US1897618A - Recovering condensable vapors from incondensable gas - Google Patents

Description

Feb. 14, 1933. J. c. MORRELL 1,397,518

RECOVERING CONDENSABLE VAPORS FROM INGONDENSABLE GAS Filed Nov. 25, 1929 2 Sheets-Sheet 1 Feb. 14, 1933. J. C. MORRELL 1,397,618

BECOVERING CONDENSABLE VAPORS FROM INCONDENSABLE GAs Filed Nov. 25, 1929 2 Sheets-Sheet 2 Fla. 2

Patented Feb. 14, 1933 UNITED STATES PATENT @FFEfiE JACQUE C. K031831513, OI GHICAGO, 11515117018, ASSIGNOB TO UNIVERSAL PRODUCTS COMPANY, 01' CHIGAGO, ILLINOIS, A COBPOBATION.OI BQUTH DAKOTA BEGOVEBING CONDENBABLE M2038 m1: INGONDENSABLE GAS Application fled Iovember 85, 1988. Serial No. 400,487.

This invention has for its purpose the removal of gasoline from the uncondens'able gases produced in the crackln of oils; the stabilization of the pressure istillate, and the removal'of gasoline or condensable materials from the gases produced during this stabilization, as well as frorn the see evolved from the pressure distillate when the pressure thereon is reduced.

In the commercial cracking processes in,

common use the pressure distillate is usually a very unstable roduct, havingdissolved in it a relatively arge quantity of non-condensable gas, which in handling escapes, carrying with it substantial percentages of the valuable condensable hydrocarbons. Moreover, the non-condensable or fixed gases released from the high pressure receiver usually contain certain percentages of condensable materials. The escaping vapors from the pressure distillate as well as the fixed gases are normally passed throu h an absorption plant in refineries emp oying the cracking process. This procedure involves the use of auxiliary equipment entirely apart from the cracking plant, and requires special and more or less expensive heating means for recovery of the gasoline absorbed.

In the improved method of operation which is the main object of this invention I am able to use the heat available in the cracking plant for the recovery of the absorbed gasoline which of course will have the additional effect of more economical operation of the cracking plant by reducing the quantity of condensing and cooling water required therein.

Fig. 1 and Fig. 2 together constitute a diagrammatic side elevational view of an apparatus in which my process may be carried out. Raw oil is supplied through line 1,

pump 2, and valve 3 to dephlegmator 4,-

where it aids in partial condensation of the vapors entering the dephlegmator through line 18. The reflux condensate therefrom, together with the pro-heated raw oil, passes out of the bottom of dephlegmator 4 through line 5 and by means of pump 6 and line is charged to heating coil 8, valve 3' being of furnace capable of heating the oil to the desired crackmg temperature may be employed. The heated oil then passes out through line 11, controlled by valve 12, to

reaction chamber 13, from which the unva-' porized residue may be withdrawn through line 14, controlled by valve 15.

The va ors from reaction chamber 13 are removed t rough line 16, controlled by valve 17, and introduced, wholly or in part to dephlegmator 4 through line 18, controlled by valve 18. Vapors from the dephlegmator discharge through line 19, controlled by valve 20, to condenser 21. The condensate and uncondensable as will pass out through line 22, controlled by valve 23, to receiver 24. The uncondensable gas from the latter may be released through line 25, controlled by valve 26, to a bottom section of absorber 27. The condensate from receiving drum 24 passes by means of line 28 and valve 29 to a stabilizing drum or low pressure distillate receiver 30. A portion of the condensate may, however, be returned through valves 31 pump 32, line 33 and valve 33 to the top of dephlegmator 4 to facilitate fractional condensation therein.

A heating means is provided in stabilizing drum 30 as hereinafter described. Vapors from drum 30 discharge through valve 34' and line 34, in which may be interposed a pump 35, if required, to the bottom of absorber 27. Absorbing oil is supplied to the an improved method whereby a very stable out from vaporizer 44 through line 44' into fractionating tower 45 in va or form and out through line 46, controlle by valve 47, to condenser 48, and finally to receiver 49. The pressure on the latter may be controlled by valve and the absorption asoline withdrawn through valve 51 for binding with na htha or heavier asoline.

In or er to facilitate t e vaporization of the absorbed gasoline from the absorption oil, steam may be introduced through line 52 and valve 53, although in many instances this procedure will not be necessary.

Heat is supplied to vaporizer 44 in either one of two ways; first, by passing a certain portion of va ors from the reaction chamber 13 through lme 16 and valve 54 in indirect contact with the absorbing oil in va orizer 44 by means of tubes. The cooled an artially condensed vapors then pass out rom vaporizer 44 through valve 53' line 55, and valve 56 (valve 57 b ein closed) back to dephle ator4. The ot er means of heating w' be to pass the vapors from de hlegmator 4 through line 58 and valve 59 l valve 54 in line 16 being closed) and then in indirect heat exchange relation with the absorbent oil in vaporizer 44. The cooled and partially condensed vapors then pass out throu h valve 53 line and valve 57 (valve 56 be1n closed) to condenser coil 21. The strippe absorption oil is discharged from va orizer 44 through line 60, and by closing va ye 61, and opening valve 62 may pass through a coil 63 in stabilizing drum 30, emergln from the coil through line 64, valve 65, and if necessary through a cooler 66 for recirculation through line 67 valve 68, pump 38 and line 39, back to the top of the absorbing drum 27. In this manner the pressure distillate is freed of its excessively light fractions by va orization thereof.

It will be un erstood of course, that any desired de ree of heat for stabilizer 30 may be obtaina le by manipulation of valves 61, 62 and normally only a relatively small portion of the hot, stripped absor tion oil will pass through coil 63, although do not wish to limit myself to this partlcular type of operation, and I may find it necessary, under certain conditions, to pass all or any part of the absorption oil through coil 63. Vapors may also ass through coil 63 from line 19 through val e 57, lines 55, 55, valve 62 and return through valve line 42' back into line 55. Valves 53', 62', 62 and 65 are control and by-pass valves. In like manner by means not shown heat from the vapors enterin vapor line 16 ma be utilized. The stabi ized pressure distil ate from stabilizer 30 will pass out through line 69 to cooler 70 and finally to storage or for chemical treatment throu h valve 71.

It will t us be seen that I have devised 900 F. and dpressure on the receiving drum of 200 poun A yield of 68% of pressure distillate was recovered, havin a gravity of 57.5 and an initial boiling-pomt of 115 F. This distillate was chemically treated and rerun with a loss of only 2%. A 3.5% yield (based on the raw oil) of a 73 gravity absorption gasoline was recovered by the process having an initial boilingflpoint of 75 and'an en point of 280 F. is material, after caustic washing, was blended with a heav 50 B6. naphtha into a gasoline meeting S. motor specifications. The incondensable gases in this operation from the absorber contained only 0.05 llons per 1000 cubic feet of condensables y the charcoal method.

In another operation, in a similar cracking unit not employing my improved process for stabilization, operating upon the same char in stock, 67% of pressure distillate was 0 tamed, having a gravity of 59 and an initial boiling point of F. Upon treatment and rerunning this material lost 5%. Also the non-condensable gases from the unit contained 0.75 gallon gasoline per 1000 cubic feet. Comparison of these two operations shows the advanta es my improved operation has in the crac 'ng of hy rocarbon oils.

I claim as my invention:

1. The method of recovering condensable vapors from the incondensable gases of an oil cracking process which comprises scrubbing the gases with an absorption menstruum in a scrubbin zone, passing the menstruum in indirect eat exchange relation with cracked vapors formed in the cracking rocess to thereby volatilize the absorbed hygrocarbons therefrom, passin the heated and denuded menstruum in in meat heat exchange with pressure distillate formed in the cracking to vaporize the more=volatile portions thereof and supplying the latter to said zone, and utilizing the denuded menstruum to scrub additional quantities of gas.

2. The method of treating the incondensable as and pressure distillate formed in the crac kingof hydrocarbon oil which comprises scrubbing the gas with an absorption menstruum in a scrubbing zone, heatin the menstruum to vaporize absorbed by rocarbons therefrom, passin the heated and denuded menstruum in in ect heatexchange relation with the pressure distillate thereby distilling lighter fractions of the latter and cooling the menstruum, porized lighter fractions to said zone for contact with the menstruum therein and recycling the cooled menstruum to said zone.

3. A process for stabilizing pressure distillate obtained in the cracking of h drocarbon oils which comprises heating is e same to distil lighter fractions thereof, absorbing the vaporized lighter fractions in an absorption menstruum, heating the menstruum to separate izing the heated and denuded menstruum in the heating of said pressure distillate thereby cooling the menstruum, and subsequently returning the menstruum into absorption relation with additional lighter fractions vaporized as aforesaid.

4. A process for stabilizing pressure distillate obtained in the cracking of hydrocarbon oils which comprises heating the same to dist-ii lighter fractions thereof, absorbing the vaporized lighter fractions in an absor tion menstruum, heating the menstruum 5y heat exchange with vapors formed in the cracking operation to separate the absorbed lighter fractions, utilizing the heated and denuded menstruum in the heating of said pressure distillate thereby cooling the menstruum, and subsequently returning the menstruum into absorption relation with additiogal lighter fractions vaporized as afore sa1 o In testimony whereof I aifix my signature.

JAGQUE O. MORRELL.

introducing the vathe absorbed lighter fractions, util-

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