US2046898A - Process for converting petroleum oil - Google Patents

Description

W. R. HOWARD PROCESS FOR CONVERTING PETROLEUM OIL Original Filed March 4, 1927 ATTORNEY.

July 7, 1936.

a m w m 0 E -illlllllliiiilliiz V 3 Vl.l||||||||||||-!|||.|I||| I m n u a Y m .fi b R Q 8 8 k 2. h t 2 g at aw m J a N a w x a h k Ma w Q w Q a. R w Q Q Q R SQ N \m S 7 mwv xv -H- av Q Q n RR k w i \v -u h k W :2 |A|||| 8m Q -1 w Patented July 7, 1936 UNITED STATES- PROCESS FOR CONVERTING PETROLEUM OIL William R. Howard, Washington, D'. 0., assignor to Universal Oil Products Company, Chicago,

111., a.- corporation of Application March 4,

South Dakota- 1927, Serial No. 172,837

Renewed February 14, 1933 6 Claims.

This application is in part a continuation of my application Serial Number 525,094, filed December 27, 1921.

This invention relates to a process and apparatus for converting petroleum oil and refers more particularly to a process in which hydrocarbonoil is converted into lower boiling point fractions which are vaporized and condensed separately as distillate. As a further feature of the invention,

the vapors formed during the conversion of the hydrocarbon oil are subjected to a series of dephlegmations and the reflux condensates formed in said dephlegmations are separately retreated under suitable conditions to cause further conl5 version thereof.

The single figure is a side elevational view of an apparatus which can be used to carry out the process.

In operation, the oil is introduced from storm age through the line I and is charged by means of pump 2 through the line 3, controlled by valve 4, into the heating-coil 5- mounted in a.

furnace 6. The-oil in the coil is raised to a temperature at'which substantial conversion of the 5-011 is promoted. The hot oil from the still 5 passes through line I, controlled by, valve 8, into reaction chamber 9 in which the greatest part ofthe. conversion takes place. During the conversion, a pressure of the generated vapors' is maintained upon the oil in heating coil 5 and reaction chamber 9. From time to time, or continuously, according to the rate of reaction, the heavier or residuum oil separated in reaction chamber 9 may be drawn oii through the lines I0, controlled by valves II. The reaction chamber 9 is also provided with suitable cleaning man-holes (not shown). The vapors evolved during the conversion pass ofi from reaction chamber 9 through line I2, controlled by valve I3, into a partial condenser or dephlegmator I4 in which partial condensation or fractionation of said vapors occurs, being assisted in any usual manner, such as the introduction of a. cooling medium at the top of the dephlegmator I4. The unc0ndensed vapors from condenser I4 pass out through line I5, controlled by valve I6, into a second dephlegmating tower IT in which further fractionation and condensation of another portion or the vapors occur. The vapors which are still uncondensed in dephlegmator I'I pass off the top thereof, through line I8, controlled by valve I9, into condensing coil 20,. and thence through line 2|, controlled by valve 22, intoreceiver 23, where said vapors are collected as liquid distillate. This receiver is provided with gas and distillate draw-offs respectively shown at 24 and 25, and controlled by valves 26 and 21.

Referring back to dephlegmator I4, the reflux condensate which is separated out in dephlegmator I4 is drawn oil the bottom thereof through line 28, in which may be interposed a hot oil pump 29,- controlled by valves 30. The hot oil pump 29 may be by-passed, and the reflux condensate from the dephlegmator I4 passed through line 3!, controlled by valve 32. The reflux condensate from line 28 isthence charged through heating coil. 33 positioned ina furnace 34.; This reflux condensate will be subjected in heating coil 33 to further conversion.

The furnace 34 can be heated in any suitable manner, and I have shown, for instance, that it can'be heated by the spent combustion gases from furnace 6 in which the oil was originally heated. This can bedone by closing damper 35 and opening damper 36, or, if desired, damper 35 can be opened and damper 36 can be closed, andfurnace 34 can be independently heated, for instance, by means of burner 31.

.The reflux condensate from dephlegmator I4, after being heated to proper temperaturein heatthe coil 33, is discharged into separating chamber 38 and the vapors separated will pass off through line 39 and line 40, controlled by valve M, and combining with the vapors from dephlegmator I4 in line I5, they will be subjected to dephlegmation in the dephlegmator I I. I

If it-is desired to separately collect the vapors formed in the conversion of the reflux condensate from dephlegmator I4, said vapor evolved in chamber. 38 can be passed through line 39- and through line 42, controlled by valve 43 (valve 4I- being closed), into dephlegmator 4'4 in which fractionation of the vapors is eifected in any well-known manner. The vapors are condensed in dephlegmator 44, passed up through line 45, controlled by valve 4%, into condenser 4.1, and thence throughlinela into the receiver 49 provided with gas and distillate draw-offs 50 and 5|, controlled by valves 52 and53.

The portions of the' reflux condensate from dephlegmator I4 which have not vaporized in separating chamber 33 after retreatment of .said reflux. condensate through heating coil 33,- are withdrawn from chamber 38 through line 54, controlled by valve 55; and can be evacuated to storage or: elsewhere. The reflux condensates. separated. out. in. dephlegmator 44 can also be Withdrawn. therefrom through line 56, controlled by valveS'I, anddirected to storage or elsewhere. But in a preferred. form of operation, the unvaporized portions collected in chamber 38, or the reflux condensate formed in dephlegmator 44, or both, are subjected to further conversion in the manner hereinafter described. The unvaporized oil draw-off line 54 is provided with a branch 58 controlled by valve 59, whereby said unvaporized oil can be directed into line 60. Also, reflux condensate draw-ofi line 60 is provided with a branch 6| controlled by valve 62, whereby the reflux condensate from dephlegmator 44 can be directed into said line 60. In this manner, the reflux condensate from dephlegmator 44, or the unvaporized oil from expansion chamber 38, or both, are directed to pump 63 controlled by valve 64, and charged through line 65 into a heating coil 66 positioned in a furnace 61. The pump 63 can be by-passed by means of line 68 controlled by valve 63.

This heating coil 66 is supplied both with the unvaporized products of the conversion of the reflux condensate formed in dephlegmator l4, hereinbefore described, and with the reflux condensate formed in dephlegmator l1. Referring back to said dephlegmator H, the reflux condensate formed therein is discharged at the bottom thereof, through line 10 and charged by means of pump ll, controlled by valves 12, through line 73 into heating coil 66. Pump H can be by-passed through line 14, controlled by valve 15.

In the heating coil 66, the condensate returned from dephlegmator l7, and the liquid fractions drawn off from chamber 38, or dephlegmator 44, or both, are subjected to conditions of temperature and pressure sufficient to produce further conversion. The hot oil from the heating coil 66 passes into reaction chamber 16, and the vapors separated in this reaction chamber pass out therefrom through line 11, controlled by valve 18, into dephlegmator H, where they are subjected to reflux condensation with the vapors from dephlegmator I 4 and chamber 38.

If desired, the vapors evolved in reaction chamber 16 can be separately condensed and collected by usual means which, for the sake of simplicity, have not been shown in the diagrammatic drawing. In this case valve 18 on line 11 is closed and valve 18 is opened on branch line l1 leading to conventional dephlegmating, condensing, and collecting means such as shown in connection with chamber 38. If these vapors are separately recovered, and if reflux condensate is formed during dephlegmation of these vapors, said reflux can be subjected to further treatment or separately collected.

The unvaporized oil from reaction chamber 16 is withdrawn therefrom through line 19, controlled by valve 80 and can be led to storage or elsewhere through line 8!, controlled by valve 82. Or said unvaporized oil can be directed through line 83 in which is interposed a pump 84, controlled by valves 85, back into the charging line 3. Pump 84 can be by-passed through line '86, controlled by valve 81.

The conditions of operations maintained on the various parts of the system will be regulated according to the characteristics of the materials .treated, and of the products desired. Where the material is more refractory than that from which it originated, the conditions of retreatment will be more severe in temperature and pressure than the conditions of the primary treatment. For instance, if the reflux condensate from the primary treatment is more difiicult to crack than the raw oil which is being charged into the system, it is necessary to increase the temperature and pressure conditions to a point necessary to produce conversion of the reflux condensate. This, if the reflux condensate had been retreated with the raw oil in the primary part of the sys tem, would have caused from the originally treated raw oil the formation of undesirable constituents, such as carbon and gas, while where the reflux condensates are retreated separately as in the hereinbefore explained process, the conditions on the various parts of the system are maintained independently from each other and can be regulated to give the best results in each part of the process and avoid, for instance, overheating and undue formation of coke and gas in the treatment of the original raw oil.

For instance, in one method of operation, the reflux condensate originated in the initial dephlegmation of the vapors from the primary part of the system can be subjected to retreatment in heating coil 33 under increased temperature under a pressure which can be higher or lower than that maintained on the heating coil 5. For instance, in this method of operation the oil in heating coil 5 is brought to a temperature of say 850 F. under 400 pounds pressure, more or less, the reflux condensate from dephlegmator 14 may be retreated in heating coil 33 and may be brought to a conversion temperature of 900 F, under a pressure of 500 pounds, or, if the characteristics of said reflux condensate permit, it can be brought to the same temperature of 900 F. under a pressure of only 300 pounds. The charging stock treated in heating coil 5 may be such that the condensate formed in dephlegmator l4 can be relatively easily converted and if so, the temperature at which said reflux condensate will be subjected in heating coil 33 can be lower, for instance 800 F., than that at which the original charging stock is subjected in heating coil 5, for instance 850 F. In this case, again the pressure on the heating coil 33 may be higher or lower than that maintained on the heating coil 5.

Referring back to the materials treated in the third cracking operation in heating coil 66, the conditions of pressure and temperature will be regulated according to the material treated therein and the products desired. For instance, the pressure maintained on the heating coil 65 may be lower than both pressures maintained on heating coils 5 and 33, or it can be higher than both said pressures. On the other hand, the pressure on the heating coil 66 may be intermediate the pressures maintained on heating coils 5 and 33. The temperatures on the heating coil 26 will also be varied according to the product desired, and can be higher, intermediate, or lower than the temperatures maintained on heating coils 5 and 33. In the treatment of some oils, the reflux condensate formed in the secondary dephlegmator, in dephlegmator H, is more difficult to crack than the reflux condensate formed in dephlegmator i l and in this case, the temperature and pressure maintained on heating coil 36 will preferably be higher than those maintained on heating coil 33. But, on the other hand, some oils, preferably of a parafiine base, have such characteristics that the lighter reflux condensate formed in dephlegmator I? can be converted under relatively mild conditions. Ifsuch is the case, the pressure and temperature maintained on heating coil 66 need not be higher, and can be lower, than the temperatures and pressures maintained-= onheatingcoil 33. The condition of tem dephlegmatorl4, and-*which is the unconverted oil from chamber 38 or condensate from dephlegmator 44, or both, as heretofore described. In the example heretofore given where the heating coil 5 was maintained under a pressure of 400 pounds at a temperature of 850 F., and heating coil 33 was maintained under a pressure of 500 pounds at a temperature of 900 F., heating coil 66 may be maintained at a temperature of 875 F. at a pressure of 450 pounds, more or less, or at a temperature of 1000 F. under a pressure of 600 pounds, more or less. Again, this heating coil 66 can be subjected to temperatures such that will raise the oil passed therethrough to a temperature of 800 F. under a pressure of 250 pounds, when the pressure on the coil 33 is maintained at 300 pounds.

Because of the great flexibility of this process, and of the innumerable variety of characteristics of the oil which may be treated, it will not be attempted to further illustrate other conditions of operations which can be maintained on the various parts thereof, as the determination of said conditions are well within the skill of the operator.

In the above description I have only illustrated the relative pressures and temperatures maintained between heating coils 5, 33, and 66 of the three interconnected treating zones.

The various valves and pumps shown, .allowed to maintain such difierent pressures, have been described between said various parts of the system. In each conversion zone, the expansion chamber and dephlegmator connected therewith can respectively be maintained under the same pressure as its heating coil, or the dephlegmators can be maintained undera pressure reduced below the pressure of the chamber, or above atmospheric pressure, or it can be reduced to atmospheric pressure. In the same manner, the condensing and collecting parts of each zone can be maintained under the same pressure as the balance of its corresponding zone, or under reduced or raised pressure.

I claim as my invention:

1. A hydrocarbon oil cracking process which comprises subjecting the charging oil to cracking conditions of temperature and pressure and separating evolved vapors from unvaporized oil, subjecting said vapors to primary dephlegmation to condense heavier fractions thereof as reflux condensate, heating said reflux condensate independently of the charging oil to a cracking temperature in excess of that to which the charging oil is heated, combining the vapors evolved by such heating of the reflux condensate with the vapors uncondensed by said primary dephlegmation, and subjecting the resultant vapor mixture to secondary dephlegmation thereby forming secondary reflux condensate, and subjecting said secondary reflux condensate to temperature and pressure conditions adequate to effect substantial cracking thereof and fractionating vaporous products of this cracking step in admixture with the vapors undergoing secondary dephlegmation.

2. A cracking process which comprises heating hydrocarbon oil to cracking temperature under pressure and separating resultant vapors, simultaneously subjecting additional hydrocarbon oil,

comprisingheavier fractionshof said vapors, to independently controlled crackingiconditions of temperature and pressure 'and separating vapors. therefrom, combining vapors evolved fromisaid additional 'oil with vapors evolved from the: firstmentioned oil r and dephlegmating the resultant vaporous mixture thereby forming reflux condensate, cracking such reflux condensate independently of the first-mentioned oil and said additional oil, and combining vapors formed by the cracking of the reflux condensate with the vaporous mixture undergoing dephlegmation.

3. A cracking process which comprises heating hydrocarbon oil to cracking temperature under pressure and separating resultant vapors, dephlegmating the vapors to condense heavier fractions thereof, subjecting such condensed fractions to independently controlled cracking conditions of temperature and pressure, combining vapors thus evolved from said condensed fractions with the vapors uncondensed by said dephlegmation and dephlegmating the resultant vaporous mixture thereby forming reflux condensate, and cracking such reflux condensate independently of the firstmentioned oil and said condensed fractions and dephlegmating vapors formed by the cracking of said reflux condensate together with said vaporous mixture.

4. A cracking process which comprises heating hydrocarbon oil to cracking temperature under pressure and separating resultant vapors, dephlegmating the vapors to condense heavier fractions thereof, simultaneously subjecting additional hydrocarbon oil, comprising heavier fractions condensed by said dephlegmation, to independently controlled cracking conditions of temperature and pressure, combining vapors thus evolved from the additional oil with the vapors uncondensed by said dephlegmation and dephlegmating the resultant vaporous mixture thereby forming reflux condensate, cracking such reflux condensate independently of the first mentioned oil and said additional oil and dephlegmating resultant vapors together with said vaporous mixture.

5. A hydrocarbon oil cracking process which comprises subjecting the charging oil to cracking conditions of temperature and pressure and separating the same into vapors and residue, dephlegmating the vapors in successive primary and secondary dephlegmating zones, introducing to the secondary dephlegmating zone additional cracked vapors from a concurrently operated cracking system, subjecting reflux condensate from the primary dephlegmating zone to independently controlled cracking conditions of temperature and introducing vapors thus formed to said secondary zone, supplying reflux condensate from said secondary zone to said concurrently operated cracking system and subjecting the same therein to more drastic cracking than the charging oil, and finally condensing the vapors uncondensed by the dephlegmation of said vaporous mixture.

6. A hydrocarbon oil cracking process which comprises subjecting the charging oil to cracking conditions of temperature and pressure and separating the same into vapors and residue, dephlegmating the vapors to condense the heaviest fractions thereof, combining with the dephlegmated vapors additional cracked vapors from a concurrently operated cracking system, dephlegmating the resultant vaporous mixture to condense heavier fractions thereof, supplying resultant reflux condensate to said concurrently operated cracking system and subjecting the same therein to more drastic cracking than the charging oil, subjecting reflux condensate formed in the first-mentioned dephlegmation step to independently controlled cracking conditions of temperature and pressure and combining resultant vapors with said vaporous mixture undergoing dephlegmation, and finally condensing the vapors uncondensed by the dephlegmation of said vaporous mixture.

WILLIAM R. HOWARD.

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