US1835774A - Process for cracking oils - Google Patents

Description

Dee:a 8, 1931. H. J. HALLE PROCESS FOR CRACKNG OILS 4 Sheets-Sheet l Filed sept. 22, 1924 JHM/e mi@ My.

ttot nu DeC- 8 193f H. J. HALLE 1,835,77

PROCESS FOR CRCKING OILS Filed sept. 22, 1924 4 Sheets-sheet 2 wm/lf Dea 8, 1931. H, ,j HALLE 1,835,774

PROCESS FOR CRACKING vOILS Filed Sept. 22, 1924 4 Sheets-Sheet 3 I l l 5 Dec. s, v1931.4 H, J HALLE 1,835,774

y PROCESS FOR CRACKING OILS Filed Sept. 22, 1924 4 Sheets-Sheet 4 5mm/wai IZ da/le Patented Dec. 8, 1931 ASTATES PATENT OFFICE HIBAM J. HALLE, OF NEW YORK, N. Y., ASSIGN'OII, TO UNIVERSAL OIL PRODUCTS COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION F SOUTH DAKOTA PROCESS FOR CRACKING OILS Application led September 22, 1924. Serial No. 739,138.

The invention relates to improvements in a process for the conversion of hydrocarbon oils.

It isfan object of the invention to provide a an oil conversion process utilizing a battery l@ and to reduce costs in plant construction,

operation and generally improve the results.

With the foregoing conception in mind, one of the broad features of the invention consists in returning reflux condensate obtained from the condensation of vapors produced in a battery of stills to at least two of said stills by means of a single pump for rapidly recycling said condensate through said stills in opposition to thefrictional resistance of oil passing therethrough.

In a more specific aspect, the present invention contemplates a battery of stills having suitable reflux condensing means for separating the insufficiently cracked vapors from said stills from the low boiling point oils, with a single refluxfeeding pump to which condensate is introduced adapted to feed through suitable feeding lines the desired quantity of reflux condensate with or without charging stock to two or more stills of the battery, so that said condensate with.

or without mixed charging stock is rapidly circulated' through the stills to undergo further treatment therein.

The invention is particularly applicable to the batteryv of stills of the tube and chamber type, that is, each still in the battery comprising a continuous coil through which the oil is rapidly passed and an enlarged conversion chamber where said oil completes its reaction. the vapors from this chamber being subjected to al reflux condensing action while the residue is withdrawn. The invention. however, is clearly applicable to other types of stills, as will be clearly apparent from the following description.

It is a further object of the invention to provide an improved process for supplying charging stock to the different stills constituting the battery by feeding to the inlet of two or more of the stills separate streams of charging stock from a single pump or other mechanical pressure applying device.

` It is a still further object of the invention to provide an improved process for cracking oils utilizing a number of stills constituting a battery, in which one or more pumps can be utilized for feeding both reflex condensate and charging stock to the various units in the battery, to provide a process in which charging stock can be fed to one or more of the dephlegmators, and this charging stock, together with reflux condensate returned to at least two of said units by a single pump or other mechanical pressure applying device common to ysaid units.

In 'the accompanying drawings I have shown diagrammatically the preferred embodiment of my invention, in which Figure 1 represents a view wherein a single charging pump is utilized for feeding raw oil to a battery of four units and a single reflux pump employed common to all of said units.

In Figure 2 I have shown a modification of my invention where one charging pump is common to the battery and two reflux pumps for feeding reflux condensate thereto.

In Figure 3 I have shown a modification wherein va ors from at least two stills enter a single re ux condenser and the reflux condensate from this condenser is circulated by a single pump to said stills.I

Figure 4 is an elevation, partly in section, of the structure shown kin Fig. l and showing diagrammatic details of the furnace, conversion chamber, and dephlegrlator.

Figure 5 is an elevation of the structure shown in Fig. '3.

Referring -now more particularl to the drawings wherein like reference c aracters indicate corresgpnding parts, thek reference character A in igure 1 designates a battery of stills, which may consist of two or more separate units. Four units are shown but this disclosure is merely for the purpose of illustration and any number can be employed. In this disclosure as each unit is of the same specific construction, a description of one will suffice for all. Each unit embodies a furnace structure 1 having a combustion chamber 2 heated by gases or oil from the burners 3, with a series of cracking tubes 4 disposed on one side of a bridge wall separating said tubes from the combustion chamber, through which tubes the oil is circulated under a pump pressure in a manner to be hereinafter described. A transfer lineV 5 conducts the oil from said heating tubes to an enlarged chamber 6 where conversion occurs. This chamber is shown as being insulated, but it could be otherwise constructed, if desired. It is-within the scope of this invention to apply heat to this chamber should this be found to be desirable.4 The chamber is vertically disposed, is provided with a carbon discharge opening 7 at its lower end and a series of independently controlled residual drawofl' lines 8, by means of which liquid residuum may be withdrawn from the system. A vapor transfer line 9 conducts the vapors from the chamber 6 to a dephlegmator 10 to be now described. The dephlegmator 10 may be of any approved construction.

For illustrating this invention, however, I have selecteda dephlevmator having therein a series of pans or ba es 11 for retarding the passage of vapors therethrough and in this de hlegmator I condense the insufficient- 1y crac ed vapors, preferably by introducing thereto charging stock through a feeding line 12, or pressure distillate through a line 13. The condensed vapors pass through the line 14, and the condensate from the dephlegmators of the battery flowing through the said lines 14 collect in a receiver 14 lcommon to two or more of the dephlegmators and from which receiver the condensate is fed-to the heating coil 4 in a manner to be later described.

The raw charging stock entering the system is fed to a single pump 15 through an oil feeding line 15. From this pump a series of branch lines lead respectively to -each heating coil 4 and to each dephlegmator 10. 'Ifhat is to say, a single feeding pump is utilized for feeding raw oil to each unit through a line 16, and overhead to each dephlegmator through a line 12. In the disclosure of the invention as set forth in Figures 1 and 4, lines 12 and 16 lead from the pump 15, respectively to the dephlegmator and the heating coil of each unit. Of course, as shown in the modification of the invention two or more feeding pumps may be employed, if desirable.

The condensate in the receiver 14 common to two or more of the dephlegmators enters the pump 17, and from this pump the condensate flows through the lines 18 to each charging line, merging with the raw stock at the points X of each unit. It will be clearly seen that a single pum receives condensate from a pluralit of ephlegmators and said pump is utilize to feed the condensate to a plurality of cracking units. The pumps 17 may also be arranged in parallel if desired, so that if for mechanical reasons one pump becomes inoperative the other pump can be utilized.

The uncondensed vapors from the dephlegmator 10 are discharged through the line 19 and pass through a condenser 20 where they are condensed and the distillate collected in a receivingtank 21. An incondensable gas discharge pipe 22 is provided with a valve 23 by means of which a va or pressure can be maintai-ned throughout t e system.

In operating the embodiment of the process as carried out in the apparatus shown in Figure 1, if a gas oil'is utilized the oil should be heated so that its transfer temperature approximates .85()o F. A pressure of upwards of 100 pounds per square inch can be maintained ythroughout the system by setting the vvalves 23. Differential pressures may, however, be maintained in different parts of the apparatus by operating the valves 24, 25 and 26. For instance, a reduced pressure can be maintained on the expansion chamber 6 or the expansion chamber 6 and the coil 4 of each unit may be under a uniform pressure and a reduced pressure maintained in the dephlegmator 10 and the condenser 20. A

From the foregoing description of the process as carried out in the apparatus shown in Figure 1, it will be seen that a single charging pump isA utilized for feeding the plurality of units constituting the battery, and that a single refiux pump is also employed which is common to all'of said units.

It will also be seen that the charging pump can feed a portion of the charging stock to the top of each dephlegmatol` through the valve controlled llines 12 and a portion of the stockdirectly through the lines 16 to the cracking ,coils 4 or all of the stock can be fed overhead or none overhead and all direct to the cracking coils. This `dispenses with a series of pumps and minimizes the mechanical difficulties encountered in the use of a battery of stills. It furthermore permits all of the units to be operated under the same uniform conditions resulting in the production of a uniform distillate.

In thecmbodiment of the invention as illustrated in Figure 2 the cracking apparatus employed is the same as heretofore employed in the discussion of Figure 1. That is to say each unit in the battery com rises the heating-coil 4, theconversion cham r 6, and a dephlegmator 10. In this embodiment of the invention, however, a single pump is not common to all of the dephlegmators 10 of the battery. As shown in Figure 2, the dephlegmators B and C discharged refiux condensate through the lines 14 to a common receiver D, and from this receiver the reflux is fed to a pump E common to the two units in the battery which feed vapors to said dephlegmators B and C. The reflux is fed by said pump through the lines F and G to the heating coils 4. In this embodiment of the invention a single charging pump 15 is employed, although obviously two of these pumps may be used, if desirable, in which instance each pump would feed to two yunits of the battery. The same operating pressures and temperatures can be maintained in carrying out this process as hereinbefore set forth in the description of the process as carried out by the apparatus illustrated in Figure 1.

In Figure 3 of the drawings I have shown a modilication of this invention wherein an independent dephlegmator 30 need not be utilized for each unit ofthe battery. That is to say, in this embodiment of the inventionone or more dephlegmators can be used for the entire battery of stills. In the disclosure I have shown a single enlarged dephlegmator 30 for each two units of the battery. The vapors from the conversion chambers 6 in the construction .hereinbefore described pass through the vapor lines 9 to said dephlegmator which is cooled by oil fed overhead through the charging line 12, as hereinbefore described. Of course, this dephlegmator may 'otherwise be cooled, if desired. In this embodiment of the invention the reflux condensate from the enlarged dephlegmator 30 collects in the leg 31 and from this leg it is fed by a pump 32 to the lines 33 and 34 to the two units fromvwhich the dephlegmator 30 receives its vapors. That is to say the condensate from the single dephlegmator receiving vapors from the two units is returned to these two units under the pressure by the single pump 32 and cycled therethrough. In this embodiment of the invention I may also feed charging stock partially overhead through the line 12 and partially direct to the cracking coils 4 through the lines 16 to each pair of units by a-single pump 35. Of course, all the charging stock can be fed overhead to the dephlegmator, 30, b this pump or no charging stock need be fe overhead and., all of the raw charging stock may be' fed directly through the lines 16 to the two heating coils. From this disclosure it will be seen that one charging pump for raw charging stock is utilized for each pair of units. It will be clearly understood, however. that the four or more units may be combined in the manner just described in dealing with the two units, that is to say, a single dephlegmator may be employed `for a number of units and one or more pumps utilized for feeding the reflux to the cracking coils of said units. Furthermore, a single charging pump may be utilized for any number of units depending upon the capacity of the units and size of the pump. In the operation of the various embodiments of this invention, the vapors discharged from the reflux condenser are all condensed in the final condenser, save the incondensible gases, and superatmospheric pressures may be maintained throughout the system by the control of these gases or interposed valves may be placed between the different parts of each unit, whereby differential pressure may be maintained. The temperature to which the oil passingzthrou h the heating coils is subjected may vary, ut I propose to employ a temperature suilicient to bring the oil to a conversion heat and with a gasoil from a mid-continent field a transfer temperature of about 850 degrees F. has been found desirable.

In the present disclosure, I have shown a tube and chamber type of still capable of continuous operation wherein residual oil may be discharged from the expansion chambers without being again admitted to the cracking coils wherein the reflux condensate is continuously recycled for recracking. I wish it to be understood, however, that any well known type of still can be utilized in this process. That is to say,I can employ a batch still or any still utilizing a dephlegmator.

Having thus described my invention, what I claim is:

1. An improvement in the art of pressure distillation, comprising continuously feeding a stream ofcharging oil to a plurality of separate stills maintained' undier cracking conditions of temperature and pressure, each of the stills including a heating zone through which a restricted stream of oil is passed, and an enlarged reaction zone where conversion of the oil occurs, in discharging residuum from each of said enlarged reaction zones without retreatment,in subjecting the vapors discharged from each reaction zone to ydephlegmation commingling the reflux condensates resulting from the dephlegmation of the vapors discharged from each reaction zone and in introducing under an applied mechanical pressure saidcommingled reflux condensate moving in separate streams to the o1l stream passing to each of said stills.

2.- An improvement in the art of pressure I distillation comprising maintaining oil in a plurality of separate stills under cracking conditions of temperature and pressure, in discharging the vapors generated in each still to a dephlegmating zone, in collecting in a pool reflux condensate formed in a plurality of said dephlegmating zones, and-1n introducing said condensate in separate streams to each of said stills for retreatment therein.

3. An improvement in the art of pressure distillation of hydrocarbon oils, comprising maintainingv oil in a plurality of separate stills under cracking conditions of temper? ature and pressure, 1n subjecting the vapors generated 1n each still to an independent reflux condensation, in collecting the reflux condensate from a plurality of said stills in a common receiver, and in forcing such condensate under mechanical pressure in streams, one of which passes to each of said stills for retreatment therein.

4. An improvement in the art of pressure distillation, comprising subjecting oil to cracking conditions of temperature and pressure in a plurality of separate stills, in each of which stills avstream of oil is continuously advanced through a heating zone and thence admitted to an enlarged reaction zone, in removing vapors from each of said reaction zones, in subjecting such vapors to reflux condensation in separate dephlegmating zones, in collecting the condensate from said dephlegmating zones in a common body, in introducing such condensate to each still by forcingthe same in separate streams, one stream merging with each stream of oil to undergo conversion in each cracking still.

In testimony whereof I' aix my signature.

HIRAM J. HALLE.

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