US1806036A

US1806036A - Process for distilling and cracking petroleum oils

Info

Publication number: US1806036A
Application number: US311140A
Authority: US
Inventors: John C Black
Original assignee: Individual
Current assignee: Individual
Priority date: 1928-10-08
Filing date: 1928-10-08
Publication date: 1931-05-19
Anticipated expiration: 1948-05-19

Description

J. c. BLACK May 19, 1931,

PROCESS FOR DISTILLING AND CRACKING PETROLEUM onls Filed Oct. 8.

@N\ 30 mkw INVENTOR Jay v c. BLHCK.

AT NEY Patented May 19, 1931 UNITED STATES- JOHN 0. BLACK, 01 LOS ANGELES, CALIFORNIA PROCESS FOR DISTILLING AND CRACKING PETROLEUM OILS Application iiled October 8, 1928. Serial No. 311,140.

This invention relates to a process for distilling and cracking petroleum oils for the production of a maximum percentage of gasoline stock and the production of a marketable 8 fuel oil which will be suitable forbunker fuel oil C, as specified in the Bureau of Mines Technical Paper 323 B.

This process consists first in the separation by distillation and fractionation from 1 crude petroleum oils, the natural occurring gasoline stock and a higher boiling distillate which I denominate light gas oil and a residual oil to be further processed; then to separately separating by a second distillation and fractionation a synthetic gasoline stock derived from a cracking operation, a cracked lightgas oil stock, and a distillate which I denominate heavy gas oil and a residual oil to be further processed; the heavy gas oil above referred to is a blend of distillates, one portion being obtained from the original crude petroleum and a second portion being obtained from the cracking steps. The residual oil derived from the second distillation step is now subjected to a cracking operation, said operation producing a cracked gasoline stock and a heavy gas oil distillate. I This heavy gas oil distillate is blended with the previously produced heavy gas oil of the second distlllation step. The residual oil separated by distillation after the aforesaid cracking operation is blended with the light gas oil or the light cracked. gas oil produced in the first or second distillation step.

By well-known processes, when the maximum yield of distillate suitable for the production of synthetic'gasoline stock is separated fromacrude petroleum oil by distillation, the residual oil is too viscous to be suitable for marketable fuel oil, such as bunker fuel oil C while by my process, this difiicultyis overcome by a further cracking treatment of the residual oil in which a cracked naphtha is produced and a heavy gas oil stock suitable for the production of synthetic gasoline is also produced and a residual oil which when commingled with the light gas oil obtained by the first or second distillation operation, will synthetic gasoline produced has too high a ;or'heavy gas oil stock and may be subsequent- .1. employed for reducing the viscosity of the reduce the viscosity ofsaid residual oil to the desired degree. v

I It is well-known in the art of cracking petroleum oil distillates that the lower boiling fractionswhich I have denominated light gas oil fractions are less desirable for cracking since a higher temperature and higher pressure is required to maintain the lower boiling fractions in the liquid phase and the percentage of boiling point stock in the upper range of the asoline fraction, making a gasoline stock defective in the initial, the 10,

20 and 30 per cent fractions thereby making a gasoline with poor starting and poor anti knock qualities. Also d'ue'to the higher temperature and. pressure required, there is a more rapid destruction of the cracking equipment. There fore,b my invention, these lower boiling hydrocar onswhich I have termed light gas oil'having boiling points ranging from approximately40O to 550 degrees F. are 'separated'from the gasoline boiling point stock. andthe higher boiling point distillates nal residual oil. I am aware that methods are now well-known in the art for reducing the viscosity of viscous petroleum oils by the addition of less viscous distillates thereto, produced by a'partial distillation of the vi'scous oil, or by the addition of less viscous oil obtained from other sources, or by heating the petroleum oil to a relatively high temperature while passin through a heating coil under pressure and t en cooling the oil be fore any substantial crackin takes place.

By my improved process, t e yield of a desirable heavy gas oil stock suitable for thermo cracking is increased. asmuch as 20 per cent or more over the well-known methods for obtaining a gas oil stock for the same purpose, and at the same time producing a fuel oil with a sufficiently low viscosity to be marketable as bunker fuel oil 0, or other fuel oils with a lower viscosity, depending upon ,the amount of light gas oil stock used for reducing the viscoslty.

An object of the invention is to produce .from crude petroleum oil a maximum yield of gasoline boiling point stock and under certain conditions a lamp oil stock and a residual oil which willhave a viscosity sufficiently low to meet the requirements as specified for bunker fuel oil C, in the Bureau of Mines Bulletin 323 B.

Another object of the invention is to produce amaximum percentage of gas oil stock suitable for the production of synthetic gasoline and a residual fuel oil of marketable value.

Another object of the invention is to provide a process to utilize the light gas oil fraction derived either from crude petroleum oil by distillation, or derived by distillation of cracked petroleum oils to reduce the viscosity of the final residual heavy oil.

Another object of the invention is to provide a process to produce a maximum yield of gasoline boiling point stock, both natural and synthetic; a light gas oil fraction and a marketable fuel oil from a crude petroleum oil by a sequence of operations, consisting in first separately separating by distillation and fractionation the natural gasoline stock and a higher boiling distillate or light gas oil stock derived from the crude oil distillation step of the process, then separately separating by a second distillation and fractionation operation, a higher boiling distillate or heavy gas oil stock; a synthetic gasoline stock and a cracked light gas oil stock, both being derivedfrom an introduced cracked petroleum oil, said introduced cracked oil stock being simultaneously and independently produced by cracking the heavy gas oil stock collected from the various distillation steps of the process; there is also produced in the second distillation step a residual oil which is then cracked in a separate cracking step producing a synthetic gasoline stock and a heavy gas oil stock suitable for subsequent cracking and a final residual oil, the viscosity of which is reduced by commingling the same with the light gas oil separated in the first or second distillation operation.

Another object of the invention is to provide a process wherein the natural and synthetic gasolines are independently and separately collected, for the reason that the synthetic gasoline requires a different subsequent treatment than the natural gasoline.

Another object of this invention is to provide a process wherein a uniform heavy gas oil or cracking product is obtained by blending the heavy gas oil fractions derived from the various distillation steps.

With the foregoing preliminary explanation, the preferred embodiment of my invention will now be more fully explained by reference to the accompanying drawing which illustrates a special form of apparatus which may be utilized in carrying out the objects of the present invention.

In the drawing, 1 represents generally a tank for holding the crude petroleum oil to be treated. Pipe 2 connects the tank 1 to the inlet side of pump 3. Pipe 4 connects the discharge side of pump 3 to heat exchanger 5. Pipe 6 connects the heat exchanger 5 to heat exchanger 7. Pipe 8 connects the heat exchanger 7 to heat exchanger 31. Pipe 104: connects the heat exchanger 31 to vapor separator 106. Vapor separator 106 is provided with overflow trays 105. Pipe 85 connects the vapor separator 106 to fractionating tower 88. Pipe 103 controlled by a valve connects vapor separator 106 to the suction side of pump 102. Pipe 101 connects the discharge side of pump 102 to heater coil 100. The heater coil 100 is stationed in the upper part of furnace 95. The furnace 95 is provided with a burner 95'. Pipe 98 connects the heater coil 100 to fractionuting tower 88. The fractionating tower 88 is provided with a steam spray pipe 82 which leads to a source of steam not shown, so that steam may be introduced into the fractionating tower 88 at the bottom during the distillation operation, if desired. The fractionating tower 88 is provided with bubble caps 83 and 86 and a separator plate 81. A pipe 87 connects fractionating tower 88 to a dephlegmator 90. The dephlegmator 90 is provided with a liquid inlet pipe 89 leading to a source of water or oil not shown, which is connected to tubes 89 for conveying a cooling medium through the dephlegmator 90. Dephlegmator 90 is also provided with liquid outlet pipe 89. A pipe 91 connects the dephlegmator 90 to condenser coil 92. The condenser coil 92 is stationed in the condenser box 96. Pipe 93 connects condenser coil 92 to a naphtha storage tank 109. Pipe 90' controlled by a valve, connects the naphtha storage tank 109 atthe bottom and leads to a source of storage not shown. Pipe 93 is connected to the pipe 93 and leads to a gas stor' age not shown. Pipe 99 connects the fractionating tower 88 to heat exchanger 5. Pipe 81 controlled by the valve 81 connects the fractionating tower 88 at the bottom to the inlet side of pump 80. A pipe 77 connects the discharge side of pump 80 to heater coil 76. The heater coil 76 is stationed in the furnace 79 which is provided with a burner 78. Pipe 75 controlled by valve 75 connects the heater coil 76 to fractionating tower 59. The fractionating tower 59 is provided with bubble caps 57 and 70,

separator plates

58 and 58, and a steam spray line 56. The steam spray line 56 leads to a source of steam not shown. The fractionating tower 59 is connected to dephlegmator 59. Dephlegmator 59 is provided with a liquid inlet pipe 7 2 and a liquid outlet pipe 73. Pipe 63 connects the fractionating tower 59 at the top to condenser coil 62, which is stationed in the condenser box 61 and is connected to synthetic naphtha tank 6 1 by pipe 61. A pipe 62' is connected to the pipe 61 and leads to an absorber not heat exchanger 7. Pi e 129, controlled by a valve, connects the ractionating tower 59 just above the separator plate 58'- to light gas oil tank 130. Pi e 131, controlled by a valve, connects the lig t gas oil tank 130 to the suction side of pump 133. Pipe 132. con-- trolled by a valve, connects the discharge side of pump 133 to pipe 124. Pipe 54 controlled by the valve 54, connects the fractionating tower 59 at the bottom to the inlet side of pump 53. Pipe 51, controlled'by valve 51 connects the discharge side of pump 53 to heater coil 50. The heater coil 50 is stationed in the furnace 49 provided with a burner 52. Pipe 47 controlled by pressure regulating and discharge valve 48, connects the heater coil 50 to the fractionating tower 11. The fractionatin tower 11 is provided with tile or checker rick work 21, bubble caps 19 and a separator plate 22'. Pipe 12 connects fractionating tower 11 at the top to condenser coil 13 which is stationed in the condenser box 14. Pipe 15 connects the condenser coil 13 to a synthetic naphtha tank 16.

17 is a pipe controlled by a valve connectedv to the bottom of the synthetic naphtha tank 16 and leads to a-source of storage not shown. Pipe 28 controlled by a valve, connects the fractionating tower-11 at the bottom to the inlet side of pump '27.-' Pipe 30 connects the discharge side of pump 27 to heat exchanger 31. Pipe 32 connects the outlet side of heat exchanger 31 to cooler 33. Pipe 34 connects the cooler 33 to residual oil tank 35. Pi e 36 controlled by valve 110 is an outlet pipe eading'to a sourcepf storage not shown.

123 is a pipe which connects heat exchanger 5 to light gas oil tank 127. Pipe 128 controlled by a valve, is connectedto light gas oil tank 127 and leads to a source of storage not shown. 126 is a pipe connecting the light gas oil tank 127 at the bottom to the inlet side of pump 125. 124, controlled b the valve 124, is a pipe connecting the disc arge side of pump 125 to the inlet side of pump water outlet pipe 108 whichleads to a source. of waste not shown. 38 is a pipe connecting the coolerlll to the top of heavy gas oil tank 68. Pipe- 69 controlled by valve 67 connects the heavy gas oil tank 68 at the bottom to the inlet-'side of pump 66. Pipe 65, controlled by valve 65 connects the discharge side of pump 66 to heat exchanger 9.

Pipe 118 connectsthe heat exchanger heater coil 116. Pi

pe 120 connects heater coil 116to p'pe 121. The pipe 121 is provided with a valve 121. Branch pipe. 122 controlled by valve 122 connects the pipe 65 to pipe 118. Branch pipe 117 controlled by valve 117 connects pipe 65 to heater coil 11.6

which is employed for the introduction" of cool oil into the hot oil stream as it leaves the heater coil 116. The heater coil .116 is stationed in the furnace 114 provided with a burner 115. Pipe 9 controlled by a valve, connects a source of water or steam not shown to pipe 118. Pipe 37, controlled by a pressure regulating and discharge valve 37 connects the heat exchanger 9 to fractionating tower 59. r

The preferred process as carriedout with the apparatus just described-is as follows:

Crude petroleum oil contained in thetank i 1 is caused to flow through the pipe 4 by operating pump 3, which takes suction on the crude oil tank 1 through the pipe 2. From pipe 4 the crude petroleum oil passes through heat exchangers 5, 7 and 31 whichare-connected by pipes 6 and 8. The crude petro leum oil passing through said heat exchang- Y ers 5, 7 and 31underg'oes a heat exchange with the hot dis'tillates comingfrom frattionating towers 88and 59 and the residual oil coming from the bottom of the fraction ating tower 11. By this exchange, the crude petroleum oil is preheated to a temperature of approximately 200 to 300 degrees F. From the heat exchanger 31, the preheated inc crude petroleum oil passes through the pipe 104 into vapor.separator 106 flowing over plates 105. The vaporized hydrocarbons rouced by this heat exchange pass onto the separator 106 through the pipe and into the middle section of fractionatin tower. 8 8.

and are thereafter condensed an collected along with other gasoline boilingpointstock.

From the vapor separator106, the crude petroleum oil, separated from the vapors produced by the said heat exchange, passesthrough the pipe 103 into the suction side of pump 102 which discharges the same through the pipe 100. he heater coil is maintained at a 101 and then through the heater coil temperature suflicient to raise the temperature of the oil to approximately 450 to 600 degrees F. by means of burner 95' which is stationed near the bottom of the furnace 95. From heater coil 100 the heatedoil passes through pipe 98 and into the lower sectlon of fractionating tower 88 where a fractional separation of the lower boilin hydrocarbons is effected, the distillation being assisted by the injection 'Oflsteam from steam spray line 82. -The ,vaporiz'ed hydrocarbons pass up through th'ei-blibble caps 83 and then through the separator-plate 84 and are thereafter further fractionated on passing through the bubble caps 86 and dephlegmator 90, by regulation of which, gasoline boiling point stock or naphtha is separated from a higher boiling distillate or light gas oil. The gasoline boiling point stock passes from dephlegma- 5 tor 90 into pipe 91 and is condensed as it passes through the condenser coil 92. The condensed gasoline boiling point stock is collected in the naphtha receiving tank 109. The temperature of theoil vapors passing through the dephlegmator 90 is controlled by the introduction of a regulated supply of oil or water which passes through the pipe 89" and then through the tubes 89 and out through the pipe 89 to a storage not shown. The higher boiling distillate which I have denominated light gas oil separated and condensed by the fractionation operation in the upper section of the said fractionating tower 88, passes into pipe 99 and thenthrough the heat exchanger 5 Where the temperature is reduced by a heat exchange with the cool crude petroleum oil coming from the crude oil tank 1. From heat exchanger 5 the light gas oil passes through pipe 123 and then valve 126 the light gas oil may be permitted to flow into the suction side of pump 125 which discharges the same into pipe 124. From pipe 124 the light gas oil passes into the suction side of pump 27, the flow being regulated by valve 124'. The light gas oil passing into pump 27 mixed with the light gas oil from tank 130, is commingled with the residual oil coming from the bottom of fractionating tower 11 through pipe 28, the flows being regulated so as to produce a fuel oil with a desired viscosity. In case an excess of light gas oil collects in the tank 127 it ma be conducted to a storage not shown throng the pipe 128 controlled by a Valve and thereafter treated for lamp oil or other uses. Pump 27 discharges the said commingled light gas oil and residual oil or fuel oil, through the pipe 30, heat exchanger 31, pipe 32, cooler 33, pipe 34, and then into the res1dual oil tank 35. From the residual oil tank 35 a fuel oil having a desired viscosity may be conducted to a storaganot shown, by opening the valve 110, which permits the fuel o1l-to flow into pi e 36. The residual oil as it collects in the ottom of fractionating tower 88 passes into pipe 81, the flow being regulated by operatingvalve 81. From pipe 81 the residual oil passes into the suctlon side of pump 80 which discharges the same in a'regulated continuous flow through pipe 77 and heater coil 76. The burner 78 which is stationed in the lower section of furnace 7 9, is regulated so that the residual oil passing 60 through the heater coil 76 will be heated to a temperature of approximately 550 to 656 degrees F., the regulation of this temperature depending upon the rate of flow, the quality of the residual oil and the per cent of 65 distillate or 'heavy gas oil stock desired.

into the light gas oil tank 127. By opening From heater coil 76 the hot residual oil passes through ipe and then into the lower section of ractionating tower 59, the rate of flow being regulated by operating valve 75. The fractionating tower 59 is provided with a steam spray pipe 56 which leads to a source of steam not shown by means of which steam in desired amounts may be introduced into the said fractionating tower to assist the distillation operation. The fractionating tower 59 is provided with bubble caps 57, a separatorplate 58, an upper set of bubble caps 70, an upper separator plate 58 and a dephlegmator 59.

Cracked petroleum oil produced by continually cracking the heavy gas oil as it collects in the heavy gas oil tank 68, is continuously introduced into the bottom of the fractionating tower 59, coming through pipe 37, controlled by the pressure regulating and discharge valve 37, and is therein fractionated together with said heated oil coming from the heater coil- 76, as heretofore described. In the fractionating tower 59 the gasoline boiling point stock contained by the introduced cracked petroleum oil is vaporized and fractionally separated from a light cracked gas oil stock, the lightcracked gas oil stock passing out through the pipe 129 and then into the light gas oil tank 130.

The vaporized synthetic gasoline boiling point stock passes from the fractionating tower 59 through dephlegmator 59, pipe 63, condenser coil 62 and is collected in the synthetic'naphtha tank 64. The higher boiling distillate, or heavy gas oil stock, which is condensed in the fractionating tower 59, passes through the pipe 55, heat exchanger 7, pipe 74 and then into the heavy gas oil tank 68. The residual oil which collects in the bottom of fractionating tower 59 below the separator plate 58, passes out through the pipe 54 and into the suction side of pump 53, the flow being controlled by valve 54. Pump 53 discharges this hot residual oil through the pipe 51 controlled by valve 51 and then through the heater coil 50 at a pressure sufficient to prevent any substantial vaporization thereof, approximately 450 to 1000 pounds. A burner stationed in the lower part of furnace 49 is so regulated that the residual oil passing through the heater coil 50 will attain a temperature from 700 to 900 degrees F., the regulation of this temperature depending upon the rate of flow, the viscosity of the residual 1 oil and the amount of cracking desired. As the residual 'oil leaves the heating coil 50 at a cracking temperature, a cooler oil distillate coming through the pipe 46 from the hea gas oil tank 68 is introduced into the pipe 4 in quantities sufficient to lower the temperature of the mixed oil below a cracking temperature. From the pipe 47 the mixed oils pass through pressure regulating and discharge valve 48 and then into the lower section 130 through pipe 43 and pipe which ends in a spray pipe as shown, the flow being controlled by valve 44. A part of the flow of oil passing through the pipe 43 enters the branch pipe 46, the fiow being controlled by the valve 45 and is introduced into the hot flow of oil coming through the pipe 47 as heretofore =de"- scribed. The oil which passes through pipe 20 is employed as a wash oiltocondense and dissolve .the higher boilingzdistillates pro 'duced by the cracking of the residual oil.

The wash oil passes from pipe "20 througha spray ipe'stationed'between the bubble caps 19 an the checker brick work or spaced tile 21. The wash oil after passing over the spaced tile 21 passes down to the separator plate 22 together with the condensed distillate, and then'through the pipe 10, cooler 111, pipe 38 and then into the heavy gas oil tank 68, from whence a part is again re-circulated and the excess ortion employed as a crackin stock as will be hereinafter more fully explained. The residual oil which passes to the bottom of fractionating tower 11 is permitted to flow through the .pipe 28'into the suction side of pump 27 whereit is commingled with the light gas oil stock'coming from the

tanks

127 and 130 through the pipe 126,.pump 125 and pipe 124, the flow being controlled by valve 124. Pump 27 discharges the commingled light gas oil and residual oil through pipe 30, exchanger 31, pipe 32, cooler 33, pi

I 44 and then into the residual oil tank 35. The

light gas oil from tanks 127, and 130', which is commingled with the residual oil by pump 27, is regulated so that the viscosity of the resultant mixture will be suitable for bunker fuel oil C, as specified in the Bureau of Mines Bulletin 323 The synthetic gasoline stock and higher boiling distillate or heavy gas oil produced by the cracking of the residual oil passing f through the heater coil 50, are separated from the viscous residual oil in the lower section of the fractionating tower 11, and the synthetic gasoline stock is separated from the heavy gas oil stock in the upper section of said fractionating tower 11, passing out through pipe 12 and then into cooling coil 13 where this separated synthetic gasoline stock is condensed and passes through the pipe 15 into the storage tank 16.

Theheavy gas oil as it collects in tank 68 passes in a regulated continuous flow through pipe 69 and then into the suction side of pump 66,"controlled by the valve 67 Pump pipe 65, valve 65', valve 65", heat exchang r 9 and heater coil 116. Arrangements ae made so that a part of the oil stream before passing through heat exchanger 9 may be in- 66 discharges the heavy gas oil stock throuEh troduced into the oil'stream as it leaves the heating coil 116, which is accomplished by partly opening valve 117', thereby permitting a regulated part of the oil stream to pass through the pipe 117 and into the pipe 120 where it is commingled with the cracked oil leaving the heating coil 116, thereby lowering; the temperature of the mixed oil stream below an active cracking temperature. Also, arrangements are made for bypassing the heat exchanger 9 or diverting a portion of 1118011 stream through the pipe 122 by opening valve 122 and closing, or partly closing, valve 65". The oil stream passing through the heater coil 116 is maintained under a pressure sufiicientto prevent substantial vaporization therein'( 500 to 2000 pounds) and is heated to a' temperature sufficient to obtain the maximum yield of synthetic gasoline stock, preferably the oil leaving the coil is maintained at a temperature of approximately 840 to 880 degrees F. and is reduced toa temperature of approximately 750 to 800 degrees F. or lower by the introduction of the g cooler oil. The cracked oil commingled with the introduced pil passes-in a continuous stream flow from the heating coil 116 through heat exchanger 9, pipe 37, pressure regulating and discharge valve 37 and. into the lower section of fractionating tower 59 wherein a synthetic gasoline stock and a heavy gas oil stock are separated as heretofore described. 7

While the process herein described is well adapted for carrying out the object of the P invention, it is to be understood that various changes and modifications may be made without departing from the spirit of the invention, and the invention includes all such changesand modifications as come within the scope of the appended claims.

What I claim is:

1. A- process of producing a maximum percentage of gasoline boiling point stock and a reslduum of marketable fuel oil quality om a crude petroleum oil, comprising, separately separating by distillation and fractionation gasoline boiling point stock and a higher boiling light gas oil stock from a crudepetroleum oil; separately separating by a second distillation and fractionation a light and a heavy gas oil fraction and a synthetic gasoline boiling point stock, from the crude petroleum. oil residuum resulting from the first distillation and a cracked petroleum oil continuously introduced at adistillation tem erature into a fractionating tower, said crac ed etroleum oil being continuously produced y n-asking the heavy gas oil stocks collected from the said second -collected from said second distillation and collected from the said second distillation step and from a subsequent cracking and dis tillation step of the residual oil produced in the said second distillation step, and then reducing the viscosity of the residual oil after the final distillation by commingling the same with a light gas oil separated by the first distillation.

2. A process of producing a maximum percentage of gasoline boiling point stock and a residuum of marketable fuel oil quality from a crude petroleum oil, comprising, separately separating by distillation and fractionation gasoline boiling point stock and a higher boiling light gas oil stock from a crude petroleum oil; separately separating by a second distillation and fractionation a light and a heavy gas oil fraction and a synthetic gasoline boiling point stock, from the crude petroleum oil residuum resulting from the first distillation and a cracked petroleum oil continuously introduced at a distillation temperature into a fractionating tower, said cracked petroleum oil being continuously produced by cracking the heavy gas oil stocks distillation and from a subsequent cracking and distillation of the residual oil produced in the'said second distillation, and then reducing the viscosity of the residual oil after the final distillation by commingling the same with a cracked light gas oil separated by the second distillation.

3. A process of producing a maximum percentage of gasoline boiling point stock and a fuel oil whichwill not have a viscosity greater than 300 seconds at 122 degrees F. by

the Saybolt furol viscosimeter, comprising separately separating by distillation and fractionation the naturally occurring gasoline boiling point stock and a higher boiling light gas oil stock from a crude petroleum oil; separatel separating by a second dis-V tillation and ractionation, a synthetic gasoline boiling point stock, a cracked light gas oil and a heavy gas oil stock, from a cracked petroleum oil and the petroleum oil-residuum resulting from the first distillation, said cracked petroleum oil being continuously produced by cracking the heavy gas oil stocks from a subsequent cracking and distillation of the residual oil produced in the said sec- (hrd distillation, and then reducing the viscosity of the residual oils after the final distillation, to the required degree, by commingling the same with a mixture of the light gas oil stocks separated by the first and second distillations.

4. A process of producing a maximum percentage of gasoline boiling point stock and a fuel oil which will not have a viscosity greater than 300 seconds at 122 degrees F. by the Saybolt furol viscosimeter, comprising, separately separating by distillation and fractionation the naturally occurring gasoline boiling point stock and a higher boiling distillate from a crude petroleum oil; separately separating by a second distillation and fractionation, a synthetic gasoline boiling point stock, a cracked light gas oil and a heavy gas oil stock, from a cracked petroleum oil andthe petroleum oil residuum resulting from the first distillation, said cracked petroleum oil being continuously produced by cracking the heavy gas oil stocks collected from said second distillation and from a subsequent cracking and distillation of the residual oil produced in the said second distillation, and then reducing the viscosity of the residual oils after the final distillation, to the required degree, by commingling the same with the cracked light gas-oil separated by the second distillation.

5. A continuous process of producing a maximum percentage of gasoline boiling point stock and a fuel oil which will have a viscosity substantially not greater than 300 seconds at 122 degrees F. by the Saybolt furol viscosimeter, comprising, separately separating by continuous distillation and fractionation, the naturally occurring gasoline boiling point stock and a higher boiling light gas oil stock, from a crude petroleum oil; separately separating and collecting by a second continuous distillation and fractionation operation, synthetic gasoline boiling point stock, a cracked light gas oil stock and a heavy gas oil stock, from a cracked oil continuously produced from heavy gas oil stocks, and the petroleum oil residuum resulting from the first distillation; continuously cracking the resultant residuum separated by the said second distillation operation under a pressure suflicient to prevent substantial vaporization, at a cracking temperature; then separately separating by fractionation the synthetic gasoline boiling point stock produced and a heavy cracked gas oil stock from the cracked residuum, and finally reducing the viscosity of the residual oil from the said last named fractionation, by commingling the same with a mixture of the light gas oil stock separated by the first and second distillations.

6. A continuousprocess of' producing a maximum percentage of gasoline boiling point stock and a fued oil which will have a viscosity substantially not greater than 300 seconds at 122 degrees F. by the Saybolt furol viscosimeter, comprising, separately separating by continuous distillation and fractionation, the naturally occurring gasoline boiling point stock and a higher boiling light gas oil stock, from a crude petroleum oil; separately separating and collecting by a second. continuous distillation and fractionation operation, synthetic gasoline boiling point stock, a cracked light gas oil stock and a heavy gas oil stock, from a cracked oil constock,

vsynthetic, gasoline boiling point stock pro duced and a heavy cracked gas oil stock from the cracked residuum and finally reducing the viscosity of the residual oil from the said last named fractionation, cby commingling the same with the light cracked gas oil stock separated by the second distillation.

- 7. A process of producing a maximum percentage of heavy gas oil stock suitable for the production of synthetic gasoline, comprising, separately separating by distillation and fractionation, the natural gasoline boiling point stock and a higher boiling light gas oil stock from crude petroleum oil, separately separating by a second distillation and fractionation, synthetic gasoline boiling point stock and a light and a heavy gas oil from cracked petroleum oil and a petroleum oil residuum resulting from the first distillation step. continuously introduced into a fractionating tower at a distillation temperature, said cracked petroleum oil being continuously produced by cracking heavy gas oil: stock produced in the operations; passing the residual oil from this second distillation and fractionation operation through a heating coil at a temperature sufficient to bring the oil to a cracking temperature and maintained at a pressure sufiicient to prevent any substantial vaporization thereof; continuously introducing into the oil stream, leaving the heating coil a cool mixture of the heavy gas oil stockseparated by the second distillation, and alsoeontinuously separated from the cracked-residual oil, in quantities sufi'icient to lower the temperature of the oilstream below a cracking temperature of approximately 750 degrees F.; separately separating by fractionation the synthetic gasoline boiling point stock and the heavy gas oil stock produced by the said last named cracking operation, from a viscous residual oil and then commingling the sald vlscous residual Oll resultlng from the said last named fractionation operation with a mixture of the light gas oil separated a by the first and second distillations, to pro-- duce a fuel oil with a viscosity substantiallynot greater than 300v secondsat 122 degrees F., by the Saybolt furol viscosimeter.

8. A process of producing .a maximum percentage of heavy gas oil stock suitable for the production of synthetic gasoline and a residuum or fuel oil which will comply with the specifications for bunker fuel oil C, comprising, separately separating by distillation and fractionation, the natural gasoline boiling point stock and a'higher boiling light gas oil stock from the crude petroleum oil,separately separating by a second distillation and fractionation, syn thetic gasoline boiling point stock, a light and aheavy gas oil stock, from cracked pe= troleum oil and the petroleum oil residuum resulting from the first distillation, continuously introduced into a fractionating tower at a distillation temperature, said cracked petroleum oil being continuously produced by cracking the heavy gas oil stock produced in the operations; passing the residual oil from this second distillation and fractionation operation through a heating coil at a temperature sufficient to bring the oil to a cracking temperature maintained at a pressure sufiicient to prevent any substantial vaporization thereof; continuously introducingwinto the oil stream,--leaving thev heating coil a cool mixture of the heavy gas oil stock separated by the secbnd distillation and from the distillation step of the cracked residuum, in quantities suflicient to lower the temperature of the Oil stream below a cracking temperature of approximately 750 degrees separately separating by frictionation the synthetic gasoline boiling point stock and the heavy gas oil stock produced by the said cracking operation, from a vicons residual oil and then commingling the said viscous residual oil resulting from 'the said last named fractionation operation with the light cracked gas oil separated by'the second distillation to produce a fuel oil with a viscosity substantially not greater than 300 F., by the Saybolt tion the natural gasoline stock and a higher boiling light gas oil stock, from a crude petroleum oil, then separately separating by a second distillation and fractionation operation, a heavy gas oil stock, a synthetic gasoline stock and a cracked light gas oil stock, from the residualoil separated in the first distillation step'and an introduced cracked petroleum oil, said cracked petroleum oil being simultaneously and independently pro.- duced by cracking the heavy gas oil stocks collected from the distillation steps of the process; then cracking the residual oil ob tained from the second distillation step and separating by distillation and fractionation a synthetic gasoline stock and a heavy gas oil stock, and finally commingling the residual oil from the last distillation "step with a light gas oil stock from distillation steps.

10. process of producinga maximum percentage of gasoline boiling point stock and a fuel oil which will not have a viscosity 12s. the first and second 1 greater than 300 seconds at 122v degrees F. by the Saybolt furol viscosimeter, comprising, separately separating by distillation and fractionation the naturally occurring gasoline boiling point stock and a higher boiling light gas oil from a crude petroleumoil; separately separating by a second distillation and fractionation operation a heavy gas oil stock,.a synthetic gasoline boiling point stock, and a ight cracked gas oil stock, from the petroleum oil residium resulting from the first distillation operation and a cracked petroleum oil, this said cracked petroleum oil being simultaneously and independently produced by cracking the heavy gas oil stocks collected from the distillation steps of the rocess then cracking the residuum resulting rom the said second distillation step, separately separating therefrom synthetic gasoline boiling point stock and a heavy gas oil stock and then reducing the viscosity of the resultant residual oil to the required degree by commingling the same with the light gas oil derived from the first and second distillation steps.

11. A process of producing a maximum percentage of gasoline boiling point stock and a' fuel oil which will comply with the specifications for bunker fuel oil G, comprising, heating a residual oil from which the gasoline stock and light gas oil have been separated by a distillation operation, to a distillation temperature, passing said heated residual oil into a'fractionating tower along with hot cracked petroleum oil coming from a cracking system, separately by distillation a synthetic gasoline stock, a light cracked gas oil stock and a heavy gas oil stock; then cracking the residium resulting from the second distillation operation, separately separating therefrom by fractionation synthetic gasoline boiling point stock and a heavy gas oil stock and then reducing the viscosity" of the residual oil after the said last fractionation step, to the required degree, by commingling the same with the light cracked gas oil stock derived from the distillation step first mentioned.

' 12. A process of producing a maximum percentage of gasolineiboiling point-stock and a fuel oil which will not have a viscosity greater than 300 seconds at 122 degrees F. by the Saybolt furol viscosimeter, comprising, separately separating by distillation and fractionation the naturally occurring gasoline boiling point stock and a higher boiling light gas oil from a crude petroleum oil; separately separating by a second distillation and fractionation operation a heavy gas oil stock, a synthetic gasoline boiling point stock, and a light cracked gas oil stock, from the petroleum oil residuum resulting from the'first distillation operation and a petroleum oil, said cracked petroleum oil being simultaneously produced bycracking a petroleum oil previously produced in the 7 process, which is introduced directly into a ond distillation step, separately separating therefrom synthetic gasoline boiling point stock and a heavy gas oil stock and then reducing the viscosity of the resultant residual oil to the required degree by commingling the same with the light gas oil derived from the first and second distillation steps.

13. A process of treating crude petroleum oil, comprising, separately separating by distillation and fractionation gasoline boiling point stock and a higher boiling light gas oil stock from a crude petroleum oil; separately separating by a second distillation and fractionationa light and a heavy gas oil fraction and a synthetic gasoline boiling point stock, from the crude petroleum oil residuum resulting from the first distillation and a cracked petroleum oil continuously introduced at a distillation temperature into a fractionating tower, said cracked petroleum oil being continuously produced by cracking the heavy gas oil stocks collected from the said second distillation step and from a subsequent cracking and distillation step of the residual oil produced in the said second distillation step.

In testimony whereof I affix my signature.

' JOHN G. BLACK.

cracked