US1901931A - Process and apparatus for treating oil - Google Patents

Description

March 21, 1933. R. T. POLLOCK PROCESS AND APPARATUS FOR TREATING OILS- Original Filed Sept. 22. 1920 4 Sheets-Sheet 1 UT I i I I MN NN Wm, M j

March 21, 1933. R PQLLOCK 1,901,931

PROCESS AND APPARATUS FOR TREATING OILS Original Filed Sept. 22. l920 4 Sheets-Sheet 2 March 21, 1933. R POLLQCK 1,901,931

PROCESS AND APPARATUS FOR TREATING OILS Original Filed Sept. 22- 1920 4 Sheets-Sheet 3 March 21, 1933. R. T. POLLOCK PROCESS AND APPARATUS FOR TREATING OILS Original Filed Sept. 22- 1920 4 SheetsSheet 4 TWJ/ M Patented Mar. 21, 1933 UNITED STATES PATENT OFFICE ROBERT T. POLLOCK, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR TO UNIVERSAL OIL PRODUCTS COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS PROCESS AND APPARATUS FOR TREATING Application filed September 22, 1920. Serial No. 411,913.

This invention relates to a process and apparatus for treating oils and refers more particularly to a continuous process for cracking hydrocarbon oils to produce light hydrocarbons such as gasoline or the like.

Among its salient objects are to provide a process in which special provision is made for taking care of the carbon formed in the heating zone, and one especially adapted to the cracking of heavy oil in which there is an excessive collection of carbon in the reacting or vapor chamber as the rearrange ment of molecules takes place during the cracking reaction; to provide a process whereby the vapor or reacting chamber may be cut out and another cut into the system without shutting down the progress of the distillation; to provide a process in which the vapor chamber which is cut into the system may be preheated to a proper tempera ture and a desired pressure imposed upon the same by diverting the residuum and incondensible gas to this chamber, thereby subjecting it to like conditions of the vapor chamber then in operation; to provide a process in which the conditions of condensation may be regulated between narrow limits thereby determining the nature of the distillate; to provide an improved type of apparatus for the efi'ecting of this process and in general to provide a process and apparatus of the character referred to.

In the drawings:

Fig. 1 is a side elevation of the apparatus.

Fig. 2 is a plan view of the apparatus shown in Fig. 1.

Fig. 2A is a detail shown in Fig. l. I

Fig. 3 is a sectional side elevation of the furnace and heating zone construction.

Fig. 4 is an end view partly in section of furnace construction.

Fig. 5 is a detaiLof the furnace construction whereby the tile bafiles between the combustion chamber and heating chamber may be arranged as desired.

In the treating of hydrocarbon oils and particuluarly heavier oils such as Mexican and California gas oil, special provision must be made for the. accumulation of carof residuum pump cess and apparatus here explained to meet these difiiculties.

Referring to the drawings, the raw oil is introduced from any convenient source, not shown, to the inlet pipe 1 into the top of the dephlegmator 2 where it passes down in an opposed direction to the travel of the oil vapors and collects in the lower leg 3 of the dephlegmator 2 and is directed therefrom by pipe 4 to the cracking tubes 5. The cracking or heating tubes 5 are mounted in the furnace 6 which is preferably heated by means of gas burners 7. The oil, after be ing heated in the cracking tubes which are mounted in two banks as shown at 5 and 5a is directed through lines 6a and 61) through header 7 a to the line 8 which connects header 7a and the header 9. Secondary feed lines 10 and 11 transfer the oil from the header 9 to either of the vapor tanks or reacting chambers 12 and 13. Valves 14: and 15 are interposed in the header 9 and provide a means for cutting out either of the tanks when desired.

Describingin detail the construction of one of these vapor tanks, it will be noted that the tank is cylindrical in form having a rounded top and bottom with large cleaning openings at either end shown at 16 and 17. The lower cleaning door 17 is pivoted at 18 and may be swung down so that easy access may be had to the interior of the tank in cleaning.- A residuum draw off line 19 communicates with the lower portion of the tank and is controlled by a valve 20 by means of which the heavy residuum and precipitated carbon maybe drawn off from time to time into a car 21 which is operated on track 22 whereby" the residuum may be carried oil to any desired storage. A second residuum line 23 is connected into the bottom of the tank as are other vertically spaced residuum draw off lines 24, 25 and 26. As the carbon rises in the tank these residumm draw ofis may be brought into service as the heavy oil rises through the level. By positioning the residuum drawofi's in this manner, a very heavy load of carbon may be permitted to collect inthe vapor chamber before necessitating the cleaning of the vapor chamber or tank. Also a vertical arrangement of the tanks and their large diameter facilitates the cleaning of the tanks as distinguished from a long narrow tube lying horizontally. The tanks are identical in construction each being equipped with the same number of draw-offs and each drawofi' being controlled by throttle valve. The tanks are mounted within a heavily insulated enclosure 27 and one or more tanks may be surrounded with a single insulation. Fire brick, KieselGurh or other heat insulation may be used. From the top of each of the tanks are vapor lines 28 and 29 controlled by valves 30 and 31 which connect to dephlegmator 2. The vapor lines are so arranged that any condensate forming in the line will flow into the dephlegmator and there combine with the raw oil to be retreated in the cracking tubes. The oil vapors which are released in the vapor tank and rise to the vapor lines 28 and 29 are dephlegmated in aerial dephlegmator 2 by the incoming raw oil and pass over into a second dephlegmator 32 through the line 33. Here additional condensation takes lace, the liquid condensate collecting in the ttom of the dephlegmator and being directed back to the heating tubes through line 34. The oil vapors which still remain in a gaseous state pass out of the top of the dephlegmator through the pipe 35 to a small water condenser 36 from which they pass down through the line 37 to the main water condenser 38. From this condenser they pass through pipe 39 to a receiver 40 from which they may be drawn off through draw off line 41 controlled by valve 42. A gas outlet 43 in the top of the receiver is connected to a gas line 44 by means of which the gas may be directed back to either of the vapor tanks 12 or 13 through the line 44, and header 45 which connects to both. of the oil inlet pipes 10 and 11.

A small condenser 36 is used merely as a balancing condenser and serves to regulate within very small limits the temperature of the vapors as they are received from the dephlegmator 32. This dephlegmator has water connections for introducing cold" or hot water so that the temperature regulation is positive.

In the oil outlet of the lower water condenser 38 is a U-pipe 46 which keeps the lower coils of the water condenser completely full of liquid distillate and thereby greatly increasing the efliciency of the condenser. Explaining now the furnace construction, the cracking tubes which are drawn steel tubes are connected .by headers in staggered relation thereby providing a most efiicient heating arrangement as each tube is subjected to practically the same amount of heating gases. The tubes besides being staggered as shown in Fig. 4, are connected so that each is inclined slightly with respect to the other which gives .a continuous upward travel to the oil. That is, the oil bein introduced through line 4 to the crac in tubes 5 and 5a travels continuously throug inclined tubes until it reaches the upper tube from which it is drawn through the outlet lines 6a and 6b which are corresponding outlet lines in the two banks of the tubes. The advantage of the inclined tubes is that gravitation will tend to back u the oil and keep the cracking tubes comp etely full of oil during the heating and prevent hot spots forming in the tubes. A central support. 47 is arranged centrally in the furnace to prevent the warping of the tubes. The furnace proper comprises insulated walls 48, the combustion'chamber 49 being in its upper portion. As shown in Figs. 3 and 4 the furnace is top fired by gas burners or other heating means, the heated ases passing in the direction'of the arrows rom the combustion chamber down through the ports 50 arranged between the shelving projections 51 and 52 in the bottom of the combustion chamber. These shelving projections 51 and 52 have vertical cut out portions 53 indicated in dotted lines in Figure 4 and shown in full lines in Figure 5 which permit the heating gases to pass directly to a second bafiling shelf built directly below the upper shelf portions 51 and 52.

Describing the details of the upper baflle wall, there are two projecting shelves 51 and 52 which extend out into the bottom of the combustion chamber and on these shelf portions are arranged at intervals, tiles 54. These tiles are slidably arranged so that they may be positioned to regulate the ports 50 so that the heating gases are directed to be evenly distributed over the heating tubes. The cut out portions 53 and the ports 50 permit the gases to pass directly to the second baffling shelf which, similar to the first, comprises two projecting shelves 55 and 56 upon which are set tiles 57. As before, these tiles are slidably arranged on the shelving portions so they may be slid'back and forth and alternately arranged with the tiles of the upper baflle so that the live flame and excessive heat may be completely bafiled from direct-contact with the heating tubes and a more even distribution of the gases obtained. It will be noted also that the lower shelf portions 55 and 56 have no cut-out portions as have the upper shelf portions so that the gases passing through the cut-away portions 53 will be effectively baflled. Therefore the gases must pass through the ports 58 between the lower tiles to enter the heating chamber in which are mounted the cracking tubes. A portion of the upper baflie is built solid as shown at 59 to prevent short circuiting of the gases and direct them to the central portion of the combustion chamher before they are permitted to pass down through the ports. As an arch for this furnace, patented tiles 60 having slots therein, are hung by means of hangers 61 from the top of the furnace frame. The construction of this arch forms no part of this invention. A straight arch of this type is desirable due principally to the economy of the construction.

The heated gases after being evenly distributed by the double bafiie, pass over the cracking tubes and out through the ports 62 to the flue 63 from which they are directed to a stack 64. Another feature important in the heating of the oil is that cool oil is introduced to the coolest portion of the furnace or heating chamber and is withdrawn from the top or the hottest portion of the cracking tubes. By heating the oil in this manner, a much greater efiiciency is obtained and a greater number of heat units utilized in the cracking of the oil.

In operation, the process is as follows: The oil, after passing through the cracking tubes, is introduced to either one or both of the vapor tanks. The advantage of having two vapor tanks connected as they are to two or more banks of cracking tubes, is that in case one tank becomes clogged with carbon, it may be cut out of the system and the other tank used during the period that the first tank is cut out as the vapor or reacting chamber for the process. In case one tank has been cleaned and it is desired to cut out the other tank, it is necessary to make some provision "for heating the tank to be substituted and at the same time the pressure in the tank must be raised so that with the cutting in of this second tank, there will not be a decided change in the character of the dis tillate which passes over to the receiver. It is essential that the conditions of pressure and temperature during operation be kept as uniform as possible so that the distillate will be constant both in quality and quantity. To procure these conditions the residuum from the tank which is in use is diverted from the residuum draw-ofi line 65 through the pump 66 and back into the other tank through line 67. This pump may be operated so that the residuum drawn 05 from either tank may be diverted to the the other. By diverting the residuum in this manner, the temperature of the tank, which is to be cut in, may be raised substantially to the temperature of the residuum, the incondensible gases which are taken from the top of the receiver through the draw-ofi' line 4-1 having been previously introduced to the tank which is to be cut in and its pressureraised to substantially the pressure in the tank which is in use.

Describing the method of transferring the residuum from one tank to another to raise the temperature and pressure conditions in the tank to be cut into the system, assume that the residuum is to be transferred from tank 13 to tank 12. The residuum drawn ofi through the line 67 is directed through the line 68 in which are interposed throttle valves 69, 70 and 71. A continuation 72 of the line 68 directs the residuum to any storage means, not shown, in case it is not desired to pump residuum back into the system. An enlarged pipe 7 3 surrounds a portion of the residuum line 72 furnishing a means for heating crude oil or the oil char e to be used in the system by circulating t e same within this enlarged tube 73 prior to its introduction to the process. The residuum drawn from the tank 13 flows through the line 67 and into the line 68 in which the valves 69, 70 and 71 are open permitting the oil to pass into the connecting line 74: which leads to the suction line 75 of the pump 66. From the pump, the oil is forced through the outlet line 76 into the crossconnecting line 77 to the residuum draw-off 65 of the tank 12. During this circulation a valve 78 in the cross-connecting line 77 is closed and the valve 79 in the same line is open. Also a valve 80 in the line 72 and the valves 81 and 82 in the line 6-5 and the Valve 83 in line 74 are closed. A valve84 corresponding to the valve 83 but in the opposite side of theconnecting line is in an open position and permits the oil to flow to the suction line 75 of the pump. An additional valve 85 is positioned in the line 65 for further controlling the flow of the oil during its circulation. When the residuum is drawn from the tank 12 and directed through the ump to the tank 13, its travel will be as ollows. 'Passing through the line 65 with the valves 85, 81 and 82 in an open position, the heavy oil will flow through part of the cross-connecting line 74 with the valve 83 in an open position and the valve 84 in a closed position which will cause the oil to pass into the suction line 75 of the pump and be discharged through the outlet line 76 in which is interposed the valve 86 which is likewise in an open position. From this outlet line 76, the oil will pass to the cross-connecting line 77 in which the valve 79 is closed and the valve 78 is open, causing the oil to pass into the line 68 through a vertical connection and through the line 67 to the tank 18.

In normal operation the residuum from either of the tanks will be piped direct to storage through the lines 72 and 72a, the valves in the connecting lines and 68 being open while those leading to the pump are closed. As previously explained, when the residuum is being directed to storage, oil may be circulated in the tubular shells 73 and 73a positioned about these lines leading to storage. 7

The raw oil line 87 is tapped into the suction line 75 of the pump and a valve 88 interposed in this line for controlling same. If it is desired to flush out the residuum lines to either of the tanks or the lines to the storage, raw oil ma be drawn in through this intake line 87 rom any convenient source not shown and forced out through any of the lines desired to perform this cleaning function. 1

By this means, the conditions of pressure and temperature may be made substantially identical to the tank then in operation in the process and when the operating tank is cut out to be cleaned, the second tank which is cut in will effect ver slightly the operation of the process and the character of the distillate. This maintenance of pressure and temperature conditions in a continuous process of this type is of vital importance to its efficient operation.

A battery of stills of this type may comprise a series of banks of cracking tubes in combination with a number of vapor chambers. Also it may be an advantage to arrange the vapor chambers in line with the cracking tubes but these conditions depend altogether on the space to be occupied and the character of the construction.

I claim as my invention:

1. A continuous process for the treating of heavy oils, consisting in feeding the oil in a constricted stream through a heating zone, directing the heated oil to one of a plurality of enlarged expansion tanks outside of the heating zone, permitting the cracking reaction to take place in said expansion tank and when an excessive amount of carbon has collected therein, diverting a portion of the residuum from said expansion tank and uncondensible gas, to a second expansion tank to bring the same to approximately 0 rating temperature and pressure, then cutting the tank, havin the excessive collection of carbon, out of t e system and thereafter vaporizing the oil in the second expansion tank, dephlegmating, condensin and collecting continuously the generate oil vapors and maintaining a regulated pressure during operation.

2. In an apparatus for treating oils, the combination with a means for heating the oil, of alternate enlarged vapor tanks vertically positioned having residuum draw off pipes connected thereto. means for isolating cm or cutting said tanks into the system, means for diverting the residuum from each tank to the other, meansfor condensing and collecting the generated vapors, a pressure relief hne connected to said collecting means adapted to return the incondensible gas to either of said vapor tanks.

3. A process for treating oil consisting in feeding the oil in a relatively small stream in a heating zone and there raising it to a conversion temperature under a superatmospheric pressure, passing the heated oil to either of alternate conversion chambers and there maintaining it at a suflicient temperature to cause a continued conversion, utilizing the alternate chambers successive- 1y as conversion stages while one is isolated from the system, subjecting the evolved vapors to a dephlegmating and condensing action, withdrawingthe residual products from the chamber under operation, and diverting portions thereof to the chamber isolated from the system to return the same to operating conditions prior to diverting the heated oil thereto and maintaining a regulated pressure upon the system durmg treatment.

4. In a process for the conversion of hydrocarbon oil into low boiling-point hydrocarbon oil products wherein oil previously heated to conversion temperature is passed through an enlarged passage-Way wherein it is maintained at conversion temperature and coke deposition and conversion take place, in which process the heated oil is diverted from the enlarged passage, when the latter becomes coked, intoa like or alternative enlarged passage, the improvement which consists in filling the alternative passage with heated oil before diverting the stream of previously heated oil from the first passage.

5. A rocess for the conversion of oil, consisting m heating an oil stream to a conversion temperature, in. passing the heated stream of oil.to an enlarged chamber where conversion and carbon deposition occurs, in diverting the previously heated stream of oil from the enlarged chamber when substantial quantities of carbon accuinlate therein into an alternative enlarged chamber, and in introducing to the alternative chamber heated oil from the first mentioned chamber before diverting the stream of previously heated oil from the first mentioned oil chamher.

6. A hydrocarbon oil cracking process which comprises heating the oil to conversion temperature in a heating zone; discharging the heated oil into an enlarged chamber maintained under-conversion conditions of temperature and superatmospheric pressure and wherein carbon deposition occurs; diverting the heated oil from said chamber, when substantial carbon accumulation has deposited therein, into a second enlarged chamber; condensing the vapors evolved by the heating and conversion of the oil and separating the same from the incondensable gases formed in the process; and, before diverting the heated oil into said second chamber, introducing to said second chamber a portion of said incondensible gases to build up a superatmosphericpressure therein; and also a hot oil which has been heated externally of said second chamber to bring the same to operating temperature.

7. A hydrocarbon oil cracking process which comprises heating the oil to conversion temperature in a heating zone; discharging the heated oil into an enlarged chamber maintained under conversion conditions of temperature and superatmospheric pressure and wherein carbon deposition occurs; diverting the heated oil from said chamber, when substantial carbon accumulation has deposited therein, into a second enlarged chamber; condensing the vapors evolved by the heating and conversion of the oil and separating the same from the incondensible gases formed in the process; and, before diverting the heated oil into said second chamber, introducing to said second chamber a portion of said incondensible gases to build up a superatmospheric pressure therein; and also hot residual from the first mentioned chamber to bring said second chamber to operating temperature.

8. A hydrocarbon oil cracking process which comprises heating the oil to conversion temperature in a heating zone; discharging the heated oil into an enlarged chamber maintained under conversion conditions of temperature and superatmospheric pressure and wherein carbon deposition occurs; diverting the heated oil from said chamber, when substantial carbon accumulation has deposited therein, into a second enlarged chamber; condensing the vapors evolved by the heating and conversion of the oil and separating the same from the incondensible gases formed in the process; and, before diverting the heated oil into said second chamber, building up a superatmospheric pressure therein by introducing hydrocarbon gas thereto, and bringing the same to operating temperature by the introduction of a hot oil which has been heated externally of said second chamber.

9. A hydrocarbon oil cracking process which comprises heating the oil to conversion temperature in a heating zone; discharging the heated oil into an enlarged chamber maintained under conversion conditions of temperature and superatmospheric pressure and wherein carbon deposition occurs; diverting the heated oil from said chamber, when substantial carbon accumulation has deposited therein, into a second enlarged chamber; condensing the vapors evolved by the heating and conversion of the oil and separating the same from the incondensible gases formed in the process; and, before diverting the heated oil into said second chamber, building up a superatmospheric pressure therein by introducing hydrocarbon gas thereto, and bringing the same to operating temperature by the introduction of hot residual oil from the first mentioned chamber.

10. An oil cracking apparatus comprising oil heating means; a pair of reaction chambers, means for cutting each of said chambers into. and out of communication with said heating means; condensing means adapted to communicate with said chambers; means for introducing gases uncondensed in said condensing means to each of said chambers; and means for passing residual oil from each of said chambers to the other.

ROBERT T. POLLOCK.

CERTIFICATE OF CORRECTION.

Patent No. 1,901,931. March 21, 1933.

ROBERT T. POLLOGK.

It is hereby certified that the State of Incorporation of the assignee in the above numbered patent was erroneously described and specified as "Illinois" whereas said State of Incorporation should have been described and specified as "South Dakota", as shown by the records of assignments in this office; and that the said Letters Patent should be read with thia correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 16th day of May, A. D. 1933.

ll. 1. Moore.

(Seal) Acting Commissioner of Patents.

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