US2037933A - Treatment of hydrocarbon oils - Google Patents

Description

April 21, 1936. J. asl-:GUY

TREATMENT OF HYDROGARBON OILS Filed Nov. 22, 1950 Patented Apr. 21, 1936 UNITED STATES PATENT OFFICE TREATMENT oF HYDROCARBON ons Ware Application November 22, 1930, Serial No. 497 ,372 Renewed October 23, 1934 9 Claims.

This invention relates toa process for the treatment of hydrocarbon oils, and refers more particularly to the conversion of hydrocarbon oils of relatively high boiling point range into products of relatively lower boiling point range by the application of heat and pressure and by the use of chemical reagents whereby the yield of hydrocarbons of desired boiling point range is increased and the formation of undesirable fractions of fixed gases and heavy residues is decreased.

In general the maximum yield of hydrocarbons of any given boiling point range that may be expected from the heat treatment or pyrolysis of relatively heavy hydrocarbon oil mixtures is limited by the constitution of the heavy oils treated, or in general the ratio of the percentage of total hydrogen to the percentage of total carbon. Usually an optimum set of conditions can be chosen under which the yieldA of hydrocarbon mixtures of boiling point range suitable for use as fuel in internal combustion engines may be a maximum with the yield of fixed gases and heavy highly carbonaceous residues a minimum. When the severity of these optimum conditions is exceeded the yield of hydrocarbons of the desired boiling point range decreases and the yield of xed gases and carbonaceous residues increases according to general laws governing the carbon hydrogen equilibrium. When the optimum conditions are exceeded to a certain degree there are sometimes produced residues of a semi-solid or pitchy nature in which particles of solid carbon are suspended, these suspended particles tending to reduce the value of the residue as a commercial fuel owing to the tendency for the particles to settle and clog lines, burners; et cetera. One of the objects of the present invention is to allow the production of residues of true liquid character which give less oi the troubles mentioned.

In a specific embodiment of the invention a heavy natural residuum typied by a crude oil from which the gasoline or motor fuel fractions have been removed is pumped through a heating element wherein heat is supplied to initiate desired conversions into lighter hydrocarbon products. The combined products from the heating element may then pass to an enlarged zone in which further reactions of conversion occur and the vaporous products from this reaction chamber pass to a fractionator of any suitable type from which vapors of gasoline boiling point range are evolved, condensed and cooled and the fractionator bottoms returned along with the charging stock for further heat treatment and conversion. The unvaporized portions of the pro- (Cl. ISG-53) ducts from the reaction chamber are preferably reheated, mixed with hydrogen preferably preheated to a suitable temperature and the mixture passed to hydrogenating units wherein reactions occur resulting in the alteration of the heavy material to produce certain percentages oi' light hydrocarbon materials which are separated by fractionation, removed, condensed and collected, such portions of the products of the hydrogenation reaction as are too heavy for gasoline being retreated either in admixture with the original charging oil undergoing treatment or in a supplementary cracking unit.

As a particular example of the operation of the process of the present invention reference is made to the accompanying drawing which shows diagrammatically some of the details of an equipmentl which may be used to effect the process. Pump 3 may take heavy oil from line I controlled by valve 2, and discharge it into line 4 which branches into lines 5 and l, controlled by valves 6 and 8, respectively. Line 'I discharges into fractionator 9 in which the cracked vapors from the primary or liquid-vapor phase cracking unit are undergoing final separation into products of desired low boiling range and a reilux condensate which is to be returned to the primary cracking zone for further heat treatment. The admission of the charging oil to fractionator 9 serves to effect heat exchange with the vapors and incidentally assist fractionation thereof. The reflux condensate from fractionator 9 flows through line I, controlled by Valve I I, into a pump I2 which then discharges into line I3, controlled by valve I4, to line 5, meeting whatever portion of the original raw oil may have been diverted as direct feed to the heating element 2l of the primary cracking unit. Line 5 connects with line 20 which receives from line I8, controlledY by valve I9, some or all of the intermediate liquid products from the hydrogenating zone to be later described. Thus, there may be fed to the heater coil 2| in furnace A'a kmixture of varying proportions of raw oil, reux condensate from the primary cracking zone and reflux condensate from the hydrogenating zone.

In the primary cracking zone temperatures ofV B. and which may contain pitchy or carbonaceous particles up to 50% or more by weight are discharged through line 25, controlled by valve 26, into pump 21 which then discharges into line 28, controlled by valve 29, into heating element 30 disposed in furnace B.v In this element the residue is brought to temperatur-es suitable for subsequent hydrogenating reactions and upon its exit is mixed with a certain excess of hydrogen or hydrogen-containing gases which have been taken by pump 33 from. line 3|, controlled by valve 32, passed through heater coil 34 disposed in furnace C and line 35, controlled by valve 36.

The mixture of heavy oil and hydrogen-containing gases then passes to pump 96 which discharges into line 31', controlled by valve 35', into either of hydrogenating chambers E and F which typify. any number of chambers in series or multiple arrangement. In these chambers suitable catalysts are employed, for example, nely divided metals such as Fe, Ni, Co and their oxides l alone or in combination, pressures of the order of 2000 to 3000 pounds, more or less, and temperatures suitable to the effecting of the desired reactions which are preferably lower than the temperatures employed in cracking reactions.

Also, since the reactions of hydrogenation are in general exothermic, means are provided for abstracting heat in order to prevent undue rise of temperature with attendant reversal of the desired reactions. Lines 95 and 91, controlled by valves 96 and 98, respectively, typify lines through which may be introduced or removed fresh or spent catalytic materials. Lines 99 and controlled by valves |00 and |02, respectively, typify lines leading to suction line |03 to pump |04 which may release residues from the hydrogenating chambers through line |05, controlled by valve |06, or discharge same through line |01, controlled by valve |08, into line 40 through which are flowing the vaporous products from the hydrogenating chambers. These products pass preferably through separator 45 and then to fractionator 48 wherein ultimate separation of such hydrocarbons of desired boiling point range as have been produced in the hydrogenating chambers is effected. Through line 14 containing valve 15 suitable distillates may be admitted to control the quality of the emerging vapors, these distillates being preferably a portion of those produced in receiver 80. These products pass through line .16, controlled byvalve 11, through condenser 18 and liquefied and gaseous products pass through line 19 to receiver 80 from whence the gases may be withdrawn through line 8|, controlled by valve 82 and the liquid products similarly disposed of through line 83, controlled by valve 84. The reux'condensate from fractionator 48, which represents the heavier products from the hydrogenators, is taken through line l either to line I4', controlled by valve I5, to pump I1 or to line 6, controlled by valve I6' to pump 49. Pump I1 discharges through line I8 and valve I9 to line 20 which feeds the heater coil of the primary cracking unit previously described. Pump 49 discharges through line 50 and valve 5| to heater coil 52 of a secondary cracking unit in which preferably higher pressures and lower temperatures are maintained than in primary cracking units, for example, temperatures of the order of 850 to 900 F. and pressures of the order of 400 pounds to 2000 pounds may be maintained on heater coil 52.

The products of the heating in coil 52 pass through line 53 and valve 54 into reaction chamber 55. The liquid residue passes through line 69, controlled by va1ve,10,'into pump 1| which discharges into line 12. Line 61, controlled by valve 68, allows withdrawal of the liquid products as desired and line 12, controlled by valve 13, leads to line 28 and the'preheating furnace 30 already described in connection with the hydrogenating unit. Vapors from the reaction chamber 55 pass through in series a fractionator and condenser similar to that described in connection with the primary cracking unit.

From line 6| containing valve 62 the vapors pass through condenser 63 then through line 64 containing valve 65' to receiver 66'. From receiver 66' such gases as are not to be utilized further in the process are passed through line 61' and valve 68' to suitable storage. Similarly, liquid condensate of proper boiling point range is removed through line69 and valve 10. For accurately controlling the boiling point range of the vapors leaving fractionator 50 pump 13 may take suction on the liquid condensate in receiver 66 through line 1| and valve 12', discharging through line 59 containing valve 60 to the top of the fractionator. The reflux condensate from fractionator 58 passes through line 62, controlled by valve 63, into pump 64 which discharges through line 65 and valve 66 furnishing a combined feed for the heater coil 52 in admixture with the reflux condensate from fractionator 48.

It is evident from the preceding description that a process has been disclosed which admits of operation in numerous Ways. While the essential feature has been shown to be the control of the quality of the more or less pitchy residues tending to be produced in the cracking of heavy hydrocarbon oils, there is effected concurrently an overall increased yield of hydrocarbon oils of motor fuel boiling point range. Troubles with coke deposits are practically eliminated, and in general the efficiency of the cracking process as ordinarily practiced commercially is improved to a material degree.

As a specific instance of the operation of the process of the invention, a 25 gravity topped Mid- Continent crude substantially free from gasoline fractions was fed to the process unit at the rate of 1,000 barrels per day by pump 3, 75% of this being fed through line 1 to fractionator 9 and the remaining 25% through line 5 to line 20 and into heating element 2|. A temperature of 900 to 910 F. was maintained at the exit of heating element 2| and a pressure of approximately 250 pounds per square inch was maintained in reacf tion chamber 24 which resulted in a pressure of approximately 225 pounds in receiver 90, this differential being necessary to cause suitable flow. There was produced in reaction chamber 24 a liquid residuum of a heavy asphaltic and carbonaceous nature which had a specific gravity of 4approximately 1.03 to 1.02 and contained cokelike particles in suspension up to as high as 20% as determined by the centrifugal method of testing. 'I'he amount of this heavy liquid produced was 250 barrels per day, this being passed through heating element 30 and heated to a temperature sufficient to insure a temperature of approximately 800 F. in the hydrogenating chambers E, F wherein a. pressure of the order of 2000 to 2200 pounds was maintained and an iron and nickel oxide mixture was provided as a catalyst.

There was obtained from fractionator 48 as an overhead product condensing ultimately in receiver 80 about 50 barrels per day of saturated compounds within the gasoline boiling point range and at the same time 200 barrels of bottoms of a highly saturated nature which was further heated in heating element 52, temperatures of 850 to 875 F. being maintained at the exit of this heating element and pressures of approximately 400 pounds in reaction chamber 55. In this secondary cracking zone there was produced 140 barrels of gasoline, 20 barrels of intermediate-boiling compounds and of bottoms from reaction chamber 55 returned by pump 1| and line 12 to line 28, and thus to the hydrogenators. There was thus produced as an overall yield from the operation of the process on this basis 84% of hydrocarbon mixtures of suitable boiling point range for use as gasoline. By utilizing-the intermediate-boiling products produced in the subsequent distillation of the liquid condensate from receivers 90 and 66', this yield was still further increased.

I claim as my invention:

1. A hydrocarbon oil conversion process which comprises subjecting the oil to cracking conditie-ns of temperature and pressure in a primary cracking zone and separating the same into vapors and unvaporized oil, dephlegmating the vapors to condense insufficiently cracked fractions thereof and returning resultant reflux condensate to the primary cracking zone, passing the unvaporized oil to a hydrogenating zone and subjecting the same therein to destructive hydrogenating conditions of temperature and pressure in intimate contact with a hydrogen-containing gas, removing the hydrogenated vapors from the hydrogenating zone and dephlegmating the same to condense heavier fractions thereof, passing such condensed heavier fractions to a secondary cracking zone maintained under higher pressure and lower temperature than said primary cracking zone, and subjecting the same to cracking conditions of temperature and pressure therein, separately removing vapors and residuum from said secondary cracking zone, and supplying such residuum to the hydrogenating zone for further subjection to hydrogenating conditions therein.

2. A hydrocarbon oil conversion process which comprises subjecting the oil to cracking conditions of temperature and pressure in a primary cracking zone and separating the same into vapors and unvaporized oil, dephlegmating and condensing the vapors, passing the unvaporized oil to a hydrogenating zone and subjecting the same therein to destructive hydrogenating conditions of temperature and pressure in intimate contact with a hydrogen-containing gas, removing the hydrogenated vapors from the hydrogenating zone and dephlegmating the same to condense heavier fractions thereof, passing such condensed heavier fractions to a secondary cracking zone maintained under higher pressure and lower temperature than said primary cracking zone and subjecting the same to cracking conditions of temperature and pressure therein, separately removing vapors and residuum from said secondary cracking zone, and supplying such residuum to the hydrogenating zone for further subjection to hydrogenating conditions therein.

3. A hydrocarbon oil conversion process which comprises subjecting the oil to cracking conditions of temperature and pressure in a primary .cracking zone and separating the same into vapors and unvaporized oil, dephlegmating and condensing the vapors, passing the unvaporized oil to a hydrogenating zone and subjecting the same therein to destructive hydrogenating conditions of temperature and pressure in intimate contact with a hydrogen-containing gas, removing the hydrogenated vapors from the hydrogenating zone and dephlegmating the same to condense heavier fractions thereof, passing such condensed heavier fractions to a secondary cracking zone maintained at cracking temperature and under higher pressure than said primary cracking zone and subjecting the same to cracking conditions of temperature and pressuretherein, separately removing vapors and residuum from said secondary cracking zone, and supplying such residuum to the hydrogenating zone for further subjection to hydrogenatlng conditions therein.

4. A hydrocarbon oil conversion process which comprises subjecting the oil to cracking conditions of temperature and pressure in a primary cracking zone and separating the same into vapors and unvaporized oil, dephlegmating and condensing the vapors, passing the unvaporized oil to a hydrogenating zone and subjecting the same therein to destructive hydrogenating conditions of temperature and pressure in intimate contact with a hydrogen-containing gas, removing the hydrogenated vapors from the hydrogenating zone and dephlegmating the same to condense heavier fractions thereof, passing such condensed heavier fractions to a secondary cracking zone maintained under pressure and at a lower temperature than said primary cracking zone and subjecting the same to cracking conditions of temperature and pressure therein, separat-ely removing vapors and residuum from said secondary cracking zone, and supply-ing' such residuum to the hydrogenaflng zone for further 'subjection tohydrogenating conditions therein.

5. A hydrocarbon oil conversion process which comprises subjecting the oil to cracking conditions of temperature and pressure in a primary cracking zone and separating the same into vapors and unvaporized oil, dephlegmating and condensing the vapors, passing the unvaporized oil to a hydrogenating Zone and subjecting the same therein to destructive hydrogenating conditions of temperature and pressure in intimate contact with a hydrogen-containing gas, separating motor fuel boiling hydrocarbons from heavier constituents of the thus hydrogenated oil, subjecting constituents of the hydrogenated oil heavier than motor fuel in a secondary cracking zone to independently controlled cracking conditions better suited to the cracking thereof than the oil cracking conditions prevailing in said primary cracking zone, removing vapors and residuum from said secondary zone and supplying such residuum to the hydrogenating zone for subjection to hydrogenating conditions therein.

6. The process as defined in claim 5 further characterized in that the secondary cracking zone is maintained under higher pressure and lower temperature than the primary cracking zone.

7. The process as dened in claim 5 further characterized in that the secondary cracking zone is maintained under higher pressure than the primary cracking zone.

8. The process as defined in claim 5 further characterized in thlat the secondary cracking zone is maintained under lower temperature than the primary cracking zone.

9. A hydrocarbon oil conversion process which comprises subjectingy the oil to cracking conditions of temperature and pressure in a primary cracking zone and separating the same into vapors and unvaporized oil, dephlegmating and condensing the vapors, passing the unvaporized oil to a hydrogenating zone and subjecting the same therein to destructive hydrogenating conditions of temperature and pressure in intimate Contact with a hydrogen-containing gas, separating motor fuel boiling hydrocarbons from heavier constituents of the thus hydrogenated oil, subjecting constituents of the hydrogenated oil heavier than motor fuel in a secondary crack-- 10 ing zone to independently controlled cracking con-v ditions better suited to the cracking thereof than the oil cracking conditions prevailing in said primary cracking zone, removing vapors and residuum from said secondary zone and supiying such resiciuum to the hydrogenating zone for subjection to hydrogenating conditions therein, dephlegmating. the last-named vapors and returning resultant reux condensate to said secondary zone 'for'retreatment therein.

JEAN DELATTRE SEGUY.

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