US2056775A - Art of hydrocarbon oil conversion - Google Patents

Description

Oct. 6, 1936. c, P. DUBBS ART OF HYDROCARBON OIL CONVERSION Original Filed March '7, 1927 III MQ NW Patented Oct. 6, 1936 UNITED STATES PATENT OFFICE Carbon P. Duhbs,

Wilmette, Ill., assigner, by,

mesne assignments, to Universal Oil Products Company, Chicago, Ill.,

Ware

a corporation of Dela- Application March 7, 1927, Serial No. 173,268

Renewed March 24, 1934 8 Claims.

The present improvements relate more particularly to a process and apparatus primarily designedl toeffect conversion of hydrocarbon oils of' high boiling point range into hydrocarbons of lower'boiling point range suitable for commercial use.

The invention in its broad aspects embraces a process and apparatus for simultaneously topping crude oil and subjecting the topped crude to cracking conditions of temperature and superatmospheric pressure.

The invention is characterized by its adaptability, iiexibility, and economy. The arrangement isv such that the process can be operated to produce maximum yields of condensed overhead products, such asgasoline and the like, with a minimum production of non-vaporous residue, or the process may be operated to produce a minimum yield of light overhead products and a maximum yield of non-vaporous products, including all of the range between these two alternatives.

The invention is also characterized by the fact that the process may be so operated as to efciently work on any type of charging stock included in a range from a low gravity heavy viscous residue up to. and including a kerosene-.like charging stock having a Baume gravity of more or less.

As a feature of the invention, the charging stock is subjected to a preheating temperature by being caused to pass through a closed circuit, thus causing vaporization of the real light constituents of said charging stock. These vapors are permitted to be released, and separately condensed and collected. That portion of the charging stock which does not vapcrize due to this preheating is then subjected to cracking conditions of temperature and superatmospheric pressure to cause substantial conversion and separation of vapors. The utility of the invention as well as many other objects and advantages will be more apparent from the following description.

The single figure in the drawing designates a diagrammatic iiow chart of the invention.

Referring more in detail to the drawing, I designates a crude oil storage receptacle from which o-il is passed through the line 2 in which may be interposed the pump 3 and meter 4 to the coil 5 mounted in heat exchanger E connected by branches 1 controlled by valves 8. Or this preheater may be by-passed by closing valves 8 and opening the valve 9 in the line ID. The charging stock may be then passed through the closed coil II mounted in the heat exchanger I2 through the branches I3 controlled by valves I4, or by closing the valves I4 the coil Il may be bypassed, and the oil passed throughV the line I5 controlled by valve I6 communicating with line I1. The line I1 may communicate with the closed coil I8 mounted in the upper portion of a dephlegmator I9 by means of the branches 20 controlled by valves 2|. Or the closed coil I8 may be by-passed by passing the oil through the by-pass line 22 which -is controlled by valve 23. The oil in either event passes into the line 24 and into the water separator 25.

The desirability of subjecting the crude oil to the various preheating steps will be basedI upon the conditions of operation, gravity and characteristics of charging stock and products desired. Where the crude oil contains water, it Will be advisable to subject it to one or more of the preheating stages illustrated, so that the temperature of the crude by the time it reaches the water separator will be around, say 250 to 400 F. Water which may separate in the water separator 25 may be withdrawn through the line 26' controlled by valve 21. The crude passes out through the line 28 and may pass through the closed coil 29 mounted in preheater 30 through the branches 3I controlled by valves 32, or the crude may be by-passed by opening valve 33 in line 34. VThe crude may then pass through the line 35 controlled by valve 36 being introduced into a vapor separator 31. This vapor separator 31 in the present invention may preferably take the form of a fractionating column provided with the usual bafes. The vapors which have formed due to the preheating steps, separate in the vapor separator, and those which remain uncondensed after passage through the vapor separator pass out through the vapor outlet line 38 through heat exchanger 6, condenser 39, collecting as a liquid in the receiver 40. This receiver 40 may be equipped with the usual uncondensable gas relief pipe 4I controlled by valve 42, and with a liquid draw off pipe 43 controlled by valve 44. For the purpose of assisting in the fractionation of the vapors separating in the vapor separator 31, a controlledY quantity of the liquid collected in the receiver may be returned through the line 15in which may be interposed a pump 46 and valve 41, the line 45 discharging into the topV of the vapor separator 31.

From the foregoing it will be apparent that I have utilized the waste heat from the cracking system for the purpose, of vaporizing the lighter fractions contained in the crude oil, which lighter fractions are vaporized, separated, fractionated,

and those remaining uncondensed collected separately in the receiver'40.

The topped crude collecting in the lower portion of the vapor separator 31 is withdrawn through the line 48, in which may be interposed a hot oil pump 49 and valve 50, being forced through the heating tube 5| mounted in the furnace 52 where it is raised to a conversion temperature of, say '750 to 950 F. The heated oil from the heating tube 5| passes out through transfer line 53 in which may be interposed a Valve 54 discharging into a reaction chamber 55 where vapor separation is permitted to take place. The vapors separated in reaction chamber 55 may pass out through Vapor outlet pipe 56, in which may be interposed a valve 51, being introduced into a compartment 58 in thedephlegmator I9, defined by partitions 59 and 60. These vapors pass upwardly through the open ended uprights 6| discharging into the interior of the dephleg Inator |9. The dephlegmator I9 is provided with the usual bailles, pans, or the like. Reflux condensate preferably collectsyas indicated, in a pool 62 surrounding the uprights 6|. The arrangement is such that the heat of the vapors passing upwardly through theV uprights 6| strips the reflux condensate in the pool 62 of the light fractions which may be entrained therein, due to the reboiling action which takes place. VThe vapors remaining uncondensed after passage through the dephlegmator |79 pass out through the vapor outlet pipe 63 controlled by valve 64, through heat exchanger |2, condenser 65, collecting in receiver 66 as liquid condensate. The receiver 66 is provided with the usual gas relief pipe 61 controlled by valve 68, andwith the liquid draw offpipe 69 controlled by valve 10.

Regulated portions of the distillate collecting lin the receiver 66may be returned through the line 1| in which may'be interposed a pump 12 and valve 13, to the upper portion of the dephlegmator I9. Y

In one method of operation, the valve 51 in the vapor transfer line 56 from reaction chamber 55 tothe dephlegmator I9 is a pressure reducing Valve whereby the pressure maintained on the Vheating tube 5| and chamber 55 is reduced or released altogether. Y

- The non-.vaporous residue may be withdrawn from the reaction chamber 55 through any of the draw oif lines 14 controlled by valve 15 discharging into the common header 16. To assist in the Withdrawal of this residue and to prevent the Vaccumulation of Ysubstantial quantities of coke or coke-like material in the chamber 55, an agitatorV designated diagrammatically at 11 and which may be operated by the motor 18 may be provided. All or any regulated portion of the residue passing through the residue draw off line 16 may be diverted into the line 19 controlled by valve 80, which'line 19 communicates with the heat exchanger 30, Vfrom which it discharges into the line 8|, further cooling the residue byY means of the instrumentality 82, said residue being finally collected in the residue storage receptacle 83.

All or Vregulated portions of the residue pass- Ving through the line 16 may be diverted through the line 84 controlled by valve 8,5 into the interior of a flash chamber 86. In the drawing the dephlegmator 9 and ash chamber 86 are illustrated as one instrumentality. It is obvious that these-elements maybe separate instrumentalities within the contemplation of the invention.

As ,a feature of the inventirm,` the ,measureV maintained on the residue passing through the line 84 is materially reduced or released altogether, the valve 85 acting as a pressure reducing valve, whereby substantial separation of vapors due to latent heat takes place in the flash chamber 86. These vapors may be removed from, the chamber 86 through the vapor line 81 controlled by valve 88, being introduced to the interior of the dephlegmator 9 where they combine with the vapors introduced from the transfer line 56 directly from the reaction chamber 55'..

As another feature of the present invention, in order to control the gravity and quality of the residue produced, Vwhich is particularly important when the residue is to be sold commercially as a fuel oil, regulated portions of the crude oil may be diverted through the line 89 controlled by valve 90 into the line 9| through line 92 controlled by valve 93 into the residue draw of! header 16. It is to be noted that the invention contemplates that the crude oil used for the pur- Vpose of mixing with'the residue in the header16 may or may not be previously preheated, depending entirely on conditions of operation. However, to permit preheated crude oil to be diverted, I provide a branch 94 controlled by valve 95 connecting respectively the pipes 35 and 9|. In case it may be desirable to slightly cool the preheated crude oil before introducing same to the residue draw off header 16, the valve 96 in leading to cooling coil 98 may be`l and by opening valve |02 may be discharged into the residue draw off line 19 and passed to storage 83. Or the residue may be diverted from the lower line |0| into the line |03 controlled by valve 04, cooled in cooling coil |05 and collectedrin any suitable receptacle.

As another feature of it may be desirable in duce a maximum yield of overhead products, with little or no liquid residue. In other words, it may be desirable to carry out what is termed a non-residuum process in which little or no substantial liquid residue is produced, the object of the process being to produce mainly a condensed overhead product and a substantial nonilowing coke-like product. With such an operation it may be further advisable to subject a portion of the liquid residue withdrawn through the header 16 to conditions of flashing in the chamber 86 in order to maintain the4 desired capacity. In such event the residue withdrawn from the flash chamber 86 may be diverted through either or both ofthe lines |06 controlled by valves V|01 merging in a common return line |08, in which may be interposed a pump |09, returning said residue either to the transfer line 53 through the proper manipulation of the valve ||0 in the line or directly into the reaction chamber 55 by proper manipulation of the valve |2 in the branch ||3.

In addition to the methods of controlling the quantity or gravity of the residue as described, a controlled quantity of the raw oil may be diverted through the line 4, passed through closed coil H5 positioned in the vapor space of the present invention,l some operations to prothe liash chamber 86 and controlled by the valves H6. By regulating the amount and temperature of the oil passing through the closed coil H5, the condensation or cooling of the vapors released in flash chamber 86 may be definitely controlled. lIt will be obvious that the rcondensation of the vapors will directly control the quality and gravity of the non-vaporous residue produced.

Reflux from the pool E2 which has been stripped of all the light fractions may be withdrawn through the line H1 and mixed with the topped crude to be returned through the line 48 to the cracking zone.

The temperature and pressure conditions to be maintained on different parts `of 'the plant Will depend entirely upon the operating' conditions, the type of charging stock used, and the products desired. It may be stated, however, that in the preferred form of the invention, the heating tube 5l and reaction chamber 55 are preferably maintained under a higher pressure than the dephlegmat-or I9 and flash chamber 8S. For instance, the pressure in the heating tube 5I and reaction chamber 55 may be from 100 'to 33000 pounds, more o r less, while the pressure on the balance of the system may be materially reduced or even released, only carrying such a pressure as is necessary to overcome frictional resistance.

From the foreg-oing it will be apparent vthat the invention has been carefully worked out to provide a method of hydrocarbon oil conversion comprising among other features, wide flexibility in operating conditions, the use of charging stocks of wide ranges and characteristics, the production of maximum quantities of desired products, coupled with the ability to be so manipulated as to be completely reversed and produce maximum yields of entirely different products.

I claim as my invention:

l. A process for converting hydrocarbons into lighter hydrocarbons comprising subjecting the heavy hydrocarbons to cracking conditions of temperature and pressure in a heating zone, separating the vaporous from the unvaporized liquid products, passing the unvaporized liquid products to a distillation zone, materially lowering the pressure on the unvaporized liquid products delivered to said distillation zone to effect distillation of the unvaporized liquid products in said distillation zone by the contained heat thereof, passing said vaporous products to a cooling zone wherein insufficiently cracked fractions are condensed, also passing vapors released from the unvaporized liquid products in said contained heat distillation zone to said cooling zone, controlling the degree of cooling in said cooling zone and the degree of distillation in said contained heat distillation zone by circulating heavy hydrocarbons being supplied to the process through said cooling Zone and through said distillation zone, and subsequently supplying the heavy hydrocarbons so circulated to said heating zone.

2. A pr-ocess for cracking hydrocarbon oil, which consists in subjecting the oil to cracking conditions of temperature and pressure in a heating zone, separating the primary vapors from the unvaporized residue, effecting distillation of said residue by contained heat thereof under reduced pressure in a fiash distilling zone, subjecting said primary vapors to a cooling treatment to condense insufficiently converted fractions thereof, controlling the degree of said contained heat distillation, and the degree of cooling of said primary vapors by circulating heavy hydrocarbons being supplied to the process in heat interchange relationship with the primary vapors and through said flash distilling Zone, subsequently separating from said heavy hydrocarbons those constituents vaporizable 'at the temperature acquired by heat interchange, collecting such constituents independently of yother products of the process, and supplying the unvaporized heavy hydrocarbons to said heating zone.

l3. An oil cracking process which comprises heating the oil under pressure to a conversion temperature ina heating Zone, passing the heated oil to a conversion zone wherein a separation of vapors and unvaporized oil is effected, passing the vapors to a dephlegmating zone, removing said unvaporized oil from the conversion Zone and reducing the pressure thereon to effect a distillation thereof, cooling the vapors evolved by such reduction in pressure by passing in heat exchange relation therewith charging stock for the process, subsequently introducing said vapors to said dephlegmating zone to commingle therein with the ir-st mentioned vapors, cooling the vapors in said dephlegmating zone by heat exchange with charging stock for the process, stripping Yreflux condensate of entrained light fractions by indirect heat exchange with the rst mentioned vapors separated in sai-d conversion Zone, passing said charging stock and reflux condensate to said heating zone, and condensing the uncondensed vapors. Y

4. A cracking process Which comprises heating hydrocarbon oil to cracking temperature under pressure While flowing in a restricted stream through a heating zone, discharging the heated oil into an enlarged reaction zone maintained under cracking conditions of temperature and pressure, removing vapors and unvaporized oil from the reaction Zone and flash distilling the latter in a flashing Zone by pressure reduction, introducing resultant flashed vapors and the vapors removed from the reaction Zone into a dephlegmating zone and subjecting the same therein to common fractionation to condense insufficiently cracked fractions thereof, introducing fresh charging oil for the process into heat exchange relation with vapors in the dephlegmating zone, passing another portion of the charging oil in indirect heat exchange relation with vapors in the flashing zone, and subsequently supplying components of said portions of the charging oil heavier than gasoline to said heating zone.

5. A cracking process which comprises heating hydrocarbon oil to cracking temperature under pressure while flowing in a restricted stream through a heating zone, discharging the heated oil into an enlarged reaction zone maintained under cracking conditions of temperature and pressure, removing vapors and unvaporized oil from the reaction zone and ash distilling the latter in a flashing zone by pressure reduction, in-

troducing resultant flashed vapors and the va-V pors removed from the reactions zone into a dephlegmating Zone and subjecting the same therein to common fractionation to condense insufflciently cracked fractions thereof, passing crude oil containing desirable light fractions in indirect heat exchange relation with hydrocarbon constituents in the flashing zone thereby supplying heat to the crude oil and controlling the degree of distillation in the flashing zone, Vaporizing said light fractions from the crude oil and condensing and collecting the same, and supplying heavier portions of the crude oil in admixture with reflux condensate from the dephlegmating zone to said heating Zone.

6. A cracking process which comprises heating hydrocarbon oil to cracking temperature under pressure While fiowing in a restricted stream through a heating zone, discharging the heated oil' into an enlarged reaction zone maintained under cracking conditions of temperature and pressure, removing vapors and unvaporized oil from the reaction zone and ash distilling the latter in a flashing zone by pressure reduction, introducing resultant flashed vapors and the va.- pors removed from the reaction zone into'a dephlegmating zone and. subjecting the same there-V in to common fractionation to form a composite reux condensate of heavier fractions of the flashed vapors and insuiciently craokedefracrtions of the first-named vapors, passing crude oil in indirect heat exchange relation with the vapors undergoing common fractionation in the dephlegmating zone and heating the same to distillation temperature, introducing the heated crude oil into a topping and fractionating zone apart from said dephlegmating zone and topping and fractionating the same therein independently of the vapors inthe dephlegmating Zone to separate lighter Yfractions thereof as vapor, finally condensing and collecting these vaporized lighter fractions of the crude, combining heavier fractions of the crude with composite reflux condensate from the dephlegmating zone and supplying the resultant mixture to the heating Zone, and

finally condensing and collecting the vapors uncondensed in the dephlegmating zone independentlyv of said vaporized lighter fractions of the crude. Y

7. A conversion process which comprises subjecting hydrocarbon oil to ,crackingV conditions of temperature and pressure in a cracking zone, removing vapors and unvaporized oil from the cracking zone, simultaneously topping and fractionating crude oil in a topping and fractionating Zone to separate light fractions from heavier fractions thereof recovering the light fractions, combining a portion of thevheavier fractions of the crude with said unvaporized oil and distilling the resultant mixture in a'flashing zone maintained under lower pressure than the cracking zone, fractionating vapors from the flashing zone independently of the crude oil in said topping and fractionating zone and in admixture with the first-named vapors in a dephlegmating zone apart from said topping andy fractionating zone to form a composite reflux condensate, supplying such reflux condensate together With'another portion of the heavier fractions of the crude to the crack-r ing zone, and finally condensing the fractionated vapors. Y

8. The process as defined in claim 4 further characterized in that the first-named charging oil is passed in indirect heat exchange relation with vapors in the dephlegmating zone.

Y CARBON P. DUBBS.

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