US1930221A - Conversion of hydrocarbons - Google Patents

Description

Patented Oct. 10, 1933 UNITED STATES PATENT OFFIC CONVERSION OF HYDROCARBONS Joseph G. Alther, Chicago, 111., assignor to Universal Oil Products Company, Chicago, 111., a corporation of South Dakota Application May 26, 1928. Serial No. 280,704

3 Claims. 19659) This invention relates more particularly to the portion of reflux required for maintaining suitable treatment of hydrocarbons to produce therefrom, conditions of operation. by conversion, high yields of desirable conversion However, in the practice of such operations, the products. withdrawal of from thirtyto fifty percent more- 5 In the cracking of hydrocarbons where it is or less, of the raw material in the form of residu-' 60 desired to obtain substantially high yields of um from the flash chamber may not produce as gasoline-like products from the charging stock, high a percentage of gasoline-like products from the residuum produced in the process may conthe charging stock as could be obtained otherwise, tain objectionable amounts of solids comprising because after the flashing operation, there still carbon, coke,sludge, pitch or the like, which freremains in the residuum withdrawn fromthe 65 quently make the residuum undesirable. for use flash chamber a portion of lighter fractions which as fuel, recharging stock, or for other commercial would, if separated, be suitable for cracking. I purposes. have further found in carrying out the process In a process of the type of the so-called recyof conversion in the manner above described cling process wherein the oil is first passed where the conditions of operation are so con- 70.

through a heating tube and then into an enlarged o d that excess conversion of the p expansion, reaction and/or separating chamber ized oil in the pressure chamber is avoided, for from which the residuum is withdrawn, and from instance, by maintaining a low level in Said which the vapors evolved pass into a dephlegb d Cooling the non-vaporized Oil as Seen as mater where they are subjected to fractionapracticably possible, that the characteristics 01 tion, the condensed vapors being returned as rehi r id m wh h in a relatively low flux condensate to the inlet of the heating tube Proportion Coke-like Ditch-like ate for retreatment, a method is successfully carried are Such that if this Solid -50 d ma erial out whereby conversion of the oil can be accomiS a ow to Separate from the lighter Portions 25 plished with a relatively high yield of desirable 0f the residuum, Substantially all Of the quid lighter gasoline-like products, together with the residuum forms a C a Stock y Suitable production of a residuum containing a very small for Crackingamount of carbon, sludge or the like, while the It is the Objeet Of s i v therefore, to production of carbon, coke, pitch, sludge and nonmaintain uch co d tions in t e c ac n zone 30 nd nsable gas (which are generally undesirathat a relatively large percentage of light residuble products) is materially'reduced. um is produced in th p su xpans This method comprises preventing the nonchamber; to stop undesirable reaction of this vaporized residual o tions of the oil in the pressiduum as s as p ssibl t y pr v sure reaction chamber from remaining in said it from undergoing eeSS Conversion which 35 chamber under cracking temperature for any would result in EXCESS coke and pitch and then substantial length of time, thus preventing overfl s i p f ra ly t su h xt nt that as cracking of the heavy fractions of said residuum line-like iraetions dissolved therein ay be s pto produce undesirable amounts of coke and the ereted and Collected; then permitting Settling like. The operation is so controlled that a relaseparation o the e at v y small p ce ta e of 40 tively light residuum may be produced which solid or semi-solid matters from the liquid porstitutes in quantity about forty to eighty percent n of h residuum, and h n returning r s or more of the raw material charged. The liquid leted quantities of Said liquid portion of the noil withdrawn in this operation from thepressure vaporized oil to the crackin Z n for further expansion chamber contains a large proportion treatment eommingled With fresh charging Stock 5 of lighter material suitable for cracking, which and reflux; p

for instance, may be separated from the heavier A controlled amount of the liquid portion of portions of this non-vaporized oil by such a the non-vap riz d i y be Wi hdrawn from method as flashing under reduced pressure with the flash chamber together with the solid or orwithout additional heat, so that these lighter semi-solid matter to facilitate removal of the 50 portions vaporize and separate from the heavy latter from the process.

residue, which latter is separately withdrawn. Th invention is a acte ed by ei itreme- The vapor separated by flashing under reduced flexibility, Th DreeeSS is ptable to widely pressure may be then condensed and this convarying commercial conditions, being flexible densed liquid is generally returned to the crackenough to permit an operation in which a rela- 55 ing system for retreatment, providing for the protively low yield of gasoline-like fractions and a 'll0 relatively high yield of liquid residue suitable for use as fuel is produced, while being just as equally applicable to a situation in which it is desired to produce maximum yields of gasoline-like products and minimum yields of liquid residue.

Other objects, features and advantages of the present invention will be more apparent from the following description.

The single figure in the drawing is a diagrammatic elevational flow chart to illustrate the invention.

Referring more in detail to the drawing, the charging stock to be treated by the process may be charged through line 1 in which is interposed valve 1' and through line 1" into a heating tube 2 mounted in furnace 3 which may be of any suitable design. From the tube 2 the heated oil is passed through transfer line 4 controlled by valve 5, being introduced into the expansion, reaction and/or separating drum 6. The drum 6 is of conventional type being provided with manholes 6' and with insulation if desired, to prevent loss through heat radiation. Vapors separating in the chamber 6 are removed from the upper portion thereof through vapor outlet line '7 controlled by valve 8, the line 7 discharging into the lower portion of a conventional dephlegmator 9, which may be provided with any suitable form of bailling element. In the dephlegmator 9 the vapors are subjected to dephlegmation to condense the insufliciently converted fractions. Vapors remaining uncondensed after passage through the dephlegmator 9, which comprise the sufficiently converted fractions, leave the top of the dephlegmator through vapor outlet line 10 controlled by valves 11, being condensed in condenser coil 12 and collected in receiver 14 which may be provided with the liquid drawoff line 15 controlled by valve 16, and with the incondensable gas relief line 17 controlled by valve 18.

Suitable cooling material may be introduced into the upper portion of the dephlegmator 9 through line 19 controlled by valves 20. If desired, charging stock may be introduced by means of pump 21 and line 22 provided with valves 23 into the upper portion of the dephlegmator 9 whereby it will be preheated, while at the same time assisting in fractionation of the vapors entering through line 7. The reflux condensate formed in the dephlegmator 9 together with the preheated unvaporized portions of the charging stock, is withdrawn from the bottom of the dephlegmator through line 24 controlled by valve 25 and directed to the charging line 1" by means of hot oil pump 26. All or any regulated portion of the reflux condensate may be diverted from the line 1" by suitable manipulation of valve 25 in line 24. The conditions of temperature, superatmospheric pressure and proportion of reflux condensate to charging oil are so maintained that a relatively large percentage of relatively light nonrvaporized oil forms in drum 6. This nonvaporized oil is however, not permitted to accumulate in the drum, a low level or no level at all, being preferably maintained therein. This is effected by withdrawing the non-vaporized oil continuously from the bottom of the drum 6 through line 2? controlled by valve 28. The pressure is controlled by means of valve 28 and reduced through proper manipulation thereof to the proper degree. The reduction of pressure through the medium of valve 28 causes some cooling of the oil and helps thereby to arrest further reaction in this unvaporized oil.

The latter, under reduced pressure, is directed to a flash-settling chamber 29 wherein the vapors produced by flashing of the non-vaporized oil separate from the heavier liquid portions. The degree of reduction of pressure through the manipulation of valve 28, and the temperature in the chamber 29 are preferably so controlled that only gasoline-like constituents contained in the non-vaporized oil withdrawn from chamber 6 are removed as vapors from the upper portion of chamber 29 through line 30 controlled by valve 31. These gasoline-like fractions may be condensed in condenser 32 and collected in'receiver 34, which latter may be provided with suitable liquid drawoff line 35 controlled by valve 36 and with gas relief line 37 controlled by valve 38.

In this manner the intermediate fractions contained in the non-vaporized oil withdrawn from chamber 6 remain in a liquid state in the chamber 29 and help to thin the heavier portions thereof. The carbon, coke, sludge, and pitch or the like (which for convenience will be referred to as solid and semi-solid matter) contained in the non-vaporized oil withdrawn from chamber 6 settle out in the bottom of chamber 29, and it is one of the features of the present invention to assist the separation of these solid or semi-solid matters from the liquid portion by maintaining a substantial body of liquid oil in chamber 29, and also by keeping in a liquid state in said chamber substantially all fractions of oil heavier than gasoline. This separation of the solid and semisolid matter from the relatively lighter liquid non-vaporized oil produces in the chamber 29 a relatively large proportion of substantially clean oil, which I have found to be most suitable for recracking. Therefore, as a feature of the present invention, I return this relatively clean oil produced by the separation of the gasolinelike fractions and solid and semi-solid matter from the non-vaporized oil produced in the process to the inlet of the heating tube 2 for retreatment. This oil may be withdrawn from the flash-settling chamber 29 through line 39 controlled by valve 40, the line 39 preferably connecting to the flash chamber 29 at a point substantially above its base so as to permit a space large enough for settling and accumulation of the solid and semi-solid matter. This oil is then taken by pump 41 and line 42 controlled by valve 43 and passed through charging line 1" into the heating coil 2.

The temperature in the flash-settling chamber 29 may be controlled by any suitable means. For instance, I may employ a regulated portion of the relatively cool charging stock to be treated in the system to regulate this temperature in a heat interchange fashion. For this purpose, regulated quantities of the charging stock may be diverted from line 22 through line 44 controlled by valve 45 and introduced directly into contact with the contents of chamber 29 through spray 46. In this method of operation, the charging stock is directed to the heating coil 2 through the line 39 together with the relatively clean oil from chamber 29. Or the cooling of the contents of chamber 29 may be eifected by keeping the charging stock out of contact with the material contained in said chamber. This may be effected by passing regulated quantities of the charging stock through line 47 controlled by valve 48 and through heat exchanging coil 49 positioned in the upper portion of chamber 29, from which coil the charging stock returns to line 22 through branch 50 controlled by valve 51. Any suitable quantity of the charging stock may be directed to the chamber 29 and to the dephlegmator 9 by proper control of valves 23, 51, 48 and 45. Also any proportion of charging stock directed to the chamber 29 may be charged thereto directly or passed through said chamber in indirect contact by proper control of valves 51, 45 and 48.

Heavy material including solid and semi-solid matter separated in the chamber 29 may be withdrawn therefrom through line 52 controlled by valve 53 and directed to storage. Drum 6 may also be provided with the drain 5.4 controlled by valve 55.

It will be appreciated from the above description, that the process of the present invention is very flexible, and may be operated in many ways depending upon the characteristics of the oil treated, and the types of products desired.

For instance, it may be desirable to produce from a cracking stock a maximum of liquid products and a minimum of coke and gas, while at the same time producing a high yield of liquid residuum compatible with specifications as to its content of coke and solid matter. In operating in this manner, I may continuously withdraw from the bottom of the flash-settling chamber 29 a relatively large proportion of heavier residuum while returning to the cracking coil 2 through the lines illustrated, a small proportion of the liquid oil remaining in chamber 29 after separation of the solids and coke.

In another method of operation, it may be desirable to convert the charging stock into gasoline-like products and into coke and gas. I am aware that cracking processes have already been operated in such a manner as to produce substantially no liquid residue, but as far as I am aware, the production of coke from the process accumulated in the pressure reaction chamber. In some instances, this may be objectionable because the pressure reaction chamber is generally an expensive part of the apparatus, its size being limited not only by the cost of the drum, but by the pressure maintained thereon. The use of alternate chambers under pressure although possible, represents of course, a much greater investment By means of the present invention, I propose, in operating the process in this manner,.to permit all of the carbon and solid matters produced in the process to accumulate in the chamber 29, which is maintained at a substantially lower pressure than the chamber 6, and generally at pressures slightly above atmospheric, or even at atmospheric pressure. It can be readily seen that this permits the use of alternate chambers with a lesser expense and easier operation, and that in this manner the length of the run maybe prolonged far beyond the length of the runs made by other processes.

The high pressure cracking zone comprising tube 2, drum 6 and dephlegmator 9 may be maintained under suitable superatmospheric pressure say from 100 to 500 pounds more or less, while.

this pressure may be reduced in the chamber 39 through manipulation of valve 28 down to say atmospheric. The oil passing through the heating coil 2 may be heated to a temperature of say 850 to 900 degrees F. more or less, it being understood that this temperature is merely illustrative, and that a skilled operator will change conditions of temperature'and pressure to suit the characteristics of the material treated, and the products desired.

As a further feature of the present invention,

I provide means for thinning the non-vaporized oil in chamber 6, or the non-vaporized residue in chamber 29 to help separation of the solid and semi-solid matter from the liquid portion. This may be effected for instance, by returning a por-- tion or all of the reflux condensate from line 24 to the chamber 29 through branch line 56 controlled by valve 57. The raw oil may also be combined as hereinbefore described, with the reflux condensate by introduction to the dephlegmator. In this method of operation, all of the material for cracking will be withdrawn from the chamber with non-vaporized oil from drum 6 before if enters the flash chamber 29, by suitably controlling valve 60in branch line 61 connecting lines 27 and 56.

All or any regulated portion of the condensed liquid collecting in receiver 34 may be returned through branch 62 controlled byvalve 63 to the heating coil 2 for further treatment, if desired.

It is to be understood of course, that if it is founddesirable to apply heat to either drum 6 and more particularly to the drum 29, that this is within the contemplation of the invention.

I claim as my invention:

1. The art of hydrocarbon oil conversion which comprises subjecting said oil to cracking conditions of temperature and superatmospheric pressure in a heating zone, passing the heated oil to a conversion zone, separating vaporous products from said'heated oil, continuously withdrawing non-vaporized oil from said conversion zone at such a rate as to prevent substantial accumulation therein, reducing the pressure on said withdrawn oil while the latter is in heated condition whereby lighter fractions will be released therefrom in the form of vapors, maintaining said withdrawn oil in a substantial body, separating and removing the lighter vaporous fractions released therefrom, settling the solid and semi-solid portions of said body and removing from the upper portion of said body regulated portions of liquid oil freed from said solid and semi-solid matter, and returning same for retreatment to the oil undergoing cracking.

2. The art of hydrocarbon oil conversion which comprises subjecting said oil to cracking condiand semi-solid portions of said body and removing from the upper portion of said body regulated portions of liquid oil freed from saidsolid and semi-solid matter, and returning same'under the influence of applied pump pressure for retreatment to the oil undergoing cracking.

3. A hydrocarbon oil cracking process which comprises passing the oil in a restricted stream sure on the withdrawn unvaporized oil while in heated condition whereby lighter fractions thereof are released, separating solid and semi-solid matter from the remaining liquid unvaporized oil, and returning regulated portions of the remaining liquid unvaporized oil from which solid and semi-solid matter has been removed to said heating zone.

JOSEPH G. ALTHJER.

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