US2370507A - Production of gasoline hydrocarbons - Google Patents

Description

Feb. 27, 1945. c, F. TEICHMANN ET AL 2,370,507

PRODUCTION OF GASOLINE HYDROCARBONS Filed Aug. 22, 1941 F G I WA TER 14 SC BEE R U R 5 E PA R A Tl ON HEAT EXCHGP. HEATER CONVERSION 2 3 4 .WAVAVAVAVAVRVAVIL 1 V V Y V V V X I [I] OUTLE T WE LL [I2 FRACT/ONA TOR v 4 AND/OR c5 TANK ETC.

2 HIGHER BOILING FR A c r/o/v SEPARATION SEPARATION I22 CATALYTIC HEATER CONVERSION g qu/sursa 45 f24 /25 c FRACTION c HEAVIER v TANK TANK 30 .CA TALYT/C CON VERSION CONVER TED HYDROCARBONS CHARLES F. TEICHMANN ARTHUR R. GOLDSBY GoRoo/v A. KESSLER MAX NEl/HAus THE! .4 TTORNE 145' Patented Feb. 27, 19 45 PRODUCTION OF GASOLINE HYDROCARBON S Charles F. Teichmann, Mount Vernon, and Arthur B. Goldsby, Beacon, N. Y., Gordon A. Kessler, Ridgewood, N. J and Max Neuhaus, Bronxville, N. Y., assignor's, by mesne assignments, to The Texas Company, New York, N. Y. a corporation of Delaware Application August 22 7 Claims.

This invention relates to production of valuablegasoline hydrocarbons from subterranean distillate reservoirs and particularly to the treatment of low boiling gasoline hydrocarbon constituents of the' distillate obtained from such reservoirs.

In its broadest aspect the invention contemplates subjecting thedistillate fluid obtained from a distillate reservoir, or suitable fractions of such fluid, to conversion so as to produce gasoline hydrocarbons of improved antiknock value from the distillate. The converted hydrocarbons are removed and the residual gaseous hydrocarbon constituents of the well fluid, including, if desired, gaseous constituents produced in the conversion treatment, are returned under elevated pressure to the subterranean distillate reservoir.

, 1941, Serial No. 407,984

lication, for every binary or other mixture of normally gaseous hydrocarbons, there is a boundary on the pressure-temperature plane within Advantageously the conversionis effected under pressure which is not substantially different from that at which the distillate -fluid is'obtained from the well.

The fluid from subterranean distillate reservoirs is composed mainly of normally gaseous in the subterranean formation. Reduction in the formation pressure is usually accompanied by substantial condensation of liqueflable hydrocarhens in the reservoir itself thereby resulting in the permanentloss of useful hydrocarbons. For this reason it is desirable to avoid reduction in the formation pressure.

This condensation which occurs upon reduction vof the pressure is known as retrograde condensation. Retrograde condensation, as described in the articleby George G, Brown entitled Retrograde condensation and the critical phenomena". published inthe Proceedings of the 18th Annual Convention of the Natural Gasoline Association of America, held May 3-5, 1939, is

that condensation Which-is brought about by reduction. in pressure even though the temperature remaiiis constant. As de scribed in this pub- Therefore, if the temperature and pressure of a mixture of hydrocarbons which is already under conditions of temperature and pressure substantially above the critical point, are reduced through th two-phase boundary, retrograde condensation occurs as described in the foregoing publication.

Consequently, it is desirable to return the residual gases, after recovery of the gasoline hydrocarbons, to the reservoir or subterranean formation under elevated pressure so as to maintain the formation pressure and thereby avoid the 'foreg'oing'condensation of liquefiable hydrocarbons within the formation.

Preferably in accordance with the present invention the well fluid is treated without substantial reduction in pressure so as to convert gaso-.

line hydrocarbons such as normal butane and normal pentane, etc., to gasoline hydrocarbons of improved antiknock value. The converted hydrocarbons are separated from the treated fluid without substantial reduction in pressure and the residual gases then returned to the formation.

The conversion treatment may involve thermal or catalytic reforming at temperatures of about 700 to 1100 F; One advantageous form oftreatment comprises hydroforming by contact with a hydroforming catalyst such as a mixture of aluminum and molybdenum oxides or aluminum and chromium oxides at a temperature inthe range about 800 to 1000 F. Still another form of treatment comprises isomerization by contact with an isomerization catalyst such as an active metallic halide .at a temperature of about 200'to 400 F.

The recovered hydrocarbons includingmainly converted hydrocarbons are of improved antialkylation reaction for'reaction with -.lowboiL ing olefin hydrocarbons to produce normally liqvalue. Isopentane may be separately reacted with hydrocarbon polymers such as (11- and triisobutylenes by contact with a suitable alkylation catalyst for the production of safety fuel of high antiknock value.

The temperatures of distillate fluids at the well head are usually of the order of about 100 to 175 F. while the pressures are of the order of about 1000 to 5000 and usually of about 2000 to 3500 pounds per square inch gauge.

In order to efiect the desired conversion it is conditions which are near to or outside the twophase boundary for the well fluids so that the fluid is substantially entirely in a single homogeneous phase. The conversion reaction may be carried out under temperature and pressure conditons which are somewhat above the critical point for the reacting hydrocarbons, for example, above the critical point for butane and lighter hydrocarbons, so that the pressure upon the hydrocarbon reaction mixture may be subsequently reduced through or within the retrograde condensation range oi liqueflable hydrocarbon constituents of the mixture such that substantial condensation occurs. The resulting condensate comprising converted hydrocarbons is separated and the residual gases are thereafter forced hacl: into. the subterranean formation.

By effecting the conversion treatment of the hydrocarbons without substantial reduction in the pressure or in other words, at about the pressure corresponding to the pressure of the fluid as obtained from. the well, the reed hydrocarbons undergoing treatment are thus in a dense phase during the reaction. This favors more efiective contact between the hydrocarbons undergoing conversion and the catalyst. 'It also permits a higher throughput with a short time of contact.

The well fluid consists mainly of gaseous hy drocarbons, particularly methane. Normal butane ma amount to about 1 or 2 moi per cent of the fluid so that the proportion of gaseous material such as methane is relatively large as compared to the content of butane and higher molecular weight hydrocarbons.

The presence of relatively inert gaseous material such as methane in relatively large proportion to the hydrocarbons undergoing conversion is advantageous from the standpoint of inhibiting undesired side reactions and catalyst deterio- 2,370,507 uid gasoline hydrocarbons of high antiknock mal butane and normal pentane. Removal of the hexane and heavier may be efiected by selective absorption, adsorption or by retrograde condensation, and these higher molecular weight hydrocarbons may be subjected to separate conversion treatment or separately disposed of as desired.

In order to describe the invention more fully reference will now be made to the figures of the accompanying drawing.

Referring to Fig. 1, well fluid is obtained from an outlet well I tapping a subterranean distillate reservoir.

The fluid is obtained under a pressure, for example, of about 2000 pounds and at a temperature of about 125 F. This fluid ma have the following approximate composition:

- I Moi per cent Methane 89.46

Where the fluid is subjected to an isomerization reaction by contact with a catalyst comprising aluminum chloride and hydrogen halide, the well fluid without substantial reduction in pressure is passed through a heat exchanger 2 and heater 3 wherein it is raised to a mmperature of about 200 to 250 F. The so heated fluid is then conducted to an isomerization plant 3 wherein the normal paramn constituents such as normal butane and normal pentane are converted to isoparaflins.

The fluid containing converted hydrocarbons is advantageously passed through pipe ii to the previously mentioned exchanger 2 wherein it flows in indirect heat exchange relationship with the entering ieeol. Thereafter it is conducted to a hydrocarbon recovery plant '5 wherein th butanes and higher molecular weight hydrocarbons including converted hydrocarbons are separated from the residual gases. This separation may be eflected by absorption in a suitable absorption oil, by adsorption during contact with a solid adsorptive material or by retrograde condensation.

Where the operation is efiected by absorption the fluid leaving the catalytic treating plant it is cooledto a temperature of about to F. and the cooled fluid subjected to contact. with heavy oil, gas oil or other suitable absorption menstruum. The absorption may be carried out either by concurrent or countercurrent contact between the well fluid and the absorption oil, without substantial reduction in pressure and under conditions of temperature and proportion of absorption oil to fluid such that normal butone and higher molecular weight hydrocarbons are selectively absorbed from the residual gases.

Where the separation is effected by adsorption the catalytically treated fluid without substantial reduction in pressure and advantageously after having been cooled to a temperature of about 90 to 100 F. is conducted through a tower packed with a solid adsorptive material such as charcoal or silica gel under conditions such that a normal butane and higher molecular weight hydrocarbons are selectively adsorbed in the adsorbent material.

The adsorption operation is advantageously ef-,

fected in a plant having a plurality of adsorption towers so that while one adsorption'tower is onstream anothertower is oifstream for-regeneration during which the adsorbed hydrocarbons are stripped from the adsorbent material inthe conventional manner.

' Where the separation is efiected by retrograde condensation this may be accomplished by passing the catalytically-treated fluid to a closed vessel wherein the pressure is-reduced through or motor fuel stock or for further fractionation to segregate the isoparamns therefrom for further reaction with olefins to form alkylated hydrocar bons. I

- The recovered hydrocarbons from the tank ll may be passed to a fractionator l2 for the purpose of segregating hydrocarbons or fractions therefrom. Th recovered hydrocarbons ,accumulating in the tank It may contain substantial amounts of gaseous material which will be released upon reduction of pressure. Accordingly,

in the fractionator I! the overhead fraction may The gaseous fraction removed as an overhead from the fractionator i2 is advantageously in-' jected by means of a compressor into the untreated well fluid passing to the catalytic conversion plant 4 and in this way the gaseous hydrocarbons may be ultimately returned to the reservoir while at'the same time taking advantage of the promotional effectof the retained hydrogen chloride during the catalytic reaction.

On the other hand, the gaseous fraction may be injected directly to the eflluent'fluid passing through the pipe 9 for return to the input well. The hydrogen chloride present in the returning residual gases thus serves, upon return to the input well, to open up the formation.

If desired to avoid or substantially reduce'the amount of hydrogen chloride passing to the inletwell, the thermally orcatalytically treated well' fluid may be subjected to scrubbing withwater.

, Thus, the treated mixture flowing through the previously mentioned separator The water containing'absorbed hydrogen chloride-is withdrawn from the absorber and may be disposedof in anysuitable manner or may be concentrated in order to recover. the acid.

The scrubbing or washing step may be applied following the separation treatment in the separator I. In other words, the residual gases flowing through the pipe 9 may be subjected to the scrubbing or washing treatment to remove hydrogen chloride.

If instead of subjecting the liquefiable hydrocarbons of the well fluid to the isomerization they are subjected to hydroforming, the methodof flow is generally similar to that already described above in connection with Fig. 1 with the exception that the water. washing or scrubbing. of the treated hydrocarbon mixture is omitted. Thus,

the well fluid from the outlet well I is passed through the heat exchanger and the heater so as to heat it to a temperature in the range of about 850 to1050 F. The heated mixture is then passed to the conversion zone 4 wherein it .is subjected to contact with a suitable hydroforming catalyst, as, for example, a mixture of aluminum and molybdenum oxides.

Since the feed mixture contains a relatively large proportion of methane there is thus present in the reaction a large amount of hydrogen-comtaining gas. Provision may be made for recycling hydrogen and hydrogen-containing gases produced in the reaction.

It is contemplated that the .well fluid prior to introduction to the catalytic conversion unit t may be subjected to chemical treatment such as scrubbing with caustic or other alkali solution for the purpose of removing sulfur compounds and other impurities which if not removed would cause catalyst deterioration in the subsequent catalytic conversion operation.

Referring now to Fig. 2 the well fluid from the outlet well 20 which may be similar to that discharged from outlet well I of Fig. 1 and may also be under similar conditions of temperature and pressure, is conducted through a pipe 2! to a separation plant 22 wherein the fluid is separated into fractions, one fraction consisting, for example, of butane and lighter hydrocarbons; and the. other fraction consisting of hydrocarbons heavier than butane, namely, pentane and hexane, etc.

This separation may be eiTected by absorption in a suitable absorption liquid or adsorption by contact with a suitable solid adsorptive material.

The absorption or adsorption operations may be carried out in the conventional manner such as described in connection with similar operations in the recovery plant I of Fig. 1. In any case the separation into 04 and lighter and Cs and heavier fractions is efiected without substantialreduction in pressure. If desired the pressure on the well fluidmaybe increased so that the separation may existing at the outlet of well 20.

The C4 and lighter fraction consisting mainly of methane is passed through a heater or heat exchange apparatus 23 wherein it is raised to the requisite temperature for efiecting the subsequent catalytic-conversion, in this case isomerization.

The heated fluid is then passed through a cata- 'lytic conversion unit 24, wherein the 'normal butane is subjected .to contact with an isomeriza tion catalyst maintained underisomeriz-fng conditions, but without substantial reduction in pressure of the well fluid;

The catalytically treated fluid is then passed to a separation or recovery unit 2i similar to the recovery unit I of Fig. 1, and by which means C4 and heavier hydrocarbons are separated and recovered from the residual gases. The residual gases are thereafter forced by means of a pump or compressor 26 into an input well 21 for return to the subterranean formation.

The recovered C4 and heavier fraction is passed to a storage tank 28. The recovered fraction may be disposed of as described in connection with the liquid accumulating in tank II in Fig. 1.

The C and heavier fraction removed from the separation unit 22 is passed to a storage tank 29 and may be disposed of as blending stock for gasoline. Advantageously, however, it is subjected to a catalytic conversion treatment such as previously disclosed. In such case the fraction is conducted from the tank 29 to a separate conversion unit 30 wherein it is subjected to the conversion treatment.

The resulting converted hydrocarbons rich in isoparaffins can then be used as a blending stock or can be fractionated to segregate individual hydrocarbons or hydrocarbon fractions therefrom for such further disposition as may be desired.

While reforming and isomerization have been mentioned in connection with the catalytic conversion of readily liquefiable hydrocarbons of the Well fluid, nevertheless it is contemplated that the conversion treatment may comprise other desired types of conversion reactions either catalytic or pyrolytic such as cracking and dehydrogenation, for example, in order to obtain the desired type of converted hydrocarbon products. More elevated temperatures are usually required Where a cracking type of operation is employed, and the catalysts used may be aluminum silicates, natural or artificial, or silicate or other solid adsorptive materials impregnated with metals and metal compounds.

Where a simple isomerization reaction is involved the catalyst is advantageously one selected from the group of metallic halides such as aluminum chloride, iron chloride, zirconium chloride, metallic mixed halides such as aluminum chlorofluoride (AlClFz), aluminum fiuorochloride (AlFClz) and the like,.promoted with a hydrogen halide such as hydrogen chloride.

Under certain conditions a promoter may not be required, for example, in the isomerization of pentane and the like with a metallic mixed halide catalyst.

The isomerization of the normally liquid fraction accumulating in the tank 29 of Fig. 2 is ad- ---'cyclohexane, etc., for the purpose of inhibiting cracking of hydrocarbons and deterioration of the catalyst. For example a portion of the residual gases from the reaction in conversion zone 24 may be mixed with the hydrocarbon feed to the isomerization reaction in conversion zone 30.

Provision may be made for recycling hydrogen and hydrogen-containing gases, formed in the conversion, through the conversion reaction zone as described in connection with Fig. 1. Moreover the conversion in unit 30 may be carried out underpressure corresponding substantially to that of the well fluid at the head of the outlet well.

Provision may be made for altering the pressure prevailing at any stage in the process. For example, in the absorption or adsorption operations the pressure may be adjusted, depending upon temperature and other conditions, in order to obtain the desired separation. If it is necessary to reduce the pressure, then provision must be made for increasing the pressure in a, later stage or stages of the process inorder to force the residual gases back into the inlet well. Advantageously a substantial reduction in overall pressure is avoided so as to reduce the amount of compression required in order to return the residual gases to the subterranean reservoir.

While return of residual gases to the same reservoir has been described, it is contemplated that they may be returned, all or in part, to a different or neighboring subterranean reservoir for the purpose of maintaining or aiding in maintaining reservoir pressure.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A process of producing low boiling gasoline hydrocarbons of improved antiknock value from the well fluid of a subterranean distillate reservoir which comprises obtaining well fluid from an outlet well of the reservoir at a high well head pressure, said fluid containing gaseous hydrocarbons having 4 carbon atoms and less per molecule and higher molecular weight hydrocarbons having 5 and more carbon atoms per molecule, removing said higher molecular weight hydrocarbons from said fluid without substantial reduction in pressure, and then subjecting the residual fluid while at substantially well head pressure to contact with an isomerization catalyst in the presence of hydrogen halide at an elevated temperature in the range below about 400 F. such that substantial isomerization of normal paraffin constituents of the residual fluid to isoparafilns occurs, thereafter separating from said residual fluid containing isomerized hydrocarbons and hydrogen halide at pressures within the retrograde condensation range a hydrocarbon condensate, removing the resulting condensate from residual gas and recycling residual gas containing hydrogen halide to'an inlet well of said reservoir.

2. A process of producing low boiling gasoline hydrocarbons of improved antiknock value from the well fluid of a subterranean distillate reservoir whichv comprises obtaining well fluid from an outlet well of the reservoir at a. high well head pressure said fluid containing gaseous hydrocarbons having less than 4 carbon atoms per molecule and higher molecular weight hydrocarbons having 4 and more carbon atoms per molecule, separating from said fluid without substantial reduction in pressure a fraction comprising C4 hydrocarbons and lighter constituents of the fluid,

' subjecting said C4 and lighter fraction while under substantially well head pressure to contact with an isomerization catalyst maintained in the presence of hydrogen halide at an elevated temperature in the range below about 400 F. such that substantial isomerization of normal butane to isobutane occurs, passing the isomerized fraction containing some hydrogen halide to a separating zone, effecting separation therein ,of a hydrocarbon condensate without substantial reductlon in pressure, removing the resulting condensate from residual gas and recycling residual gas containing hydrogen halide to an inlet well of said reservoir.

3. A process of producing low boiling gasoline hydrocarbons of improved antiknock value from the well fluid of a subterranean distillate reservoir which comprises obtaining well fluid from an outlet well of the reservoir at a high well head pressure, said fluid containing gaseous hydrocarbons having less than 4 carbon atoms per molecule and higher molecular weight hydrocarbons having 4 and more carbon atoms per molecule, separating said fluid without substantial reduction in pressure into a fraction comprising C4 hydrocarbon and lighter constituents of the fluid and a fraction comprising higher molecular weight hydrocarbons, subjecting said C4 and lighter fraction while under substantially well head pressure to contact with an isomerization catalyst maintained in the presence of hydrogen halide at an elevated temperature in the range below about 400 F. such that substantial isomerization of normal butane to isobutane occurs, passing the isomerized fraction containing some hydrogen halide to a separating zone, effecting separation therein of a hydrocarbon condensate without substantial reduction in pressure, removing the resulting condensate from 'the residual gas, separately subjecting said higher molecular weight fractionto an elevated temperature in the range 700 to 1100 F. whereby said hydrocarbons undergo conversion into hydrocarbons of improved character for gasoline manufacture and some gas, removing the gasoline hydrocarbons from the products of said conversion and recycling the residual gas containing hydrogen halide from the isomerization reaction and the conversion reaction to an inlet well of said reservoir.

4. A process for recovering hydrocarbons from high pressure well fluid which comprises obtain ing well fluid from an outlet well of a subter ranean formation, said fluid containing gaseous hydrocarbons having 4 carbon atoms and less per molecule and some higher molecular weight hydrocarbons, removing said higher molecular weight hydrocarbons from the residuaLfiuid, subjecting the residualfluid to contact with an flns, which comprises flowing said fluid from an outlet well of a subterranean formation, subjecting normally gaseous and liquefiable hydrocarbon constituents of said fluid to contact with an isomerization catalyst in the presence of hydrogen halide at an elevated temperature such that substantial isomerization of normal parafiin hydrocarbons occurs, passing resulting catalytically treated hydrocarbons containing some hydrogen halide to a separation zone, effecting separation therein of a hydrocarbon condensate, removing said condensate from residual gas containing hydrogen halide, and recycling said residual gas containing hydrogen halide to an inlet well of said formation.

6. A' process for recovering hydrocarbons from high pressure well fluid containinggaseous and liquefiable hydrocarbons includin normal parafflns, which comprises flowing said fluid from an outlet well'of a subterranean formation, subjecting normally gaseous and liqueflable hydrocarbon constituents of said fluid to contact with a metallic halide catalyst in the presence of hydrogen halide at an elevated temperature not exceeding about 400 F., passing resulting catalytlcally treated hydrocarbons containing some hydrogen halide to a separation zone, effecting separation therein of a hydrocarbon condensate, removing said condensate from residual gas containing hydrogen halide, and recycling said residual gas containing hydrogen halide to' an inlet well of I said formation.

7. A process for recovering hydrocarbons from high pressure well fluid containing gaseous and liqueflable hydrocarbons including normal paraffins which comprises flowing said well fluid from an outletwell of a subterranean formation, subjecting normally gaseous and liqueflable hydrocarbon constituents of said fluid to contact with an isomerization catalyst in the presence of hydrogen halide at an elevated temperature such that substantial isomerization 0! normal paraflins occurs, passing resulting catalytically treated hydrocarbons containing hydrogen halide to a sepisomerization catalyst in the presence of hydrogen halide at an elevated temperature not exceeding about 400 F., such that substantial isomerization of C4 hydrocarbon occurs, passing the catalytically treated fluid containing some hydrogen halide to a. separating zone, effecting separation therein of a hydrocarbon condensate, re-

moving said condensate from the residual gas containing hydrogen halide, and recycling said residual gas containing hydrogen halide to an inlet well of said formation.

5. A processior recovering hydrocarbons mm high pressure well fluid containing Sasecus and limieflable hydrocarbons including normal para!- arating zone, effecting separation therein from residual gas of a hydrocarbon condensate containing some normally gaseous constituents including hydrogen halide, removing said condensate from residual gas, subjecting the removed condensate to fractionation into a normally gaseous fraction containing some hydrogen halide and a higher boiling traction, removing the higher boiling fraction and recycling residual gas and said normally gaseous fraction containing hydrogen halide to an inlet well of said formation.

- CHARLES F. 'IEICHMANN.

ARTHUR R. GOLDSBY. GORDON A. KESSLER. MAX NEUHIiUS.

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