US1843710A - Process and apparatus for cracking hydrocarbon oils - Google Patents

Description

Feb. Z, E932. c. P.. D UBBS PROCESS vAND APPARATUS FOR CRACKING HYDROCARBON OILS original Filed Nov. io. 1922 5% Mw, m

@WH m Patented Feb. 2, 1932 UNITED STATES PATENT OFFICE CARBON-P. DUBBS, OF WILMETTE, ILLINOIS, ASSIGNOR TO THE UNIVERSAL OIL PROD- UCTS COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF SOUTH DAKOTA PROCESS AND APPARATUS FOR CRACKING HYDROCARBON OILS Application led November 10, 1922, Serial No. 600,003. Renewed November 3, 1928.

This invention relates to improvements in a process and apparatus for crackinghydrocarbon oils and refers more particularly to a process in which the oils are treated at a conversion temperature, and circulated through expansion stages wherein the oils are maintained in a substantial body under pressure, the vapors being relieved therefrom and the unvaporized oil either recycled or drawn from the system.

Among other objects of the invention are:

To provide a process in which relatively high boiling point oils are cracked to produce oils of a relatively lower boiling point having the characteristics of gasoline and the like, and a recess in which during the initial stages of) operation substantial portions of the unconverted oils passing through the conversion stage may be recycled for retreatment together with portions of the reflux condensate.

rll`he single figure is a diagrammatic side elevational view of the apparatus.

Referring to the drawing, the oil to be treated is introduced from storage through the line 1 and is charged in the form of a spray 2 into the dephlegmator 3, where it is percolated down over perforated pans 4 in a finely divided condition and in an opposed direction to the rising oil vapors. The charging stock thus serves as a dephlegmatin medium coming into intimate contact wit the heated vapors and removing therefrom the higher boiling point fractions. rllhe oil, with what condensate it may collect in the dephlegmating or refluxing column, is drawn off through the line 5 regulated by a valve 6 and is directed to al line 7 connected with the suction side A of the charging pump 8. rlhe line '7 also communicates between the charging pump and the final expansion chamber 9. 'Valves 10 and 11 are interposed in the line 7 for controlling the flow of liquids' therethrough. A by-pass 12 regulated by valve 13 is positioned around 'the pump 8 and may be utilized for cutting out the pump by regulation of the valves'lO and 13. rl`he oil is charged by means of the pump 8 through the line 14 in which is interposed the Valves 15 and 16 to the heating coil 17 mounted in furnace 18. The oil, while circulating through this furnace or heating zone, is raised to a conversion temperature and is directed through the transfer line 19 regulated b a valve 20 to the initial conversion cham er 21. The conversion chambers, comprising chambers 21, 22 and 9, are connected in series so that the oil will circulate from one chamber to the next. The chambers 21 and 22 are connected at their rear ends by the lines 23 and 24 which are controlled by valves 25 and 26 respectivel while the chambers 22 and 9 are connectedy at the forward ends by the pipes 27 and 28 controlled by valves 29 and 30 respectively. Thus the oil is caused to circulate by the most circuitous route through the successive chambers. Double connections are made between the chambers in order that both the vapor spaces and the liquid spaces will be connected by communicating lines. The chambers are equipped with residual draw-od lines 3l controlled by valves 32.y rllhe chambers are also heavily insulated to prevent loss of heat through radiation, and function as digesting or conversion chambers in which the oil is maintained in a substantial body during the conversion or reacting stages. The vapors evolved from the separate chambers pass off through the risers 33, 34 and 35, respectively, combined in a single vapor line 36 controlled by a valve 37 which is connected with the lower part of the dephlegmator 3.

s explained, the vapors are subjected to a dephlegmating action by the incoming raw oil and by re-circulation of the pressure distillate, as will hereinafter be mentioned, and pass oil' from the top of the dephle mater through the line 38, regulated by a va ve 39, to the nal condenser 40. rThe vapors, after passing through the final condensing stage, are collected as liquid distillate in the receiving tank 41 which is connected to the final condensing coil by means of a pipe 42 in which is interposed a valve 43. rlhe receiving tank is equipped with a liquid draw-O1 valve 44, pressure relief valve 45, pressure gauge 46 and a liquid level gauge 47. A second liquid draw-olf line 48 connects to the suction side of the pump 49, the discharge titl \ line 50 being connected to a spray 51 mounted in the top of the dephlegmator 3. rlhis return line for the pressure distillate is controlled by a valve 52.

5 In operation, the oil is charged, as exconsiderable eriod of time. 'lhis obviously is due to the act that the system has not completely been raised to temperatures conducive to conversion of the oil and consequently a large portion of the oil will remain unconverted in its travel through the conversion or evaporating chamber.

As the operation proceeds, more and more of the oil will pass overhead in the form of vapors and produce, as a consequence, heavier residual material collects in the Vaporizing chamber. 'llhis material is objectionable as a recycling product, as it contains substantial quantities of free carbon in suspension;

By proper regulation, and a high rate of vaporzatlon, ll am enabled to improve materially the efficiency of the process, due to the fact that it is unnecessary to return the unvaporized residue back to the charging tank or storage tank. rl`he utilization of the heat from the unvaporized oil `Will materially reduce the percent of fuel necessary for treatment of the oil.

By operating the apparatus on 32 lBaum gravity, mid-continent gas oil at temperatures from 700 to 900 degrees F. and substantial pressures ranging from 50 to 300 pounds, a yield of from E30-65% of high quality distillate was obtained, based on the charging stock.

ll claim as my invention:

l, A process for cracking hydrocarbon oil consisting in utilizing the oil charge as a dephlegmating medium, passing the oil with its reflux condensate content to a heating zone, and there raising it to a cracking temperature, assing the heated oil through successive c embers of conversion `wherein no substantial drop in oil temperature occurs, tal:- ing on the evolved vapors and subjecting them to the dephlegmatin laction of the oil charge and then to a con ensing action, returnmgportions of the distillate roduced to and forcing same through the dep ilegmating stage under pressure,'returning selected ortions of the unvaporized oil from the al conversion chamber with the mixture of ravv charging stock and reflux condensate to the mesmo heating zone for further treatment, Withdrawing other portions of the unvaporized oil from the system and maintaining a regulated pressure during operation.

2. ln an apparatus for treating hydrocarbon oils, the combination with a heatingA coil, mounted in a furnace, of a plurality of serially connected enlar ed insulated conversion chambers communicating with the heating coil, vapor drawos from the conversion chambers, a dephlegmator connected to said vpor drawoi's, unvaporized residue drawo s from the conversion chambers, means for returning the redux condensate and portions of the unva orized residue from the last of the series o chambers to the heating coil, means for condensing the uncondensed vapors from the dephlegmator, means for returning portions of the distillateto the dephlegmator, a pump in said return means, and means for mamtaining a superatmospheric pressure on the system.

CARBON l. DUBBS.

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