US1982469A - Process of cracking hydrocarbon oil - Google Patents

Description

Nov. 27, 1934. G. EGLoFF PROCESS OF CRACKING HYDROCARBON OIL Filed April 3, 1950 2 Sheets-Sheet l NOV. 27, 1934. G, EGLQFF PROCESS OF CRACKING HYDROCARBON on;

Filed April 5, 1950 2 Sheets-Sheet 2 dill lll a: l uhp l luwv HHI H HWH l l l l l l I valve 25.

Patented Nov. 27, 1934 UNITED STATES PROCESS OF CRACKING HYDROCARBON OIL Gustav Eglofli, Chicago, 111., assignor to Universal Oil Products Company, Chicago, Ill., a corporation of South Dakota Application April 3, 1930, Serial No. 441,429

. 1 Claim.

This invention relates to the improvements in a process of cracking hydrocarbon oils, and in the specific application of the invention hereinafter described relates more particularly to that type of process in which the oil after having been initially cracked, has the generated vapors separated from the residue and the latter subjected While still hot to a so called flash distillation.

As a feature of the invention, the residue remaining after the flashing operation, preferably together with more or less of the reflux condensate obtained from the initial dephlegmation of the vapors from the primary cracking operation, are subjected to a further cracking at elevated temperatures so as to in effect convert such last mentioned oil into gases and vapors and a cokelike residue.

The novel features of the invention will appear more clearly in the following description and in the appended claim.

designates a furnace in which is mounted a heating coil 2. The oil passes from the coil 2 through transfer line 3, having throttle valve 4, to an expansion chamber 5, preferably insulated and unheated. The vapors pass out of the chamber 5 through line 6, having throttle valve '7, to a suitable dephlegmator 8. The incondensable gases and vapors which are not condensed in the dephlegmator pass through line 9, having throttle valve 10, to condenser 11 and thence to receiver The last mentioned is provided with gas outlet 13 having throttle valve 14 and liquid drawoii 15 having throttle valve 16.

Raw oil may be fed to the dephlegmator from a suitable source of supply through line 17, valve 65 and pump 18. The reflux condensate and raw oil in the dephlegmator 8 may be fed to the coil 2 through line 19 by means of pump 20. If desired, the raw oil in whole or in part may be fed direct to the coil 2 through line 21, having valve 22, this line 21 being in turn connected to pump and line 19, as shown.

The residue may be continuously drawn oil through the line 23 into flash chamber 24, the line 23 being provided with a pressure reducing If desired, more or less of the oil going through the pipe 19 may be directed into the flash chamber. To this end I have provided branch line 26, having throttle valve 27, and in the line 19 Ihave provided valve 28. A second valve 29 may be interposed in the line 23. The

(Cl. 196-49) I arrangementis such that the raw oilmay, if desired, be fed direct through line 21, in which event no raw oil will be fed through the line 17, and the temperature of the dephlegmator may be controlled in other well known ways. If so desired, all of the reflux may pass into the flash chamber, valve 28 being closed, or valves 28 and 2'7 be so regulated that only a portion of the reflux condensate will pass into'the flash chamber. 1

After the oil enters the flash chamber at reduced pressure further distillation takes place and the vapors pass out through line 30 having valve 31, into condenser 32 and thence into receiver which provided with gas release line 60 having valve 61 and with distillate drawofi line 62 having valve 63.

The material remaining unvaporized in the flash chamber 24 after flash distillation has taken place is drawn out from chamber 24 through line 34, having valves 35, 36, 64 and pump 37 interposed therein whereby the material withdrawn from the flash chamber 24 may be passed through a heating coil 38 positioned in a furnace 39 provided with suitable burners 40. After passing through coil 38 the oil is discharged through line 41, having control valve 42, and discharged into chamber 43, where separation of vapors and unvaporized materials takes place.

The vapors separated in chamber 43 may pass 35 from said chamber through line 44, having valve 45 interposed therein, thence to condenser 46 to receiver 47, having usual gas drawoif line 48, controlled by valve 49, and distillate drawoff line 50, having valve control 51.

The vacuum pump 52 may be connected to the gas space of receiver 47, and a distillate drawoff pump 53 may be connected to the distillate drawoff line 50 through branch line 54, having valve 55, for a purpose hereinafter described.

Chamber 43 may be provided at the bottom with drawoff line 56, having control valve 57. If desired, and depending upon the characteristics of the reflux condensate formed in the dephlegmator 8 of theprimary cracking zone, the said reflux condensate may in turn be directed to the flash chamber 24 in admixture with the residual oil from chamber 5, but the reflux condensate in whole or in part may be passed directly to the heating coil 38 by means of by-pass line 59, having valve 58 therein. If such operation is utilized the residuum from chamber 5 will alone be subjected to flash distillation and flashed residuum removed from chamber 24 will mix with a part of or all of the reflux condensate from the dephlegmator 8 to pass through the heating coil 38.

As a feature of the invention, the conditions maintained on the primary cracking zone are preferably such that the residuum removed therefrom is substantially free from sludge and coke. In this manner the flash residuum removed from flash chamber 24 may not contain more than such proportion of sludge and coke therein that would render further cracking of said residuum impractical.

As a feature of the invention, said flashed residuum removed from chamber 24 in admix ture with the unvaporized portion of part or all of the reflux condensate from dephlegmator 8, if such reflux has been directed to flash chamber 24, or any admixture with a part or all of the reflux condensate, without subjecting the latter to flash distillation, is subjectedto temperature in heating coil 38 capable of promoting further conversion of the mixture. The conditions maintained upon said heating coil 38 are such that 'the products of conversion separate in chamber 43 into gas and vapors and a substantially solid or non-fluid or coke-like residuum. To this end high temperatures of the order of say 900 to 1200 degrees F. may be maintained on the oil passing through the heating coil 38, While this coil may be maintained under superatmospheric, atmospheric or sub-atmospheric pressure.

The chamber 43 may also be maintained under superatmospheric, atmospheric or sub-atmospheric pressure, but it is a preferable embodiment of the invention that to enhance the vaporization of the products of conversion from heating coil 38 a relatively low pressure, or atmospheric or sub-atmospheric pressure, may be maintained on chamber 43. For this purpose a differential pressure may be maintained between the heating coil 38 and the chamber 43. Pump 37, valve 42, valves 5 and other valves shown on the condensing and receiving apparatus connected to the upper part of chamber 43 permit the maintaining of equalized or such difierential pressures or vacuum as is desired in the system. In the event that a vacuum is to be maintained either on chamber 43 or on heating coil 38 and chamber 43 together, vacuum pumps 52 and 53 are used.

As an illustration of an operation of the process, the oil may be heated in heating coil 2 to a temperature of say Bill) to 1000 degrees F., under a pressure of say 200 pounds, more or less. The chamber 5, dephlegmator 8, condenser 11 and receiver 12 may be maintained under the same pressure as the heating coil, or under differential pressures. The residuum removed from chamber 5 may be passed to the flash chamber with a part of the reflux withdrawn from dephlegmator 8, and there the pressure on the mixture may be reduced to say 25 to 50 pounds, more or less. The mixture of flashed reflux and residuum removed from the bottom of flash chamber 24 may be passed through the heating coil 38 under a pressure of, say 25 pounds more or less, and heated therein to a temperature of approximate- 15 1900 degrees F. The products from the heating coil 38 may be passed to chamber 43 and may be maintained under a pressure of say 10 pounds per square in absolute pressure.

In such an operation a substantial non-fluid residuum is produced in chamber 43 and a yield of say 58 to 60% of end point gasoline may be produced from the process.

I claim as my invention:

A hydrocarbon oil cracking process which comprises heating the oil in an initial heating zone to cracking temperature under pressure, sep arating the heated oil into vapors and an unvapo'rized oil substantially free of coke, deph1eg-- mating said vapors thereby forming reflux condensate, flash distilling said unvaporized oil by lowering the pressure thereon, combining the residuum of the flash distillation with portions of said reflux condensate, passing the resultant mixture in a restricted stream through a second heating zone and heating the same therein. to a cracking temperature adequate to enable subsequent separation of the mixture into vapors and a coke-like residue, discharging the thus heated mixture into an enlarged zone and separating the same therein into vapors and a coke-like residue.

GUSTAV EGLOFF.

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