US1831975A - Process for cracking hydrocarbon oils - Google Patents

Description

Nov; 17, 1931.

J D. SEGUY PROCESS FOR CRACKING HYDROCARBON OILS Filed Jan. 19, 1928 Jan fiel ame z Patented. Nov. 17, 193k UNITED, STATES PA ENT OFFICE 7 JEAN DELATTRE SEGUY, OF CH ICAGO, IILINOIS, ASS IGNOB '10 UNIVEBSAIi OIL PROD- UCTS COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF SOUTH DAKOTA PROCESS FOR CRACK LNG HYDROCARBON OILS 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. The present application is a continuation in part of my copending application, Serial No. 242,434, filed December 24,1927.

With the increasing advent of combustion engines having high compression ratios, it

has been found desirable to use motor fuels containing what are commonly known as.

anti-knock compounds. These anti-knock compounds are in some instances increased 5' or produced by the formation of a relatively large percent of unsaturates in the gasohne 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.

In this application, as will hereafter more clearly appear, I have described my basic 3'0 process, together with various specific examples 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 gasoline constituents so formed may then, if desired, be removed from the system while thereflux condensate from such pressure cracking may then be subjected to vapor phase cracking, at atmospheric or reduced pressures.

By such operation the reflux condensate so formed is preferably separated from the carbon containing residues, and becomes a relatively clean charging stock .for the vapor phase cracking operation.

Application filed January 19, 1928'. Serial 170. 247,807.

' At the same time, if desired, the residue produced from the liquid-vapor phase pressure operation may be flashed and the flashed vapors from the residue also become a highly desirable ar d relatively clean charging ess as to-more or less crack them, whereby subsequent'cracking of such reflux or vapors in the vapor phase part of the process, is much easier than would be the case were the raw charging stock initially subjected to straight vapor phase cracking.

It is well known to present vapor phase cracking that the fuel consumptionis high and the incondensable gasrloss is large. "In

addition, in present types of vapor phase cracking the carbon production is high.

means of the present invention the fuel consumption 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 carbon productionis 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 present 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 already been initially cracked with the formation of some unsaturates and the vapor phase part of the operation in reality completes the maximum for.-

' by the present invention .heavy mation of anti-knock compounds already previously started. 7

Heretofore, vapor phase processes have only been partially successful on gas oil,'but

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 that the reflux produced from the vapor phase cracking, may, if desired, be mixed with the raw charging stock in the pressure part of the process, and inasmuch as this reflux contains in itself a large amount of anti-knock compounds the gasoline from the pressure part of the process will in such case be produced with a. large amount of anti-knock compounds.

I have above referred to a certain part of the process as liquid-vapor pressure operation and another part asvapor phase cracking at atmospheric pressure. It is to be understood however, that in its broader aspect the invention is not limited to the vapor phase cracking at 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 sub-atmospheric pressure. For.

example, the liquid vapor pressure part of the process may be at say 100 pounds upwards, and the vapor phase cracking at pressures of 50 pounds 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.

The invention will be more clearly under- .stood from the following description, reference being drawing. v

This drawing shows a diagrammatic illustration of an apparatus and in my opin ion a novel form of apparatus suitable for carrying out the invention. It is to be understood that this diagrammatic drawing is not to scale or intended to be. 4

Referring to the drawing, a cracking coil 1 is positioned in a suitable furnace 2. is supplied to the coil 1 through feed hne 3 and feed pump 4, leading to any suitable source of supply. The oil passes from coil 1 to transfer llne 5, having throttle valve 6, into expansion chamber 7. The vaporspass out of expansion chamber 7 through vapor had to the accompanying .line 8 andthence, if desired, into the lower side ofdephlegmator 9. Throttle valve 10 is interposed in line 8 for a purpose hereinafter described.

From the top of the dephlegmator the vapors may passthrough vapor outlet pipe 12 into condenser coil 14, and thence to recelver 15. Receiver 15 is provided with gas outlet Raw oil control valve 16, and liquid drawofi 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 undesirable to introduce the raw oil directly to the dephlegmator, as is true in certain cases hereinafter 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 tothe raw oil feed line 3. A by-pass 24 may be provided in line 22 around the pump 23, suitable valves 25 being provided as shown.

In the line 21, is provided a throttle valve 26. The reflux may also be passed through line 27 and branch 28 to vapor phase feed line 29, hereinafter referred to.

A pump 30 may be interposed in line 27, and a by-pass line 31 around the pump may also be provided, throttle valves 32 being interposed as shown in the drawing.

The reflux condensatemay instead of being sent through branch 28, after it reaches 27, be diverted through pipe valve 34, and then combined with the residuum drawn off from chamber 7 by means of drawofl line'35 and branch 36, the latter leading to the residuum flash 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 system, if desired.

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 drawofl" 42 having throttle controlvalve 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 suchcases 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 through delivery line 49 having throttle valve 50, into chamber 51. This separating chamber 51 is provided with a carbon or residue drawofl pipe 52, having 33, having throttle controlled either by introducing raw oil directlyinto dephlegmator 56, by pipe 57, having control valve 58, or if desired raw oil may be passed through the closed coil 59, and thence if desired, led to the feed pump 4.

mV The raw oil is not introduced directly intoeither dephlegmator unless it is desired to sendit tothe 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 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 wwith gas outletcontrol 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

5 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 pum 68 to line 69. The :0 by-pass 70 may be provi ed around the pump 'with'the usual valves 71. The reflux from line 69 may be passed directly, if desired, to line 29, by means of pipe 72, having throttle valve 73, and line 28, or if desired, it may pass via-line 7 2 into line 33 by opening the valve 34 and closing the valve 74 in the line 28, or the condensate "may be passed from the pipe 69 into the line 22 by closing the valve 73 and opening the valve 7 The reflux from either dephleginator. maybe drawn out of the sys-.

'tem through branch 77 having throttle valve 78. or branch 79, having throttle valve 80.

Describing now the manner in which the invention may be operated, one desirable 5 method of carrying out the invention is to subject the raw charging stock to a liquidvapor phase pressure cracking operation, flash the residuum therefrom and subject the flashed vapors to vapor phase cracking at atmospheric pressure or pressure lower than the pressure on the liquid-vapor phase cracking operation, and to also subject the reflux condensate from the main dephlegmator to vapor phase cracking. In such case, the raw oil, if desired, may be passed through the dephlegmator connecting the vapor phase cracking coil, either in direct or indirect contact with the vapors in such dephlegmator and thence to the main cracking coil. The reflux from the second dephlegmator or the dephlegm ator connected, to the vapor phase cracking coil, is or may be returned to the main high pressure cracking coil.

Describing the above method of carrying out the invention more in detail,,the raw Oil is fed into the coil 1 where it may be heated to a V 7 transfer temperature of say 7 5 0 to 900 degrees F. more or'less, and thence into the expansion chamber 7. The vapors 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 rece1ver15 or receiver 62 by suitably regulating the valves shown in the accompanying drawin The reflux condensate may be drawn out t rough pipe 21 and thence if desired passed through p pipes 31, 27 and 28 into the line 29, and thence I v 1 to the vapor phase cracking coil 47. If de- 15 directly to the vapor phase cracking coil 47,

sired, the reflux condensate instead of assing to pipe 28 may go trom pipe 27 via t e pipe I 33, to the line 36. The residuum is drawn oil the bottomof chamber 7 continuously and thence may be passed through the pressure reducing valve 38, and be flashed into cha-m ber 37. The vapors from such flashing operation thence pass through the pipe 29 into the vapor phase coil 47. A pressure of 100 pounds 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 in-' stead of using valves 32.

The vapors from the flashing chamber 37 mix with the reflux condensatev from the dephlegmator 9 as they pass through the vapor cracking coil 47, and are there subjected to temperatures in said coil of say 900 degrees F. to 1150 degrees F. more or less.

It is to be understood that the temperatures here given are illustrative as well asthe temperatures in the transfer line 5. The vapor phase cracking coil may be maintained under substantially atmospheric pressure, or if desired, under a pressuresomewhat above at- If desired, the vapor phase cracking coil may be even maintained under a vacuum, by connecting suitable vacuum pump not shown 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 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 then be passed through the lines 67 and 69 directly back to the main heating coil 1. In such case the Valves 26 and 73 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 phase cracking coil is converte into a relatively large percent of unly desirable clean charging stock already par tially 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 vapor cracking 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 process 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 this manner of carrying out the invention is that the rate and extent of cracking in the pressure part of the process may be regulatedentirely independently of the vapor phase part of the cracking, and also the reverse is true. 1

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 senselimit 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 fuel consumption and a highly desirable charging stock.

In some cases where the reflux from either dephlegmator 9 or dephlegmator 56 is directed to the vapor phase cracking coil 47, directly through line 28. .or through the flash chamber 37, as heretofore explained, it has been found that the reflux from these dephlegmators may not contain enough heat to cause complete vaporization of said reflux before entering the vapor phase cracking coil.

To remedy this, and as a further feature of the invention, the reflux from either dephlegmator, or both, may be passed through are beating coil whereby enough additional heat may be im arted to said reflux to make up for the latent heat necessary for its vaporization. This heating coil is preferably positioned between the dephlegmator and the point at which the pressure is reduced on the reflux, and, for instance, it may be positioned as shown at 81. Reheati'ng coil 81 is positioned in a suitable furnace 82, and reflux from dephlegmator 9 may be directed through heatirfg coil 81 through lines 83 and 84 controlled by suitable valves 85. By suitably regulating the opening of valves 85 and'86, any pro ortion of reflux may be passed through 0011 81 and the temperature and heat imparted to the reflux from dephlegmator 9 may be accurately controlled. 4

Should it be desired to return to the vapor phase cracking coil reflux from the de hlegmator 56, a similar heating coil may Be positioned as shown at 82 in the furnace 83', and by controlling suitable valves. 87 on branches 88 and on line 69, any desired amount of reflux from dephlegmator 56 may be reheated to a suitable temperature before returning to the cracking zone.

I claim as my invention 1. A process for cracking hydrocarbon oil consisting in subjecting said oil to cracking conditions of temperature and pressure in a zone of reaction, taking off vapors from said zone and subjecting themto dephlegmation thereby obtaining reflux condensate, witha drawing the residuum from said zone and subjecting it to flash distillation at a reduced pressure, subjecting the vapors from said flash distillation and said reflux condensate to vapor phase cracking, removing the vapors from said vapor phase cracking step, subjecting them to dephlegmation, and finally condensing, as the product of the process the vapors uncondensed by dephlegmation.

2. A process for cracking hydrocarbon oil which consists in heating the/oil to a cracking temperature under pressure, passing said oil to an enlarged chamber, withdrawing liquid oil from said chamber, releasing the pressure thereon to permit flash distillation, subjecting the flash distilled vapors to vapor phase cracking, subjecting vaporstherefrom to dephlegmation, forming reflux condensate, vaporizing said reflux condensate, and returning it to the vapor undergoing vapor phase cracking.

3. A hydrocarbon oil cracking process which comprises subjecting the oil to cracking conditions of temperature and pressure and separating evolved vapors from unvaporized oil, dephlegmating said vapors thereby forming reflux condensate, lowering the izing it therein, subjecting the vapors produced in said heating zone and said additional vapors to vapor phase cracking, dephlegmating the vapor phase cracked vapors thereby forming a second reflux condensate, and returning said second reflux condensate to the process for re'treatment.-'-

4. A hydrocarbon oil cracking process which comprises subjecting the oil to, cracking conditions of temperature and pressure and separating evolved vapors from unvaporized oil, dephlegfnating said vapors there by forming reflux condensate, lowering the pressure on said unvaporized oil thereby forming additional vapors by flashdistillation, passing at least a portion of said reflux condensate through a heating zone and vaporizing it therein, passing the vapors produced in said heating- 'zone and said addiv forming additional vapors by flash distillation, passing at least a portion of said reflux condensate through a heating zone and vaporizing it therein, subjecting the vapors produced in said heating zone and said additional vapors to vapor phase cracking, de-

phlegmating the vapor phase cracked va ors to condense insufficiently cracked fractions, and returning said fractions to the vapors undergoing vapor phase'cracking.

In testimony whereof I aflix my si ature.

J'EANDELATTRE SE UY.

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