US1839031A - Process and apparatus for cracking oil - Google Patents

Description

Dec. 29, 1931.

L. C. HUFF PROCESS AND APPARATUS FOR CRACKING OIL Original Filed April 14 192:5

Patented Dec. 29, 1931 UNITED STATES PATENT orrlcs LYMAN G. HUI'F, OF CHICAGO, ILLINOIS, AS SIGNO B 10 OIL PRODUCTS PANY, OF CHICAGO, ILLINOIS, A CORPORATION OF SOUTH DAKOTA PROCESS AND APPARATUS FOR CRACKING OIL Application filed April 14, 1928, Serial 110. 682,018. Renewed October 1, 192s.

. This invention relates to improvements in a process and apparatus for cracking oil, and

. refers more particularly to the cracking of petroleum oils to recover therefrom the low boihng point fractions, producing a distillate having the characteristics of gasoline.

Among the important objects of the invention are to provide a process in which one or more perfecting chambers are interposed in the path of the vapors between the carbon separating chamber and the dephlegmating stage in order to subject the evolved vapors and any condensate separated therefrom, to

the action of heat and pressure, thereby increasing the time element for reaction to take place, which results in increasing the capacity of the still. The intermediate vapors or those vapors which normally are returned as reflux condensate from the dephlegmating stage, would be held in the perfecting chambeis and subjected to prolonged crackin conditions of heat and pressure, while 0111? the lighter vapors would pass on to the dephlegmater. The condensate from vapors which 28 were condensed in the perfecting chambers could be returned to the heating coil for further treatment. The vapors and any condensate separated therefrom would beheld in the perfecting stages at high temperatures and under pressures substantially the same as to which the oil is subjected in theheating tubes. These oil constituents progress ing through the perfecting stage would remain therein for a relatively long period of time, and would not besubjected to alternate condensing and evaporating conditions, as is commonly the case with the use of large dephlegmating areas.

Normally, during the dephlegmation of vapors, they are first required to give up a considerable portion of their heat immediately on entering the dephlegmatmg stage, and arethereafter not subjected to conditions of constant temperature which are known to be most favorable to conversion and cracking.

Further, the fuel consumption of a cracking still using perfecting or consummating chambers, such as described, will be materially reduced, for only the condensate and reflux from the vapors which had not reacted, would be returned to the heating tubes to be again subjected to the cracking conditions therein.

' Operating the process in a manner described, would, eliminate the necessity of reheating a large quantity of reflux, the vapors of which had been prematurely condensed in the dephlegmator, and not given suflicient time for complete conversion.

On account of the longer time element possible by using the perfecting or consummating chambers, it is unnecessary to heat the oil to such extremely high temperatures in the heating coil, and lower temperatures can be carried in the transfer line, thus subjecting the oil while in'the heating tubeto conditions more favorable to conversion concharging stock to be treated is introduced from any convenient source through the pipe land is charged into the top of a dephlegmator 2 where it is utilized as a refluxing medium flowing in an opposed direction to the heated oil vapors rising therethrough. The charging stock with what reflux condensate itcolleots in the refluxing tower, will flow down through the column, and may be drawn oil from the bottom of the reflux leg 3 through the line 4 in which is interposed a. valve, 5. This 'line communicates with the suction side of a hot Oil. pump 6 which charges the oil to the heating coil 7 mounted in the furnace 8, the latter being preferably heated by means of gas burners 9. 'A by-pass 10 controlled by a valve 11 is connected around the pump in case it is desired to eliminate the pump from the'system.

In the heating coil, theoil is raised to a conversion temperature, while a substantial pressure is maintained thereon. In this condition,-it is directed through the transfer line 12 regulated by a valve 13, and is introduced. into the vaporizing or separating chamber 14. Here the oil is collected in a substantial body, the vapors passing off through the vapor line 15 re lated by a valve 16, to a perfectingcham er 17, while the residual products may bedrawn ofi either continuously or intermittently through the residuum lines 18 controlled by the valves 19.

The chambers 14 and 17 have upper and lower removable heads which facilitate cleaning. The chambers are heavily insulated to minimize the loss of heat by radiation.

The vapors introduced to the perfecting chambers collect therein and assume a partial stagnation, that is their travel due to the character of the chamber, is materially retarded, and due to the high temperature and pressure conditions maintained upon this stage, they have sufficient time to permit the consummation of the cracking reaction initiated in the chamber 14.

It will be noted that in place of one cham-.

ber, a series of similar chambers may be connected into the system, whereb considerable greater quantities of hy rocarbon vapors are subjected to this perfecting or consummating action. 7

' In these perfecting stages there will result "a condensate which when collected in the bottom of the chamber may be drawn off throu h pipes such as that shown at 20, regulated y valve 21 and returned to the ipe 4 which connects to the suction side of t e recirculating pum 6.

The vapors after having been maintained for a period of time under the cracking conditions of temperature and pressure maintained in the perfecting stage, pass oif through the vapor line 22 in which is interposed a valve 23. These vapors are introuced into the lower part of the dephlegmator where they rise and are refluxed by the cooling action of the raw oil with which they come into intimate contact. After being dephlegmated, the vapors pass off throu h a gauge 27, a pressure relief valve 28,

differential pressures may be maintained upon the separate stages by manipulation of the valves in the several connecting lines.

By treating a mid-continent gas oil of approximately 32 Baum gravity to temperatures ranging from 600 to 900 F, and pressures ranging from 50 to 500 pounds, a normal yield of pressure distillate may be obtained from which 55% of Navy specification gasoline may be extracted.

By utilizing the perfecting chambers from a ,60% yield of pressure distillate may be separated from 75% to 80% of oil having the characteristics of gasoline.

splitting up of the hydrocarbon constituents where the vapors are maintained for a considerable period of time under pressure and temperature conditions of cracking subsequent to their vaporization. Obviously, the

ture and pressure conditions of the conversion zone, in passing the vapors. from said enlarged chamber to a 'de hlegmator, in condensing the dephlegmate vapors, in collecting the resulting distillate, in returning the condensate collected in said enlarged chamber and the reflux condensate from the dephlegmator to the heating zone for retreatment an'din maintaining a regulated pressure on the oil undergoing conversion.

2. A process of cracking hydrocarbon oil, consisting in passing the oil through a heating coil located in a furnace wherein the oil is subjected to a conversion temperature, in discharging theheated oil into an enlarged conversion zone, in maintaining a substantial bodfy of liquid oil therein, in continuously wit drawing residual oil from said conversion zone to be isolated from the system, in passing the evolved vapors to an enlarged chamber maintained at substantially the conditions of temperature and pressure maintained in said conversion zone wherein the vapors undergo additional reaction and portions thereof are condensed, in withdrawing said condensed portions and returning them to the heating zone for retreatment, in passing the still vaporized portions from said enlarged chamber to a dephlegmator, in introducin raw oil into said dephlegmator to act as a ephlegmating medium for said va- Thus it is ob- ,vious that there is a substantially greater pors, in condensing the dephlegmated vapors incollecting the resulting distillate, in passing the raw oiland reflux condensate from said dephlegmator under an applied pressure to and through said heating coil and in maintaining a superatmospheric vapor pressure 011 the oil undergoing conversion.

' 3. An apparatus for treating hydrocarbon oil, consisting of a coil located in a furnace, a transfer line connecting said coil with an enlarged conversion zone, means for withdrawing residual oil from said conversion zone, means for passing vapors from said conversion zone to an enlarged insulated chamber, means for withdrawing liquid condensate from said chamber and means for, returning such liquid condensate free from residual oil removed from said conversion zone to said coil, means for dephlegmating the vapors issuing from said enlarged chamber,

means for condensing and collecting the dephlegmated vapors, means for introducing charging oil to said dephlegmating means,

and means for passing reflux condensate together with the charging oil from the de phlegmating means directly to the heating coil without previously admitting the same to said chamber or to said conversion zone.

LYMAN o. HUFF.

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