US2697718A - Method of producing gasoline - Google Patents

Description

Dec- 21, 1954 E. J. GOHR ETAL METHOD OF PRODUCING GASOLINE ummum. NOU

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United States Patent METHOD :or PRODUCING GAsoLINE Edwin J. Gohr, New York, N. YaFrank T. Barr, Summit, N. I., and Bruno E. Roetheli, Putney, London, England, assignors to Standard Oil Development Company, a corporation of Delaware Continuation of application Serial No. 549,530, August 15, 1944. This application September 429, 1949Seri`a'l No. 118,552

'5 Claims. I(Cl. 26o-449) The present invention relates 'to fthe novel features disclosed in the following specification and claims considered in connection with the accompanying drawing. More particularly, the present invention relates lto the utilization of coal for the production yof gasoline. In a preferred modification, the .coal is subjected to Icolti-ng temperatures to form xed ycarbon or coke and tvolatile kconstituents; thereafter, the `coke `is `converted to water gas which, after adjustment of the hydrogen to ratio, is subjected to a conversion in the presence of a suitable catalyst which formsr normally liquid hydrocarbons, from which hydrocarbons including gasoline. may be obtained by further treatment; the volatile constituents from the original vcoking operation may be treated to recover arnmonia, light aromatic 'spiritsfand normally gaseous olefins which may be pol-ymerized and/or alkylated, according to known procedure, to form further quantities of .gasoline; and the tar is hydrogenated to form a quantity of gasoline.

The main object .of vour invention, therefore, relates to the improvements in the utilization of coal for fthe production of maximum quantities of motor fuel in `an integrated operation which may be. performed eiciently and economically.

A more specic object of our invention is to process coal in powdered form and ilnidized condition to convert the powdered coal vto Avolatile constituents and coke, which coke may then be converted to water gas and `thereafter into normally liquid hydrocarbons by reacting carbon monoxide and hydrogen.

Many other objects and advantages of our invention will appear from the following more `detailed description and claims.

In the accompanying drawing we have indicated diagrammatically, by means ofk a tlow plan, a preferred embodiment of our invention.

Referring in detail to 4the drawing, coal n powdered condition having a particle size of from 50-400 mesh enters the present system through line 1 by any sut able means (not shown) which may be, for instance, by means of a screw feeder in communication with a suitable supply hopper. The coal is discharged into a preheater 3. The purpose of introducing the coal into the preheater 3 is, of course, to :dry it and raise its temperature, say to about 250-600 F., and this is accomplished by also discharging into the preheater 3 volatile constituents from 'a subsequent cokiing step, via line 4c which are withdrawn through line 5. The preheated coal is then withdrawn through line and discharged into the gas stream 11 `which comprises, say, normally gaseous hydrocarbons, as, for instance, recycled scrubbed coal gas from line 50, later described, and conveyed into coking vessel 12 where it forms a dense suspension of powdered coal and large amounts of coke in the gas as will appear hereinafter. This phenomenon is accomplished in known manner by controlling the velocity of the gas in the coker within the range of 1/z--10 ft. per second, preferably to 3 ft. per second. To aid in the distribution of the entering gas suspension, a foraminous member 14 may be disposed near the bottom of coking vessel 12. Cok' vessel 12 is in communication with a standpipe 15 rom which coke may be withdrawn continuously. The suspension in Coker 12 will have an upper dense phase level at L, the height of which may be controlled by means of a slide valve yin draw-olf standppe 15. As stated, the coal and coke 2,697,718 Patented Dec. 21., 1.954

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in the Coker 12y are in the form of a dense suspension of powdered' solids inv gas, and a temperature of between 1.000'r and' 2000 F., but preferably between 1000 and 1`209 F. is maintained in the coking vessel, whereupon the coal is destructively distilled into volatile constituents whichv are. withdrawn. overhead through line 4, and the coke is: withdrawn from standpipe l5 as previously indi cated The average residence time of the powdered coal undergoingv coking in` the coker may range from several minutes to l or 2 hours. The longer residence times may be obtained by recycling the partly carbonized coal to the coking vessel.

The. products withdrawn from the coker are then processed further as follows.: First, with respect to the volatile constituents, these are preferably passed vthrough a condenser or cooler 30 where they are cooled to a temperature of about 600' F., and then a portion of this cooled material passes into the preheater 3 as previously described. It will be understood that the hot vapors Ain line. 4 may be passed uncooled via lines 4b into 4c and thereafter into preheater 3. Now of course provision -is made for withdrawing condensate from cooler 30, yand we have indicated condensate cooling means (diagrammatically) as withdrawn through line 4e. Any con venient means may be used for cooling lthe hot vapors in line 4 such as a tubular heat exchanger and a separator tank or the. like. Another portion of the coker vapors passes via line 4a into line 40 and then to a tar and naphtha recovery sys-tem 42 of conventional construc tion where the products are cooled to condense out tar and gasoline. The tar is recovered through line 45, while .the gasoline is withdrawn through line 48, overhead from the tar and gasoline separator 42. Through line 56,. coal gas is withdrawn and sent, if desirable, to equipment (not shown) to recover ammonia, and then the residual gas containing olens may be polymerized to form fur-ther quantities of normally liquid hydrocarbons. As previously noted, part of the coal Lgas may be recycled to line 11 by means ynot shown.

Referring :again to the kcoker 12, the coke withdrawn through standpipe 15 is mixed with a limited amount of air or vother oxygen-containing gas supplied through line 16 and conveyed pneumatically into the heater 60. The coke in heater 60 undergoes partial combustion whereby the temperature of the `coke is increased and a portion of the thus heated coke is withdrawn through standpipe 62 and returned toy coker 12 where it sunpplies at least a portion of the heat required in coker 12. A suitable lluidizing gas, such as tail gas from the synthesis unit later described, is supplied to standpipe 62, to carry the hot coke `into vessel '60 through line 6'3. The flue gases are withdrawn from the heater 60 through line 70 and passed through a Waste heat boiler `72 where at least a portion of the energy may be recovered for some useful purpose. Another portion of the coke from heater 60 is withdrawn through line 74, mixed with steam from line 75 and conducted 'to a water gas regenerator 80. Water gas regenerator 80 operates in substantially the same manner as `coker 12 and heater 60, namely, the coke is in the form of la dense suspension and maintained in that condition by regulating the upward ow of the gas within the limits of from 1/2-1() ft. per second, preferably ll/-S ft. per second. The water gas formed is withdrawn from the generator 80 through line 82 and forced through a sulfur removal step `83 which may be any known method for moving sulfur and/or its compounds from a gaseous material. Slag andfor ash are withdrawn kfrom generator 80 via line 81. The pured water gas then passes from sulfur removal unit 83 via line 85 into a hydrocarbon synthesis step 86 where it contacts a suitable catalyst adapted to catalyze the hydrocarbon synthesis. Of course, the gases, if necessary, may have additional hydrogen added to them as `they enter the unit 86 as, for example, through line 90, and as is well known in the synthesis of hydrocarbons from CO require from about .equal molecular proportions to 2 mols of hydrogen per mol of CO.

Now in order to maintain the proper temperatures in coker 12 and water gas generator 80, suiicient amounts of coke from heater 60 are supplied to the said coker and water gas generator to supply large quantitieso heat.

Thus, where the temperature of the coke leaving heater 60 is about 2400 F. (a desirable temperature), about equal gravimetric parts of this coke and the coal will give the desired temperature in the coker 12. Now, in the water gas generator, since the reaction therein occurring absorbs a large quantity of heat, the ratio of coke at 2400 F. to carbon undergoing reaction with H2O to form CO and H2, should be above 30 parts by weight of coke per part of such carbon, or thereabouts.

The catalysts for the hydrocarbon synthesis, temperatures, pressures, and other conditions are known in the art and it is unnecessary to recite them here. The hydrocarbon synthesis per se is not the exact point of novelty in our present invention for it is in the combination of steps indicated.

The crude synthesis product is withdrawn from reactor 86 through line 92 and discharged into a separator 93 where normally gaseous material or tail gas may be withdrawn through line 94, or the normally liquid material is withdrawn through line 95 and then subjected to a suitable processing step to form gasoline in 96. For instance, the hydrocarbon oil in line 95 may be fractionated into a gasoline fraction and a gas oil fraction. The gasoline fraction may be reformed to improve its octane number, and the gas oil fraction may be cracked. From either or both of these processes the improved gasoline is obtained through line 97. Here again we have not gone into detail to explain the procedure of reform ing gasoline or cracking gas oil for these processes are well known to those skilled in the art.

The normally gaseous materials resulting from the reforming and/or the cracking are withdrawn from unit 96 through line 99, 100 and mixed with that from the tar hydrogenation unit 101. Tar is discharged from 'separator system 42 via line 45 into said unit 101. In unit 101 the tar is subjected to hydrogeuation from which process a further quantity of gasoline may be recovered through line 102. This destructive hydrogenation of the tar is an operation which per se is known in the art, and any suitable catalyst may be used under the known conditions disclosed in the patents and other literature. The source of hydrogen is from the present process as will appear more fully hereinafter.

Referring to the separator 93, the overhead synthesis tail gas in line 94 may be withdrawn from the system, or it may be conveyed through line 120 into a unit 121 where it is treated with steam to form CO and hydrogen in the presence of a known catalyst and under known conditions. The mixture is then withdrawn from unit 121 via line 123 and passed into a burner 124 where a substantial portion of the CO is carefully converted to CO2, whereupon the mixture consisting substantially of CO2 and hydrogen is discharged into a CO2 scrubber 125 in which the CO2 is scrubbed out leaving a gas rich in hydrogen which is withdrawn through line 126 and a "lv portion thereof delivered to the synthesis unit 86 to increase the Hz/CO ratio via line 90 while the remainder thereof is discharged via line 128 into the tar destructive hydrogenation unit 101. It is to be noted that the hydrogen in line 126 is substantially sulfur free (purified in this regard in 83) and therefore our process provides, among other things a relatively cheap source of sulfur free hydrogen, an important feature of the combined operation. Another feature of our invention is that where a high ratio of CO in the water gas is desired, we may cause the CO2 from burner 124 to be discharged via line 129 into water gas generator 80.

In the manner of operation described above, it is possible to produce gasoline in an integrated operation starting wholly from coal to give a yield of commercial motor fuel of satisfactory quality of the order of 21/2 barrels per ton of coal charged. To explain this further, suppose we started with a ton of powdered coal of medium grade Pennsylvania bituminous coal, we could, by our process obtain2.5 bbls. of gasoline per ton of coal. Now if we used the ton of coal in other processes we would obtain gasoline yields as follows:

Yields per ton We prefer to, therefore, integrate the operation as described, so that the coke is used as a raw material for making gasoline and normally gaseous hydrocarbons. The normally gaseous hydrocarbons from the various operations may be used as fuel or to make hydrogen for saturating and/or converting the tar to gasoline. The integrated operation herein described is thus seen to improve the overall raw materials efiiciency, i. e. by balancing the operations as described, the coal charged to the system is substantially completely converted into ash, gasoline and combustible gases to supply at least a portion of the heat.

Now, of course, depending on the coal used to charge the system, the temperatures and other conditions employed for best results in a given case may require preliminary tests to arrive at the optimum conditions. But good results will be obtained following closely the directions given herein in the hands of an experienced operator. Of course, the type and nature of the coal is of importance in determining the overall production of gasoline when using our process. However, we may employ a low grade coal unsuitable for direct use in industrial operations.

The main purpose of our invention is to recover a maximum amount of gasoline from coal cheaply. The heart of our invention resides in the incidents that, (l) coal tar is more cheaply hydrogenated than coal, (2) unhydrogenatable residues (carbonaceous) are converted to gasoline bv Fischer-Tropsch synthesis and gas formed in the operation is used for heat, making hydrogen and in the case of olefins. gasoline.

Numerous modifications of our invention falling within the spirit thereof will occur to those skilled in this art.

This application is a continuation of Serial No. 549,530 filed August l5, 1944, now abandoned.

What is claimed is:

l. The process of converting coal which comprises establishing a first, second and third fluidized bed of hot finelv divided coke, each in a separate zone, bv passing a ,gasiform fiuid upwardly through each of said beds, the fluidizing gas in the second bed being a combustion supporting gas and the fiuidizing gas in the third hed cornprising ,gas reactant with said coke to produce hvdrogen and carbon monoxide, the process comprising preheating finely divided coal to a temperature between about 250 and 600 F., continuously feeding said preheated coal into mixture with the coke in said first bed. maintaining the mixture of coke and coal at coal-carbonizing temperature in said first bed to distill off volatile constituents including tar from said coal and therebv convert said coal to a residue coke, continuously feeding coke from said first bed to said second bed` carrying out combustion in said second bed to raise bed temperature substantiallv above the temperature in the first bed, continuouslv feeding a stream of hot coke from the second bed to the first bed, continuously feeding a stream of hot coke from the second bed to the third bed. recovering a -gas containing hydrogen and carbon monoxide from the third bed, catalvtically snythesizing liquid hydrocarbons from part of said last mentioned gas, and recycling an unconverted residue part of said last mentioned gas to hvdrogenate the coal tar and thereby increase the yield of licluid product.

2. The process of claim l in which part of said p0rtion of residue gas is fed to said third bed.

3. A method according to claim l in which said finely divided coal is preheated by being contacted with the vaporous product from said carbonizing zone.

4. A method according to claim l in which said reactant gas to the third bed is steam.

5. A method for converting coal which comprises establishing a system of first. second and third beds of finely divided coke, maintaining the finely divided coke Type of process: of coal, bbls.

(l) Coal hydrogeuation 2.0 (2) Fischer-Tropsch synthesis 1.4 (3) Low temperature carbonization 0.7

in each of said beds in a fluidized condition by passing a gas upwardly therethrough, the gas passed to the second bed being a combustion-supporting gas and the gas passed to the third bed comprising a gasifying medium for said coke, preheating to a temperature between 250 and 600 F. and gradually feeding finely divided coal to said first bed, maintaining said first bed at a carbonizing temperature, continuously feeding finely divided coke from said first bed to said second bed, subjecting said coke in said second bed to a combustion reaction in which its temperature is raised substantially above carbonizing temperature,fcontinuously feeding hot coke from said sec# ond bed to said rst bed, continuously feeding hot cake from said second bed to said third bed, recovering a gas containing hydrogen and cr rbon monoxide from said third bed, subjecting said recovered gas to catalysis for the synthesis of liquid hydrocarbons, separating liquid hydrocarbons and a residue gas from the product of said synthesis, subjecting at least a portion of said residue gas to a catalytic reaction with steam in a reaction zone so as to convert gaseous hydrocarbons into H2 and CO, withdrawing a product gas mixture from said reaction zone, converting at least a portion of the CO content of said mixture into CO2 to produce a second gas mixture containing Hz and CO2, returning a portion of said second gas mixture to said third bed, removing CO2 from another portion of said second gas mixture and supplying said other portion so treated to said synthesis.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,039,459 Seguy May 5, 1936 Number 15 Number Name Date Ocon Apr. 18, 1939 Keith, Jr Mar. 11, 1941 Asbury Dec. 2, 1941 Arveson Oct. 17, 1944 Black Feb. 3, 1948 Peck et al May 24, 1949 Peck Aug. 30, 1949 Johnson Sept. 20, 1949 Puening May 8, 1951 Ramseyer May 15, 1951 Roetheli Dec. 18, 1951 FOREIGN PATENTS Country Date Germany Feb. 16, 1934

Claims (1)

1. THE PROCESS OF CONVERTING COAL WHICH COMPRISES ESTABLISHING A FIRST, SECOND AND THIRD FLUIDIZED BED OF HOT FINELY DIVIDED COKE, EACH IN A SEPARATE ZONE, BY PASSING A GASIFORM FLUID UPWARDLY THROUGH EACH OF SAID BEDS, THE FLUIDIZING GAS IN THE SECOND BED BEING A COMBUSTION SUPPORTING GAS AND THE FLUIDIZING GAS IN THE THIRD BED COMPRISING GAS REACTANT WITH SAID COKE TO PRODUCE HYDROGEN AND CARBON MONOXIDE, THE PROCESS COMPRISING PREHEATING FINELY DIVIDED COAL TO A TEMPERATURE BETWEEN ABOUT 250* AND 600* F., CONTINUOUSLY FEEDING SAID PREHEATED COAL INTO MIXTURE WITH THE COKE IN SAID FIRST BED, MAINTAINING THE MIXTURE OF COKE AND COAL AT COAL-CARBONIZING TEMPERATURE IN SAID FIRST BED TO DISTILL OFF VOLATILE CONSTITUENTS INCLUDING TAR FROM SAID COAL AND THEREBY CONVERT SAID COAL TO A RESIDUE COKE, CONTINUOUSLY FEEDING COKE FROM SAID FIRST BED TO SAID SECOND BED, CARRYING OUT COMBUSTION IN SAID SECOND BED TO RAISE BED TEMPERATURE SUBSTANTIALLY ABOVE THE TEMPERATURE IN THE FIRST BED, CONTINUOUSLY FEEDING A STREAM OF HOT COKE FROM THE SECOND BED TO THE FIRST BED, CONTINUOUSLY FEEDING A STREAM OF HOT COKE FROM THE SECOND BED TO THE THIRD BED, RECOVERING A GAS CONTAINING HYDROGEN AND CARBON MONOXIDE FROM THE THIRD BED, CATALYTICALLY SNYTHESIZING LIQUID HYDROCARBONS FROM PART OF SAID LAST MENTIONED GAS, AND RECYCLING AN UNCOVERTED RESIDUE PART OF SAID LAST MENTIONED GAS TO HYDROGENATE THE COAL TAR AND THEREBY INCREASE THE YIELD OF LIQUID PRODUCT.

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