferably maintained in is suillciently high, that is, above approximately 40 20%, it may bev advantageous to further frac tionate them to remove the hydrogen and meth ane, and charge the remaining gas in the liquid or gaseous phase to the coil I05. If liquid phase charging is employed, the pressures maintained 45 in the coil I05 may be 500-3000 or more pounds per square inch and the temperatures preferably between 700° and 1000° F. If the ole?n content is su?lciently high to avoid necessitating further fractionation, the gases charged to the coil I05 60 may be maintained at low pressures of approxi mately atmospheric to 250 pounds per square inch and at temperatures of approximately l100°-1200° F. It will be understood, however.v that these conditions of temperature and pres sure may be varied in accordance with the com position of the charge to the coil. The reaction time will vary with the pressure and temperature conditions maintained. Generally the reaction time will vary directly with the pressure and in 66 versely with the temperature. In the coil I05 cracking and/or polymerization of the gases take place in the formation chie?y of liquid hydrocarbons and ole?nic gases. The reaction products issue from the cracking coil through the line I23 and are suddenly chilled by direct contact with an intermediate condensate formed in the process, which is introduced into the line I23 at the point I25.-_ The partially chilled reaction products are further cooled by passing through the cooling or condensing coil I21, and then pass through line I29 controlled by valve I3I, into gas and liquid separator I33. From the separator I33 any liquid products are withdrawn through the line‘ I35 by means of 75 “ 2,117,464 pump I 31. The gases are withdrawn by means of the compressor I39 through line Ill and cool ing coil I43 and charged to the lower portion of the absorber I45. - Intermediate condensate substantially boiling within the range of gas oil is withdrawn from 3 lighter gases and eliminating them from the sys tem, ‘charging. the remainder of the reaction products resulting from said conversion of the lighter gases to a common fractionating zone together with the reaction products of the C1. C4 ' hydrocarbons‘. separating the incondensible gases the fractionating tower 35 through line I" by from the normally liquid hydrocarbons, and unit means of pump I49 and passes through cooling ing the incondensible gases with the fresh gas . coil Iii. From the cooling coil Iii a portion of . ‘ prior to separation thereof into fractions. the condensate passes through line I53 and valve - iii to the line I23 where it is injected into the reaction products from the coil I05 in order to cool these products below reaction temperature. The remaining portion of the condensate passes through line I51 controlled by valve I59 into the 15 upper portion of absorber I45 wherein it passes counter-currently to the gases entering the bot tom of the absorber. The pressure in the ab sorber may be preferably between 175—225 pounds per square inch and the temperature approxi 20 mately 75°-100° F. Under these conditions of temperature and pressure substantially all the Ca and heavier hydrocarbons will be absorbed as well as a substantial portion of the C: hydro 2.__.The process of converting gas mixtures, con taining chie?y C2, C: and C4 hydrocarbons, to liq uid hydrocarbons which comprises separating- the 10 mixture into a fraction containing chie?y C: and C4 hydrocarbons and a fraction containing C2 and lighter gases. subjecting each fraction in a 15 separate zone to suitable conditions of time. tem perature and pressure to convert a substantial portion of the gaseous constituents to liquid hy drocarbons boiling within the gasoline range, sepé arating the resulting. products from the lighter 20 ‘ fraction conversion into liquids and gases, con-.- ‘ taoting the gases imder pressure with absorber oil in order to absorb the major portion of the C3 and C4 hydrocarbons, charging rich‘absorber carbons, mainly ethylene. The hydrogen, meth-h oil into a common fractionating zone with the 25 ane and the main portion of vthe C2 hydrocar reaction products of the C3, C4 fraction, separat bons are eliminated from the absorber and from \ ing normally gaseous hydrocarbons from the the system through line IGI controlled by, valve I63. Rich oil leaves the bottom of the absorber 30 through line I65 and is charged by pump I61 through line I69 into line. I'll. The liquid hydro carbons from the separator I33 join the rich oil in the line I60. rI'he stream of rich absorber oil together with the liquids from separator I 33 35 may be split in the line ill, a portion passing through valve I13 and entering the line 30 at the point iii in order to chill the reaction products below reaction temperature, and another portion passing through the valve I15 into the interme 40 diate portion of the fractionating tower above the normally liquid hydrocarbons in said fraction ,ating zone, and mixing the normally gaseous hy drocarbons with fresh gas prior to separation 30 thereof. into fractions. 3. Process in accordance with claim in which the rich absorber oil is used to chill‘the reaction products of the C3, C4 fraction ‘below conversion temperature, and the chilled mixture charged to 35 the common .fraotionating zone. 4. Process in accordance with claim 2 in which the liquid reaction products from the conversion of the C2 and‘lighter gases are charged to the common fractionating zone. 40 5. Process in accordance with claim 2 in which a‘condensate heavier than gasoline is withdrawn plate 31 to act as re?ux. ‘ i In the fractionating tower the absorber oil is from the fractionating zone and cooled, and a stripped of its gases which pass over from the - portion of the cooled condensate used to chill the reaction products of the C2 and lighter gases be 45 tower through line 43 and are processed as here 45 tofore described. ‘ low reaction temperature and another portion By virtue of the fact that substantially all the used as the absorption menstruum. 6. Process in accordance with claim 2 in which C2 and lighter gases. are eliminated from the charge to the‘ coil I9, the recycle ratio to this the gas mixture charged to the process contains a substantial proportion of C3 and C4 olefins, and 50 coil is kept low allowing for a greater through '50 put of fresh charging stock. Moreover, the elim in which the C3, C4 fraction is subjected to con version at temperatures of 800°-1050° F. and at ination of these light gases permits the main tenance of those conditions in the coil I9 and pressures above 500 pounds per square inch while reaction coil'29 which will produce the maximum the C2 and lighter gas fraction is subjected to amount of desired product. The C2 and lighter conversion at temperatures between 1200" and 55 55 fractions, after having been subjected to a com 1600” F. and under pressures below 100 pounds bined cracking-polymerization operation, or to per square inch. '7. Process in accordance with claim 2 in which polymerization alone, in the coil I05, are sub stantially eliminated from the system through the gas mixture charged to the process is rich the line I6I, only a relatively small portion there ‘ in ole?ns and in which the fraction containing 60 60 of being absorbed in the absorber and recycled the lighter gases is further fractionated to re move methane and hydrogen, and the remainder to the system. of the fraction is subjected to temperatures be What is claimed is: 1. The process of converting gas mixtures, . tween 700° and 1000“ F. under pressures above 500 containing chie?y C2, C3 and C4 hydrocarbons, to pounds per square inch while the C3, C4 fraction 05 65 liquid hydrocarbons which comprises separating is subjected to temperatures of approximately 1075°-1200° F. under pressures up to approxir the mixture into a fraction containing chie?y Ca mately 250 pounds per square inch. and C4 hydrocarbons and another fraction con 8. Process in accordance with claim 2 in which taining C2 hydrocarbons and lighter gases, sub the gas mixture charged to the process is rich 70 jecting each fraction in a separate zone to suit 70 able conditions of time, temperature and pres in ole?ns and in which the fraction containing sure for converting the gaseous constituents to liquid hydrocarbons boiling within the gasoline boiling range, separating the bulk of the C2 and 75 lighter gases from the reaction products of the the lighter gases is further fractionated to re move methane and hydrogen, and the remainder of the fraction is subjected to temperatures be tween 700° and 1000° F. under pressures above 75 4 2, 1 17,484 500 pounds per square inch while the C3, C4 frac tion is subjected to temperatures of approxi mately 800°-l050° F. under pressures above 500 - pounds per square inch. 9. Apparatus for converting hydrocarbon gases absorber oil directly to said fractionating means. 11. Apparatus in accordance with claim 9 in cluding means for collecting heavy condensate in said fractionating means, means for with to liquid hydrocarbons comprising means for sep drawing said heavy condensate and contacting a portion thereof with hot reaction products from arating gases into a light fractionv and a heavy fraction, means 'for charging mixed gases to said separating means, a heating and reaction means. means for charging said light fraction to said heating and reaction means, a second heating said heating‘and reaction means, and means for charging another portion of said condensate to said absorption means. 12. The process of converting gas mixtures, 10 means and ‘a second reaction means connected containing chie?y C2, C3 and C4 hydrocarbons, to liquid hydrocarbons, which comprises separating thereto, means for charging said heavy fraction to said second heating'means, means for cooling the reaction products from said ?rst heating and the mixture into a fraction containing chie?y Ca and C4 hydrocarbons and another fraction con taining C2 hydrocarbons and lighter gases, sub 15 .reaction means, means for separating normally jecting each fraction in a separate zone to suit liquid from normally gaseous constituents in said able conditions of time, temperature and pressure cooled products, means for contacting said gas for converting the‘gaseous constituents to liquid eous constituents with absorber oil under such hydrocarbons boiling within the gasoline boiling conditions as to absorb substantially only the range, separating the bulk of the C: and lighter heavier portions of said gaseous constituents, gases from the reaction products of the lighter 20 means for eliminating the unabsorbed constit-' gases and eliminating them from the system, uents from the system, means for contacting the charging separated normally gaseous andnor rich absorber oil with the hot reaction products mally liquid reaction products resulting from said from said second reaction means in order to par ‘ conversion oi’ the lighter gases to a common frac tially cool said products, means for fractionating tionating zone together with the reaction prod the partially cooled products in order to separate ucts of the C3, C4 hydrocarbons, separating the the normally gaseous from the normally liquid constituents, and means for uniting the last men tioned normally gaseous constituents with the fresh gases charged to the system. 10. Apparatus in accordance with claim 9 in cluding means for charging a portion of said rich incondensible gases from the normally liquid hydrocarbons, and uniting the incondensible gases with the fresh gas prior to separation there of into fractions. , ‘ JOHN W. THROCKMORTON.