US2157224A - Method for producting motor fuels - Google Patents

Description

May 9, 1939.

c. R. WAGNER METHOD FOR PRODUCING MOTOR FUELS 'Filed April yL21, 1953 gmc/wm 762737 1 'Vl/'agiter i Patented May 9, 1939 UNITED STATES 2,157,224 METHOD FOR. PRODUCING MOTOR FUELSv Cary R. Wagner, Chicago, Ill., assignor to The Pure Oil Company, Chicago, Ill., a corporation of Ohio Application April 21, 1933, Serial No. 667,255

8 Claims.

This invention relates to an improved system for producing hydrocarbon motor fuels of the type which contain high percentages of nnsaturated hydrocarbons and, more particularly,

the invention has to do with the treatment of unsaturated hydrocarbon gases, especially those obtained from vapor phase cracking systems, whereby a large proportion of such gases are, when subjected to controlled conditions of temperature and pressure, transformed into hydrocarbon compounds, liquid at normal temperatures and pressures, and which may be used as improved motor fuels.

I'his invention is a continuation in part of the ldisclosures contained in my prior application, Serial No. 573,233 filed Nov. 5, 1931, which has matured into PatentI No. 2,088,886, granted August 3,1931.

It is a primary object of the present invention l to subject cracked hydrocarbon gases containing ethylene and its homologues to conditions of elevated temperature and pressure to polymerize such gases, in part, into hydrocarbons of higher molecular weights and to accomplish this result l in such manner as to provide for an increased yield of the more valuable liquid products with an accompanying decrease in the unusable permanent gas production.

Fora'further understanding of the invention,

30 reference is to be had to the following description and the accompanying drawing, wherein:

'Ihe ligure is a diagrammatic view illustrating the apparatus which may be employed in carrying the present invention into ellect.

:i It will be understood that the apparatus has been but diagrammatically illustrated in order to serve as a flow chart and that the positional order and elevations of the apparatus illustrated is not necessarily that which may be used in comvMl mercial operations. i

Referring more particularly to the drawing, the

l charging hydrocarbon gas which may be of an oleflnic character and obtained, for example, from the gas separator (not shown) of a vapor 45 phase oil cracking system, is passed under ordinary flowing :pressures of the order of pounds through a pipe line I for delivery to the low pressure cylinder 2 of a two-stage compressor C. After being compressed in the cylinder 2 to 50 a pressure of the order of 250 pounds per square inch. the gas is forced through a pipe line 3, and

a heat exchanger 4 to a gas separator 5. In this separator there takes place the separation of the more readily liqueiiable constituents of the charging gas from the remaining compounds (on. 19o-s) which do not form liquids under the pressures specied.

The substantially liqueed compounds are removed from the bottom of the separator 5 and, without any substantial release of pressure theren on, are passed to a stabilizing or fractionating column 6 through the connecting pipe line l, the latter leading from the bottom of the separator 5 to a point substantially intermediate of the height of the column 6. This column may be provided with the usual internally situated baiiles or trays 8, or other standard liquid and vapor contact means, whereby low boiling compounds entrained in the oils delivered to the column 6, and present as vapors, may be brought into intimate counter-current contact with the higher boiling liquid compounds. Those compounds which accumulate in the bottom of the column 6 as stabilized liquids are withdrawn either continuously or intermittently through the valved draw-oil line' and'possess the boiling range of gasoline. These oils may be-referred toas the polymerized distillate and due to the high percentage of unsaturated hydrocarbons which they contain, may be used directly as an anti-knock motor fuel, or as a blending oil for increasing the anti-detonating value of a lower grade motor fuel oil.

The remaining vapors or gases are withdrawn from' adjacent the top of the column 6 and are passed through a pipe line I0 to a suitable ccnl denser II, and thence to a separating chamber I2 in which a variable pressure usually not in excess of 250`p'ounds is maintained. Permanent gas is removed from the top of the chamber I2 through the valved gas outlet line I3, while the condenser cooled liquid fraction is withdrawn from the bottom of said chamber through the pipe line I4 and delivered to the suction side of a pump I5. A pipe line I6 leads from the Voutlet side of said pump to a heating -coil I1 located in a pipe still I8, the latter being provided with the customary burners I8. Alsoleading from the pipe line I6 is a branch I9, which extends to the top of the column 6 to provide for the passage of a reflux oil downwardly through said column to control the fractionation taking place therein. The gases removed from the primary separator 5 by way of the top line 20 are passed to the high pressure cylinder 2| of the compressor C, wherein the pressure of the gas is'increased from approximately 250 pounds to a considerably higher pressureof the order of 500 to .2000 pounds per square inch, and under thislatter pressure, the gases aredelivered to the line I6 leading to the heating coil I1, a connecting pipe line 22 being employed for this purpose.

Naphtha obtained from topping plants or the `like may be introduced into the system by way forming of naphtha into a low boiling motor fuel oil containing high percentages of unsaturates. Thus the general utility of the present system is materially increased by its ability to reform naphtha without requiring additional refinery equipment for effecting this increasingly important operation. In the coil I1, the gases alone, or a mixture of the gases and liquids, are heated to temperatures oi' the order of 850 F. to 1100 F. while maintained under' superatmospherlc pressures varying between 500 to 2000 pounds per square inch. The system operates quite satisfactorily, however, when the products discharged from the coil I1 possess a temperature of the order of 950 F. to 1000 F. and a. pressure oi about 700 pounds.

These products are then transferred to an externally disposed Areaction drum 24, which is preferably unheated from external sources, although the metallic drum maybe covered by a suitable heat insulating material if desired. 'I'he drum 24 may be lined with silica or ganister, if desired, to avoid catalytic dehydrogenation in some cases. Since the polymerizing reactions which are eifected in the zone 24 are highly exothermic in character, care must be exercised to prevent the reaction compounds from attaining undesirably high temperatures, such as 1100 F. to 1200 F., since such high temperatures tend to crack or decompose the compounds, thereby causing excessive fixed gas formation and marked reduction in the recovery of the desired liquid products and also undesirable coke formation. Suitable pressure and temperature recording instruments 24` may be employed in connection With the reaction drum, as in other parts of the system, to enable an operator to exercise accurate control over the functioning thereof, The temperature of the products within said drum is preferably maintained at substantially 950 F. to l025 F., together with pressures of the order of 600 pounds per square inch.

Further, regulation of the temperature in the polymerization zone, which includes the reaction drum 24 may be effected by regulating the introduction of naphtha into the polymerizing zone. Thus naphtha may be added in such quantities so that the endothermic heat of the reactions involved in cracking or reforming naphtha approximately balances the exothermic heat produced by the polymerizing of oleflns. In this manner effective control of reaction-producing temperatures in the polymerizing zone is obtained.

Following the completion of the desired reactions in the drum 24, the heated products are then passed through'a pipe line 25 toa cooler or heat exchanger 26 and thence to a final separator 21; 'Ihis separator is maintained under a variable pressure, but usually one of the order of 450 pounds. The fixed gas may be withdrawn from the separator 21 by way of the overhead valved line 28 and removed frpm the system for storage or other suitable use, While the liquid fraction is withdrawn from the bottom of the separator and transferred by way of the pipe line 29, containing the 'pump 30, and delivered to the pipe line 3 for passage through the heat exchanger 4, the gas separator 5 and the stabilizing column 6. A branch pipe line 3| may be employed to divert a part of the liquid passing through the line 29 to a jet cooler 32 disposed in the pipe line 25 at the outlet of the reaction drum 24, whereby accurate control is obtained of the temperature of the products delivered to the separator 21, insuring condensation of all normal liquid-like products together with minimum formation of carbon deposit, the products discharged from the drum 24 being shock chilled to nonreacting temperatures in a very short interval of time.

The present system provides for a very high recovery of liquid oils of motor fuel boiling'range from cracked refinery gases or other oleflne-containing gases. It will be noted that waste or fixed gas may ,be withdrawn optionally through the lines I3 and 28, insuring a complete elimination of those gaseous compounds which do not polymerize and, conversely, the system provides for the subjection in a sustained manner of all hydrocarbons which under the conditions of temperature an'd pressure specified tend to polymerize into higher boiling hydrocarbons, thus effecting the formation and recovery of a maximum quantity of liquid oils or motor fuels from a given amount of charging gas.

What is claimed is:

1. In a process of producing motor fuel of high anti-knock rating which comprises mixing gas having an olefin content sufliciently high to react exothermically with rise in temperature and a hydrocarbonr oil which reacts endothermically under the conditions to which the mixture is subjected, heating the mixture to a temperature of the order of 850 to 1100? F. under pressures of from 500 to 2000 pounds per square inch, and maintaining the mixture Within the reacting temperature range for a period of time suiiicient to bring about the desired conversion, the step which consists in proportioning the gas and oil in such quantities that the heat liberated by the reactionV of the gas is substantially balanced by the heat absorbed by the reaction of the oil.

2.'In a process of simultaneously reforming naphtha and polymerizing olefin containing gases to liquid hydrocarbons which comprises heating a mixture of 'said gases and naphtha in a restricted stream sufficient to enable the mixture to attain a temperature of from 850 to 1100 F. un-

der a pressure above 500 pounds per square inch but not substantially in excess of 2000 pounds yper square inch, passing the heated mixture into an enlarged reaction zone Without substantial reduction in pressure, and maintaining said mixture in said zone for a period of time suiicient to convert a substantial portion of olefinic gases to liquid hydrocarbons of gasoline boiling range, the step which consists in proportioning the gases and naphtha in the mixed stream subjected to heating and polymerization in such quantities that the heat evolved by the exothermic polymerization of the gases substantially balances the heat absorbed by the endothermic reforming of the naphtha.

3. In a process for simultaneously reforming naphtha and polymerizing olefin containing gases to liquid hydrocarbons which comprises heating a mixture of said gases and naphtha in a restricted stream, and passing the heated mixture into an enlarged reaction zone wherein the mixture is maintained under pressures of from 500 to 2000 pounds per square incht and at temperatures of 850 to 1100 F. for a period of time sumcient to convert a substantial portion of oleflnlc gases to liquid hydrocarbons of gasoline boiling range, the step which consists in adding additional quantities of naphtha to the reaction zone in such amounts that the heat absorbed by the endothermic reaction of the naphtha' will substantially. balance the heat liberated by the exothermic reaction of the gases. y

4. The process for converting oleflnic gaseous hydrocarbons to normally liquid hydrocarbons which comprises. heating said gases to a temperature sufficient to initiate exotherrnic polymerization of the gases while maintained under super-atmospheric pressure, maintaining the heated gases in a.' polymerization zone under temperatures and pressures sufficient to convertk a substantial portion of the gases to normally liquid hydrocarbons, and regulating the temperature in the polymerization zone by introducing polymerization of said gases and maintaining the mixture at such temperatures and pressures for a period of time sumcient .to convert a substantial portion of said gases to liquid hydrocarbons, the step which consists in proportioning the gases vandnaphtha in the mixed stream subjected to heating and polymerization in such quantities that the heat evolved by the exothermic polymerization of the gases substantially balances the heat absorbed by the endothermic reforming of the naphtha.

7. The process of simultaneously polymerizing hydrocarbon gases rich in olens and reforming hydrocarbon oil which comprises heating a mixture of said gases and hydrocarbon oil under high superatmospheric pressure to a temperature suitable for polymerization of said gases,.main taining the mixture in an unheated polymerization zone at such temperature and pressure for a period of time sufiicient to convert a substantial portion of said gases to liquid hydrocarbons. and adding further quantities of hydrocarbony oil to the reaction products in the reaction zone in amounts sufcient to prevent excessive temperature rise but in insuiilcient amounts to effect material lowering of the temperature.

8. The process of simultaneously polymerizing hydrocarbon gases rich in olens and reforming naphtha which comprises heating a mixture of said gases and naphtha under high super-atmospheric pressure to a temperature suitable for polymerization of said gases, maintaining the mixture in an unheated polymerization zone at such temperature and pressure for a periodoi' time suilicient to convert a substantial portion of said gases to liquid hydrocarbons, and adding further' quantities of naphtha to the reaction products in the reaction zonein amounts sumcient to prevent excessive temperature rise but ln insufficient amounts to effect, material lower- 35 ing ofthe temperature.

CARY R. WAGNER.

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