US2146504A - Conversion of hydrocarbon oils - Google Patents

Description

Feb. 7, 1939. 1.. c. HUFF QONVERSION OF HYDROCARBON OILS Original Filed Nov. 15, 1930 a 25 w 4 5% my 7 0 M M Mfg m @0 c J F 0 mum 5M 7 1 A: V m d w lta t e 0 a #6 2 z a .6 L .m r r 6 M F m a I w Mv m 1 i 2% 9 w Chevalier Patented Feb. 7, 1939 UNITED STATES CONVERSION OF HYDROCARBON OILS Lyman C. Huff, Chicago, Ill., assignor, by mesne assignments, to Universal Oil Products Com pany, Chicago, 111., a corporation of Delaware Application Claims.

' This invention relates to the conversion of hydrocarbon oils and particularly. refers to the simultaneous conversion of various charging stocks together with intermediate products there- 5 from in the same system under independently regulated conditions. I

The present invention provides an improved process and apparatus in which raw oil charging stock is subjected to conversion temperatures in a primary heating element, the heated materials are discharged into an enlarged reaction zone in which vapors and liquid are separated, the vapors are subjected to fractionation in a primary fractionating zone, reflux condensate from which is lit; returned to the primary heating element for reconversion, vapors from the primary fractionating zone are subjected to further fractionation in a secondary fractionator, vapors from which are condensed, cooled and collected and reflux condensate from which is subjected to reconversion conditions in a secondary heating element and heated materials from the secondary heating element are combined with the heated materials from the primary heating element entering the aforementioned enlarged reaction zone' which is common to both. Unvaporized residual oil from the reaction chamber of the system may be withdrawn to storage but preferably is subjected to further vaporization. in a zone of'reduced pres- 30. sure, vapors from which are subjected to fractionation followed by condensation and collection of their lighter components while the unvaporized material is withdrawn from the system.

As a feature of the invention a secondary charging stock, preferably lighter and more refractory to cracking than the primary charging stock, is supplied to the secondary heating element for conversion together with reflux condensate from the secondary fractionator of the cracking system.

As a further feature of the invention primary charging stock for the cracking system may be supplied to the fractionator of the residuum redistilling system and reflux condensate from this 5 zone, together with preheated raw oil, is returned to the primary fractionator of the cracking system or may be fed in part into the body of residual liquid in the reaction chamber or into the stream of residual liquid being withdrawn from the reaction chamber.

The various features of the invention will be more apparent with reference to the attached diagrammatic drawing illustrating one form of apparatus in which the process of the present 55 invention may be practiced.

November 15, 1930, Serial No. 495,911

Renewed June 5, .1937

-' Referring now to the drawing, primary charging stock supplied through line I and valve 2 to pump 3 is fed through line 4 and valve 5 into fractionator 6 of the residuum redistilling system where it is preheated by contact with the 5 relatively hot vapors in this zone assisting in their fractionation and passing together with their condensed heavier portion through line 1 and valve 8. to pump 9 wherefrom the combined material is fed through line Ill and valve II to fractionator l2. Fractlonator I2 is the primary fractionating zone of the cracking system and the oil fed thereto is further preheated by contact with the ascending vapors which it assists to fractionate, passing together with the relatively heavy components of the cracked vapors which are condensed in this zone through line l3 and valve l4 to pump l5. Pump l5 supplies the combined material through line I6 and valve I! to heating element I8. 20,

Heating element I8 is located in any suitable form of furnace l9 and oil passing therethrough is heated to the desired conversion temperature under any desired pressure conditions and passestherefrom through line 20, valve 2!, line 22 and valve 23 into reaction chamber 24, The vapors are withdrawn through line 25 and valve 26 to. fractionator l2 where they are subjected to primary fractionation, their heavier portions returning to reconversion, as already described, while their lighter fractionated'portion is passed through line 28 and valve 29 to fractionator 30. The vapors are subjected to further fractionation in fractionator 30 and the light components of the vapors remaining uncondensed in this zone, which preferably correspond in boiling range to motor fuel, pass through line 3| and valve 32, are subjected tocondensation and cooling in condenser 33, condensed distillate and uncondensable gas from which passes through line 34 and Valve 35 to be collected in receiver '36. Distillate may be withdrawn from receiver 36 through line 31 and valve 38 while uncondensable gas may be released through line 39 controlled by valve 40. A portion of the distillate from receiver 36 may be withdrawn through line 4| and valve 42 to pump 43 by means of which it is recirculated through line 44 and valve 45 to fractionator 30 to assist fractionation of the vapors in this zone.

Reflux condensate resulting from the secondary which is located in any suitable form of furnace 53 55;;

and in which the oil is heated to the desired conversion temperature under any desired pressure conditions. Heated materials from heating element 52 pass through line 54 and valve 55 into line 22 combining therein with heated materials from heating element I 8, the combined materials passing through valve 23, in line 22, into reaction chamber 24 to be subjected to further treatment, as already described.

Unvaporized residual oil from reaction chamber 24 may be withdrawn from the system by well known means, not shown, but preferably passes through line 55 and valve 5? to chamber 58 where it is subjected to further vaporization preferably under substantially reduced pressure. Oil remaining unvaporized in chamber 58 is Withdrawn through line 55, valve 66, heat exchanger 5|,line 62 and valve 53. Vapors evolved in chamber 58 pass through line 64, valve 55, heat exchanger 65, line 6'! and valve 68 to fractionator 6 where they are subjected to fractionation assistedby raw oil introduced into contact with the vapors, as already described.

Vapors from fractionator 6 pass through line 59 and valve 15, are subjected to condensation and cooling in condenser l 5, products from which pass through line i2 and valve 13 to receiver '54. Condensed distillate may be withdrawn from receiver M through line '55 and valve l6. Uncondensable gas may be released from receiver 14 through line it controlled by valve 18.

A portion of the reflux condensate and preheated raw oil from fractionator 5, which is supplied to fractionator I2 and thence to reconversion, as already described, may be diverted from line I G and consequently from fractionator l2 through line and valve 95 and may be fed through line 91 and valve 98 into the lower portion of reaction chamber 2 or may'pass, all or in part, through line 99 and valve 550 into line 55, combining in either case with unvaporized residual oil from the cracking reaction to cool this product and prevent excessive formation of coke or carbonaceous material. The oil diverted from line 15 for the purpose of cooling the residual liquid may, if desired, be passed all or in part through cooler H)! by regulation of valve 552, in line H13, valve H34; in line I05 and valve 95, in line 95.

Secondary charging stock for the system which is preferably of a lighter nature and more refractory to cracking than the raw oil charging stock and may, for example, be a fraction of distillate boiling within the range of motor fuel, straightrun gasoline, kerosene or a h'eavier'distilla'te, is supplied through line 19 and valve Bilto pump 8i and may be fed through line 82, valve 81, line 90, valve 9!, line 5! and valve 92 to heating element 52 where it is subjected to conversion temperatures together with reflux condensate from fractionator 3B. The secondary charging stock may be preheated in any well known manner, for example, a portion or all of the charging stock may be diverted from line 82 through line Bii'and valve 84 to heat exchanger 66 where it is preheated by indirect contact with vapors from chamber 58 and thence passes through line 85 and valve 36 back into line 82 and/or any portion or all of the secondary charging stock may pass through valve 88, in line 82, into heat exchanger 6! where it is preheated by indirect contact with unvaporized residual liquid from chamber 58, thence passing through valve 89 in line 5| to heating element 52.

Pressures employed within the system may range from sub-atmospheric to super-atmospheric pressures as high as 1500 pounds or more per square inch. Substantially equalized pressure may be employed throughout the system or differential pressures may be employed between the various elements. Preferably fractionators l2 and 3B are maintained under substantially equalized pressures, which pressure is preferably substantially the same as that employed in the reaction chamber 24 but may be substantially lower. Heating elements i8 and 52 may be operated under substantially the same or under diiferential pressures and the pressure employed in reaction chamber 24 may be substantially the same as that in the heating element operated at lowest pressure or may be substantially lower. The residuum redistilling system is preferably operated under substantially reduced pressure relative to that employed in reaction chamber 24.

Conversion temperatures employed may range from 750 to 1200 F., more or less. Preferably more severe conversion conditions are utilized in heating element 52 than in heating element l8.

As a specific example of operating conditions which may be employed in the apparatus illustrated and described and as an example of results which may be obtained from such operation: The primary charging stock is a Pennsylvania topped crude of about 28-30 A. P. I. gravity and is subjected in the primary heating element to a temperature of about 900 F. under a super-atmospheric pressure of about 300 pounds per square inch. The pressure upon the reaction chamber is reduced to about pounds per square inch and this pressure is substantially equalized in the primary and secondary fractionators of the cracking system and in the succeeding condensing and collecting equipment. The secondary charging stock, comprising about 20 percent of the total charge, is a water white straight-run distillate from Pennsylvania crude, boiling within the temperature range of 400 to 550 F. or thereabouts, and is subjected to conversion together with reflux condensate from the secondary fractionator of the cracking system at a temperature of approximately 1050 F. under a super-atmospheric pressure of about 100 pounds per square inch. This operation may yield about 56 percent of motor fuel having an anti-knock value equivalent to a blend of about 60 percent benzol and 40 percent Pennsylvania straight-run gasoline. About 30 percent of residual oil is produced, having characteristics which render it suitable for sale as low grade commercialfuel.

In a similar operation deviating from the above only in hat a portion of the preheated raw oil and reflux condensate from the dephlegrnator of the residuum redistilling' system is injected into the body of residual oil in the reaction chamber. The percentage of residual oil produced, based on the raw oil charging stock, is increased to about 35 percent and, in this case, possesses characteristics which render it suitable for sale as premium fuel. In this operation the gas loss is decreased somewhat and a slight decrease in the production of gasoline may also re sult.

I claim:

1. A conversion process which comprises heating hydrocarbon oil to cracking temperature under pressure in a heating coil and thence discharging the same into a reaction chamber maintainedunder cracking conditions of temperature and pressure, effecting substantial cracking of the oil in said coil and chamber, separating Vapors from unvaporized oil in the chamber and separately removing the same from the chamber, introducing the unvaporized oil into a flashing zone maintained under lower pressure than said chamber and flash distilling the same therein by pressure reduction, fractionating resultant flashed vapors in contact with charging oil for the process thereby forming a mixture of unvaporized charging oil and flash reflux, supplying a portionof said mixture to the heating coil and commingling another portion thereof with said unvaporized oil prior to introduction of the latter to the flashing zone, fractionating the vapors withdrawn from said chamber to form a reflux condensate of lighter character than said mixture, cracking said condensate by passage through a second heating coil maintained at higher temperature than the first-named coil and thence into said chamber, and finally condensing the fractionated Vapors.

2. A conversion process which comprises heating hydrocarbon oil to cracking temperature under pressure ina heating coil and thence discharging the same into a reaction chamber maintained under cracking conditions of temperature and pressure, effecting substantial cracking of the oil in said coil and chamber, separating vapors from unvaporized oil in the chamber and separately removing the same from the chamber, introducing the unvaporized oil into a flashing zone maintained under lower pressure than said chamber and flash distilling the same therein by pressure reduction, fractionating resultant flashed vapors in contact with charging oil for the process thereby forming a mixture of unvaporized charging oil and flash reflux, supplying a portion of said mixture to the heating coil and commingling another portion thereof with said unvaporized oil prior to introduction of the latter to the flashing zone, fractionating the vapors withdrawn from said chamber to form relatively heavy and light reflux condensates, returning the heavier reflux condensate to said coil, cracking the lighter reflux condensate by passage through a second heating coil maintained at higher temperature than the first named coil and thence into said chamber, and finally condensing the fractionated vapors.

3. A conversion process which comprises heating hydrocarbon oil to cracking temperature under pressure in a heating coil and thence discharging the same into a reaction chamber maintained under cracking conditions of temperature and pressure, efiecting substantial cracking of the oil in said coil and chamber, separating vapors from unvaporized oil in the chamber and separately removing the same from the chamber, introducing the unvaporized oil into a flashing zone maintained under lower pressure than said chamber and flash distilling the same therein by pressure reduction, fractionating resultant flashed vapors in contact with charging oil for the process thereby forming a mixture of unvaporized charging oil and flash reflux, separately fractionating vapors withdrawn from said chamber in contact with at least a portion of said mixture and then supplying the mixture, together with reflux condensate formed by this fractionation to said heating coil as said hydrocarbon oil, commingling another portion of said mixture with said unvaporized oil prior to introduction of the latter to the flashing zone, further fractionating the vapors uncondensed by the last-named fractionation independently of said 4. A process for the simultaneous conversion of relatively heavy and light hydrocarbon charging stocks which comprises heating hydrocarbon oil to cracking temperature under pressure in a heating coil and then introducing the same to an enlarged chamber, maintaining the oil in the coil and chamber for a time period adequate to effect substantial cracking thereof, separating vapors from unvaporized oil in the chamber and separately withdrawing the same, further distilling the withdrawn unvaporized oil thereby forming additional vapors, fractionating the latter in contact with the heavy charging stock and supplying a portion of the admixed charging stock and reflux condensate thus formed to said coil, combining another portion of said admixed charging oil and reflux condensate with said unvaporized oil prior to the further distillation of the latter, subjecting the first-named vapors to primary and secondary fractionation independently of said additional vapors thereby forming primary and secondary reflux condensates, returning the primary reflux condensate to the heating coil, combining the light charging stock with the secondary reflux condensate and cracking the resultant mixture by passing the same under pressure through a second heating coil maintained at higher temperature than the firstnamed coil and then into said chamber, and finally condensing the fractionated vapors.

5. A conversion process which comprises heat ing hydrocarbon oil to cracking temperature under pressure in a heating coil and then introducing the same to an enlarged chamber, maintaining the oil in the coil and chamber for a time period adequate to effect substantial cracking thereof, separating vapors from unvaporized oil in the chamber and separately withdrawing the same, further distilling the withdrawn unvaporized oil thereby forming additional vapors, fractionating the latter in contact with hydrocarbon charging stock for the process and supplying a portion of the admixed charging stock and reflux condensate thus formed to said coil, combining another portion of said admixed charging oil and reflux condensate with said unvaporized oil prior to the further distillation of the latter, subjecting the first-named vapors to primary and secondary fractionation independently of said additional vapors thereby forming primary and secondary reflux condensates, returning the primary reflux condensate to the heating coil, cracking the secondary reflux condensate by passing the same through a second heating coil maintained at higher temperature than the first-named coil, combining the resultant products with heated products removed from the first-named coil, and finally condensing the fractionated vapors.

LYMAN C. HUFF.

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