US1954331A - Process of cracking hydrocarbon oils - Google Patents

Description

April 10, 1934. J. D. SEGUY PROCESS OF CRACKING HYDROCARBON OILS Filed Jan. 2, 1930 v glwuentoz Jean fielallre Jeylg Patented Apr. 10, 1934 PATENT OFFICE' PROCESS OF CRACKING OILS nYnnooARBoN Jean Delattre Seguy, Chicago, 111., assignor to Universal Oil Products Company, Chicago, Ill., acorporation of Delaware Application January 2, 1930, Serial No. 418,043

11 Claims. (Cl. 196-60) This invention relates to improvements in process of cracking hydrocarbon oils, and its novel features are more particularly directed to certain improvements in so-called vapor phase cracking. This is a continuation in part of my application, Serial No. 242,434jflled December 24, 1927.

With the increasing advent of combustion en gines having high compression ratios, it has been found desirable to use motor fuels containing what are commonly known as antiknock compounds. These anti-knock compounds are in some instances increased or produced by the for.- mation of a relatively large percent of unsaturates in the gasoline or motor fuel. The present invention is adapted in its novel features to produce these anti-knock compounds in part, at least, through the cracking of the vapors in what is generally known as vapor phase cracking.

The invention is also adapted as part of a continuous process to produce gasoline or gasoline-like bodies, which are relatively low in unsaturates. In addition, the process can be so operated as to more or less quantitatively control the percent of unsaturates. v

In this application, as will hereafter more clearly appear, I have described my basic process, together with various specimens which may be carried out utilizing the broader idea of the invention, but with modified details depending upon the results desired, or the character of oil under treatment.

This process is of such a character that the raw charging stock, whether gas oil, fuel oil, crude or reduced crude, or the like, may be first subjected to the well known so-called liquid-- vapor phase cracking under pressure and certain of the lighter products so formed with or without first removing gasoline-like material produced, may then be subjected to vapor phase cracking.

At the same time, if desired, the residue produced from the so-called liquid-vapor phase pressure operation may be flashed and the flashed vapors from the residue also become in whole or in part a highly desirable and relatively clean charging stock for the vapor phase operations.

.The process may be so carried out that the lighter products, as above described, from the main pressure cracking operation may be independently treated from the vapors produced by the flashing of the residuum, or they may be treated together, as a common vapor phase cracking stock.

Another feature of this invention is that the hydrocarbons which are subjected to the vapor phase cracking, have prior thereto already been so treated by the liquid-vapor step as to more or less crack them, whereby the subsequent cracking of such hydrocarbons in the vapor phase part of the process,,may be easier than would be the case were the raw'charging stockinitially subjected to straight vapor phase cracking;

It iswell known in present vapor phase cracking that the fuel consumption is high and the incondensible gas loss is large. In addition, in present types of vapor phase cracking the carbon production is high. By means'of the present invention the fuelconsumption is materially lowered, the gas losses materially reduced, due in part to the ability to crack in the vapor phase at a lower temperature than has heretofore been done, and also the carbonproduction is materially lessened because of the previously prepared charging stock for the vapor phase operations. These advantages are all' obtained without in any way lessening the production of the desirable anti-knock compounds, but quite the contrary such anti-knock compounds are produced in excess of that heretofore possible and with much more satisfactory cracking conditions.

It is to be understood that by means of the presout process the oil is so preliminarily treated prior to the vapor phase operation that it is-in prime condition for vapor phase cracking, because it has i already been initially cracked with the formation of some unsaturates and the vapor phase part of the operation in reality completes the maximum formation of anti-knock, compounds already previously started.

Heretofore vapor phase processes have only been partially successful on gas oil, but by the present invention heavy fuel oils or crude petroleum may be cracked to obtain the maximum amount of gasoline, and certain of the constituents thereof converted into a maximum amount of anti-knock compounds.

Another feature of the invention is thatthe reflux produced from the vapor phase cracking, may, if desired, be re-treated in the liquid-vapor phase part of the process, and inasmuch as this reflux contains in itself a large amount of antiknock compounds the gasoline from the liquidunderstood, however, that its broader aspect the invention is not limited to the vapor phase cracking at substantially atmospheric pressure, as good results may be obtained even though the vapor phase cracking part of the operation is carried out at superatmospheric pressure or at subatmospheric pressure. For example, the liquid-vapor phase part of the process may be at'say 100 lbs. upwards and the vapor phase cracking at pressures of lbs. or lower.

It is to be understood that these figures are merely illustrative and in no sense intended to limit the scope of invention on the degree of pressure. r

The invention will be more clearly understood from the following description, reference being had to the accompanying drawing.

This drawing shows a diagrammatic illustration of an apparatus and in my opinion a novel form of apparatus suitable for carrying out the invention. 'It is to be understood that this dia-' grammatic drawing is not to scale or intended to Referring to the drawing, a cracking coil 1 is positioned in a suitable furnace 2. Raw oil is supplied to the coil 1 through feed line 3 and feed pump 4, leading to any suitable source of supply. The oil passes from coil 1 to transfer line 5, having throttle valve 6, into expansion chamber '7. The vapors pass out of reaction chamber 7 through vapor line 8 and thence, if desired, into the lower side of dephlegmator 9. Throttle valve 10 is interposed in line 8 for a purpose hereinafter described.

From the top of the dephlegmator the vapors may pass through vapor outlet pipe 12, into condenser coil 14, and then to receiver 15. Receiver 15 is provided with gas outlet control valve 16,, and liquid draw ofi control valve 17.

The temperature of the dephlegmator may be controlled either by introducing raw oil directly into the vapors in the dephlegmator through pipe 18, having'control valve 19, or in the event it is inafter described, then the raw oil may be fed through a closed coil 20, which closed coil may, if desired, lead the oil in its passage thereto, to the pump 4.

The reflux condensate from the dephlegmator 9 is drawn off through the lower end thereof through pipe 21, and thence may be returned through lines 21 and 22 and pump 23 to the raw oil feed line 3. A by-pass 24 may be provided in line 22 around the pump 23, suitable valves v25 being provided as shown.

In the line 21, is provided a throttle valve 26.

The reflux may 0also be passed'through line 27 and branch 28 to vapor phase feed line 29, hereinflash chamber 37. A valve 38 is interposed in the line 36 and a throttle valve 39 is interposed in an extension of the line 35, below the juncture of the line 35 with the line 36, whereby some of the residuum may be drawn entirely out of the sys- 7, flash chamber 37 and vapor phase coil 47,.

through the proper manipulation of the lines and valves described and provided for this purpose.

The vapors which are flashed from the flash chamber 37 pass out through the upper part thereof through pipe 40, having throttle valve 41 and thence to the line 29. At the lower end of the flash'chamber 37 is a residuum draw-01f 42 having throttle control valve 43.

In certain cases the flash chamber 37 may be by-passed and the chamber 7 used as a combined reaction or expansion and flash chamber. In such cases all of the vapors from chamber 7 may either pass to the dephlegmator 9, or they may pass directly to line 29 by means of a branch pipe 44, having throttle valve 45.

A throttle valve 46 may be interposed in line 8 as well as valve 47A in line 29, for a purpose hereinafter described. This line 29 leads to the vapor phase cracking coil 47, seated in a suitable furnace 48. The outlet end of the coil connects I The temperature in this dephlegmator may be controlled either by introducing raw oil directly intodephlegmator 56, by pipe 57, having control valve 58, orif desired raw oil may be passed through the closed coil 59, and thence if desired led to the feed pump-4. The raw oil is not introdueed directly into either dephlegmator unless it is desired to send it to the pressure cracking coil 1, or unless it is of such a character that it is so clean a charging stock that it can be passed directly to the vapor phase cracking coil 47, without materially increasing carbon formation in the vapor phase coil.

The vapors pass out of dephlegmator 56 through vapor line 60 to condenser coil 61 and thence to receiver 62, which is provided with gas outlet control valve 63 and liquid outlet control valve 64. If desired the vapors from dephlegmator 9 may also pass into receiver 62, thus eliminating receiver 15. To this end a vapor pipe 65 having control valve 66 may lead from the line 12 to the line 60.

The reflux condensate from dephlegmator 56 passes out of the lower end through pipe 67, and

thence through pump 68 to line 69. The by-pass 70 may be provided around the pump with the usual valves 71. The reflux from line 60 may be passed directly, if desired, to line 29, by means of pipe 72, having throttle valve 73 and line 28 thereby going to vapor phase coil 47, or if desired it may pass via lines Hand 83 having valve '84 into line 33 by opening the valves 84 and 34 and closing the valve 73 in the line 72, thereby going to flash chamber 37, or the condensate may be passed from the pipe 69 into the line 22 by closing the valve 73 and opening the valve '75, thereby going to heating coil 1; or the condensate may be passed to reaction chamber 7, through line 85 having valve 86, valves 75, 73 and 84 being closed; or the condensate may be directed, by proper manipulation of the various lines and connections shown and described, simultaneously to two'or more steps of the process as described. The reflux from either dephlegmator may be drawn out of the system in part or in toto through branch 77 having throttle valve 78, or branch 79, having throttle valve 80. It may be desirable, particularly when the flashed vapors removed 'from chamber 37 contain substantial proportions of light desirable portions, to subject said flashed vapors to dephlegmation before subjecting them to vapor phase cracking, thereby subjecting only the intermediate portions of the products removed from reaction chamber 7 to jurther vapor phase cracking. To this effect I 'provide for a dephlegmator 87 to which flashed vapors from chamber 37 may be directed through line 88 having valve 89. Suitable cooling means are provided in dephlegmator 87 in the usual manner and raw oil or other oil distillate may be used therein, in direct or indirect contact with said vapors. may be removed from dephlegmator 87 through line 90 having valve 91, and depending upon their characteristics and the relative pressures maintained in the various parts of the system, collected with the other light products of the system or passed through line 92, having valve 93, condenser 94 and collected separately at 95. p

The condensate formed in dephlegmator 87 may then be directed through line 96, having pump 97 to line 29 and vapor phase coil 47. Portions of said condensate may be removed from the system through line 98, having valve 99, or it may be returned for further treatment to coil 1, chamber 7 or flash chamber 37 through lines not shown. It will be understood that, should vapors from .chamber 7 be subjected to vapor phase cracking without dephlegmation in column 9,and would they be directed to coil 47 through line 44, they would be subjected to dephlegmation with the flashed vapors in dephlegmator 87, the reflux condensate from said mixtureof vapors being then directed to vapor phase cracking as above described.

Should it be desirable to subject all vapors from chamber 7 to vapor phase cracking, line 100 having valve 101 is' provided to by-pass dephlegmator 87 and direct said vapors directly to vapor phase coil 47.

Upon certain .instances dephlegmators 9 and 87 may be combined, and the flashed vapors combined with vapors from chamber 7, the mixture being either dephlegmated, the mixed condensate being then treated further according to any of the alternatives described; or the mixture being cracked in vapor phase without preliminary dephlegmation. a

To better control the reaction in the vapor phase part or the process, cold or heated oil may be injected into the discharge of the vapor coil 47 through line 102 having valve 103, said oil helping to regulate the temperature after the oil leaves coil 47.

Describing now the manner in which the invention may be operated, one desirable method of carrying out the invention is to subject the raw charging stock to a liquid-vapor phase'pressure cracking operation, flash the residuum therefrom and subject the flashed vapors to dephlegmation and the condensate therefrom to vapor phasecracking at atmospheric pressure or pressure lower than the main pressure, and toalso subject the reflux condensate from the dephleg- 'mator 9 in toto or in part to further treatment in chamber 7L In such case, the raw 011, if

The vapors remaining uncondensed fer temperature of say 750 F. to 950 F. more or less and thence-into the expansion chamber 7.

The vapbrs pass out of expansion chamber 7 through line 8 into main dephlegmator 9. Here the heavier portions are condensed while the lighter vapors pass out through line 12, either into receiver 15 or receiver 62 by suitably regulating the valves shown in the accompanying drawing. The reflux condensate may be drawn out through pipe 21 and thence if desired pass through pipe 81 to reaction chamber 7, or it may in part also pass through pipes 31, 27 and 28 into the line 29, and thence to the vapor phase cracking coil 47. If desired, part of the reflux condensate, instead of passing to pipe 28 may go from pipe 27 via the pipe 33, to the line 36. The residuum is drawn off the bottom of chamber 7 continuously and thence may be passed through the pressure reducing valve 38, and be flashed into chamber 37. The vapors from such flashing operation thence pass through the pipe 29 into the vapor phase coil 47 or subjected to dephlegmation in 87, the reflux therefrom being subjected to vapor phase cracking. A pressure of 100 lbs. upwards may be maintained in coil 1, chamber 7, dephlegmator 9 and on receiver- 15, by suitably regulating the valves 16 and 17 on receiver 15 and valves 32 and the reducing valve 38. If desired the valves 74 and 34 may be used as reducing valves depending upon whether the line 28 or 33 are used instead of using valves 32.

The material passing through the vapor cracking coil 47, is subjected to temperatures in said coil of say 900 to 1150 more or less.

It is .to be understood that the temperatures here given are illustrative as well as the temperatures in the transfer line 5. The vapor phase cracking coil may be maintained under substantially atmospheric pressure, or if desired, under a pressure somewhat above atmospheric, say 20 to 50 lbs. more or less. If desired, the vapor phase cracking coil may be even maintained under a vacuum, by connecting suitable vacuum pump to the receiver 62. In such case the pump 68 may be used as a double action pump, vacuum on the inlet and pressure on the discharge side.

The contents of vapor phase coil 47 are then .preferably passed at a controlled temperature to chamber 51 where any carbon containing portions may be dropped out and be drawn out of the system, while the balance goes through the line 54 to dephlegmator 56. In this dephlegmator 56 the heavier portion will be condensed, and may I then be passed through the lines 67 and 69 directly back to the main heating coil 1. In such case the valves 26, 73, 84 and 86 are closed and the reflux condensate from dephlegmator 56 may then readily pass directly to coil 1. The portion of the oil which is passed through the vapor phasecracking coil is converted into a relatively large percent of unsaturates, aromatics or other anti-knock compounds, and may then, if desired,

be blended with straight run gasoline or with raw charging stock used may, as heretofore stated, be either gas oil, heavy fuel oil or crude, and it may be noted that by the present invention I not only crack such heavier oils but in doing so separate out therefrom highly desirable clean charging stock already partially cracked, which is very suitable for the vapor phase operation.

At the same time it will be noted that the charging stock which goes to the vapor phase cracking coil has not only been partially cracked as heretofore stated, but it thus necessitates a minimum amount of. additional fuel for the vaporcracking coil. Furthermore, inasmuch as the portion of the oil which passes through the vapor phase cracking coil has already been more or less cracked lower temperatures may be used in the vapor phase coil, thus materially lessening the objectionable high gas losses incident to heretofore known vapor phase cracking processes. It will be further noted that by this process the gasoline produced by the pressure operation of the proc ess is removed and not subjected to the vapor phase cracking. In addition, if the reflux condensate from the vapor phase cracking operation-is returned to the main cracking coil then the gasoline formed by the pressure part of the process will have mixed with it a certain amount of desirable anti-knock compounds.

Another important feature of thismanner of carrying out the invention is that the rate and extent of cracking in the pressure part of the process may be regulated entirely independently of the vapor phase part of the cracking, and also of the reverse is true.

While I have stated that by this process the vapor phase cracking can be carried out at a lower temperature than in certain heretofore known processes, it is to be understood that I in no sense limit myself to such temperatures relative to prior processes, because it may be desirable to subject the oil passing through the vapor phase cracking coil to very high temperatures, and while this, of course, will not tend to lessen the gas losses, nevertheless the process will still have the advantages of a low fuelconsumption and a highly desirable charging stock.

What I claim as my invention is:

l. A process for cracking hydrocarbon oils,

consisting in passing the oil through a heating coil to an enlarged conversion zone maintained under pressure at a cracking temperature, passing products of conversion to a zone of lower pressure thereby causing flash distillation, subjecting the flashed vapors to vapor phase cracking, subjecting the vapors from said vapor phase crack- .ing to reflux condensation, and returning said condensate to said enlarged zone under pressure.

2. A process for cracking hydrocarbon oils, consisting in passing the oil through a heating coil to an enlarged zone maintained under pressure at a cracking temperature and where vaporization occurs, separately removing vapors and unvaporized products, passing the latter to-a zone of reduced pressure, thereby causing flash distillation, subjecting the flashed vapors to vapor phase cracking, subjecting the vapors from said vapor phase cracking to reflux condensation and returningsaid reflux condensate to said enlarged zone under pressure. I i

3. A process for cracking hydrocarbon oils, consisting in passing the oil" through a heating zone to an enlarged conversion zone underpressure, separately removing vapors and unvapbrized oil from said enlarged zone, passing said unvaporized products to a zone of lower pressure, thereby causing flash distillation, subjecting the flashed vapors to reflux condensation, subjecting the reflux condensate to vapor phase cracking, dephlegmating the vapor phase cracked vapors, and returning reflux condensate thus formed to said enlarged zone under pressure.

4. A process for cracking hydrocarbon oils, consisting in passing oil through a heating zone to an enlarged conversion zone under pressure, wherein vapors are evolved, separately removing from said conversion zone the evolved vapors, and unvaporized products, passing the latter to a zone of reduced pressure, thereby causing flash distillation, subjecting flashed vapors and vapors evolved in the enlarged conversion zone to vapor phase cracking, dephlegmating vapors from said vapor phase cracking, and returning reflux condensate' thus formed to the said enlarged zone under pressure.

5. A process for cracking hydrocarbon oils, consisting in passing oil through a heating zone to an enlarged conversion zone under pressure, wherein vapors are evolved, separately removing from said conversion zone the evolved vapors, and unvaporized products, passing the latter to a zone of reduced pressure, thereby causing flash distillation, subjecting flashed vapors and vapors evolved in the enlarged conversion zone to reflux condensation, removing the non-condensed vapors, subjecting the reflux condensate so obtained to vapor phase cracking, dephlegmating vapors from said vapor phase cracking, and returning reflux condensate thus formed to said enlarged zone under pressure.

6. A process for cracking hydrocarbon oils, consisting in passing the oil through a heating zone under a superatmospheric pressure, passing the heated oil to an enlarged zone at conversion temperature, but under a lower superatmospheric pressure, separately removing vapors and unvaporized oil from said enlarged zone, subjecting cracked vapors, and returning reflux condensate thus formed to said enlarged conversion zone.

7. A process for cracking hydrocarbon oils, consisting in passing the oil through a heating zone under a superatmospheric pressure, passing the heated oil toan enlarged zone at conversion temperature, but under a lower superatmospheric pressure, separately removing vapors and unvaporized oil from said enlarged zone, subjecting said unvaporized products to flash distillation by further reduction in pressure thereby separating vapors, subjecting said flashed vapors to reflux condensation, removing uncondensed vapors, subjecting the reflux condensate to vapor phase cracking, dephlegmating the vapor phase cracked vapors, and returning reflux condensate thus formed to said enlarged conversion zone.

8. "A process for cracking hydrocarbon oils, consisting in passing the-oil through a heating coil to an enlarged zone maintained under pressure at a cracking temperature and where vaporization 'occurs -separately removing vapors and unvaporized products,,passing the latter to a zone of reduced pressure, thereby causing flash said enlarged zone under pressure, and subjecting vapors from said enlarged zone to vapor phase cracking.

9. A process for cracking hydrocarbon oils, consisting in passing the oil through a heating zone to an enlarged conversion zone under pressure, separately removing vapors and unvaporized oil from said enlarged zone, passing said unvaporized products to a zone of lower pressure,

thereby causing flash distillation, subjecting the flashed vapors to reflux condensation, subjecting.

the reflux condensate to vapor phase cracking, dephlegmating the vapor phase cracked vapors, and returning reflux condensate thus formed to said enlarged zone under pressure, and subjecting vapors from said enlarged zone to vapor phase cracking. i

10. A hydrocarbon oil cracking process which comprises passing the oil through a heating zone and heating the same therein to cracking temperature under suflicient pressure to maintain a substantial portion thereof in liquid phase, discharging the heated oil into an enlarged reaction zone maintained at cracking temperature and under superatmospheric pressure, removing unvaporized oil from said enlarged zone and flash distilling the same by pressure reduction, passing the resultant flashed vapors and the vapors evolved from the oil in said enlarged zone, without prior condensation of any substantial portion thereof, to a dephlegmating zone and subjecting the same to common dephlegmation therein to condense heavier fractions of the admixed vapors, subjecting resultant reflux condensate in a second heating zone to an independent cracking while substantially in the vapor phase, and dephlegmating and condensing the vapor phase cracked vapors.

11. A hydrocarbon oil cracking process which comprises passing the oil through a heating zone and heating the same therein to cracking temperature under suflicient pressure to maintain a substantial portion thereof in liquid phase, discharging the heated oil into an enlarged vap01 separating zone and separating the same therein into vapors and unvaporized oil, separately removing the vapors and unvaporized oil from the enlarged zone and flash distilling the latter by lowering the pressure thereon, combining the flashed vapors, without prior condensationof any substantial portion thereof, with the vapors removed from the enlarged zone and dephlegmating the vaporous mixture to condense heavier fractions thereof, passing resultant reflux condensate to a second heating zone maintained at higher temperature than the firstmentioned heating zone and cracking the same therein while substantially in vapor phase, and dephlegmating and condensing the cracked vapors from said second heating zone.

' JEAN DELATTRE 'SEGUY.

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