US2010982A - Cracking of hydrocarbon oil - Google Patents

Description

Aug. 13, 1935.

c. P. D uBBs CRACKING OF HYDROCARBON OIL Original Filed May 29, 1930 N fllllillllll /M/f/Wm Carbon j? Dubbs A27/wwf Patented Aug. 13, 1935 UNITED `STATES PATENT OFFICE CRACKING 0F HYDROCARBON OIL Application May 29, 1930, Serial No. 457,000 Renewed November 12,` 1934 4 Claims.

'I'his invention relates to the conversion of hydrocarbon oils, and refers more particularly to hydrogenation of hydrocarbon oils, particularly those which are formed during the cracking process and which are deficient in hydrogen with respect to saturation.

In the conversion o f higher boiling hydrocarbons into lower boiling hydrocarbons at elevated temperatures, and usually under pressure, pitchy material or heavy asphaltic residue may be formed under certain conditions of operation in addition to a carbonaceous product and a gaseous product. Analysis of the gaseous product shows it to contain considerable elementary hydrogen, as well as combined hydrogen. When the process is operated to produce a heavy fuel oil, this product contains a much higher ratio of carbon and hydrogen than the motor fuel product, and it is possible by the addition of hydrogen to the heavier hydrocarbon to supply this hydrogen deficiency and convert the same into a lower boiling product suitable for motor fuel; otherwise the chief product of further reaction or cracking of the heavy residue is coke and gas.

It is not the object of this invention necessarily to completely saturate the motor fuel product with respect to hydrogen, that is, to have all the carbon atoms of the molecules of the gasoline hydrocarbons contain all of thehydrogen which the quadrivalent character of the carbon atom demands. So far as the motor fuel product is ccncerned, it is quite desirable that ysome of the components be unsaturated, and particularly belong to that group of unsaturated carbons known as the mono-oleflns. However, it is desirable that the reaction be carried out in such manner as to convert an otherwise heavy asphaltic product defi- -cient in hydrogen into lower boiling hydrocarbons and to prevent the formation of carbon by causing the same to enter into combination with hydrogen before separating out as such.

In carrying out my invention I aim to effect a balance so that the hydrogen which separates out in the gas, either as such or in combined form,

will enter into combination with components of a pitchy or asphaltic nature, or will`prevent their amples of which are potassium, sodium, calcium, barium, strontium, magnesium, aluminum, zinc, tin,` iron,. chromium, nickel, manganese, copper, silver, platinum, palladium and osrnium. Oxides lof the metals may also be used, as well as other 5 compounds of the said metals.

Referring to the accompanying drawing diagrammatically illustrating the process, the raw oil is charged through line I, controlled by valve 2, and is forced by means of pump 3 into line 4, 10 controlled byvalve 5, and thence into heating coil 6 located in furnace' setting l. The heated oil leaves the heating coil 6 through transfer line 8, controlled by valve 9, and is discharged into reaction chamber I0 maintained under conversion and 15 hydrogenation conditions of temperature and pressure. "Ihe non-vaporized liquid residue from reaction chamber I0 is withdrawn through line I I and may be removed from the system through line 52 and valve 53. Preferably, however, the 20 liquid residue is passed through valve I2 to further treatment in a manner which will hereinafter be described.

The vapors separated in reaction chamber I0 pass through vapor line I3, controlled by valve I4, and enter dephlegmator or fractionating column I5. A portion or all of the raw oil can be pumped through line I 6, controlled by valve I1 into dephlegmator I5 where it undergoes heat exchange with the ascending vapors, condensing a portion thereof and becoming heated. The reflux lcon-- densate from dephlegmator I5 together with unvaporized raw oil is returned to the heating coil 6 for reconversion through line I8, controlled by valve I9, and through hot oil pump 20 and line 2 I, 35 controlled by valve 54.` The suiiiciently converted vapors leaving ."dephlegmator I5 pass through line 22, controlled byvalve 23, into cooler and condenser 24, the condensate being collected in receiver 25. Valve 55 assists in controlling the 40 flow of the fluids into the receiver, as well as to control the pressure `upon the condenser.

The distillate collected in receiver 25 is passed through line 26, controlled by valve 21, to storage.

A portion of this distillate, however, is preferably withdrawn through line 56 and valve 51 and by means of pump 58 may be returned through line 59 and valve 60 to thedephlegmator I5 to assist in the cooling of the vapors therein and to assistJ in controlling the character of the distillate passing into receiver 25. The uncondensed gas is removed through line 28, controlled by valve 29, which valve may also be used to control pressure upon the entire system. A portion of the gas may then be passed to storage or diverted for other uses and this portion may be scrubbed or otherwise treated to remove the condensabl'e material therefrom. Any desired amount of gas is recirculated to the process through line 3|, controlled by valve 32, and is boosted to any desirable pressure by pump orA compressor 33. The gas may be returned directly to the heating element 6 through line 3|, valve 32, pump 33, line 34 and valves 35 and 36, or it may be passed, all, or in part, by the manipulation of valves 30 and 35, prior to injection to heating coil 6, into the heating element 31 located in furnace setting 38 to be heated to a temperature which will cause both cracking and polymerization, increasing the hydrogen content of the gaseous product entering heating coil 6, as well as increasing the total liquid product formed from the process by the polymerization of a portion of said gases. The temperaturel to which the gases may be heated in heating element 31 may vary between 800 and 1500 F., more or less. The gases leaving heating element 31 pass through valves 39 and 36 and line 34 into heating coil 6.

The catalyst, preferably in suspension in the charging oil, is introduced into heating coil 6 by means of pump 40 through line 4I, valve 42, and line 4 and valve 5.

The liquid residuum, including any vapors leaving reaction chamber IIJ through line II, controlled by valve I2, may be passed into heating element 46 located in furnace setting 41 for separate treatment with the gas which may enter line II directly from line 34 through line 43, controlled by valve 44, and through line 49, or from the heating element 31 through valves 39 and 48 and line 49. The catalyst for assisting in the hydrogenation ofthe residuum is introduced into line I I through pump 40, line 50 and valve 5I. The residual ma-` terial treated together with gas and catalyst in heating element 46 is preferably passed to a vaporf i'zlng vessel and associated dephlegmating and condensing equipment (not shown) through line 45 and valve 6I for recovery of the vapors evolved and the final liquid residue may be removed to storage. A portion or all of the residuum may be withdrawn through line 52, controlled by valve 53, and may be passed to storage or into a chamber (not shown) under reduced pressure where it may undergo flashing or vaporization. The distillate resulting from the vaporization of the residue so treatedmay be returned for further conversion into the heating element 6, and the residue from this flashing zone may be returned to heating element 46 for treatment in the manner described for the non-vaporlz'ed liquid residue leaving reaction chamber I0.`

As examples of operating conditions, the pressure upon heating element 6 and on reaction chamber II) may vary from pounds per square inch, more or less, to several thousand pounds. Differential pressures may be maintained upon these elements which in the case of heating element 6 and reaction chamber I0 will be controlled by valve 9. Likewise, the pressure on heating elements 31` and 46 may be controlled over a wide range varying from 100 pounds per square inch, more or less, to several thousand pounds. The pressure upon any of these heating elements may be independently controlled by means of pumps (not shown). The temperatures in heating elements 6, 31 and 46 may vary from 800 F., more or less, to l400 F., more or less. i

As examples of the yields of products obtained-- by my process: Mid-Continent topped crude was treated. which would normally produce, by nonresiduum operation, 60% gasoline; 50 pounds of coke per barrel; 650 cubic feet of gasper barrel, and the remainder a gas oil known as pressuredistillate bottoms; whereas, by my process I may be able to obtain 70% gasoline, 30 pounds of coke per barrel and 300 cubic feet of gas per barrel, in addition to the pressure-distillate bottoms, the

. most desirable product, gasoline, being increased,

while the least desirable products, namely, gas and coke, are decreased. The results will vary depending upon the manner of treatment; for example, preheating the gas will increase the yield of liquid products as will also the heat treatment of the residuum oils while passing the gas therethrough or varying the conditions of treatment on the reflux condensate passing through `heating element 6, e. g., increasing the temperature will increase the anti-knock value of the gasoline produced. It is obvious that increased temperature and pressure on heating element 46 will increase the conversion of the residual oil passing therethrough and increase the overal] yield of low boiling products.

It will be understood that the above examples are purely illustrative, and that the results obtained will vary accordng'to the conditions of treatment and kinds of charging stock used, and

that my invention is not limited in any manner by the examples cited.

What I claim as my invention is:

1. A process which comprises subjecting hydrocarbon oil ina cracking zone to cracking conditions of temperature and sufficient pressure to maintain a substantial portion thereof in liquid phase and separating the same into vapors and unvaporized oil, passing 'said unvaporized oil, without substantial cooling thereof, to a`hydrogenating zone, dephlegmating said vapors to condense insuiiiciently cracked fractions thereof and returning resultant reux condensate to the cracking zone, finally condensing the dephlegmated vapors and separating the distillate thus formed from the incondensible gases produced in the process, introducing at least a portion of said gases to said hydrogenating zone, Vintroducing another portion of said gases to said cracking zone to saturate unsaturated constituents of the light cracked product, subjecting the unvaporized oil in the hydrogenating zone to hydrogenating conditions of temperature and pressure 4adequate to form lower boiling hydrocarbons therethereto, the last named pressure being sufficient to maintain a substantial portion of the unvaporized oil in liquid phase in the hydrogenating zone and recovering the resultant hydrogenated products.

2. The process` as deflned in claim 1 further characterized in that the incondensible gases, prior to introduction to the cracking and hydrogenating zones, are heated to temperature adequate substantially to increase the free hydrogen content thereof.

3. A conversion process which comprises subjecting hydrocarbon oil in a cracking zone to cracking temperature under sufficient pressure to maintain a substantial portion thereof in liquid phase, separating the heated oil into vapors and unvaporized oil, lpassing at least a portion of the separated unvaporized oil, without substantial cooling thereof, to a hydrogenating zone, condensing said vapors and separating therefrom the incondensible gases produced in the process, in-

'from in the presence of the gases introduced troducing separate portions of said gases to the 75 cracking temperature4 under suilcient pressure to i cracking zone and to the hydrogenating zone, subjecting the unvaporized oil in the hydrogenating zone, in the presence ofthe gases introduced thereto, to hydrogenating conditions of temperature and pressure adequate to form lower boiling hydrocarbons therefrom and to maintain a substantial portion of the unvaporized oil in liquid lphase, and recovering resultant hydrogenated products.

4. A conversion process which comprises subjecting hydrocarbon oil ina'cracking zone to maintain a substantial portion thereof in liquid phase, separating the heated oil into vapors and unvaporized oil, passing at least a portion 'of the separated unvaporized oil, without substantial cooling thereof, to a hydrogenating zone, condensing said vapors and separating therefrom Vthe incondensible gases produced in the process, heating such gases to a temperature adequate substantially to increase the free hydrogen content thereof and then introducing separate portions thereof to the cracking zone and to the. hydrogenating zone, subjecting the unvaporized oil in the hydrogenating zone, in the presence of the gases introduced thereto, to hydrogenating conditions of temperature and pressure adequate to form lower boiling hydrocarbons therefrom and to maintain a substantial portion of the unvaporized oil in liquid phase, and recovering resultant hydrogenated products.

CARBON P. DUBBS.

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