US1763604A - Vacuum system of oil conversion - Google Patents

Description

June 10, 1930. A. E. HARNSBERGER VACUUM SYSTEM OF OIL CONVERSION Filed May 31, 1928 I l I I Patented June 10, 11930 UNITED STATES PATENT OFFICE AUnLnY E. IIARNSBERGZER, OF CHICAGO,- ILLINOIS, ASSIGNOR TO THE PURE 011.comrANY, or CHICAGO. InLIIIoIs. A CORPORATION or OHIO VAGUU'M SYSTEM OF OIL CONVERSION F Application filed May 31, 1928. Serial No. 281,785.

This invention relates to improvements in the art of manufacturing gasoline like hydrocarbons, and has particular reference to a system of oil conversion wherein the oils are maintained substantially in a state of vapor While passing through a heated cracking or reaction zone, and one of the outstanding features of the presentinvention resides in a vap011 phase method of oil conversion wherein the oils while undergoing conversion are maintained under subatmospherlc pressure conditions atmospheric pressure conditions in the converter proper so that the oil or oil vapor while undergoing conversion is maintained either in part'or all together under sub-atmospheric pressures.

There are certain advantages resulting in cracking'oi-l or oil vapors under sub-atmos pheric pressures as compared with the.cutom'ary methods of converting oil under hign super-atmospheric pressures. For example, there is-obtained (1) a reduction in fixed gas formation perunit quantity of gasoline like hydrocarbons produced, (2) reduction in time the vapors are exposed to cracking tem-' peratures 'by increased velocity of travel of the vapors through the cracking zone, (3) improved control in the temperature of the vapors leaving the converter and other factors aifecting the molecular decomposition of oil by vapor phase methods of conversion.

- Again, it is the purpose of thisinvention to overcome some of the difficulties in connection with sub-atmospheric vapor phase systems of cracking. One of the chief-of these difliculties is the removal of the so-called permanent gas from the system and condensation of the lighter hydrocarbons which fall First,

fractions and the removal of the permanent gas presents no difliculty, since it eliminates large vacuum pumps and similar equipment.

In the apparatus described it is desirable that on the outlet side of the jet condenser a temperature of from 400 F. to 600 F. be maintained so that the gasoline produced as a result of the cracking reaction may be easily recovered by the well-known principles of fractional condensation. The degree of vac'- uum carriedon the inlet side of the jet condenser will depend largely on the pressure I ,and quantity of hurling liquid used therein.

This hurling liquid may beof diflerent temperatures ranging from below 100 F. up to as highas 400 F., thus permitting of a wide variance in the weight of hurling liquid used and consequent control of the degree of vacuum carried on the converters. Thus with converter tubes of a given cross sectional area, the velocity of vapors traveling therein can be greatly varied by increasing the vacuum on-the outlet side and in this, manner control of the time which the vapors are exposed'to high temperatures can be varied to suit the type of charging stock.

For a further understanding of the inventionreference is to be had tothe following description and the accompanying drawings-i.

wherein Figure 1 is a diagrammatic view of apparatus which maybe used in carrying out the present invention, Figure 2 is an enlarged sectional view taken through the jet condenser which operates as a heat transfer agent at the end of the converting zone, a I

Figures 3, 4 and 5 are detail views showing modified types of converter tubes.

Referring more particularly to'thedetails of the process the numeral 1 designates a pipe still or vaporizer, which is formed to include a-setting 2, which is divided internally by a bridge wall 3 into combustionand tube heating chambers. Oil burners or the like are situated in the combustion chamber and operate to develop heat which is carried to a bank of tubes 1 arranged in the heating chamber. Oil under process of treatment such for example, as a gas oil fraction, enters the tubes 4 by Way of the pipe line 5, and is discharged from the tubes 4, after heat treatment, by way of the outlet line 6. In one form of the invention it is customary to heat the oil passing through the vaporizer until it attains a temperature bordering on molecular decomposition such, for example, as from 700 to 750 F.' This temperature reduces the oil to a very large extent to-a state of vapor, and the combined oil and'oil vapors are then transferred, under circulation pressures merely, to an evaporator 7 which is connected with the discharge end of the outlet line 6. X

The evaporator is of customary form and includes an enlarged base portion adapted to receive the unvaporized or liquid fractions of the oil discharged from the vaporizer. It is desired that these heavy fractions, which do not vaporize at temperatures of from 700 to 750 F. shall be independently collected and removed from the system. This is efii-v ciently done by the evaporator 7, which functions to collect such heavier fractions in the base portion thereof, and to permit such heavy fractions to be removed by way of a discharge line 8 as fuel oil. The top of the evaporator may include a tower which is provided with suitable baflles, arranged to intercept the flow ,of the oil vapors and to knock down entering liquid: The vapors leaving the top of the evaporator pass by way of a pipe line 9 to a liquid trap or separator 10. This trap includes a plurality of vertically arranged relatively spaced and staggered baflies 11 which act to supplement the action of the evaporator 7 in that the separator serves to insure substantially the complete removal of all entering liquid from the vapors, before such vapors enter the converter -12.

The converter 12 comprisesa setting 13 formed to include a transversely extending bridge wall 14 which separates the converter into radiant and convected heat chambers 15 and 16 respectively. Communicating with the pipe line 9 on the outlet side of the separator 10 is a tubular heating element 17 formed from materials possesmg good heat conductivity but capable of withstanding relatively high furnace temperatures without undue deterioration or destruction. The inlet portion of the heating element 17 is situated in the, radiant heat chamber 15 in order thatthe temperature of the oil vapors passelevating thevapor temperatures within the limits specified very little or no free carbon precipitation'or accumulation takes place in the inlet portions of the converter tubes. If desired, a relatively small percentage of steam may be admitted into vapor lines between the vaporizer and the converter. Experience has demonstrated that a small quan tity of such steam is helpful in minimizing carbon formation in the converter and is believed to assist conversion reactions in the converter tubes 17.

The oil and steam vapors flow at relatively high velocities through the heated tubular element 17 during which time the vapors are maintained preferably at temperatures in excess of 1000 F. and for a period of time not in excess of two seconds.

When the vapors are discharged from the converter it is necessary to effect an abrupt and substantially instantaneous drop in the temperature of the vapors from, for example,-1000 F. to 600 F. To accomplish this there is employed, in the present instance, a unit known as a jetcondenser or a hurling liquid type booster. Asshown in figure 2 this unit comprises a casing 18, which is formed to include a flanged head 19 suitably secured to the outlet side of the converter elements 17. Within the central portion of the head 19 there is situated a vertically disposed injection nozzle 20, which is connected with a fresh oil supplyline 21. This line leads from a source of fresh oil supply such as a tank 22, and the line 21'is provided with a pump 2'3 between the tank 22 and the nozzle 20, so that the fresh oilmaybe discharged at high velocity in jet formation. Due to the location of the nozzle 20 the oil released therefrom is brought into very intimate con- I tact with the highlyheated vapors issuing from the converter While both the cooling oil and the heatedvapors are moving at the same velocity. Immediately below the nozzle 20' the casing 18 includes a restricted throat 24, which terminates in a flaring expans'ion chamber 25.

It has been noted that in the operation of vapor phase systems of this kind that best. operation is obtainable, that is maximum motor fuel yields with but minimum formation of fixed gas, when the vapors pass through the converter elements under the lowest pressures. Heretofore these pressures have always been super atmospheric but by the provision of the jet condenser unit, above described, the system operates ordinarily, with the converter under sub-atmospheric pressures It will be observed that the liquid substantially instantly check conversion of cracking reactions on the part of the oil Vapors leaving the converter, by sharply dropping the temperatures of such vapors from 1000 to 600 F. or lower. This has been obtained by previous types of coolers, but

in the present invention not only is the oil vapor cooled but in addition conditions are created by which sub-atmospheric pressures obtain within the heating element 17 of the converter.

The oils leaving the outlet side of the jet condenser unit at a super-atmospheric pressure pass into the bottom of a fractionating tower 26. The volatile fractions of the oils entering the tower, or those fractions which remain in a state of vapor at temperatures below 600 F. pass-upwardly through the tower and are suitably condensed, collected, treated and stored for use as a 'motor spirit. The fractions which are not vapors at temperatures below 600 F. accumulate as a liquid in the bottom of the tower 26 and by means of a pump 27 may be forced through the inlet line 5 back through the system for recirculation with a certain proportion of the fresh oil. In the operation of the system a greater amount of fresh oil is forced through the jet condenser than is actually needed to replenish thefresh oil demands of the system as the finished motor spirit is drawn.

ofi. As a result ofthis condition there accumulates from time to time an excess'quantity of liquid oil in the base of the tower 26. Through suitable automatic valve mechanism, whenthe liquid level reaches a certain point in the bottom of the tower 26 the excess liquid is returned to the fresh 011 tank 22 and may then be re-introduced into the system by way of the jet condenser, as previously explained.

The freshoil or liquid introduced by way of the jet condenser unit into the system possesses'ordinarily an atmospheric temperature but which may of course be higher, and in its et form, when it issues from the nozzle 20-, the oil effectively serves to cool the heated converted vapors by effecting the temperature drop specified in approximately one-fifth part of a second. It has been found that by pre venting a long drawn out cooling of theoil vapors, when they leave'the converter, as is secured by means of ordinary vapor con- .dens'ers, practically all free carbon, deposition or formation in thisiportion of the system is eliminated. The operation must be substantially instantaneous to obtain the greatest degree of success, and the present invention secures this result to a remarkable de gree by reason of the peculiar formation of the interior ofthe jet condenser unit and thefact that construction provides for positive contact ofiall parts of the vapor. and liquid streams. In addition the unit provides for producing the'sub-a-tmospheric pressures in the converter, which provides for higher velocity of oil vapor travelling through the high temperature zone of the converter and in this'manner reduces the formation of fixed gases or non-condensables. Heretofore, it

has been a difliculty in sub-atmospheric systems to separate the so-called permanent gases of the system from thedighter hydrocarbons which fall into the gasoline series under normal or atmospheric pressures. This difficulty has been overcome entirely by using the hurling liquid type of jet condenser, as shown, in which the stored energy in a liquid,

suchas oil, is utilized to increase the pressure of vapors passing through the condenser from sub-atmospheric to super-atmospheric conditions. It will be understood that when these vapors are again at a pressure above atmosphericthe condensation of the gasoline fractions and the removal of the permanent gas presents no difficulty and involves ordinary operations with'standa-rd equipment.

In the apparatus described it is desirable that on the outlet side of the condenser a quantity of hurling liquid used therein.- This liquid may be of different temperatures ranging from below 100 F. up to as high as 400 F., thus. permitting a wide variance in the weight of the hurling liquid used and consequent control of the degree of vacuum carrived on the converters. Thus with the convert-er tubes of a given cross sectional area, the velocity of vapors travelling therein can be greatly varied by increasing the vacuum on the outlet side-and in this manner ontrol of the time to which the vapors are exposed to high temperatures can be varied to best conform with the type of charging stock employed. Additional control can be secured by providing the tubular converter elements with tapering cores of a-catalytic material such as ferrous oxide mixed with concrete, or if desired theconverter tubes themselves may be of conical or tapering form. In this manher the effective area for vap'or travel through the converter elements may be regulated at will to secure high or low velocities of oil travel with a substantially constant vacuum.

- jector 18 which functions to provide for intimate mixing of the cracked vapors with the fresh liquid oil of lower temperature, whereby a rapid exchangeof heat takes place between' the oil vapors andthe liquid oil to arrest abruptly conversion reactions in the discharged vapors. Due to its location in relation to the, vapor outlet of the converter the jet cooler tends to produce a suction or par -tial vacuum in the vapor passages of the converter so that lower furnace temperatures within the converter may be utilized with the consequent reduction in the formation of fixed gases.

What is claimed is:

1. The process of converting high boiling point hydrocarbons into those of lower boiling point, which comprises heating the oil initially introduced into the process to a temperature sufiiciently high to convert the same from its normally liquid to'a substantially dry vaporous state, then subjecting the vapors to temperatures in excess of approximately 1,00O F., maintaining the vapors at such latter temperature for a period of time sufiicient to effect desired conversion reactions, and then forcing the vapors through a restricted conduit together with'a liquid jet of cooler oil for the purpose of abruptly lowering the temperature of the vapors to a point not in excess of 600 F. and to produce sub-atmospheric pressures in the conversion such passage bringing the vapors into intizone.

2. The process of treating hydrocarbon oil, which comprises continuously passing a confined stream of vaporized oil through a heated conversion zone, abruptly arresting conl version reactlonsof the vapors leaving sald conversion zone by passing the vapors,

through a restricted passage and while in mate contact with a confined and positively advanced moving stream of liquid oil having a temperature materially lower than that of said vapors, the merging of said vapors and moving stream of liquid oil in.said restricted passage serving to providefor. the maintenance of subatmospheric pressures in the vapor assages ofsaid conversion zone.

3. T e process of treating hydrocarbon 011,

which comprises converting the oil in the' yapor phase, and immediately upon completmg the desired conversion of the oil in the vapor phase abruptly and substantially in-.

stantly arresting the conversion reactions by bringing the highly heated vapors into-physical contact with a forced moving stream of relatlvely cool liquid oil, said liquid oil and vapors being continuously passed at the time of merger through a passage of restricted cross-section whereby to produce sub-atmospheric pressures in the zone of vapor conver- I sion and super-atmospheric pressures in the zone lmmedlately beyond said restricted passage.

4. The process of treating hydrocarbon oil,

-which comprises passing a constantly movtion ina single passage of restricted crosssectional area whereby the movement of said confined stream of liquid oil and vapor serves to produce sub-atmospheric pressures in the outlet portion of said conversion zone and an immediate reduction in the temperature of the vapors leaving the conversion zone to non-reacting temperatures not inexcess of 600? F. H

5. The process of treating hydrocarbon oil which comprises passing a continuous moving stream of oil vapor through an elongated conversion zone of restricted cross-sectional area and heating the vapors during their passage through said zone to a temperature in excess of 1,000 E, immediately upon completing the desired conversion of the oil in the vapor phase abruptly and substantially instantly arresting the conversion reactions by bringing the moving stream of highly heated vapors into physical contact with a forced moving stream of liquid oil of relatively low temperature, said liquid and vaporous oil streams being merged in a confined passage of restricted cross-sectional area whereby to produce sub-atmospheric pressures in the vapor passages of said conversion zone and super-atmospheric pressures in the zones immediately following the restricted passage wherein said liquid and vaporous oil streams are merged, and then continuously passing the combined liquid and vaporous oil streams at a non-reacting temperature not in excess of 600 F. into a fractionating zone and therein fractionating the liquid and'vaporous oil stream.

In testimony whereof I afiix my signature.

AUDLEY E. HARNSBERGER.

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