US2067865A - Process of treating hydrocarbon oil - Google Patents

Description

Jan. 12, 1937. I LE ROY G. STORY 2,067,865

- PROCESS OF TREATING HYDROCARBON OIL Filed Nov. 15, 1932 VAPOR PHASE FURNACE REFO/FMER F URMCE t COKE DRUM INVENTOR- ATTORN EY- e Patented Jan. 12, 1937 PROCESS OF TREATING' HYDROCARBON ()ILv Le 'Roy G. Story, Beacon, N. Y., assignor to The Texas Company, New York, N. Y., a corporation of Delaware Application November 15, 1932, Serial No. 642,691

' 18 Claims.

This invention relates to the production of lower boiling hydrocarbon oils from higher boiling hydrocarbon oil's.

It is an object of my invention. to provide an improved process for the treatment of hydro carbon oils for the production of high anti-knock value gasoline.

Another object is the provisionof an improved heat from the treating process tocoke the charging stock residue.

In accordance with my invention a relatively clean hydrocarbon oil fraction is subjected to cracking in the vapor phase and is subsequently introduced into a soaking drum, after which the h'it soaked products are combined with fresh charging stock and introduced into a low liquid level towe'r wherein separation of the lighter products, including any gasoline, from heavy residuelike oil results. The light products pass overhead as vapors and are introduced into a separator wherein a rough separation of the products into a light overhead vapor and heavier conden-.

sate is brought about, the light overhead vapor being subsequently transferred to a fractionator for further treatment and the condensate being removed from the separator and, if desired, combined with the stock subjected to the vapor phase cracking operation or otherwise treated.

In the 'fractionator the vapors undergo partial condensation, light-products of the desired end point passing out from the top of the fractionator and thereafter being condensed and collected in a receiver. One or several naphtha side streams may be removed from the fractionator for fur- ,ther heat treatment and reformation in a separate stage which may comprise a cracking furnace wherein the products are raisedto' a relatively high temperature, e. g. 1050 F. and/means for subsequen'tly cooling and fractionating the cracked products to form a final desired distillate.

The residue resulting from the stripping of the .a vapor phase crackingfurnace; 2 a soaking charging stock in the low liquid level tower is introduced into a coke drum, wherein heat from the hot reformed vapors is used toinslire completion of the coking step. The heat exchange between the reformed vapors and residue may be carried out indirectly or directly. Vapors from the coke drum are transferred to an evaporator into which fresh charge may likewise be introduced and wherein lightproducts are separated from a heavy residue. The light products are subsequently passed to a fractionator wherein reflux condensation takesplace, the uncondensecl vapors being either combined with those introduced into the fractionator first mentioned or passed through a condenser into a collecting drum, while the condensate is removed and used as the vapor phase charging stock for the vapor phase cracking operationfirst mentioned. The residue from the evaporator, being of a heavy character, is combined for coking with the residue from the low liquid level tower either before or after the passage of that residue in indirect heat exchange relation with the hot vapors from the reformation unit.

Direct heat exchange between the hot reformed vapors and the combined residues may be used where a larger amount of heat is needed for coking; in this case all three products would be introduced directly into the coke drum. Or a portion only of the hot vapors might be injected into the coke drum, the rest-.beingpassed either directly to a fractionator, or first in indirect heat exchange with the residue'to aid in raising the I latter to a coking temperature.

The above mentioned and further objects and advantages of my invention and the manner of obtaining them will be made clear in the following description taken in conjunctionwith the accompanying drawing.

In the drawing, reference numeral l indicates drum; 3 a low liquid level tower; 4 a separator; and. 5 afractionator. Clean charging stock such as gas oil having a boiling range of from 400-750 F. is introduced into the vapor phase heater I through line 6 by the action of pump i and is heated in the furnace to a high cracking temperature, for example 1000" F. under low or moderate pressure, .for example 175-200 pounds per square inch, and is thereafter passed into soaking drum 2. After being digested in the soaking drum for a period of time, the vapors 'travel through conduit 8, wherein they are joined by fresh charging stock such as til-32 A. P. 1., M. 0. gas oil, or a gasoline containing charging stock such as ass-40 A. P. 1., M. c. crude, introduced through pipe 9, the combined products subsequentlyentering low liquid level tower 3. This tower, which may be at a temperature of about.

850 F. is preferablyheld at a reduced pressure by action .of reducing valve 13, for example 50 pounds per square inch, in order to promote quick separation of the lighter products of the fresh charge and vapors from the heavier ends or residue, the lighter products passing overhead as vapors through pipe line Ill into separator 4, while.

the heavy residue is withdrawn from the bottom of the tower through conduit II and introduced into' coke drum l2, to prevent any. substantial accumulation of liquid in the tower. Additional pressure reduction may be accomplished by valve 14, but this usually will not be necessary. In the separator a portion of the light vaporous products is separated by condensation and removed through line l3, the uncondensed-vapors passing out of the topof the separator through vapor line l4 to the fractionator 5. In the fractionator reflux condensation of the vapors occurs with the result that a product of desired end point is removed from the top of -the fractionator through vapor line l5 and is subsequently passed through condenser I 6 into receiver l1. This receiver is furnished with the usual gas drawoif line It! and withdrawal pipe 20, both of which have suitable valves.

Line 2| is provided for withdrawing from the fractionator a side stream of gasoline fractions, e. g. heavy naphtha or comparable product, which is of such character as to require reformation in order to produce gasoline of a required high antiknock value. This side stream is conducted through condenser or cooler 22 into manifold 23,

from whichit may be withdrawn by pump 24 and forced through line 25 and heating furnace 26 wherein it is raised to a reforming temperature,

' for example 975 F. under a moderate pressure,

e. g. 400 pounds per sq. in. After leaving the furnace the reformed high anti-knock vaporous prod ucts pass through heat exchangers 21 and 28 into fractionator wherein partial condensation of the vapors occurs and aflnal desired high antiknock gasoline product'is removed through vapor through heatexchanger" in any desired quan tities, the flow of naphtha through the heat 'exchanger 28 being controlled by valves 33, 34 and 35. Reflux condensate from the bottom of fractionator 5 maybe withdrawn through pipe 36 and either diverted from the system through pipe 31 having valve 38 or it may be passed through cooler 39 into themanifold 23 for passage to the reformation furnace 26. Valve 40 is for controlling the flow of condensate from the pipe 36 to manifold 23.

Vapors from the coke drum I 2 pass overhead through pipe 4| into evaporator 42 where they may mingle with fresh charge introduced through line 43 having. a'control valve 44. In the evaporator separation of light vapors, including the vaporizable portions of the fresh charge takes I place, the resulting vapors traveling through vapor line 45 into fractionator 46. The unvaporized portions of the products in the evaporator are withdrawn through drawofi' line 41 and are forced by pump 5| into the coke drum l2 in combination with the residue from the low liquid level tower 3. The residue from the evaporator 42 may either pass directly into the pipe line I I to be combined with the residue from tower 3 prior to the passage thereof through the heat exchanger 21 or the residue may be introduced into the pipe line ll near its point of connection withthe coke 1 drum I2, by proper manipulation of. valve 48 in pipe line 49 and valve 50 in the line 41. The path of travel of the residue to the coke drum will be determined by the amount of heat necessary for the coking operation. The temperature of the coke drum may vary but should ordinarily be such that the vapors leaving the drum have a temperature of at least 840 F. If but a small amount of heat is necessary it may be found advisable to close the valve 50 and open the valve 48, thereby permitting the residue from the evaporator 42 to enter the coke drum at a moderate temperature and so exert a slight cooling effect upon the products entering the coke drum through the line II. This optional arrangement permits of close control of the temperature in the coke drum. Uncondensed va ors from fractionator 46 travel tofractionator 5 t rough vapor line 62 hav-' ing valve 63, for further treatment, .or may be diverted to receiver 6| through pipe 64 and con- 23 if desired. It may be found advantageous in' certain cases to reform this distillate, although in most cases it probably would be found best to reform only the heavy naphtha withdrawn through the pipe 2| as a side stream or that withdrawn through pipe line 36.

Added heat for coking may be obtained by introducing all or part of the hot reformed vapors directly into the coke drum l2; this may be done by proper manipulation of valves 59 and 60. In this case the desired final high anti-knock gasoline distillate is preferably collected in receiving drum 6|, the valve 63 being closed to prevent the vapors from passing to fractionator 5, but retreatment of the vapors in fractionator 5 may be carried out as before. Where the distillate is collected in drum 6| it may be blended with that collected in drum l6, if desired. The flow of residue through heat exchanger '21 is under control of valves 61 and 68 and by closing 68 and opening 61 the exchanger is rendered completely inopa erative. a

The condensate from fractionator29, being relatively refractory, may well-be introduced into drum l2 for coking. Valved line 69 is provided to accomplish this purpose. Cross-over line '16 serves to combine condensate drawn off from separator 4 with the residue from low liquid level tower 3, the routing of the condensate being controlled by valves 1| and 12, and the necessary pressure being supplied by pump I05. The character of this condensate canbe controlled by the amount of fresh charge introduced into tower 3 and by the amount of cooling fluid passed through coil 52; when the amount of cooling supplied by the fresh charge and/or cooling coil 52 is relatively large, the condensate drawn off through line [3 will be lighter in character and more ,suit- 'able for treatment in vapor phase coil I. With in a coil and is more profitably, mixed with the residuefor coking. Valved draw-off lines 100,

. llll, |02, I03 and I04 are provided for vessers 3, 4,

29, 42 and 46 respectively, whereby products may be diverted from the system whenever desired. The vapor phase furnace I is adapted to heat the oil passing therethrough to a temperature of 900 to 1100 F., although a temperature of 950-1040 F. is preferable, while thepressure on the oil in the vapor phase heater may range from 50400 lbs. per square inch, but it, is preferably in the neighborhood of 175-200 lbs. per square inch. The cracking per pass inthe vapor phase coil and drum may range from 12 to 35% but is preferably from to The temperature of the low liquid level drum may be from 800 to 900 F. but is preferably about 850 F. The refformation furnace may heat the oil to a temperature of from 900-1050 F., and the pressure may range from 250-750 lbs. per square inch or higher; however, conditions of 975 F. and 175-200 lbs. per square inch will usually be found best. The fresh charging stock may vary considerably in character. for example it mav range from 20 A. P. I., M. C. reduced crude to 35 M. C. gas oil or may comprise 35-40 A. P. 1., M. C. crude but generally 31-32 A. P. I. gas oil will be found most suitable.

I have described a particular embodiment of my invention for purposes of illustration. but it should be understood that various modifica ons and adaptations thereof may be made with n the spirit of the invention as set forth in the Iclaim:

1. The process of treating hydrocarbon oil which comprises raising a clean distillate to a vapor phase cracking temperature, combining the resulting cracked products while hot, in a stream of restricted cross-sectional area, with fresh relatively heavy chargingfstock in order quickly to raise the charging stock to a distillation temperature', subsequently reducing the pressure on the mixture ahd separating it in a separating zone into vaporsand a liquid residue, fractionating resulting vapors to segregate a light gasoline distillate and alheavy naphtha condensate comprising gasoline constituents, raising said heavy naphtha condensate, to a high cracking temperature in an independent heating zone to cause an increase in the anti-knock value thereof, removing residue from said separating zone at such a rate as to prevent the accumulation of any substantial body of liquid therein in order to prevent liquid phase digestion, passing hot vapors from the heated heavy naphtha in heat exchange with the removed 7 residue, coking the heated residue in a coking zone, and removing vapors from said coking zone and passing them directly to a fractionating zone separate from said separating zone first mentioned to form a desired distillate.

2. A process in accordance with claim 1 where in vapors from said coking zone are subjected to partial condensation to produce a light vaporous product and a clean condensate, said light vaporous product is combined with the light 3. A process in accordance with claim 1 wherein vapors are removed from said coking zone and combined with fresh charging stock in a' zone independent of said separating zone to produce light vapors and a heavy residue, said light vapors are subjected to fractionation, and said heavy residue is returned directly to the cokng zone.

4. A process in accordance with claim 1 wherein vapors are removed from said coking zone and combined with fresh charging stock to produce;

light vapors and a heavy residue, said light vapors are subjected to fractionation, and said heavy residue is combined with said residue first men tioned prior to the passage thereof in said heat exchange relation with the hot reformed vapors.

5. A process in accordance with claim 1 wherein vapors from said coking zone are introduced into an evaporating zone independent of said separating zone in contact with additional fresh charging stock to produce vapors and a residue. said vapors are subjected to further partial condensation to produce light vapors end a clean condensate, and said clean condensate is utilized as said clean distillate stock first mentioned.

6. The process of treating hydrocarbon oil which comprises raising a clean distillate stock to vapor phase cracking temperature. c mbining the resulting cracked products while hot, in' a stream of restricted cross-sectonal area with fresh relatively heavy charging stock in order quickly to raise the charging stock to a distillation temperature, subsequently separat ng the mixture under reduced pressure in a sep-rating zone into vapors and a liquid residue, fractionating resulting vapors in a fractionating zone to segregate a light gasoline disti late and a heavier in said reformed products are combined while hot with said res due in a coking ,zone.

'8. A process in accordance with claim 6 wherein saidreformed products are combined with said residue in a coking zone wherein vapors are formed, and said vapors are subjected to fractlonation to produce a condensate, said condensate being used as said clean distillate stock first mentioned.

9. The process of treating hydrocarbon oil which comprises passing a clean distillate stock through a heating zone wherein it is raised to a cracking temperature and subjected to conversion, passing resulting hot cracked products into a separating zone wherein vapors separate from liquid residue, introducing fresh charging stock into said separating zone in contact with the hot products therein to cause partial vaporization of said charging stock, withdrawing liquid residue from said separating zone at such a rate as to prevent the accumulation of any substantial body of liquid therein, removing vapors from said separating zone and subjecting them to fractional condensation to form a quantity of desired light distillate in'the gasoline boiling range, an intermediate condensate comprising gasoline constituents which it is desired to increase in antiknockvalue, and a heavy condensate, returning c said heavy condensateto said heating zone, passing said intermediate'condensate through a second heating zone wherein it is raised to a cracking temperature sufiicient 'to' cause conversion thereof into relatively high anti-knock gasoline bonstituents, separating the resulting cracked products into vapors and 'aliquid residue, fractionating said vapors in a separate fractionating zone to form an additional quantity of final desired light distillate and leave heavier products liquid form, passing liquid residuewithdrawn from said separating zone, in indirect heat exchange relation with hot products from said second heating zone prior to the fractionationfthereof, to cause heating of said withdrawn residue toa higherjtemperature, and introducingthe resulting highly heated residue-into a separate coking zone sub-' jecting it therein to coking by its contained heat.

10. A process in accordance with claim 9 wherein said heavier products last mentioned are introduced into said coking zone in contact with the highly heated residue to undergo coking therewith.

11.- A process in accordance with claim 9 wherein a portion of the hot products from said second heating zone is passed directly, into said coking zone to aid in the maintaining of the products therein at a suitable coking temperature.

12. A process in accordance with claim 9 wherein vapors are removed from said coking zone and subjected to fractional condensation-to form an additional quantity of final light distillate, an

intermediate condensate, and a heavy condensate, said heavy condensate is returned to said coking zone and said intermediate condensate is passed a through said first mentioned heating zone for additional conversion.

13. The process of treating hydrocarbon oil whichcomprises passing a clean distillate stock through a' heating zone wherein it is raised to a cracking temperature and subje'ctedto conver a rapid rate as to prevent the accumulation therein of any considerable quantity of liquid in order to prevent liquid phase digestion, passing residue so withdrawn into a coking zone wherein it is subjected to coking, segregating a heavy gasoline fraction from the vapors removed from said sepa-, rating zone, passing said heavy gasoline fraction through -a. separate heating zone wherein it is raised to a cracking temperature sufficient to in= .crease the anti-knock value thereof, and subjected to reformation, separating the resulting reformed products into vapors and a liquid residue, fractlonating the vapors to form'an additional quantityof final desired light distillate, and utilizing heat derived from the hot" reformed products to aid in carrying out the coking operation in said coking zone. i

14. A process in accordance with claim 13 wherein said liquid residue withdrawn from said separating zone is passed in indirect heat exchange relation with the hot products removed from said second heating zone, prior to the introduction of the said residue into said coking zone. 15. A process in accordance with claim 13 wherein a portion of the hot cracked products from the said second heating zone is introduced directly into said coking zone to aid in maintaining.the temperature thereof.

16. A process in accordance with wherein vapors derived from the coking operation taking place in the coking zone are combined with vapors removed from saidseparating-zone, for fractional condensation to form a desired light distillate.

17. A process in accordance with claim 13 wherein the freshrelatively heavy charging stock is combined with the hot cracked products formedv in said first heating z'one prior to the introduction thereof into said'separating zone.

18. The process of treating hydrocarbon oil which comprises raising a clean distillate stock toa cracking temperature to cause conversion thereof, passing the resulting cracked products while hot in a-stream of restricted cross-sectional area into a separating zone,introducing fresh relatively heavy charging oil into mixture with said cracked products in said stream in order quickly to raise the charging stock to a distillation temperature andseparating the mixture in said separating zone into light 'vapors'and a residue, fractionating said light vapors in a fractionating zone to form a light gasoline distillate and aside stream of heavy naphtha, raising said heavy naphtha, free from said residue, to a cracking temperature sufficient to cause an increase in the anti-knock value thereof, to cause reformation of, said heavy naphtha, removing said residue from said separating zone and coking it by the aid of the heat of the reformed naphtha comprising heavy gasoline constituents, removing vapors from the coking operation and passing them directly to a fractionating zone separate from said separating zone first mentioned and subjecting them to fractionation to produce a clean condensate and light vapors of the desired and point, utilizing said con .densate as said clean distillate stock first mentioned and condensing said light vapors last mentioned and combining this condensate with said light gasoline'distillate to produce a final blended gasoline-like product of high anti-knock value.

, I LE ROY G.- STORY.

claim 13v CERTIFICATE OF CORRECTION.

Patent No. 2,067,865. January 12, 1937.

LE ROY G. STORY.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 4, second column, lines 49 and 50, claim 18, strike out the words "comprising heavy gasoline constituents" and insert the same after naphtha." and before the comma first occurrence, in line 45, same claim; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 2nd day of March, A. D. 1957,

Henry Van Arsdale (Seal) Acting Commissioner of Patents.

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