US2018708A - Treatment of hydrocarbon oils - Google Patents

Description

Oct. 29, 1935. c DUBBS 2,018,708

TREATMENT OF HYDROCARBON OILS Filed June 1, 1951 FURNACE l4 INVENTOR CARBON P. DUBBS BY M0256 ATTO Patented Oct. 29, 1935 UNETED STATES 2,018,708 TREATMENT or HYDROCARBON OILS Carbon P. Dubbs, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, 111., a corporation of South Dakota Application June 1, 1931, Serial No. 541,149

3 Claims.

This invention relates to the treatment of hydrocarbon oils, and more particularly refers to an improved process for the conversion of rela-- tively high boiling hydrocarbons into more valu- 5 able products. Among its aims and objects is the production of high yields of high anti-knock quality motor fuel.

In one of its specific embodiments the invention comprises subjecting hydrocarbon oils to heat treatment at elevated temperature and superatmospheric pressure, discharging the heated hydrocarbons at their conversion temperature into a reaction zone wherein the non-vaporized V residue is maintained at what is commonly termed a low level to avoid a long time element in the treatment of the said non-vaporized hydrocarbons and to. avoid the production of suspended carbonaceous or pitchy material commonly referred to as B. S.; separately withdrawing the non-vaporized residue and the vapors, the withdrawal of the latter being effected at a point remote from the point of introduction of the heated hydrocarbons into the reaction zone, separately discharging the vapors and non-vaporized residue into a zone of reduced pressure wherein the vapors and non-vaporized residue are separated, the nonvaporized residue being sent to storage and the vapors passing to a fractionating zone, returning the reflux condensate from the reaction zone to the heating element for reconversion, passing the fractionated vapors to a cooler and condenser and collecting the condensed overhead product.

Among the important improvements of the in- -vention is the withdrawal of the vapors from the reaction zone at a point remote from the point of introduction while separately withdrawing the non-vaporized residue. The removal of the vapors in this manner permits a prolonged and uniform treatment in the reaction zone, pre- Venting over-cracking of hydrocarbon components on the one hand and under-cracking on the other. Likewise, the maintenance of a low level of liquid in the reaction zone prevents over-cracking and undue formation of suspended carbonaceous material therein. Other features and advantages of the invention will become more apparent by reference to the accompanying dia-' grammatic drawing illustrating one form of apparatus suitable for carrying out the operation of the invention.

Raw oil charging stock may be fed through line I, valve 2 and pumped by means of pump 3 through line 4., valve 5, into fractionator 6, wherein it undergoes heat exchange by direct contact with the vapors arising therein, cooling the vapors and assisting in control of their fractionation, while at the same time heating the charging stock. The reflux from the condenser 6 together with the raw oil passes through line 1,- valve 8, 5

and is pumped by means of pump 9 through line Hi, controlled by valve II and valve I2 into the heating element I3 located in furnace M, wherein it is raised to a suitable conversion temperature, or a portion or all of the raw oil may be fed 10 erably under superatmospheric pressure leaves 15 the heating element'l3 and passes through line l5, valve l5, intothe reaction chamber ll, wherein it undergoes conversion and separates into vapors and non-vaporized residue. The non-vaporized residue may be withdrawn through line 20' I8, valve I 9 and introduced into the vaporizer or flashing zone 20. The vapors are withdrawn at a point remote from the point of introduction of the hydrocarbons into the reaction chamber through line 2|, valve 22 and may be intro- 25 duced into the vaporizing or reduced pressure zone 20.

It is one of the preferable features of the process, if not essential, to maintain a low liquid level in the reaction chamber ll so that the major con- 30 version will occur in the vapor phase and the conversion of the non-vaporized liquid residue be reduced to the minimum consistent with the prevention of the formation of suspended carbonaceous or pitchy material. 35

Non-vaporized liquid residue in reaction chamber 20 may be withdrawn through line 23, and valve 24. Vapors leaving the vaporizing or flashing zone 20 may be passed through line 25 and valve 26 into the fractionator 6, wherein they 40 undergo heat exchange as heretofore described with the oil introduced therein and the heavier portions of reflux condensate may be returned together with the raw oil for reconversion. The

fractionated vapors leaving the fractionator 6 45 may pass through line 21, valve 28, cooler and condenser 29 and through line 30, valve 3|, into receiver 32, wherein the fractionated overhead product of the process is collected. Liquids accumulating in receiver 32 may be withdrawn 50 though line 33, valve 34 and pass to storage. Gases may be withdrawn through line 35, controlled by valve 36, which may also serve in part to control the pressure on the process.

The operating conditions may vary over a wide 55 range of temperatures and pressures, temperatures ranging from 850 F. to 1200" F. and pressures ranging from atmospheric to high superatmospheric pressure, for example up to 2000 pounds per square inch may be employed. The preferred range of temperatures may vary from 900 F. to 975 F. and preferred pressures may range from 100 pounds per square inch to 500 pounds per square inch. Pressures upon the process will be equalized with respect to each other or differential pressures may be employed. Preferably the pressures on the heating element and reaction chamber are high with respect to those upon the vaporizing zone, fractionator, condenser and receiver.

The specific conditions employed will depend upon the charging stock being treated as well as upon the results desired.

As a specific example of the results obtainable by the operation of the process of my invention, a Pennsylvania fuel oil distillate of approximately 4=0-42 A. P. I. gravity may be treated and will produce approximately 72% of gasoline having an anti-knock value equivalent to approximately 60% benzol in admixture with Pennsylvania straight run gasoline and 75% iso-octane in admixture with normal heptane. When maintaining a temperature of approximately 950 F. at the exit of the heating element IS the pressure upon the heating element and the reaction chamher is 300 pounds per square inch. Under these condition pressures of approximately 50 pounds per square inch may be maintained upon the Va porizing zone and the remaining portions of the system, namely, the fractionator, condenser and receiver. At the same time approximately 10% of non-vaporized residue which may be employed for fuel oil will be produced, the remainder of the products being gas and a very small amount of carbon.

When treating a Mid-Continent fuel oil, temperatures of approximately 925 F. may be employed in the heating element and pressures of 250 pounds per square inch upon the heating elemerit and reaction chamber are satisfactory. Re-

duced pressures upon the vaporizing zone, fractionating zone, condenser and receiver are employed. In the present operation 30 pounds per square inch on the vaporizing zone will be satisfactory with differential pressures between these elements as a result of the pressure drop therethrough.

Under these conditions approximately 58% of motor fuel having an anti-knock value equivalent to 50% benzol in admixture: with Pennsylvania straight run gasoline may be produced, making at the same time approximately 30% non-vaporized residue suitable for fuel oil, the remaining products being gas and a very small proportion of coke.

I claim as my invention:

1. A process of hydrocarbon oil' conversion 5 which comprises forcing a stream of hydrocarbon oil through a heating zone where it is raised to cracking temperature, discharging said heated stream into an enlarged reaction zone, causing the products of reaction to traverse substantially 10 the entire length of the reaction zone, separately withdrawing vapors and unvaporized oil at places remote from the place of introduction of the heated. stream of oil from the heating zone, maintaining superatmospheric pressure in the heating 15 and reaction zone, discharging the vapors and unvaporized oil from said reaction zone into the lower and upper portions respectively of a reduced pressure zone where vapors flow countercurrent to non-vaporous residue, removing the 20 residue and isolating same from the system,,subiecting the vapors to fractionation to condense the heavier fractions thereof as reflux condensate, returning regulated portions of said reflux condensate tothe heating zone and merging same 25 with the stream of charging stock being forced ther-ethrough, removing the vapors remaining uncondensed after fractionation and condensing and collecting same as a distillate product of the process. 30

A. process such as claimed in claim 1, wherein said reaction zone is vertically disposed and the heated stream from the heating zone is discharged into the upper end thereof while the vapors and unvaporized oil are separately with- 35 awn from the lower end thereof.

3. hydrocarbon oil cracking process which comprises passing the oil in a restricted stream through a heating zone and heating the same therein to cracking temperature under pressure, 40 discharging the heated oil into the upper portion of a vertical reaction zone maintained under cracking conditions of temperature and pressure, passing both vapors and unvaporized oil downwardly through the reaction zone and maintain- 45,

ing a low liquid level therein, removing the unvaporized oil from the bottom of the reaction zone and introducing the same into the upper portion of a flashing zone maintained under lower pressure than the reaction zone, separately removing 50 vapors from the lower portion of the reaction zone and introducing the same to the lower portion of the flashing zone toflow countercurrent to the unvaporized oil descending through the flashing zone, and dephlegmating and condensing 55 the vapors from the flashing zone.

CARBON P. DUBBS.

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