US1876206A - Process for treating hydrocarbons - Google Patents

Description

Sept. 6, 1932.

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Patented Sept. 6, 1932 UNITED STATES PATENT OFFICE WALTER 'M. CROSS, OF KANSAS CITY, MISSOURI, ASSIGNOR, BY MESNE ASSIGNMENTS,

T0 GASOLINE PRODUCTS COMPANY, INC.,'OF WILMINGTON, DELAWARE, A CORIfO- RATION OF DELAWARE rnoonss FOR TREATING mnocannons Application filed October 8, 1923. Serial No. 667,380.

granted Oct. 31, 1916, which process did not permit a fresh sup 1y of hydrocarbon oil to be continuously fed to the apparatus but was operated intermittently. An apparatus continuously operated as herein explained has the advantage of producing more uniform and better results in the way of an increased quantity and better quality product.

Among the advantages of the invention are an increased economy in operation, not only in fuel consumption, but also in theamount of oil that can be treated over a given period of time. A further advantage is that inasmuch as in the continuous process, the temperature can be maintained substantially constant for relatively long periods of time instead of alternate heating and cooling, the

life of the apparatus will be correspondingly prolonged as there will be much less strain, due to rapid expansion and contraction.

Further, the process permits of the continuous treatment of hydrocarbons whereby oil is treated to heat and pressure conditions regulated to effect a conversion or cracking which takes place without material vaporization and substantially while the oil is maintained in the liquid phase. The process further provides for the intermittent or continuous withdrawal of this converted oil from the zone of reaction while the same is in a heated condition, and provides for the distillation of this heated product in a sepafractionation ofthe oil takes place under reduced pressure conditions relati ve\the conditions maintained in the cracking stage.

The process is such that this distillation may take place primarily due to the reduced pressure conditions without'the addition of heat, or, as is the case with certain oils, heat may be added to the distillation stage to produce the desired amount of overhead products.

An additional feature of the process is the returning of the distillate produced by the condensation of the distilled-oil to the cracking stage and there combining it with the charging stock to be introduced to the cracking stage for retreatment.

' In the drawings:

Fig. 1 is a general viewof the apparatus with parts broken away to reduce the size of the drawing.

Fig. 2 is a vertical sectional view of the tube arrangement on an enlarged scale.

Fig. 3 is a view, partly diagrammatic and partly in section, of my improved apparatus.

Fig. 4 is a transverse sectional view taken on lines 44 of Fig. 3 but on an enlarged scale.

Referring to Figs. 1 and 2, 1 designates a. furnace having the usual fire box 2, abovewhich is located a series of tubes 3, opening at their opposite ends into hollow plates 4 and 5. A plurality of baflle plates 6 and 7 are employed in the furnaces for forcing the hot gases along substantially the entire length of the tubes 3 before passing to the stack 8. Opening into the lower portion is an inlet 9 connected to a source of supply in the manner hereinafter described and at the'upper end of the end plate 5 is an outlet 10 connected by a conduit 11 with converter tank 12. Leading from this converter tank is a pair of discharge pipes 13 and 14, the latter of which connects with a reheater 15, and the former is connected with the inlet pipe 9. Referring to Fig. 3, 1, 1a,1b, 1c, 1d, 10 represent a plurality of furnaces. '18, 18a, 18?), etc. representing the circulating pumps 19, 19a, 196, etc. represent the motors to the same. 13, 13a, 136, etc. and 11, 11a, 116 etc.

represent the circulation pipes. In the drive the same, 37 the intake to said pump, and 35 is a feed pipe extending from the pump 33 and emptying into the chamber 12.

In the employment of this apparatus, it is contemplated that the substance treated will circulate from the convertor tank 12 freely through the furnace tubes 3 (Fig. 2) of the heating furnaces 1, 1a, 16, etc. and back into the convertor tank 12. In order to cause this circulation, pumps 18, 18a, 18?), etc. are employed for forcing the oil through the inlets 9 of the heating tubes 3. As shown, these pumps are driven by motors 19, 19a, 196, etc, both pumps and motors being mounted on the common bases 20, 20a, 206, etc. The passage through the various pipes is controlled by suitable valves, a cutoff valve 22 is in position on the pipe l l for controlling the passage of treated oil from the converter tank 12 to the still 15. Also the pipe 31 is provided with a cutofi valve 32 for controlling the flow of vapor from the convertor 12 direct to the condenser 10. A pipe 28, leading from the still 15, communicates with a precooler 29 which comprises a coil subjected to atmospheric conditions or otherwise cooled. A check valve is interposed in the line 28. The discharge end of the precooler is connected by a line 38, controlled by a check valve 39, to a condenser coil 10 mounted in the water-cooled condenser box 41. natiorr or discharge end of this coil is controlled by a valve 42, from which may be drawn 03, either continuously or intermittently, the final distillate. A line 43, tapped into the lower part of the precooler, connects with a receiving tank 4% which in turn has a liquid draw-0d line 15 regulated by valve 46. This liquid drawofi line communicates with the suction side of the pump 33 by means of which the condensate separated out in the precooler may be returned, combined with the charging stock in the line 37 to be introduced therewith into the convertor tank 12.

In starting the process, the intake 37 of the pump 33 is connected with a suitable supply of oil to be'treated. Then the pump 33 is started and driven by the motor 36, pumping the oil into the convertor 12 through the intake 35. As soon as sufficient oil is pumped into the apparatus, one-third full more or less, the circulating pumps 18, 18a, 18?), etc. are all started and/ heat is applied in the furnaces 1, 1a,'lb, etc; Now the pump 33 is stopped, and the heat is applied in the furnaces 1, 1a, 1?), etc. until the pressure in the apparatus reaches the point that it increases out of proportion to the temperature, that is, when such a temperature is reached that pressure begins to rise without any further increase in temperature, the pressure in this case being that pressure due to the vapors from the hydrocarbons subjected to the treatment being generated by the heat. New this reacting temperature is maintained for The termirsvaeee a period of thirty minutes, more or less, according to the character of the oil used. In

any event, the temperature is maintained in the apparatus until a substantial amount of conversion products or gasoline-like products is obtained or formed in the oil itself. After this reacting time has been allowed, the valve 32 is opened sufliciently to permit such incondensible gases to escape to prevent an excessive rise in pressure and the pump 33 again started so that the discharge of oil through the pipe 14 together with any discharge of vapor is replaced by the oil that is pumped through the intake simultaneously. If the pressure becomes excessive, the valve 32 is opened and some of the vapors are allowed to pass out through the pipe 31 into the condenser 40 and then discharged. If satisfactory condensation and separation of condensible vapors from noncondensible vapors is not accomplished, in the condenser 29 when it is operated at atmospheric pressure, the valve 42 on the outlet of the condenser is partially closed so that suiiicient pressure is built up in the condenser 40 so as to insure satisfactory separation of the condensible from incondensible vapors in the condenser &0. When sufiicient oil has been discharged through the pipe 1 1 into the still 15 so as to partially fill it, fire is started and a distillate of gasoline or gasoline-like products is driven over through the vapor line 28 into the condenser 40. Simultaneously vapor may also be delivered into the condenser 40 through the pipe 31 and valve 32. The oil, after having been subjected to conditions of heat and pressure in the heating units and convertor tank 12, results in a synthetic crude produced while the oil is maintained substantially in the liquid phase. and without material vaporization. This synthetic crude while in the conversion state or highly heated condition is transferred either intermittently or continuously to the still 15 and is there distilled under reduced pressure conditions or under substantially atmospheric pressure, If satisfactory condensation and separation of the condensible vapors from noncondensible vapors is not accomplished in the condenser 40 when it is operated at atmospheric pressure, the valve d2 on the outlet of the condenser is partially closed so that sufficient pressure is built up in the condenser 40 so as to insure satisfactory separation of condensible from noncondensible vapors in the condenser 40. The heated oil directed to the still 15 is normally at such temperature that a distillation is etllected without addition of heat but merely due to the reduction of pressure. Oils of a certain character, however, require additional heat to produce satisfactory overhead distillation, and for this purpose heat may, if desired, be added to the oil in the still 15. Such oils as kerosene and hydrocarbons up I distillation stage to'promote the evolution of the more volatile fractions. Simultaneously vapor may also be delivered into the condenser 40 through the pipe 31 and valve 32. The length of the convertor chamber 12 and E the number of heatingfurnaces 1, 1a, 1?), etc.

will be determined entirely by the amount of oil that is to be treated in any one 24-hour period. The oil in this process, after it is started, is pumped in at such a rate that it will remain in the apparatus and be sub.

jected to the reacting temperatures thirty minutes more or less according to the time required for producing gasoline or gasolinelike bodies. A pressure of from 100 to 800 pounds may be maintained, this varying with conditions. The oil introduced to the chainber 12 by means of the pump 33 is circulated through the heating coils and back to the bulk supply, and in its travel through the cracking zone, is brought to a conversion temperature, being subjected during this heat treatment to pressure conditions sufficient to cause the conversion to take place without substantial vaporization.

It is self-evident that the longer the converter chamber 12 and the more numerous the furnaces 1, 1a, 1?), etc. the more rapidly oil can be pumped into the apparatus and still allow the necessary reactive time for the production of the gasoline-like product. In order that the oil may not circulate by convection backward, baflie plates 34a, 34b, 34c, 34d, 340, etc. may be placed in the vapor chamber 12 at right angles to its longitudi nal dimensions. A cross section of the convertor chamber 12 with baffle plates 34a, etc. is shown in Fig. 4. The heighth of this baffle plate is one-fourth the diameter of the vapor chamber 12, more or less according to the amount of oil that is being carried in the apparatus during the operation.

The operation of this process provides means for continuous operation and recovcry of gasoline and gasoline-like products during the operation of the process. It is also well known that if a hydrocarbon oil is being subjected to a cracking process or a conversion process, whereby lighter hydrocarbons are formed that there are also formed methane and other gases, which cannot be condensed into a liquid at atmospheric temperature. The amount of methane and non-condensible gas then is proportioned to the amount of like product that is condensible into a liquid at atmospheric temperature.

drawn.

In the operation of this process, such pressure is produced that gasoline or gasolinelike bodies may exist in the liquid phase, although the temperature may be somewhat high, that is, from 350 to 450 C. or more. 7 Now if the oil containing this gasoline is withdrawn through the line 14 and a less proportion of noncondensible vapor is withdrawn through the line 31 then the tendency is for an excessive amount of gasoline to be formed from the hydrocarbons inasmuch as the methane and other noncondensible vapors are not withdrawn to the same extent as the gasoline and therefore, do not have to be formed to establish the chemical equilibrium in as great amount as would be the case if the non-condensible gas and the oil were entirely withdrawn at the same time. Laboratory apparatus operated in this way, showed conclusively that if, during the ,operation of the process, non-condensible gas was withdrawn, a larger amount of gas formed than is the case were it not with- Also it was demonstrated that if gasoline were removed from the apparatus while the process was in operation, that a somewhat larger yield was obtained than was the case when the noncondensible gas was removed at the same time. It was necessary, however, to remove some of the noncondensible gas as the pressure rose excessively high if it was not done, provided the gasoline was withdrawn and new oil pumped in during the operation of the apparatus. Briefly, the process is such that the oil is 100 preferably circulated through coils 3 in the separate heating units and into the reaction chamber 12, and thence back to the coils and through the pipe 13 until the temperature of the oil has been sufficiently raised. During 105 this circulation, and with the rise in temperature, gaseous vapors are evolved which exerted pressure on the oil sufficient to prevent substantial vaporization of the bulk of the oil undergoing circulation. The heat and 110 temperature are so controlled that the cracking takes place while the oil is maintained substantially in the liquid phase. When the system has become sufficiently heated, oil may be continuously introduced to the sys- 115 tem and pass slowly therethrough, during which period it will be subjected to the temperature and pressure conditions maintained therein and undergo cracking. Simultaneously with this continuous introduction of 120 oil, the converted product may be withdrawn either continuously or intermittently through the transfer line 14 and distilledunder reduced pressure conditions with the contained heator with the addition of heat i products from the cracking stage to prevent I for a retreatment in the cracking stage. The

uncondensed portions of the vapors passing from the precooler are subjected to a final condensing action in the condenser coil 40. These latter vapors comprising principally those'fractions which produce gasoline-like bodies. As'explained, the reflux or condensate separated out of the precooler, is recycled for retreatinent with the charging and pressure, continuously withdrawing oil from the said body separate from condensible ,and incondensible gases generated from said body and passing the 'oil without cooling to a still into which the oil is released at atmospheric pressure without intermingling with said condensible and incondensible gases and without intermingling with a higher temperature inert heating medium whereby the lighter fractions will distill off, condensing such lighter fractions, and taking off condensible and incondensible gases from the cracking stage to prevent an excess rise in pressure.

2. An improvement in the art of oil conversion for the purpose of producing lighter from heavier hydrocarbon products by pyrogenesis, which consists in maintaining a considerable body of oil under cracking conditions of temperature and pressure, continuously withdrawing oil from said body separate from condensible and incondensible gases generated from said body of oil and passing the oil without cooling to a still into which it is released at a reduced pressure without intermingling with said condensible and incondensible gases and without intermingling with a higher temperature inert heating medium whereby the lighter fractions will distill off, condensing such lighter fractions and taking off condensible and incondensible excess rise in pressure. v

3. An improvement in the art of oil conversion for. the purpose of producing lighter from heavier hydrocarbon oil which comprises passing said heavier hydrocarbon oil in a relatively small stream through a heating zone, wherein it is heated to cracking temperature, conducting the oil from said stream after heating to an enlarged body of oil located outside of said heating zone, maintaining cracking conditions of temperature and pressure on said body, continuously withdrawing oil from said body and passing the oil without'cooling and without intermingling with a higher temperature inert heating medium to a zone of reduced pressure whereby the lighter fractions are distilled off, condensing such lighter fractions and taking off condensible and incondensible products from the cracking stage to prevent excessive rise in pressure.

4:. An improvement in the art of oil conversion for the purpose of producing lighter from heavier hydrocarbon products by pyrogenesis, which comprises maintaining a considerable body of oil under cracking conditions of temperature and pressure, continuouslywithdrawing oil from said body, pass ing the oil to a still without intermingling with a higher temperature inert heating medium into which it is released at a reduced pressure whereby the lighter fractions are vaporized, removing the vaporized lighter fractions from said still, separating the removed vaporized fractions into a lighter portion and a heavier portion taking off condensible and incondensible products from the cracking stage to prevent excess rise in pressure and contacting said products with only said light portion of said vaporized fractions.

5. An improvement in the art of oil conversion for the purpose of producing lighter from the heavier hydrocarbon products which comprises maintaining a considerable body of oil under such cracking conditions of temperature and pressure as to prevent substantial distillation of the lighter oil fractions, continuously withdrawing oil from the body and passing the oil withdrawn to a stage into which it is released at reduced pressure whereby the lighter fractions will distill off, condensing such lighter fractions and separately taking off incondensible gases from the cracking stage to prevent excess rise in pressure.

6. A process in accordance with claim 5 wherein the incondensible gases taken off from the cracking stage are combined with said lighter fractions prior to the final condensation of said fractions.

WALTER M. CROSS.

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