US1770098A - Method of cracking oil - Google Patents

Description

Patented `uly 8, 1930 PATENT OFFICE JOHN C. BLACK, OF DESTREHAN, LOUISIANA METHOD F CRACKING OIL Application filed November 16, 1926. Serial No. 148,734.

Processes are known wherein oil is subjected to cracking heats under super-atmospheric pressure. It is well known that oils so heated decompose to give lighter bodies.

In my Patent 1,456,419 I have disclosed such aprocess wherein the oil is subjected to cracking temperatures for a prolonged period of time.

I have found that in cracking oil by this process I obtain a gasoline which has a very good anti-knock character. This is due, I believe, to the presence of substantial amounts of unsaturated bodies and also cyclic' hydrocarbons formed as a result of the cracking reaction.

A process of cracking oil wherein oil is distilled in the presence of aluminum chloride, is also known. This process gives a gasoline composed of saturate-d hydrocarons, which, asis well known to those skilled in the art, has anti-knock characteristics.

This process has the advantage, also, of producing a gasoline which needs very little or no refining. The gasoline after treatment with caustic is sulphur free and doctor sweet,

and has good color. The oil is distille-d with aluminum chloride and uncracked oil continually reuxed back to the still.

It is an object of this invention to devise 3o a process which has the.advantages of both of the above processes, and in which there is an economical use of heat for the production of gasoline from hydrocarbons of higher boiling points. i

The invention will be better understood by reference to the accompanying drawing, which shows a schematic arrangement of an apparatus for carrying out the process of this application.

1 is a tank holding charging stock, which may be gas oil. Line 2, in'which there is a valve 2 and a pump 3, connects tank 1 with heat exchanger 4. 5 is a line connecting heat exchanger 4 with still 6. 7 is a vapor-line 45 which connects still 6 to condenser 8. 9 is a look box situated in condenser run-down line which connects condenser 8 with tank 10. 11 is a line, in which there is a valve 11', connecting still 6 with tank 12. 13 is a feed hopper connected to tank 12. 14 is a line controlled by a valve 14 which connects tank 15 with the feed hopper 13. 16 is a line controlled by a valve 16 which connects tank 12 with pump 17, which is in turn connected by line 18 with heat exchanger 20. In line 18 there are valves 18 and 18 and a pump 19. 21 connects the heat exchanger 20 with the coils 23. `By-pass 22, in which there is a valve 22', connects line 21 and line 18. The

coil 23 is situated in furnace 24, and is con- (i.

nected by meansof cross-over 25 to coil 27 situatedin furnace 26. 28 is a line connecting coil 27 with heat exchanger 20, and 29, in which there is a pressure reduction valve 29 and a pressure indicator 30, connects heat exchanger 2O with the evaporator 31. wIn evaporator 31 are plates 32. 34 is a fractionating tower connected to evaporator 31. 33 is a condensate trap. 35 is acondensate draw-off containing a valve 35. 37 is an Aanalyzer situated in the fractionating tower 34. 38 is a vapor line connecting tower 34 with condenser 39. 40 is a look-box situated -in condenser run-down line 42, andis con- 44 is 7 a residuum draw-ofi' connected to the bottoni nected to tank. 43. 41 is a vapor vent.

1 is pumped in heat exchange with residumn in the evaporator 31, and the heated oil, at approximately 200 to 300 F. is passed into still 6 where it is dehydrated. The dehydrated and heated oil is then passed to tank 12, while the overhead vapors are drawn oiiv and condensed in 8 and collected in tank 10.

vThis condensate consists of light oils and 1 water. The unvaporized oil in tank 12 .is mixed with aluminum chloride, or any equivalent catalyst, such as iron chloride or zinc chloride. This is fed to the oil by a conveyor schematically indicated as 14. The material in tank 12 may be slightly heated, if desired, to ensure solubility of the catalyst. I'prefer to use a volatile catalyst, and particularly aluminum chloride. The oil plus the aluminum chloride is then pumped by pump 17 through the line 18 where it meets the condensate coming through line 35 from the bottom of the .fractionating tower 34. This condensate, as will be explained later, also contains aluminum chloride. The mixture is controlled so that the mixed oil Contains from 2 to 10 percent'of aluminum chloride, depending upon the material cracked. The combined oil is then pumped with pump 19 under a pressure of approximately one thousand pounds or more, through heat exchanger 20, with by-pass 22 being so controlled as to regulate the heat exchange in 20. The hot oil, at a temperature of about 600 F., is passed through coils 23 where it is raised to the cracking temperature of approximately 800o F. to 900 F., maintained atthat temperature in coil 27 for a period of approximately twenty minutes. The oil issuing through 28 passes through 20 where its temperature is dropped to about 700 F. to 800 F., on passing through the heat exchanger, and the pressure of approximately one thousand pounds, which is maintained by the valve 29', is released, and theoil is passed on to evaporator 31. The released vapors Aare cleaned of entrained oil by trays 32. The

vapors which rise through trays 32 are at such temperature that substantially all of the active aluminum chloride in the oil is vaporized, together-with the uncracked oil and produced gasoline. The ractionating tower is controlled by means of the analyzer 37. An oil, if desired, may be passed through 3 6 to aid this fractionation. This fractionation is controlled so as to recondense all of the aluminum chloride and the vaporized uncracked oil. The vapor rising through 38 is gasoline and this is condensed in 39 and collected in 43. Unvaporized residuum is removed through 44, passed through heat exchanger 4 and collected in tank 47. By controlling the temperature of the oil passing to thek evaporator, substantially all of the active aluminum chloride can be vaporized out of the oil. This allows for the partial recovery of active aluminum chloride used in the process by concentrating it in the oil to be recycled to the process except the aluminum chloride which has been combined with sulphur.

As is well known, aluminum chloride will free the oil of sulphur bodies. A part of the aluminum chloride which has been converted to aluminum sulphide passes out with the residuum and a part is evolved as hydrogen sulphide. The gasoline formed will be found substantially sulphur free, as will the condensate collected through 35. Since this condensate will also be moisture free, no additional dehydrating step is necessary, and it can be recycled through the process immediately, and constitutes a sulphur free cracking stock. The aluminum chloride `make-up in tank 12 must supply the aluminum chloride used by any reaction with the sulphur bodies, and any other losses. The gasoline which is collected in 43 will be found to be substantially free of sulphur and will require but a slight caustic treatment. At times hydrogen sulfide is formed as a result of the reaction. This goes off as a gas but may contaminate the gasoline. It is removed by treatment with caustic soda.

Another advantage of this process lies in the fact that the treatment in the tower 34 results in a further cracking of the uncracked oil, which is vaporized in 31 and refluxed and revaporized in 34. This constant retreatment of the condensed material at a relativelyhigh temperature, in the presence of aluminum chloride, causes a cracking of the oil. The introduction of make-up oil in the tower to act as a reflux will also cause a cracking of the oil by the presence of aluminum chloride andheat. Both the gasoline formed in the cracking in the tubes and the gasoline formed in the evaporator and fractionating tower, is .removed through 38. It is to be observed that the gasoline isremoved as soon as it is formed by the cracking in tower 34. In the tubes the major cracking which goes on is vliquid phase cracking. There is, however, considerable cracking as a result of the conversion with the aid of the aluminum chloride. Any reversible reaction which results in the polymerization of gasoline with the aid of aluminum chloride is cifset by the crackingof those polymerized bodies under pressure and heat. The oil is heated to a temperature at which the oil will crack substantially without aluminum chloride. The pressure employed is that which wouldr` prevent substantial vaporization, i. e. to cause cracking in the coils to proceed in the liquid phase.

This process, as will be observed, also results in the removal of sulphur bodies from an oil, with a constant recovery of the undecomposed aluminum chloride. Thus in treating a gasoline to make it sulphur free, it may be heated in the coils with aluminum chloride. A slight polymerization of the gasoline results. This gasoline can be fractionated to remove the gasoline and also to remove the aluminum chloride, which may be separately condensed, and separately remove the residuum containing the converted sulphur bodies. It can also, as is'apparent from-the above, result in the formation of a sulphur free cracking stock.

- The above is not to bel taken as limiting my invention, but merely as illustrative of ing the heating of said oil at, at least, said cracking temperature for a prolonged period of time, vaporizlng said cracked oil at a temperature suiiicient -to volatilize the aluminum chloride, fractionating said vapors to separate gasoline-like hydrocarbons and forming a condensater containing the alu minum chloride.

2. A process of converting petroleum oil into saturated hydrocarbons and then crackiing the'same by the application of heat for the production of gasoline stock, comprising,

^ heating a mixture of dehydrated petroleum oil and an anhydrous metallic halide in a continuous stream flow to a reaction temperature of about 6000 F., to convert substantially all the unsaturated hydrocarbons of the oil into saturated hydrocarbons, then cracking the same by the application 'of heat in the presence 'of the metallic halide under` a pressure suflicient to prevent any substantial vaporization thereof, continuing the heating of said oil at at least said cracking temperature, for a prolonged period of time, then vaporizing the lower boiling oils at temperatures sufficient to volatilize the uncombined metallic halide present, fractionating said vapors to separate gasoline boiling point stock, separating a high boiling condensate containing the metallichalide from a residuum and returning the condensate containing the metallichalide back into the part of the system where the heating to a reaction temperature takes place to be subjcted to cracking along -With uncracked oil containing a metallic halide. i

3. process of converting petroleum oil into saturated hydrocarbons and then cracking the same by the application of heat for the production of gasoline stock, comprising, heating a mixture of dehydrated petroleum oil and an anhydrous metallic halide in a continousstrea'm flow to a reaction temperature of about 600 F., in counterflow heat exchange with hot cracked oil continuously produced, to convert substantially all the unsaturated hydrocarbons of said oil into saturated hydrocarbons, then cracking by the application of heat said saturated hydrocarbons under pressure suiiicient to prevent substantial vaporization, continuing theheating of said oil at at least said thermo cracking temperature, fora prolonged period of time, then vaporizing the major portion of said cracked oil at a temperature sufficient to volatilize the uncombined portion of the metallic halide present, fractionating said vapors to separate gasoline boiling point stock, separating a higher boiling condensate containing the volatilized metallic halide trom al residuum and returning the condensate containing the said volatilized metallic halide back into the part of the system Where the heating to a reaction temperature takes place to be subjected to cracking along with uncracked oil containing a metallic halide.

4. A process of converting high boiling petroleum oil stocks into lower boiling oils, comprising, commingling a dehydrated high boiling petroleum oil stock With anhydrous aluminum chloride and heating the com- Kmingled mixture to a react-ion temperature of approximately 600 degrees F., under a pressure of approximately 1000 pounds, and then cracking the petroleum oil products commingled with' the anhydrous aluminum chloride by passing the same through heating coils maintained at a cracking temperature of substantially not less than 800 degrees F. and vunder a pressure sufficient to prevent substantial vaporization, then vaporizing the lower boiling lcracked oils at a temperature suliicient to volatilize all the uncombined aluminum chloride contained therein, separating a high boiling residuum, fractionating said vapors to separate gasoline boiling point hydrocarbons and forming a condensate containing the vaporized aluminum chloride.

5. A process of producing gasoline boiling point stock'irom higher boiling petroleum oils, comprising, heating a commingled mixture of dehydrated petroleum oil and anhydrous aluminum chloride to a reaction temperature of approximately 600 degrees F under a pressure i of approximately 1000 pounds Whilepassing through a heat exchanger in heat exchange relationship with duced, to convert substantially all the unsaturated hydrocarbons of said petroleum oil into saturated hydrocarbons, then cracking the petroleum oil composed substantially of saturated hydrocarbons commingled with the anhydrous aluminum chloride, under pressure sufficient to prevent substantial vaporization, .continuing the heating of said petroleum oil commingled With the anhydrous aluminum chloride While passing through Vhot cracked petroleum oil continuously propipe coils at at least a cracking temperature of not less than 800 degrees F. for a prolonged period of time, then vaporizing the'lower oiling cracked oils at a temperature suiicient to vaporize all the'uncombined aluminum chloride contained therein,- separating a residuum, fractionating said vapors to separate gasoline boiling point hydrocarbons, forming a condensate containing the Vaporized aluminum chloride and returnin the condensate containing the recovered a umi- 5 num chloride back into the part of the system where the heating to a reaction tem erature takes place to be subjected to crac ing along with uncracked petroleum oil containing aluminum chloride.

In testimony whereof I a'ix my signature.

JOHN C. BLACK

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