US2807528A

US2807528A - Apparatus and cyclic regenerative process for making oil gas

Info

Publication number: US2807528A
Application number: US424012A
Authority: US
Inventors: Elmore S Pettyjohn; Henry R Linden
Original assignee: Institute of Gas Technology
Current assignee: Gas Technology Institute
Priority date: 1954-04-19
Filing date: 1954-04-19
Publication date: 1957-09-24
Anticipated expiration: 1974-09-24

Description

Sept. 24, 1957 E. s. PETTYJOHN EIAI. 2,807,528

APPARATUS AND CYCLIC REGENERATIVE PROCESS FOR MAKING on. GAS Filed April 19, 1954 4 Sheeis-Sheet 1 MAKE O/A ATOM/Z/N' 75 5754/14 (III/.11:

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APPARATUS AND CYCLIC REGENERATIVE PROCESS FOR MAKING GIL GAS Filed April 19, 1954 4 Sheets-Sheet 2 5754M we 4r0M/z/A/6 P 1957 E. s. PETTYJOHN ETAL 2,807,528

APPARATUS AND CYCLIC REGENER'ATIVE PROCESS FOR MAKING OIL GAS Filed April 19, 1954 v 4 Sheets-Sheet 3 '5' Q g. Q $5 JAZZ/emf; A Z/zyore Harzzzg E, ZL'77a 222 p 24, 1957 I E. s. PETTYJOHN ETAL Q 2,807,528

APPARATUS AND CYCLIC REGENERATIVE PROCESS FOR MAKING OIL GAS Fnd April 19', 1954 4 Sheets-Sheet 4 526 .75 220422 .45 QUZQZ Q JNJQZZZ OZKY V gmorei zezfiyzfizz ezzz'g 22 72 United States Patent Ofiice 2,807,528 Patented Sept. 24, 1957 APPARATUS AND CYCLIC REGENERATIVE PROCESS FOR MAKING OIL GAS Elmore S. Pettyjohn, Evanston, and Henry R. Linden, Franklin Park, Ill., assignors to The Institute of Gas Technology, Chicago, Ill., a corporation of lilinors Application April 19, 1954, Serial No. 424,012 18 Claims. (Cl. 48-74) This inventionrelates to the manufacture of a fuel gas from liquid hydrocarbons. More particularly, it relates to a novel cyclic regenerative process for converting oil into a calorific gas which is absolutely interchangeable with natural gas.

In our copending United States application filed February 16, 1953, Serial No. 337,078, now Patent No. 2,759,806, we describe a method for cracking petroleum oils in the presence of hydrogen at super-atmospheric pressure to produce a fuel gas that is completely interchangeable with natural gas. The present invention relates to a cyclic regenerative process especially suitable for carrying out that method, although the present invention is also suitable for other similar oil cracking processes.

Sets of checker chambers comprising a generator and a superheater or regenerator are commonly employed for a cyclic cracking process in which the generator or generators are heated up to cracking temperature by burning oil and previously-deposited carbon therein and discharging the combustion products either directly to the atmosphere or through the superheaters or regenerators. This heating step is generally refeired to as the blast period. The heat absorbed by the checkers in the superheaters or regenerators is used to preheat air or steam subsequently introduced into the generator or generators, and to complete the oil cracking process. The make oil to be cracked is introduced into one or two generators during the make period with varying amounts of steam, and cracking proceeds at near atmospheric pressure, usually at less than 2-3 pounds per square inch gauge. The initial cracking products are then discharged through a superheater or regenerator where cracking continues at nearatmospheric pressure and tar and carbon continue to be deposited. Some of the sensible heat in these products may be stored near the cooler discharge end of the superheater, resulting in a limited amount of heat regeneration. However, the carbon deposits in the superheaters reduce the rate of heat transfer during the blast period, cause smoke formation during the initial phases of the blast period, and may cause plugging of the off-takes from the apparatus. The make gas separated from the cracking products cannot be completely interchanged with natural gas because of its high content of olefinic hydrocarbons, whose production is favored by cracking of oils at low pressures. Further, because of the tendency to smoke formation from pitch and carbon deposited in the superheaters, a considerable quantity of the blast gas has to be admitted into the product gas, thereby increasing its specific gravity and reducing its interchangeability for natural gas.

An object of this invention is to provide a cyclic process for cracking oils at elevated pressure to produce a gas interchangeable with natural gas in which the deposited pitch and carbon and additional oilrequired for meeting the heat requirements of the process are burned at atmospheric pressure. 7

Another object of the invention is to provide an improved process for cracking oils to oil gas interchangeable with natural gas in which the gaseous and vapor cracking products are discharged directly from the generator or chamber in which the cracking takes place.

Another object of the present invention is to provide a processfor making an interchangeable oil gas in a generator-regenerator set in which the cracking takes place in the generator only, the regenerators being used only for regeneration of heat in the blast gas.

Another object of the invention is to provide a cyclic regenerative process for making an interchangeable oil gas which is thermally efiicient by reason of a high degree of regeneration of heat in the blast gases.

Another object is to provide an improved process for making an interchangeable oil gas in which the vaporized tar comprising a portion of the cracked products is recovered as dry tar, and the oil gas is cooled immediately upon discharge from the cracking chamber or gas generator, with minimum change in the directional flow of the raw products prior to tar removal.

Another object is to provide an efiicient cycle for the gasification of a variety of oils, including heavy, residual petroleum oil, under pressure in an atmosphere of hydrogen-rich gas, hydrogen, or steam which yields an oil gas that is completely interchangeable with natural gas.

A further object is the provision of an apparatus in which the process of the invention may be efiiciently performed.

These and other objects will become apparent from the following description when read in conjunction with the accompanying drawings which serve to illustrated the invention.

In the drawings:

Figure 1 is an elevational diagrammatic view partly in section of a two shell apparatus suitable for practicing the invention in which the flow of hydrogen-rich gas or steam present during cracking is parallel to the flow of the make oil stream.

Figure 2 is a similar view of a three shell apparatus suitable for practicing a modification of the invention in which the flow of hydrogen-rich gas or steam may be counter to the flow of make oil.

Figure 3 is a similar view of a two shell apparatus suit- 7 able for practicing a modification of the invention in which the flow of hydrogen-rich gas or .steam may be counter to the flow of make oil.

Figure 4 is a similar view of a four shell apparatus in which the tar pots connect to the conduits connecting each generator with its corresponding regenerator.

Figure 5 is a sectional view taken along the line 5--5 of Figure 4.

Briefly, the apparatus for practicing the invention includes one or two refractory lined generators of the usual type used in making oil gas. These generators may or may not contain checkered bricks or hollow refractory pieces for storing heat during the blast period and releasing the heat during the make period. We prefer that the smallest amount of refractory shapes giving satisfactory tar pot connects with each description which appears hereinbelow.

the generator simultaneously cracking'be used, to provide a maximum volume within the generator forcombustion and for reaction.

The generator (or a pair of interconnected generators) are connected to a pair of individual regenerators, referred to for convenience as A and B, through gas channels, regenerator B being connected to the generator near one end and regenerator A being connected to the generator near the other end thereof. Thus, gases may pass freely through regnerator A, through the generator or generators, and out the regenerator B, or in the reverse direction. .Eachregenerator'connects toa stack through which gasesmaybe discharged to the atmosphere. A generator through or near the bottom thereof. The make gas is discharged from each generator'throughthe tar pot. Appropriate lines bring supplies of hydrogen, steam,-compressed air, make oil and heat oil to the'apparatus,andsuitable valves'are provided to control the flow of these reactants and to pressurize theapparatus,as willtbecome apparent from the detailed In operating the process, on an apparatus containing a single generator and tar pot, the generator is first heated to1a temperature at which" cracking of the oil will take placeQby means of two blast periods, one in each direction. The upblastperiod.constitutes passing air through regenerator A, which. hasv been previously heated, to heat the air, and upwardly through the generator where combustion of carbon deposited during the previous make period occurs. The hot products of combustion and excess air flow out of thegenerator through the upper gas channel and into regenerator B, which absorbs the sensible heat therein. The cooled, gases are discharged through the stack connecting,withregenerator B.

If necessary, further heatingis accomplished during the 'downblast period when air is brought into the generator through regenerator B. Heat oil is introduced into with, and in the same direc tion asrthe flow of the air. Combustion of the. oil takes place. Thehot combustion gases and excess air flow out of the generator through the lower gaschannel, through regenerator A, and are discharged to the stack. The hot combustiomgases and air give up heat to theregenerator A,

To prevent an explosion in the chambers during the following. make period, the set must be purged. after the blast periodand this is accomplished by passing steam sequentially through regenerator B, the generator, regenerator A and out through the stack. The steam displaces all the combustion products andair fromthe set. After heating to crakingtemperature and purging, the set is ready for accomplishing the cracking of the oil. The valves in. the discharge conduitsleading from the set are closed so that upon introduction of hydrogen-rich gas or steam into the set, the system becomes pressurized, to say 3 to 5 atmospheres. The pressure withinthe set is regulatedbymeans of a pressure control valve in the product gas discharge conduitleading from thetar pot. The hydrogen-rich gas or steam passes through the regenerator for preheating: before entering the generator. Make oil, which preferably has been preheated,.is-sprayed into the generator. The hydrogen-rich gas or steam continues toflow into the generator, simultaneously with the make oil. The. oil is cracked at elevated temperature and pressure inflan atmosphere of hydrogen or steam to produce crackingproducts which include an interchangeable oil gas ,and .tar vapors. As the cracking products are generated, the pressure inside the set exceeds the operating pressure controlled bythe pressure control valve located downstream ,of the tar pot, and are discharged directly from the lower end of the generator into the'tar pot. The products are quenched in. a stream of cooled tar being fed into the. pot to reduce the temperature of the gaseous products and remove vaporized tar therefrom by condensation. The tar is maintained at a temperature sufiiciently low to efiect condensation of tar vapors in the cracking 4 product by circulation through a suitable cooler. To supplement the cooling effected by the circulating tar, water may be introduced into the hot cracking products as they pass from the generator into the tar pot. The quantity of water fed to the tar pot must be regulated to prevent the temperature from falling below condensation temperature. The cooled gaseous cracking products, which comprise an oil gas interchangeable with natural gas and some of the light non-condensed hydrocarbon fractions, pass from the tar pot through the pressure control valve to a condenser in which the interchangeable oil gas is separated from the condensable products, including steam.

After the make period has been completed, the pressure is reduced to that of the atmosphere and the set is again purged by passing steam sequentially through regenerator B, the generator, regenerator A and out the stack. At this point the generator is again heated to cracking temperature by blasting at near-atmospheric pressure and the cycle is repeated as described.

The present process differs from the conventional oil gas production in several respects which result in important advantages. It provides for cracking to take place at superatmospheric pressures which favors the produc-' tion of methane and ethane, the major combustible constituents of natural gas, over the production, of the gaseous olefins and diolefins which have undesirable combustion characteristics. Air blasting still takes place at nearatmospheric pressure which permits the use of conventional blows with low power requirements instead of compressors. It willbe noted that the.cracking products are not discharged through the regenerator as in conventional processes where an attempt is made to continue thecracking process by superheating, or to utilize the sensible heatvtherein. These two objectives are not compatible sincetemperatures of 1300 F. or higher are necessary for reasonable rates of cracking. Temperatures in this range do not permit any significant amount of heat regeneration. In the present process the cracking products pass directly out of the generator through an opening near thelower end or through the bottom thereof with a, minimum change in. the direction of flow, into the cooling zone through which cooled tar is circulated. Water may be introduced into the, coolingzone simultaneously with the tar,. if necessary, to obtain the desired degree of cooling. Alternatively water may be used exclusively to quench the make gases. By removing the cracking products directly instead of through the regenerators, tar. and pitch, which. are. always present in the gaseous cracking products, are not deposited in the regenerator to:foul the heat i transfer surfaces. Wehave found thatprevention of foulingof the regenerators more than compensates for. the loss of anyrecoverable sensible heat inthe make gas. Under normal. operating conditions less than one quarter of the potential heat recovery can come from the cracking products. If the generators provide insufficient reaction space, little or no potential heat recovery may be realized. Therefore,:the present invention provides increased thermal efficiency. The tar is recovered very conveniently, directly in the dry state. Convenient recovery of tar is especially important in cracking processes with heavy, residual oilswhich yield relatively high proportions of tar.

In the design of the apparatus for practicing the invention, care must be taken to provide sufficient volume inthe generator'to effect cracking therein, so as notto employ the regenerators asextensions of the generators.

The use of regenerators as a generator results in high stacktemperatures and high heat requirements, because the temperature in the regenerator must be equivalent to that in the generator. When adequate generator space is i provided, the regenerators are. then available for eflicient preheating of blast air, make and purge steam and hydro gen since they are not fouled by tar, pitch and carbon.

In spite of the lack of make gas regeneration in our process, a net increase in thermal efiiciency is possible.

The make oil used in the process of the invention is preferably preheated. This practice increases the crackmg capacity and lengthens the refractory life of the generator. Introduction of non-heated oil into a generator heated to cracking temperature causes spalling of the refractory and greatly shortens the life thereof.

The present cyclic process is adaptable to both parallel and reverse flow pressure hydrogasification systems. In the parallel flow system of cracking, the hydrogen or steam fed to the generator with the oil during the crack mg period flows parallel to the atomized make oil entering the generator. In the reverse flow system the hydrogen or steam is introduced at the opposite end of the generator so that the flow of hydrogen or steam is counter to the flow of oil. Counter flow increases the length of heat exposure of the largest oil droplets since they penetrate furthest in flowing against the current of steam or hydrogen, thus permitting them to crack completely without depositing on the refractory lining or checkerbrick.

The apparatus illustrated in Figure l is a cyclic regenerative parallel-flow pressure oil gas set, and exemplifies one form of the present invention. The generator designated by the reference numeral is a standard cylindrical vessel lined with refractory material 15. The generator illustrated does not contain checkered bricks or other refractory shapes, but a refractory grid 16 is provided to serve as a support for such refractories if they are desired. A suitable heat exchanger 21 is provided for heating the make oil. Coil 22 in the heat exchanger connects to a conduit 18 which in turn connects to a pipe 23 which pierces the top of the generator. A nozzle 24 is fixed to the end of pipe 23, which divides the oil stream into a fine spray. Steam pipe 17, concentric within pipe 23, provides the necessary atomizing steam to the nozzle for breaking up the liquid oil. Air may be used for atomizing in place of steam. Similar

concentric pipes

25 and 19 pierce the top of the generator to supply air and heat oil respectively to the generator.

A tar pot 13 is connected to the bottom of the generator 10 through a large discharge conduit 30, which is approximately equal in diameter to the inside diameter of the generator, and extends down into the pot for some distance. A conventional level control device, not shown, causes tar to be withdrawn through line 39, to maintain the tar level below the end of conduit 30. Combination water and steam pipe 31 connects tangentially to the interior of generator just above the conduit 30, and tar supply pipe 32 connects tangentially to conduit 30. Pipe 33 connects to the tar pot 13 near the bottom thereof and leads to a pair of coolers 34 and 36 interconnected with pipe 35. Cooler 36 connects to tar supply pipe 32. Suitable means (not shown) is provided for passing cooling fluids around the pipes 37 inside coolers 34 and 36 to cool tar circulated through the coolers. Make gas discharge conduit 46 connects to the tar pot just above the lower end of conduit 30 projecting thereinto, and is equipped with a pressure control valve 41 by which pressure within the generator may be regulated. The valve 41 is set for a predetermined maximum pressure, at which pressure it opens to permit gases to pass from the set. Conduit 46 connects to a condenser 45 for separating oil gas from the liquid components of the make gas. The condenser 45 is of conventional construction and has cooling coils 47 through which cooling water circulates. The water is discharged through drain pipe as.

Conduit 50 is joined to the condenser near the top thereof for taking off oil gas, and conduit 49 connects near the bottom thereof for removing liquids condensed from the make gas. A by-pass conduit 42 provided with a valve 43 furnishes a means for by-passing pressure control valve 41, its terminals connecting to conduit 40 just downstream and just upstream of pressure control valve 41.

Individual regenerators 11 and 12, combined in a single shell, contain checkered bricks 52 supported by refractory grids 53 through which gases may pass freely to give up or absorb heat. The upper regenerator 12 has a cross over conduit 54 which connects the regenerator 12 with the generator 10 near the top thereof. Lower regenerator 11 is connected to the generator 10 near the bottom thereof by means of a similar cross-over conduit 55. Regenerator 12 connects to a source of air, hydrogen,

or steam and to the stack 61 through conduit 60. Purgesteam and make steam or hydrogen are supplied from pipes 62 and 63 respectively which connect to conduit 64 which is connected to conduit 60. Communication between the stack 61, or the air line, and regenerator 12 is established through three-way valve 65 in conduit 64. Line 69 connects to pipe 76 which connects directly to three-way valve 65. The stack 61 connects to conduit 64 through pipe 68.

Regenerator 11 communicates with the stack 61 and the air line 69, but not with the source of hydrogen or steam which may enter the generator only from the top in a parallel flow system. Communication with the stack is established through pipe 68, conduit 66, three-way valve 67 and conduit 71, which forms part of regenerator 11 and is identical to conduit 60 of regenerator 12. Air is introduced into regenerator 11 through line 69, pipe '70, three-way valve 67, conduit 66 and conduit 71.

The cycle of operation for the parallel flow cyclic regenerative set just described is as follows. The generator 10 is first heated to cracking temperature, which may range, for example, from 1500-1700 F., during the blast period. The blast period consists of an upblast and a downblast, according to the direction of air flow through the generator. Three-way valve 67 is opened to permit air to flow from line 69, through conduit 71 and into regenerator 11. The by-pass valve 43 is closed during the blast period so that flow of combustion products from the generator 10 will be through the regenerators 11 and 12 and not through the tar pot and conduit 40. The regenerator contains some heat stored from the previous cycle and as the air passes downwardly therethrough it absorbs heat from the checkers. The heated air then flows through conduit 55 and upwardly through the generator 10, which has carbon deposited on the interior surfaces thereof from the previous make period. Introduction of hot air into the generator causes the deposited carbon to burn, and the heat produced raises the temperature of the generator. The gases of combustion pass from generator 10 through conduit 54 into regenerator 12 and are'discharged therefrom through conduit 60, conduit 64, three-way valve 65, conduit 68 and into the stack 61. The hot gases of combustion give up heat to the regenerator 12. This completes the upblast period. If the heat release from the combustion of deposited carbon is insufiicient, or if all of the deposited carbon cannot be efficiently burned by unidirectional blasting, the upblast is followed with a down blast period. The downblast is initiated by switching three-

way valves

67 and 65 to block the air passage through valve 67 to regenerator 11 and open the air passage through valve 65 to regenerator 12. Switching the valves also closes the exit from regenerator 12 to the stack and opens the exit from regenerator 11 to the stack. Air from line 69 passes into the regenerator 12, through pipe 70, valve 65, conduit 64 and conduit 60. The air absorbs heat from regenerator 12 and passes into generator 10 through cross-over 54. Simultaneously with the switching of the three-way valves, heat oil and air may be introduced into the generator through

concentric pipes

19 and 20. The heat oil is burned in a gun type burner with the generation of intense heat in the presence of excess air. The hot products of combustion and excess air pass out of the generator through lower cross-over 55 into regenerator 11 and out the stack 61 through a route previously described. Air valve 72 and the heat oil are shut off. The temperature of the generator, as the result of heat generated during the blast from line .62 through conduit 64, conduit v60, regenerator 12, cross-over 54, generator 10, cross-over 55, regenerator 11, conduit 71, conduit=66, three-way valve 67, conduit it 68 and into the stack 61. Steam from line 62 may be supplemented with make steam or hydrogen from line 63, which follows the course just traced. A short period after the steam valves have been opened, the three-way valve 67 is closed to complete the blocking of all outlets trorn regenerators 11 and 12. The purge period is about 20 seconds, after which the valves 73 and 74 in steam supply" lines 62 and 63 are closed. The set is now purged ,and pressurized. The maximum pressure within the set is regulated by control valve 41 which is set to maintain the pressure at 50 pounds per square inch gauge, for example.

The make period is initiated by opening the make oil valve 14 to permit oil, for example Bunker C oil, which has been preheated in heat exchanger 21, to flow into the generator through nozzle 24 in a fine spray. The oil is pumped so that it will flow freely against the pressure in the generator. Simultaneously steam or hydrogen or hydrogen-rich gas is introduced into the generator through pipe 63 The oil is cracked in the presence of steam or hydrogen to form oil gas, light petroleum fractions, and tar, all of which are in the form of gases or finely dispersed droplets. The residence time of the oil in the generator is, for example, seconds. The make period is terminated by closing the make oil and make steam or hydrogen valves. Oil gas and by-products produced during the cracking process flow continuously downwardly through the, conduit 30 and are discharged through conduit 40. ,During the make period cooled tar is introduced tangentially into the conduit30 to reduce the temperature of the make gas to about 400 F. and condense out tar vapors in the gas The tar is maintained at a temperature below 300' F. by circulation through pipes 37 in coolers 3 4 and 36.. To supplement the cooling efifect of the tar,

water may be introduced into the cooling zone just above the tar pot, through conduit 31. Water need not be used forcooling, but in such case tar cooling equipment must be much larger to cool the greater quantities of tar needed for effectively reducing the temperature of the make gas. To prevent the tar in pot 13 from igniting, particularly during the blast period, steam flows continuously into conduit 30 through conduit 31 from branch steam line 44. The same line is used for cooling water.

The cooling water, of course, is converted to steam immediately upon contacting the hot make gas and is discharged from the tar pot with the tar-free cooled gases through conduit 40. By conducting the tar-containing make gas directly into the tar pot there is no possibility of fouling the apparatus, or plugging the off takes, as is generally the case in conventional apparatus where the make gas containing tar vapors is passed through the regenerators and a number of conduits over an irregular path. In the latter case tar is deposited freely and in time the. apparatus may be completely fouled.

During the make period the pressure in the setis limited to the desired cracking pressure by regulating valve 41. Gases generated cause the valve to open and the make gasflows into the condenser 45 where the oil gas product is separated from the light oil and other condensable contents such as steam.

After thornake period has been completed, the bypass valve .43 is opened and the pressure in the set falls to that of the atmosphere. Purge steam valve 73 and make. steam valve .75 are then opened to till the set with p an b rs u plo ves sss- Steam ent ri 100, for heating purposes.

the generatortromline 62 is introduced through regenerator 12. Thecrackedgases are pushed out ahead of the steam through the by-pass valve 43, whereupon valve 43 1s closed. The three-way valves 65 and67 then switch to spans: position which permits air from line 69 to how through valve67 into the regenerator 11, and simultaneously connects regenerator 12 withthe stack for discharging gasese frorn the generator through .regenerator 12. The cycle described is then repeated beginning with the blast period.

The apparatus of Figure 2 is a three-shell unit adapted for reverse flow, that is, a process in which the hydrogen-rich gas, or steam introduced into the cracking vessel fiows counter to the flow of the make oil. The individual elements of this apparatus and their function are the same as those described in connection with the apparatus of Figure l, but their number and arrange nicnt is different to provide for the reverse flow system. This description, therefore, will concentrate on the differences. .Generators and 102 in separate shells are interconnected .by cross-over conduit 103. Regenerators 104. and 106 are combined in a single shell just as the regenerato-rs of the set shown in Figure l.

Conduits

109 and 110 connect to the interior of regenerators 104 and 106 respectively near their lower ends and serve to conduct hydrogen, steam and air to the regenerators and to exhaust gases and cooled steam to the stack. Conduit 108 is connectedto regenerator 106 near the top thereof and joins generator 100 near the bottom thereof. A similar conduit 111 leads from the upper portion of regenerator 104 to the lower portion of generator 102.

Oil supply conduit 112 connects to heat exchanger 114 for heatin g the oil, which in turn'connects to hot oil storage tank 116 through conduit .115. Conduit 117 servesto conductthe oil from tank 116 to the generators 100 and .102 through branchlines .118, 119, 120, 121, 122 and 123. :Branch lines and 121, containing valves .124 and 126 respectively, supply oil for cracking (make oil) to nozzles 128 and 130 mounted in the top of gen erators 100 and 102. Branch lines 119 and 122, equipped withvalves 131 and 132, supply oil to atomizing burners 13.4 and 136 mounted in the top of generators 102 and

Branch lines

118 and 123 equipped with valves 138 and 140 supply oil to burners 141 and 142 mounted in the side walls near the lower end of

generators

102 and 100 respectively for heating during reverse blast. Each of the heat oil burners 136, 142 and 134,141 have concentric valved conduits 146, 144 and 150, 148 respectively for supplying atom'izing air or steam to the nozzle. Theair or steam lines connect to a source of compressed air or steam not shown in. the drawing.

The lower portions 135 and 137 of the

generators

100 and 102 serve as quenching zones for the gas generated during cracking and for this

purpose water conduits

151 and 152 connect tangentially to the generator. The same conduits deliver steam continuously to zones 135 and 137 to prevent ignition of tar in the pots and 156. Conduits 153 and 154, tangentially connected to the generatorsltlt) and 102, conduct cool tar to the quenching zones 135 and 137. Tar pots 155 and 156 connect directly to the bottom of

generators

100 and 102 below quenching zones .135 and 137 so that the pots are in di- .rect communication with the interior of the generators. Tar discharge pipe 158 has opposite ends connected to the lower side wall of tar pots 155 and 156 and receives tar from both pots. A branch :line 159 from pipe 158 connects to a pump 160, the discharge side of which connectsto conduit 161. Coolers 162 and 163 receive hot tar from conduit ,161 and discharge relatively cool tar to conduit 153 and its branch conduit 154. Pump 1.60. moves the tar continuously from the pot, through the coolers and backto the pot.

Large conduits 165 and 172 lead from the tar pots to condenser 180. Conduit 172 connects through a T to conduits 173 and 174, containing valves 175 and 176 respectively. Valve 175 is a maximum pressure regulating valve. Conduits 173 and 174 connect to conduit 177 leading to condenser 180. Condenser 180 has a discharge conduit 181 near the upper end thereof for gases and a discharge conduit 182 near the lower end thereof for condensed vapor products. Conduit 165 joins conduit 172 just downstrea-m of the T; thus, the valves 175 and 176 and the condensing equipment serve both generators.

'Valved supply lines 185, 186 and 188 for hydrogen, steam and air connect to conduit 109 through which these materials may be introduced into the set through regenerator 104. The downstream end of conduit 109 leads to the stack 190. Similarly, valved supply lines 192, 193 and 194 connect to conduit 110 for supplying hydrogen, air and steam to regenerator 106. Branch steam lines 187 and 195 permit flowing smaller volumes of steam into the regenerator for make purposes. Normally lines 187 and 195 are used for make steam, with the supply for purging being supplemented through larger lines 186 and 194. The opposite end of conduit 110 connects to stack 191.

The operation of the reverse flow apparatus is as fo1- lows. The cycle will be described beginning with the make period in generator 100. Make oil furnished from the preheated supply in storage tank 116 is introduced into generator 100 through

lines

117, 121 and nozzle 128. (If desired, the oil may be split and introduced into both

generators

100 and 102 simultaneously.) The generator has been previously pressurized and heated to cracking temperature as will appear hereinbelow. Simultaneously with the introduction of make oil, hydrogen or steam or both are introduced into the generator 100 for provision of the cracking atmosphere. In this example hydrogen will serve to illustrate the atmosphere gas. The hydrogen is fed from line 192 into conduit 110, through regenerator 106 and conduit 108, and into generator 100.

Cracking occurs initially in generator 100 with the formation of initial vapor-phase cracking products and deposited carbon. The initial cracking products flow with the hydrogen counter to the oil spray, through the cross-over 103 and into the generator 102. Here the cracking is completed with the formation of gaseous cracking products, including a gas completely interchangeable with natural gas, tar vapors, light aromatic hydrocarbons and additional deposited carbon. The product gases are discharged directly from generator 102 through the cooling zone 137, where they are quenched by contact with tar entering the zone through conduit 154, and water and steam from conduit 151, and into the tar pot 156. The water, of course, is immediately converted to steam with the absorption of large quantities of heat, since the temperature in the pot is always in excess of condensation temperature. The reduction in temperature due to contact with cooling tar and Water, condenses heavy tars or pitch in the cracking products which would tend to foul the apparatus. The condensed tar is deposited in the tar pot 156. The partially cooled, tar-free gaseous cracking products and steam then pass from the tar pot through conduits 165 and 172, pressure regulating valve 175, conduit 177 andinto the condenser 180 where the normally liquid constituents of the cracking products: and the steam are condensed and separated from the oil gas. The make period is ended by closing the valve in oil supply line 120 and the valve in hydrogen supply line 192. The flow of make gas is continuous to the end of the make period. The fiow of quenching water from line 151 is then discontinued by closing the valve in that line. Steam continues to flow from line 151 to provide a seal against combustion of tar. By-pass valve 176 is then opened to reduce the pressure in the set to that of the condensing system, which is essentially atmospheric.

Next, the set must be purged by displacing all gaseous cracking products with steam. Steam from line 194 is permitted to flow into conduit 110, through regenerator 106, out conduit 108, into generator 100, through crossover conduit 103, into generator 102, out through quenching zone 137, conduit 165, and into the condensing system. The gaseous products displaced are discharged ahead of the steam.

When the set is filled with steam the valve in steam line 194 is then closed. By-pass valve 169 is also closed to prevent blast air from escaping through conduit 172, and to permit pressurizing the set during the next succeeding make period. The valve in line 109 to stack 190 is opened.

The set is now purged and ready for the forward blast period during which the generators and regenerators are heated. Air from line 193 is passed through conduit 110, into regenerator 106, out through conduit 108, into generator 100, through cross-over conduit 103 and into generator 102. The hot flue gases or products of combustion are discharged through conduit 111 into regenerator 104, out through conduit 109 and discharged into stack 190. As the air enters the generator 100, cross-over 103 and generator 102, the carbon deposited on the surfaces. thereof during the previous make period is burned to raise the temperature Within the generators to cracking temperature. Steam delivered to zones 135 and 137 through

conduits

152 and 151 prevent combustion of tar in pots 155 and 156. If necessary, heat oil may be burned in the generators during this portion of the cycle to attain the maximum temperature desired. In such case at this point heat oil is introduced into generator 102 through line 119 and burned in the burner 134. The hot gaseous products of combustion and the excess heated air are discharged from generator 102 through regenerator 104 and out stack 190 as previously described. Heat from the products of combustion and the air is absorbed by the checker refractories in regenerator 104. The blast period completed, air supply from line 193 is shut off and the valve in line 109 leading to stack 190 is closed. The valve in line leading to stack 191 is then opened to permit discharge of gases and steam during the next period of the cycle.

The set is then purged by opening steam lines 186 and 187 to permit steam to flow through conduit 109 into regenerator 104, out conduit 111, into generator 102, through cross-over conduit 103, into generator 100, out through conduit 108 into regenerator 106, out conduit 110 and be discharged into stack 191. Thus, the set is completely purged. The valve in line 110 leading to stack 191 is then closed. Steam valves in lines 194 and 195 are closed.

The make period in generator 102 is then carried out. The valve in hydrogen supply line 185 is opened to permit pressurizing the set with hydrogen. Make oil is introduced into generator 102 through the nozzle which connects to

conduits

121, 117 and the hot oil storage tank 116. Hydrogen from line 185 continues to flow through conduit 109 into regenerator 104 where it absorbs heat from the hot refractories therein. The hydrogen then passes through conduit 111, and rises upwardly in generator 102 counter to the spray of atomized make oil. Cracking products flow upwardly in the direction of the flow of hydrogen through cross-over 103 and downwardly through generator 100 in which they are quenched by contact with water entering quenching zone through conduit 152, and tar, which enters the quenching zone through conduit 153. Cracking will take place in both generators and in cross-over 103. The heavy tar vapors are condensed and the cooled tar-free gaseous cracking products are discharged from the tar pot through conduit 172, past pressure regulating valve 175, through conduits 173, 177 and into the condenser where separation of the normally liquid and normally gaseous products is effected, as previously described. When the make period has been completed the flow of hydrogen and oil to the generator is cut 011. The set is depressurized by opening by-pass valve 176.

Next, the set is purged by admitting steam from lines 86 an 187 th num ra orh generator 2 the generator-100, and outcondensing system. As the by passing air from line 1188, through conduit 109, into regenerator 104, throughconduit 111, into generator 102, through cross-over 103, into generator 100, out through conduit 108, into regenerator 106, out, through conduit 110 and discharging to stack 191. If the combustion of the deposited carbon does not heat the generator sufiiciently for cracking,heat oil may be burned during the blast period by introduction through burner 136 from conduit 122. The flow of oil is parallel to the flow of air through the generator. Thus, the generator 100 and the regenerator 106 are thoroughly heated. After the blast period the .valve in line 110 leading to stack 191 is closed and the valve in .line 109 leading to stack 190 is opened.

The blast period is followed by another purge period in which steam is admitted to the set from lines 194 and 195, and passes through regenerator 106, generator 100, generator 102, regencrator 104 and out stack 190 through connecting conduits, as previously described. The cycle is then repeated from thebeginning.

An alternative method for operating this apparatus may be described as a reverse blast cycle. The procedure outlined above is repeated with a make period carried out in generator 100 followed by a steam purge. Then instead of blasting air downwardly through generator 102 as in the forward blast, the air is introduced from the bottom. The air source is line 188 from which the air flows through .regenerator .104 and into the bottom of generator 102. If heat oil is required it is introduced into the generator through conduit 14 1. The cycle then continues with a steam purge, a make period-in generator 102, and a second steam purge. Then instead of blasting air downwardly through generator 100 as in the forward blast cycle, this generator is heated by blasting upwardly, introducing air through regencrator 106 from supply line 193. Heat oil, if required, is introduced into generator 100 through burner 142. The reverse blast cycle is then completed by following the purge and make procedures set forth in the description of the forward blast cycle.

A two-shell reverse flow regenerative, set is illustrated in Figure 3. Instead of employing individual generators in separate shells as in Figure 2, each of the generators of Figure 3 is housed with its corresponding regenerator in a single shell. Thus, generator 200 and regenerator 204. are housed in a one shell, and generator 202 and regenerator 206 are housed in a second shell. In Figure 3 the generators are located in the upper portion of the shells and are joined near their upper ends by a crossover conduit 203. Conduit 210 connecting to regenerator 204 suppliesair, steam and hydrogen and provides stack discharge just as corresponding conduit 110 in Figure 2. Likewise, conduit 209 supplies air, steam and hydrogen to regenerator 206 and discharge to the stack. The two generators and regenerators and their respective supply and discharge conduits bear the same relationship one to the other as corresponding parts in Figure 2. However, tar pots 155 and 156 have been replaced with a single tar pot 255 mounted between generators 200 and 202 and connected to the lower portions of the generators by means of conduits 215 and 21.6. With such an arrangement the cracking products are discharged from an opening in the lower side wall of the generator rather than from an opening in the bottom of the generator. The tar pot has an axial partition 256 down the center which dips below the level of the tar and divides the pot into two separate sections. Generator, 200. discharges into one section and generator 202 into the other section. The

upper portion of the tar pot constitutes the cooling zone .for discharged cracking products, each space astride the partition 256 .being provided with separate cooling tar through conduits 253, 254 and cooling water and steam .through conduits 252 and 251. Cracking products are discharged separately from each space through conduits 272 and 265 into a common condensing system. The tar pot 255 dueto its-partition 256 functions as two individual pots, as in Figure 2, although it is constructed as a single integ ni The apparatus of Figure 3 functions in identical manner to that of Figure 2 so the description of operation will not be repeated. By removing the tar pot beside the generator rather than beneath it, contamination of the tar by refractory lining, ash, or similar contaminants that might fall from the generator is eliminated. Furthermore, the tar is not subjected to direct radiation from the generator.

Reference is now made to Figures 4 and 5 which illustrate a four-shell apparatus similar to that of Figure 3 in construction and operation. The only significant structuraltdiffcrence is in the arrangement and number of tar pots and the manner in which the tar pots are connected to the set. A pair of

generators

300, 302 are connected near their upper ends by a cross-over conduit 301. Generator 300 connects to regenerator 304 through the T 308 near the bottom of the vessels. Similarly, generator 302 connects to the regencrator 306 through the T 310.

Tar pots

312, 314 connect to the vertical arm of TS 308 and 3.10, respectively. Provision is made for introducing heat oil and make oil to the generator 300 through line 320. A similar line (not shown in the drawing) supplies oil to the generator 302 which is directly behind generator 300 in Figure 4. Steam, air and hydrogen are supplied from appropriate sources to the line 322 which connects to the stack at one end and to the top of regenerator 304 at .the other. A similar arrangement is provided for regenerator 306. Cooling tar is supplied through line 324 to the down-comer conduit 309 which joins tar pot 312 with T 308, while water and steam are supplied to conduit 309 through line 326. Make gas take-off conduit 316v conducts gas from tar pot 316 to the condensing system, not shown in these figures.

With the arrangement illustrated in Figures 4 and 5, the advantages that accrue by reason of moving the tar pot beside the generator rather than beneath it (as shown in Figure 3), still prevail. In addition, the arrangement permits blasting the gas off-take connecting the generator to the tar pot. Thus deposited carbon and pitch which might plug the off-take are burned off during each blast period, because the blast air may pass directly through the

T

308 or 310 in llowing in either direction between the generator and the regenerator. The make gases, of course, must follow the turn in the T, but carbon and pitch deposition is not a problem because blasting is possible. The down-comer or throat 309 connecting the T to the tar pot is cleaned constantly by the flow of steam, water and tar introduced tangentially through lines 326 and324.

From the foregoing description it becomes apparent that the cyclic regenerative apparatus of the present invention is susceptible of a variety of arrangements, particularly with respect to the location of the generators and regenerators and the number of shells employed.

The data below illustrates the use of the process and apparatus of the invention in manufacturing a gas interchangeable with natural gas from various oils. The product gases were tested in different types of gas appliances adjusted on natural gas and were found to burn satisfactorily without readjustment of the burners. Examples l-3, 79, 13-15 illustrate cracking in an atmosphere of steam, and Examples 4-6, 10-12, 16-18 illustrate cracking in an atmosphere of hydrogen with the hydrogen feed rate varying from 30 to 90 s. c. f. per gallon of oil.

lson of oil gas processes for 21 .4 API, 7.04 C/H ratio, 4.4 wt. percent Conradson carbon residue reduced crude oil Compar 1 Corrected to 100% material balance.

Comparison of Oll gasrficatzon processes for diesel oil 373 API, 6.30 CIH .'35;7.API, 6'.74;CiH.ratio,. wt.

ratio, 0 wt. perpennant R cent CCR Typical high B. t. u. Typical pressure hydrogasioilgas operation Typical fleation,:s. c. t. Hilgal.

pressure gasifica- Low High tion 60 90 severity severity Example number 13 14 15 16 17 18 Cracking temperature, "F 1, 470 1, 570 1, 400 1, 400 1, 400 1, 400 Residence time, sec 2. 07 2.56 5.43 5. l7 5. 22 6.12 Pressure, p. s. i. g 0 00 60 60 60 Net B. t. u. recovery, M B. t. '81. 95 81.45 08. 57 72. 76 80.85 83. 84 Inert-tree product gas yield, s o /g 1 Total 68.86 79.42 57.91 77. 54 100. 12 122. 99 Net 08.-80 79. 42 57. 91 60.48 09.03 68. 59 Tar yield, wt. pcrce 43. 3 42.15 52. 0 40. 5 43; 8 40. 5 Carbon deposition, wt. percent. 0. 8 3. 3 '3. 3 0.7 0. 5 0. 2 Inert-free product gas properties:

Composition, mole percent:

Hydrogen 17.3 26. 3 13.1 22. 0 31. 1 44.3 Methane 41. 8 44; 0 56.- 0 53. 3 45. 2 33. 0 Ethane 4.1 2. 4 10. 5 10.6 ll. 5 12. 3 Propane and higher paraffinsu. =0. 3 0.5 0. 4 0.3 0.5 Ethylene 28. 4 22. 8 13. 3 -9. 8 9. 5 7. 5 Proplylenc A. 0 1. l -4. 4 2.0 1. 4 1. 6 Big er unsaturates. 3. 2 3. 4 2. 2 1. 9 1.0 0. 8 Heating value, B. t. u./s. c. 1,190 1,025 1,184 1, 066 086 913 Specific gravity, Air= 1 0.707 0. 600 0. 679 0. 587 0. 534 0. 492 Tar properties:

Specific gravity, 60 F./60 F 1. 055 1.088 1.046 1.031 1.047 0. 997 Free carbon, wt. percent..- 6.1 7. 6 8.2 6. O 1. 1 0.9 Sulfongtion index, Ml. unsulf. residue/100 For distillate 0-300 0 7. 32 4. 77 0.16 8. 73 0.00 5.31 For distillate soc-355 C 1.11 0.71 1:01 1:94 0.00 1.03

I Corrected to 100% material balance.

It will be noted from the data that the olcfinic hydrocarbons in the product gas are greatly reduced by pressure gasification. If, in addition, feed hydrogen is used, the olefinic hydrocarbons in the product gas are further reduced, the amounts of oil converted to gas are increased, and the quantities of carbon deposited are reduced. The by-product tar is of better quality as the amount of hydrogcn present is increased, as indicated by its reduced 7 to those skilled in the art without departing from the scope and spirit of the invention.

We claim:

1. In a cyclic regenerative apparatus for cracking liquid hydrocarbons under pressure, comprising at least one generator interconnected with a pair of rcgcncrators, a tar pot communicating with the generator through the lower portion thereof, a vtakerott' conduit containing a pressure reducing valve leading from said tar pot to a condenser, a valved conduit lay-passing said pressure reducing valve, and means for introducing cooled tar. into the upper portion of the tar pot to cool gases discharged fromthe generator.

'2. A cyclic regenerative apparatus comprising a retractorylined chamber defining a space for generating gaseous and liquid cracking products, two regencrators each communicating with an extremity of said chamber as would be expected, the results are superior in; that substantially complete gasification is effected when producing gases of approximately 1000 B. t. u./s. c. f.

through open passageways for gaseous flow thcrothrough, a tarpot communicating directly with said chamber for freely receiving said products, and means Within said tarpot for cooling said products, said apparatus being free of valves and obstructions hindering free flow of fluids Runs were made on diesel oil, reduced crude and Bunker C fuel oil in accordance withgthe process of the invention to determine the improvement in gas yicldsand in by-product quality due to the presence of hydrogen during cracking. The following table summarizes the results of runs made at 1400 F., 5 seconds residence time, 5-;

atmospheres pressure, without hydrogen and with hydrogen (90 s. c. f./gal. of oil).

Other modifications of the invention will be evident between said chamber and said regenerators and between said chamber and saidtarpot.

3. The apparatus of claim 2 wherein said chamber comprises two interconnected shells, each having a tarpot communicating directly therewith.

4. The cyclic regenerative process of claim 1 wherein the set is maintained at superatrnospher'ic pressure while said cracking'step is being carried out.

5. In a cyclic regenerative apparatus for cracking liquid hydrocarbons, a refractory-lined generator and a pair of individual checkcrbrick rcgenerators capable of absorbing and releasing heat, a conduit connecting one of said regencrators to the generator near the upper end thereof, a second conduit connecting the other regcnerator to the generator near the lower end thereof, a tar pot communicating with the generator through the lower portion thereof, a take-oif conduit :leading from said tar pot to a condenser, means for introducing liquid hydrocarbons in to said generator, valved conduits connecting said re generators to a stack for discharging fluids from the apparatus, valved supply lines connecting to each of said regenerators for introducing steam and air into said generators, and means for introducing cooled tar into the upper portion of the tar pott'o cool gases discharged from the generator.

6. In a cyclic regenerative apparatus for cracking liquid hydrocarbons under pressure, a refractory-lined generator and a pair of individual checkerbrick regenerators capable of absorbing and releasing heat, a conduit connecting one of said regenerators to the generator near the upper end thereof, a second conduit connecting the other regenerator to the generator near the lower end thereof, a tar pot communicating with the generator through the bottom thereof, a take-off conduit containing a pressure regulated valve and leading from said tar pot to a condenser, a valved conduit by-passing said pressure regulating valve, means for introducing liquid hydrocarbons into said generator, valved conduits connecting said regenerators to a stack for discharging fluids from the apparatus, valved supply lines connecting to each of said regenerators for introducing steam, air and hydrogen-rich gas into said generators, means for introducing cooled tar into the upper portion of the tar pot to cool gases discharged from the generator, and cooling means connected with said tar pot for cooling the tar.

7. In a cyclic regenerative apparatus for cracking liquid hydrocarbons under pressure, a first and second refractorylined generator and a first and second checkerbrick regenerator capable of absorbing and releasing heat, a first conduit connecting the generators near the upper ends thereof, a second conduit connecting the first generator to the first regenerator and a third conduit connecting the second generator to the second regenerator, a tar pot communicating with each generator through the bottom thereof, take-off pipes connected to each pot and joining a single product-discharge conduit having a pressure regulating valve therein, a by-pass conduit having its terminals connecting to said product-discharge conduit on either side of said pressure regulating valve, a condenser connecting to the downstream end of said product-discharge conduit, means for introducing liquid hydrocarbons into said generators, valved conduits connecting said regenerators to a stack for discharging fluids from the apparatus, valved supply lines connecting to each of said regenerators for introducing steam, air and hydrogen-rich gas into said generators, and means for introducing cooled tar into the upper portion of the tar pot to cool gases discharged from the generator.

8. In a cyclic regenerative apparatus for cracking liquid hydrocarbons under pressure, a first and second refractory-lined generator and a first and second checker-brick regenerator capable of absorbing and releasing heat, a first conduit connecting the generators near the upper ends thereof, a second conduit connecting the first generator to the first regenerator and a third conduit connecting the second generator to the second regenerator, a tar pot having a vertical baflie extending longitudinally thereof and below the level of the tar in the tar pot to divide the pot into a first and second section which sections communicate below the baflie, fourth and fifth conduits leading from the lower end of said first and second generators to said first and second section of said tar pot, a pair of take-01f pipes connected to said first and second sections and joining a single product-discharge conduit having a pressure regulating valve therein, a by-pass conduit having its terminals connecting to said productdischarge conduit on either side of said pressure regulating valve, a condenser connecting to the downstream end of said product discharge conduit, means for introducing liquid hydrocarbons into said generators, valved conduits connecting said regenerators to a stack for discharging fluids from the apparatus, valved supply lines connecting to each of said regenerators for introducing steam, airand hydrogen-rich gas into said generators, and means 1 t for introducing cooled tar into each section of the tar pot near the top thereof to cool gases discharged from the generator and cooling means connected with said tar pot for cooling the tar.

9. In a cyclic regenerative apparatus for cracking liquid hydrocarbons under pressure, a first and second refractory-lined generator and a first and second checker-brick regenerator capable of absorbing and releasing heat, a first conduit connecting the generators near the upper ends thereof, a second conduit connecting the first generator to the first regenerator and a third conduit connecting the second generator to the second regenerator, a tar pot communicating with each generator through the lower portion thereof, make-gas take-off pipes connected to each pot and having a pressure regulating valve associated therewith, a condenser connecting to the downstream end of said take-off pipes, means for introducing liquid hydrocarbons into said generators, valved conduits connecting said regenerators to a stack for discharging fluids from the apparatus, valved supply lines connecting to each of said regenerators for introducing steam and air into said generators, and means for introducing cooled tar into the upper portion of the tar pot to cool gases discharged from the generator.

10. A cyclic regenerative process for making a high B. t. u. oil gas in a gas generating set including a generator in communication with a first and second regenerator capable of absorbing and releasing heat upon passage of fluids therethrough which comprises burning heat oil in said generator to heat it to cracking temperature, discharging the products of combustion from the set through the first regenerator to heat the regenerator, introducing a hydrogen-rich gas into the set through said first regenerator to heat said gas, introducing make oil into the generator simultaneously with the flow of said hydrogen-rich gas to crack the oil with the formation of gaseous and liquid cracking products including tar, withdrawing the gaseous and liquid cracking products directly from said generator to a quenching zone for contacting the cracking products with cooling liquid to condense the tar therein, and separating the gaseous cracking products from the liquid cracking products.

7 11. A cyclic regenerative process for making a high H. t. u. oil gas in a gas generating set including a first and second generator and a first and second regenerator capable of absorbing and releasing heat, said first generator being interconnected with said second generator through a valveless conduit near the upper ends of said generators, said first regenerator and said second regenerator being interconnected with said first generator and said second generator, respectively, near the lower ends of said generators, and a tar pot communicating directly with each of said generators through openings in the lower portions thereof, which process comprises passing air sequentially through said first regenerator upwardly through said first generator and downwardly through said second generator to burn carbon deposited in said generators during the previous cracking step and introducing heat oil into the top of said second generator simultaneously with the flow of air therethrough, thereby heating said generator to cracking temperature; discharging the hot combustion products through said second regenerator to impart heat thereto; flowing steam through the set to purge the combustion gases; introducing a hydrogen-rich gas through said second regenerator and upwardly through said second generator; introducing make oil into said second generator simultaneously with said hydrogen-rich gas and counter to the flow thereof to initiate cracking of the make oil with the formation of initial vapor-phase cracking products and deposited carbon; passing said initial cracking products downwardly through said first generator to complete cracking to an oil gas, tar vapors, light aromatic hydrocarbons and additional deposited carbon; withdrawing said cracking products from said first generator directly to said tar pot connected thereto while contacting 19 said products with cooling liquids to reduce the temperature of said products sufliciently to condense tar vapors therein; and passing the cooled tar-free products through means for separating the oil gas therefrom.

12. The process of claim 11 wherein the make oil is split into two streams and introduced into said second generator counter to the flow of 'said hydrogen'rich gas and into said first generator concurrent with the flow of said hydrogen-rich gas.

13. The process of claim 11 wherein the heat oil is introduced into the bottom of said first generator, the flow of hydrogen-rich gas is in the same direction as the air blast through saidfirst regenerator, first generator and second generator and the make oil is split into two streams and introduced into said first generator counter to the fiow ofhydrogen-rich gas and into said second generator concurrent with the flow of said hydrogen-rich gas. i 14. The process of claim 11 wherein the heat oil stream is split and introduced simultaneously into the bottom of said first generator and the top of said second generator, and the make oil stream is split into two streams and introduced into said second generator counter to the fiowof said hydrogen-rich gas and into said first generator concurrent with the flow of said hydrogenrich gas.

15. The process of claim 11 wherein the heat oil stream is split and introduced simultaneously into the bottom of said first generator and the top of said second generator, the flow of hydrogen-rich gas is in the same direction as the air blast through said first regenerator, first generator and second generator, and the make oil stream is split into two streams and introduced into said first generator counter to the flow of said hydrogen-rich gas and into saidsecond generator concurrent with the flow of said hydrogen-rich gas.

16. The process of claim 11 wherein the flow of hydrogen-rich gas is in the same direction as the air blast through said first regenerator, first generator and second generator, and the make oil stream is split and introduced into said first generator counter to theflow of hydrogen rich gas and into said second generator concurrent with the flow of said hydrogen-rich gas. j

17. The process of claim 11 wherein the heat oil is introduced into the bottom of said first generator and 20 secondary air is introduced into the top of said second generator, and the make oil is split into two streams and introduced into said first generator counter to the flow of hydrogen-rich gas and into said second generator concurrent with the flow'of said hydrogen-rich gas.

18. A cyclic regenerative process for making a high B. t. 11. oil gas in a gas generating set including a genorator in communication with a first and a second regenerator capable of absorbing and releasing heat upon passage of fluids therethrough which comprises burning carbon previously deposited in said generator to heat it to cracking temperature, discharging the products of combustion from the set through the first regenerator to heat the regenerator, introducing a hydrogen-rich gas into the set through said first regenerator to heat said gas, introducing make oil into the generator simultaneously with the fiow of said hydrogen-rich gas to crack the oil with the formation of gaseous and liquid cracking products including tar, withdrawing the gaseous and liquid cracking products directly from said generator to a quenching zone for contacting the cracking products with cooling liquid to condense the tar therein, and separating the gaseous cracking products from the liquid cracking products.

References Cited in the tile of this patent UNITED STATES PATENTS 100,208 Stevens Feb. 22, 1870 682,038 Cornell Sept. 3, 1901 1,230,226 Rose June 19, 1917 2,071,286 Johnson et a1 Feb. 16, 1937 2,605,176 Pearson July 29, 1952 2,605,177 Pearson July 29, 1952 2,609,282 Hang Sept. 2, 1952 2,714,058 Stookey July 26, 1955 2,721,888 Harris Oct. 25, 1955 2,734,811 Totzek et al. Feb. 14, 1956 OTHER REFERENCES Gas Age, Gasification of Hydrocarbons, J. J. Morgan, Sept. 25, 1952, pages 30-37.

Gas Age, Gasification of Hydrocarbons, I. J. Morgan, Oct. 9, 1952.

Claims

1. IN A CYCLIC REGENERATIVE APPARATUS FOR CRACKING LIQUID HYDROCARBONS UNDER PRESSURE, COMPRISING AT LEAST ONE TAR POT COMMUNICATING WITH THE GENERATOR THROUGH THE LOWER PORTION THEREOF, A TAKE-OFF CONDUIT CONTAINING A PRESSURE REDUCING VALVE LEADING FROM SAID TAR POT TO A CONDENSER, A VALVED CONDUIT BY-PASSING SAID PRESSURE REDUCING VALVE, AND MEANS FOR INTRODUCING COOLED TAR INTO THE UPPER PORTION OF THE TAR POT TO COOLED GASES DISCHARGED FROM THE GENERATOR.

10. A CYCLIC REGENERATIVE PROCESS FOR MAKING A HIGH B.T.U. OIL GAS IN A GAS GENERATING SET INCLUDING A GENERATOR IN COMMUNICATION WITH A FIRST AND SECOND REGENERATOR CAPABLE OF ABSORBING AND RELEASING HEAT UPON PASSAGE OF FLUIDS THERETHROUGH WHICH COMPRISES BURNING HEAT OIL SAID GENERATOR TO HEAT IT TO CRACKING TEMPERATURE, DISCHARGING THE PRODUCTS OF COMBUSTION FROM THE SET THROUGH THE FIRST REGENERATOR TO HEAT THE GENERATOR, INTRODUCING A HYDROGEN-RICH GAS INTO THE SET THROUGH SAID FIRST REGENERATOR TO HEAT SAID GAS, INTRODUCING SAID OIL INTO THE GENERATOR SIMULTANEOUSLY WITH THE FLOW OF SAID HYDROGEN-RICH GAS TO CRCK THE OIL WITH THE FORMATION OF GASEOUS AND LIQUID CRACKING PRODUCTS INCLUDING TAR, WITHDRAWING THE GASEOUS AND LIQUID CRACKING PRODUCTS DIRECTLY FROM SAID GENERATOR TO A QUENCHING ZONE FOR CONTACTING THE CRACKING PRODUCTS WITH COOLING LIQUID TO CONDENSE THE TAR THEREIN, AND SEPARATING THE GASEOUS CRACKING PRODUCTS FROM THE LIQUID CRACKING PRODUCTS.