US1923540A - Gas making process - Google Patents

Description

v Aug. 22, 1,933. A. JoHNsoN 1,923,540

GAS MAKING PROCESS Filed June 19, 1929 4 Sheets-Sheet. l

Aug. 22, 1933 A. JOHNSON 1,923,540

GAS MAKING PROCES S.

Filed June 19, 1929 4 Sheets-Sheet 2 NVNTOR ALFRED doHNsON hig ATTORNEY Aug. 22, 1933. A, JOHNSON GAS MAKING PRocEss Filed June 19, 1929 4 Sheets-Sheet 3 SWW/who@ ALFRED JOHNSON 3613 his Aug. 22, 1933. A, JQHNSQN v 1,923,540

GAS MAKING PROCES S Filed June 19, 1929 4 Shets-Sheet 4 @da i [O50 IIOO OO |300 |400 (500 |600 IIOO mEAN MeTAL TEMPERATURE-"F Swix/whom ALFRED JOHNSON www Patented Aug. 22, 1933 1,923,540 Y GAS MAKING PROCESS Alfred Johnson, West Brighton, Y., assigner to Combustion Utilities Corporation,

New

York, N. Y., a Corporation of Maine Application June 19, 1929. serial No. 372,112

19 claims. (o1. iii-202) The present invention relates to processes `and apparatus for the distillation and gasification of carbonaceous fuels, and more especially it concerns a process and apparatus for the concurrent carbonization in place of high volatile bituminous fuels such as coal and the gasification of the residual coke in a semi-continuous succession 0I" operations in an integral unit having a car`1 bonization zone. of limited annularcross section positioned inthe upper end of'a gas generator casing directly above the fuel bed of the latter.

YThe advantages to be gained by the carboni- Zaton of fuels in thin layers is now well known. It has been determined that the rate of fuelcarn bonization by external heatingwparticularly when employing temperatures within the low temperature carbonization range,-is rsubstantially inversely proportional to the square of the thickness of the fuel layer being carbonized;for example a fuel layer y3" in thickness, when heated to a given temperature from each of the sides of the said layer, will carbonize in onequarter the time required under similar conditions for carbonizing a 6" layer of fuel.

Carbonizing processes as at present coinrnonly performed in vertical retorts or the like in which the coal is progressively fed downward through the retorts have not proven suitable for carbonizing thin layers of fuel, due to the mechanical difficulties, both in moving such thin layers of material through the carbonizing chambers of such retorts and in discharging the coked product. The material tends to form a plasticsticky mass at an intermediate stage of the carbonization and to adhere to the walls of the ccking chamber.

Accordingly, it has heretofore been standard practice to carbonize a relativelythickv column of fuel; and this is essentially true where the distillation apparatus has been directly associated with an apparatus for the complete gasification of the carbonized fuel. It is preferable that the fuel be fully carbonized before being r moved onto the generator `fuel bed. Because however of the very slow rates at which thiol: layers of solid fuel can be heat-treated 'to yield a properly carbonized product, it has been necesu sary in the past either to undertreat the fuel so Y that it was not completely carbonized, or alternatively to seriously reduce the carbonizing capacity of the installation by prolonging the carbonizinfT time of the charge.

Among the principal objects of the presentinvention are to provide in an improved manner for the rapid uniform carbonization of a column heated indirectly While held in place; to provide for the carbonization of coal in thin, annular" layers on water gas and/or` producer cycle.`r These and other important objects will be clearly indicated in the course of the following de` scription, `and in the appended claims.

Broadly considered the present invention involves the carbonization of a solid fuel such as bituminous coal or lignite in elongated retorts of annular 'cross section, ya plurality of whichv are suspended in a vertically-disposed heat-insulated gas generator4 directly above the fuel bed of the Y latter. `The gas generator may be either a Water gas generator or aproducer gas generator. The( carbonization of the fuelis effected within the annularl space confined between the concentricY inner and outer vvalls of each of the. said annular retorts. Heat for, the carbonization is trans`' mitted to the said walls of each retort, in part by radiation from the incandescent fuel bed and in part by means of the sensible and potential heat in the gaseous products passing in contact v.

with the said walls of the annular retorts, as will` be more specifically `described hereinafter. Y

Therate of carbonization of the fuel has beenV greatlyV accelerated according to the presentin- -vention by exposing a relatively thin annular column of the fuel to carbonizing heat applied preferably simultaneously to ,two opposite sides thereof. In practice the thickness ofthe fuel column annulus is less than 5 and is preferably about 3".

As rapidly as the annular column of fuel is carbonized, the resultant coke is discharged di.- rectly onto the fuel bed of lthe gas generator by suitable means. The coke is thenr gasiiied in the said generator on standard water gas cycle or producer gas cycle, or upon a slightly modified series of cycles, the preferred modifications of which are hereinafter set forth.

To offset or neutralize the effect of the uneven vertical distribution of heat along the respective walls of the annular vertically mounted retorts during the producer gas and water gas cycles by heat transferred from the hot gases7 the invention comprises a further stage of indirectly heating the annular column of fuel being carbonized 1y means of highly superheated steam passedin' downrun Contact with either the inner or the outer walls of each retort, but preferably with both of them, the said superheated steam transferring portions of its heat during such passage to the upper relatively cooler end of each of the retorts while Yitself being sufficiently cooled in its downward passage, so that as vit moves past the lower portions of the respective retorts which are constantly exposed to the heat directly radiated and that otherwise conveyed from the incandescent fuel bed, the stream acts to absorb heat from the said lower portions so as to lower the temperature of the latter. In this manner the downrun steam functions both as a carbonizing agency and as a means for equalizing theretort wall temperatures at' the respective end portions thereof. This tends to preserve the life of the retorts. Preferably potential heat recovered from the waste blast gases from an earlier cycle is employed for superheating the steam employed in the last named or downrun steam cycle.

, Undesirable variations in temperature between the lower and upper'ends of the carbonizing retorts also can be preventedin large part kby the successive addition of secondary air around the outer Walls ofV the retorts at suitable points spaced vertically ofthe Vretorts. The amounts of such air preferably` areso controlled asto efectthe combustion of predetermined proportions of the gases issuing lfrom the fuel bed at different elevations lengthwise of thegenerator housing. This further increases the temperature of the hot gases contacting with the retort ,Walls and particularly those portions of the latter which are more remote from the generator fuel bed'.

, To further facilitate the uniform carbonization of the fuel where the said vertical tempera- ,ture gradient exists, the outer of the concentric walls of each retort may be slightly tapered outwardly in a downward direction so that the thickness of thercoal layer in the lower portion of the annular carbonizng zone, which is subjected to relatively higher temperatures than the fuel in the upper portion thereof, is thicker in annular cross section than the latter. The relative thickness of the fuel layerat the respective upper andV lower portions of the fuel column is 50. preferably adjusted in accordance with the above 55 l the annular fuel column, the inner retort wall is adapted to be filled with refractory materials such as checker brick, Raschig rings, or the like which act to absorb heat from the hot gases passing alongV in contact with the inner wall of the retort, and to transfer suchheatr to the layer of fuel being carbonized. This refractory material is very eflicient as a heat-absorbing and transfer means when employed in the manner indicated, as shown by the fact that the portion of the carbonization effected by transfer of heat vfrom the inside surface of the annular fuel layer ferred through the inner Wall of the annular retort when the inner retort member is packed with this refractory material.

In carrying out the process, the available heat in the hot gases employed in heating the respecerably balanced in accordance with the total area Referring now to the accompanying drawings v which show a preferred form of the apparatus exemplifying the present invention:-

Fig. 1 is a vertical cross sectional viewof a preferred form of a carbonizing and gasification apparatus, parts'thereof being broken away;

Fig. 2 is an elevational View on a somewhat larger scale, showing the upper end of the generator housing and certain of the parts associated therewith, portions thereof being cut away, and other portions being shown in section Fig. 3 is a horizontalsection of the apparatus taken along the line 3-3 of Fig. 2 looking in the direction of the arrows;

Y Fig. 4 is a chart which indicates the relationship between the carbonizing capacity of the retort and the thickness of the layer of fuel beingV carbonized within the scope of the present invention, at' various indicated temperatures within the preferred carbonization range; and

Fig. 5 is a chart that indicates the relationship existingbetween the carbcnizing capacity of a retort and the temperature at which the carbonization is carried out, for definite thicknesses of fuel layers.

"In the drawings 10 designates a vertically arranged, gas-generating apparatus suitably lined with refractory material throughout and provided with a cylindrical side Wall 11, a base or bottom member 12, and a closed top 14. VThe side wall 11 is suitably constricted at an intermediate portion thereof to form a lower portion 15 of reduced cross section. A grate 17 of usual construction is positioned in the bottom of the genbe substituted for that shown.

For introducing 'air under pressure into the lower portion of the generator casing,'av pipe 2l controlled by valve 23 extends through the side of the generator below the grate 17 and is connected with a suitable source of air under pressure.

Supported from the top member 14 of the gas generator and disposed in circular arrangement at uniformly-spaced intervals are a plurality of depending, elongated hollow tubular retort members 29 of steel or other suitable heat-resistant metal or metal alloy such as hybnickel.

their enlarged lower ends positioned near but somewhat above the constricted portion in the generator casing.

In a typical installation, there is approximately a 1" difference in cross-sectional diameter of the said member for each 8 feet of the length thereof. l

The upper end of each of the retort members 29 extends through the generator top 14 and to a point substantially thereabove, and each is provided with a flanged cover'plate 3l having a relatively large, centrally-disposed aperture 33 therein, and having a second aperture 35 located therein near the peripheral margin of the cover plate 3l.

A tubular metal curtain 37 is mounted on the under surface of each plate 31 .concentric with and surrounding the aperture 33, and it extends downward within the retort member 29 to a point The` depending tubular members 29 preferably taper,y outwardly in-a downward direction, and have VV grate, as for example, a non-clinkering grate, mayv depending curtain members 39, 39 extendsradially from the outer edge of the curtain 37 within each retort to the adjacent inner retort wall on.

respective sides oilthe aperture 35 to provide a passageway leading from the interior of theretort to the said aperture. Other radial members 40, 40 divide the remainder of the annular space between the curtain 37 and the retort 29 into a plurality of parts.

Each of the tubular retort members 29 has disposed therein and concentric therewith a generally cylindrical hollow inner retort member 41 having the ends extending beyond the ends of the member 29. Each of the inner retort members 41 is made of suitableresistant metal or alloy such as hybnickel, and is adapted for limited vertical movement longitudinally of the concentric member 29.

The lower margin of each of the members 41 is flared or bevelled outwardly and extends laterally beyond the bottom margin of the concentric retort member 29,-the arrangement `being such that upon moving the inner member 41 vertically upward the said flared lower end of the lat-- ter engages the bottom of the member 29 and forms a substantially gas-tight seal for 4bottom of the annular chamber defined .between the pair of concentric retort members 29, 4l. The construction of the concentric retorts 29, 41 is preferably such that the annular fuel receiving space deiined therebetween is less than 5f in effectiveiannular width, and the preferred optimum width of this annular space is approximate- 1y 3H.

Each `of the retort members 41 is substantially constricted adjacent the upper end of the retort member 29 to form an upper-end valve portion 45 of greatly reduced cross section. The said `portion 45 extends vertically upward through the aperture 33 in the cover plate 31, and its extreme upper end is closed rby a cap 46. The upper portion of each member 41 is operatively secured to a housing member 47 of a cushioningor shock-absorbing device, a second member 49 of the said device being adjustably secured to the piston 51 of a hydraulic cylinder 53 which is utilized for raising and lowering the retort member 4l. The said cylinder is mounted upon a suitable superstructure 55 supported upon the top of the generator by the column 56..

operatively interposed betweenthe members 47. 49 of each cushioning device are a pair of con-k centrically disposed compression springs 57, 53, which are so arranged as to resist the tendency toward downward movement o the respective inner retort 41 under the influence of its own weight and that of the fuel being carbonized.

.An elongated slot or opening 59 is provided in the upper constricted portion of each of the inner retorts 41 at a point above the top plate 3l.. A hollow T-shaped casting 61 surrounds the portion of the member 41 having the said slot 59 therein,V

and provides an annular chamber adapted to be in free communication with the interior of the member 41 only when the latter is in its uppermost position. The interior ofthe member 41 is adapted to be in communication with 4the upper end of the annular fuel space when the former is in its lowermost position. A stufling box associated with each top plate 31 furnishes a gas-tight seal between the interior of casting 61 and the annular fuel space and comprises a housing 68 `belt 117.

in which is mounted a metal collar or seal ring 69 provided lwith a plurality of grooves in itsinner peripheral surface, each adapted to accommodate a contracting piston ring 71 for cooperation with the adjacent surface of the inner retort member 4l.. A set screw or the like `v73` cooperates with the housing 68 to prevent movement of the collar 69 with respect to the -inner retort member.

The upper end of the T-shapedcasting 61 has an opening therein through which the constricted upper end portion 450i the inner retort member is adapted to extend. A stuffing box 75 of usual construction is mounted upon the casting 61 aroundvthe portion 45 `and seals the interior of the casting :from the atmosphere. The said interior of castingl is connected by pipe `63 controlled by valve 64, to a collecting main or junction box 65 centrally located on the top 14 of the generator.

For charging fuel to be carbonized into the annular space between each pair of concentric tubular retort members 29, 41, a fuel charging hopper 91 is centrally mounted upon the superstructure 55. The hopper 91 is provided with a gas tight closureV member 93 and is divided into three-superposed compartments 95, 97, 99, by a pair of vertically-spaced funnel shaped partitions 101, 103, v

jacent the generator top to form fuel feedv pipes. 111, 111, which open into the upper end of one' of the annular retort spaces through openings in opposite sides of the cover plate 31 between the metal curtain 37 and the outer retort Wall` 29.

Forconveying fuel from the storage compartment 95 into the compartment 97 at a uniform rate, a positive feed mechanism is provided comprising a screw conveyor 113 mounted `upon'the upper portionv of member 101 and driven from a suitable source of power through pulley 115 and Ther funnel shaped member 103 has a central opening located directly above the midportion or the bottom of the hopper 91.

The upper closure member 93 of the'hopper is controlled by a hydraulic cylinder 127 functioning inthe manner shown, through a bell crank The upper portion of the generator casing 10 is connected by means of the passageway 131 with the upper portion of a regenerator 133 of'well known type provided with checkerwork 135 of a heat refractory material, the said passageway 131 being provided with a cut-orf valve 132. vThe lower end or the saidregenerator is connected with Aa wasteheat boiler or economizer 137 by means of a passageway 139 having therein a shutolf valve 145.v The gas outlet end of the economizer communicates with a stack 141 provided with a hydraulically-operated draft regulator or closure 143. The lower end of the regenerator is also directly connected with the stack 141 by means of pipe 147 having valve 149 therein, for

cy-passing the economizer 137 when desired.

The upper end of the regenerator 133 is con-1 nected by means of a pipe 151, controlled by a hydraulic valve 153 and a checkvalve 154, with 183. valve-controlled pipes 185,187, 189, with each of a plurality of vertically-spaced bustle-pipes `like present in such vapors.

coolers and scrubbers and to a .lean gas holder (not shown). A hydraulic valve 157 and a check valve 158 are providedin the pipe` 155 between the point at which the pipe 151 opens into it and the said lean gas coolers.

For conducting lean gas from the base of the generatorV casing below the grate to suitable gas holders, a gas tuyer 159 controlled by valve 165 has one end thereof opening into pipe 21 at a point between the said casing and the valve 23. The other end of the tuyer 159 is connectedwith the pipe 155 at a point therein between the valve 157 and the lean gas coolers. A branch pipe 161 controlled by valve 163 connects the stackl 141 with the pipe 159.

For introducing steam into the apparatus, a pipe 167 controlled by valve 173 has one end thereof connected to a suitable source of steam under pressure,-the other end of the pipe 167 opening into the lower end of the regenerator 133. A branch line 169 controlled by valve 175 connects the steam pipe 167 with that portion of pipe' 21 between the generator 10 and the valve 23. f For distributing secondary air into the gener- -ator casing immediately above the fuel bed and atV vertically-spaced points in the generator casing adjacent the annular retorts 29,-and also.

for conducting air for combustion to the upper end of the regenerator 133,-a branch conduit v177 controlled by valve l179 leads from the air pipe 21 into the upper end of the said regenerator. An intermediate point in the line 177 is connected by pipe 181 with a vertically-disposed manifold The latter is connected respectively by 197, 199, 201, surrounding the generator casing. Each of thesaid bustle-pipes has leading therefrom a plurality of radially disposed valved pipes 203 provided with suitable air injecting nozzles 205 extending through the generator wall, the arrangement preferably being such that the lower set of nozzles extends through the constricted lower portion of the generator casing immediately above the fuel bed therein,-an intermediate set of nozzles extends into the casing 10 at approximately the same elevation as the lower ends of the retorts 29, and another set of nozzles extends through the casing at approximately the'same elevation as the mid-portion of the retorts 29.

For removing the gases and vapors as they are formed in the annular carbonizing space between the respective pairs of retort members 29, 41, during the carbonization of the fuel therein, each cover plate 31 has mounted thereon a header or casting 207, connecting 'the said annular fuel space through a valved pipe 209 with a bustlepipe 211. The latter is connected by pipe 213 with a set of primary rich-gas coolers and scrubbers and therethrough with a rich-gas holder (not shown). A pipe 215 extends-into the header 207 for use in injecting water into the vapors flowing therethrough for condensing tar and the A steam pipe 21'? extends into each of the fuel feed lines 107 immediately below the valve 109 therein; and a steam:

37 where tarand the like might be condensed` and deposited.

For carburetting the bluev gas made in oneof the cycles of the process according to one modi-y Va preferred application of the process in the production of a modified blue gas. Assuming that the generator is provided vwith an already ignited fuel bed of coke or the like as produced in accordance with the present invention, a charge of fuel to be carbonized filling the annular space between the inner and the outer retort members of each pair thereof, a blast of air is introduced through pipe 21 below the grate 17 and is passed through the burning fuel in the base of the generator,r the said air being mixed if desired with a relatively small amount of steam for temperature control purposes. The air blast is preferably continued for approximately two minutes, the fuel in the fuel bed becoming incandescent, and producer gas being formed. The resultant products of primary blast normally issue from the upper surface of the fuel bed at about 1600 F. Secondary air is also admitted to the generator just above the fuel bed during this period of the blast'for the purpose of burning a partof the gases as they leave the fuel bed to assist in raising the temperature of the said gases to approximately 1900o F., this being the preferred temperature for the gases employed in heating the refractory material positioned within the inner one of each pair of concentric retort members. The products of the primary air blast are then divided, part thereof moving upward within the refractory-filled inner members and vbeing withdrawn through the respective slots 59 in the upper end thereof and being conducted away through the junction box and lean gas pipe 155. Part of this said lean gas may be introduced into the upper end of the regenerator 133 through line 151 where it is burned in the presence of air introduced through the pipe 177 for thepurpose of heating the checker work in the regenerator. The resultant products of combustion of this portion of the lean gas are conducted downwardly through the regenerator and from there they may be led throughthe waste heat boiler and through the stack to the atmosphere. The balance of the lean gas flowing in pipe 155 is conducted through valve 157 through a lean gas cooler to a lean gas holder orto a common mixing holder.

Another portion of the gases leaving the generator fuel bed pass upwardly around the outer retort member 29, giving up their heat through v the said retort walls to the fuel being carbonized.

These cooled gases after such heat exchange flow from the generator through passageway 131 into the upper part of the regenerator where they mixl determined amounts of air are introduced into' and mixed therewith at a plurality of points spaced vertically of the generator, for the pur- `if and as desired into two portions.

pose of maintainingthe Vvarious portions of the outer retort walls at the desired temperature and for uniformly carbonizing the fuel.

At this point in the process the air blast is discontinued, valves 23, 191, 193, 195, 143, and 179 being closed, and the uprun make cycle is begun. Steam is admitted into the lower part of the generator beneath the grate by opening valve 175 in the steam line 169, steam valve 173 being closed. The blue gas formed by the steam in passing upward through the incandescent fuel bed is again divided, as in the previous or air blast cycle, a predetermined part of the hot blue gas being conducted along each refractoryfilled inner retort member to assist in supplying heat thereto for the carbonization of the annular layer of material. This part of the blue gas thereafter passes through the ports 59 in the upper end of the inner retort members and through the lean gas bustle-pipe and tuyer 155 to the primary lean gas coolers and thence to storage. It may be stored in aV separate holder from the producer gas previously conducted through the pipe 155, or it may be mixed with the portion of the primary blast gases that were taken to storage during the first cycle of the operation. A second predetermined portion of the blue gas generated in the second or uprun make cycle passes upward through the generator in contact with the external retort walls and is thereafter conducted from the generator through the passage 131 and the pipe 151 to the tuyer 155 where it mixes with Vthe blue gas passing upwardly through the inner retort member and is conducted therewith through the lean gas coolers to storage. i

During this uprun make cycle the fuel bed is rapidly cooled and the proportion of the heat radiated to theretort members from the incandescent fuel bed falls oifappreciably. In order to maintain a satisfactory uniformvcoking temperature vertically! along the fuel column during this cycle, sufficient air preferably is introduced through the pipes 203 to burn predetermined portions of the said blue gas so as to maintain the hot gases contacting with the inner andouter walls of the annular fuel column at the-desired temperature during such contact. upruncycle has been in operation forv the desired length `of time, it is terminated by closing the steam Valve 175, the various valves 191, 193, 195 in the air line, and valve 157. f i

A downrun cycle is now started during whic steam is admitted through line 167 into the lower portion of the regenerator, the valves`145-and 149 respectively connecting the bottom of the regenerator with the waste heat boiler and with the stack being closed, and the valve 165 in conduit 159 being opened. The steam is drawn up-Y wardly through the regenerator, at the same time being highly superheated by heat transferred thereto from the highly heated checker work. The thus superheated steam is thereafter divided One rof `the said portions passes through the passageway 131 into the upper part of the generator casing,and descends therein, in contact with the walls of the outer retort members 29. The superheated steam, being at ahighertemperature than that of the upper portion of the said retorts gives up heat to the latter, and is itself cooled and again absorbs` heat from the lower portions of the retorts adjacent the hot generator fuel bed` in a manner to oset the heating of the lower portions of the respective retort members to `of the pairs of concentric retort members.

vthrough the said members, giving up its sensible heat to the refractory fillings thereof, and it gasholder or a common storage holder.

.tionsas a'support for the fuel column when it is After the f *cession in such manner that the carbonization of the Vcontentsof one retort ata time is com- .substantially constant level -and insures a uni- `fro1n flowing through` the space lying between higher temperatures than the upper `portions thereof by the heat radiated from the fuelfbed and by the sensible and potential heat of the gases formed in. the two previous cycles. `The remaining portion of the superheated steam passing upwardly through the regenerator, is conducted 80 throughl pipes 1571 and 155, the junction box and the slots 59, and into the inner one Vofi each The said superheated steam then flows downwardly thereafter passes through the hot fuel bed 220. The blue gas thus formed by reaction of this steam with the highly heated fuel is conducted ,through conduit 159 to the primary lean gas coolers and thence to storage. f Y

The down run cycle preferably lasts for about one minute and a quarter, after which a short uprun' of purge steam is effected preparatory to again starting the air blast of another cycle. The purge steam :and gasescarried thereby are preferably conducted'either to lean gas holders or exhausted to the atmosphere..

The distillation products obtained during the carbonization of the fuel containing for example various liquefiable and gaseous hydrocarbons, coal gas, tar, water vapor, ammonia 'and the like, are withdrawn continuously from the upper part of the annulalr fuel space during each of the above mentioned cycles and pass through header 207, bustle pipe 211, and the pipe 213 to a set of primary rich gas coolers preferably under subatmospheric pressure, and thence to a rich These gas-.making cycles are continuously repeated in the order given until the .carbonization of the fuel in at least one of the retorts has been completed. Thereupon the inner retort member il is moved downward by operating the hydraulic cylinder controlling it, and the carbonized material is discharged by gravity downwardly onto the generator fuel bed. The flared portion of the bottom margin .of the inner retort member funcin its upmost position, and it also vacts as a valve to prevent substantial proportions of the heating gases such as producer gas and the like from passing to the 'fuel column and escaping into the rich gas offtake during the carbonization period. When the inner retort member is in its lowered position, the flared bottom thereof assists in breaking up large lumps of coke falling upon it duringthe discharging process. y

The retort pairs are preferably filled in sucpleted,` and so that the successive dumping of the carbonized fuel fromthe rvarious retorts onto the generator fuel bed maintains the latter at a 3a form distribution of carbonized fuel on the surface of the fuel bed. `The discharging of the coke material onto the generator fuel bed is preferably done during the. downrun cycle, and any fine dust and the like escaping Vinto the generatoris drawn into the fuel bed 229 and does not interfere with the process.

Lean producer gas and the like are prevented 140 the ytwovconcentric -retort members during the. time that the inner member is lowered for discharge ofjcokadue. to the'fact that the slot 59 then is positioned below the seal ring 69. During this time valve' 209 is vclosed'to preventthe pas- 150 sage of 4lean gas into the rich gas'bustle-pipe 211'.

-When the'inner retort memberis again raised -top of the'y hopper being closed and the proper feed vali/e109 being open.

Preferably the compartment holds just suflicient fuel to properly charge one of the said annular retort assemblies. The conveyor 113 permits a uniform, determinate rate of charging fuel to each of the said retort assemblies, regardless of the amount of fuel in thehopper.

.The fuel charging may be discontinued at any stage by stoppingwthe conveyor-.113.V A limited downward flow of steam through the fuel charging pipes 107 into the retort-offsets any tendency for distillation gases to collect in these pipes. The current of steam introduced into the upper portion of each retort between the inner retort member 41 and the metal curtain 37 preventsl the accumulation in thel space of distillation gases which might deposit therein objectionable materials such as tar.

According to a modification of the' process in which a carburetted combustible gas is produced, the uprun make cycle is so controlled that the gas passing upward through the generator is at least lin large part conducted into the regenerator by properly setting or closing .the valves-157 and 158, and opening the Valves 153 and 154, the said gases Athen being conducted downward through the highly heated checkerwork in the regenerator. Simultaneously a spray of suitable carburetting fluid such as a hydrocarbon oilor the like is introduced into the upper portion of the regenerator and if necessary is vaporizedand fixed at the temperatures existing therein. The enriched blue gas is conducted from the lower end of the regenerator direct to the pipe 141 and, through branchr pipes 161 and 159, to suitable gas coolers and scrubbers and `then to storage,-the stack Valve 143 being closed. The economizer is preferably bypassed to avoid the possibility of tar and the like condensing in the ilues thereof. In like manner the last portion of the hot 1 producer gases formed in `the generator Vduring the blast cycle may be carburetted by spraying a carburetting fluid into that portion thereof which is passed downward` through ythe highly heated checkerwork in the regenerator.V The introduction ofair to the regenerator through the air pipe 177 isvpreferably discontinuedprior to the introduction ofthe carburetting fluid intothe said gases.

Instead of conducting all of the gases formed in the generator 10 during theA uprun make cycle through the regenerator, which yhere acts as a carburetor, ak portion or all of the gases passing through the inner retort members of each pair may be conducted direct to lean gas coolers and to storage with orfwithout portions of the .gases leaving the generator vthrough the passageway y 131, by suitable adjustment of the check valves y 154 and 158. v Y Y Although boththe inner and the outer retort members of each concentric pair are preferably fabricated from the same kind of heat resistant Vmetal,`it is -within the scope of the present Yin- -vention 'to make the inner retorts of different metal or alloy than that of which the outer retorts are made, so that they will exhibit different physical characteristics under the conditions of use. unbalanced elongation ofthe inner retort members underthe effect of their own weight at the high temperatures'employed, and to properly maintain a substantially gastight seal between the lower ends of the inner and outer retorts, the

kextremeaupper end of the inner retort may be threaded'externally for cooperation with threads formed "upon the interior. of the lower end bf the housing member 47. Other similar means for L accomplishing the vsame result may be `employed if desired. For example, the flared bottom of the -inner retort of each pair may be separable from the tubular portion of such inner retort and may be adapted for adjustment longitudinally thereof. The compression springs 57 and 58 permit the raising andilowering of thev inner retort membed `without `unduejarring and ,injury to the apparatus. Y

It will vbe obvious that other methods of charging coal into the retort'may be substitutedfor that specifically shown and described. It is also within the spirit of the lpresent'inventionto makey the outer retort member cylindrical while ern- -ploying a reverse taper on the inner retort member so that the sidesof the latter slope inwardly in a downward direction; or if preferred`A both inner andouter retort members may be slightly tapered.

By employing a cylindrical inner retort member, and providing the outer retort with an'outwardand downward taper, it is possible to vary the thickness of thefannular fuel layer to compensate for the usual-.vertical temperature gradient along `the retort walls, especially in instances where the said gradient has not been substantially eliminated by the combustion of. effective amounts of secondary air as already described. In this way itis possible toappreciably increase the carbonization capacity of retorts of the type here shown .and described at approximately no additional cost.

The relative proportion of the` carbonizing heat `distributed along the respective surface of the vinner retort and the outer retort wall may be controlled byysuitable vacuum-producing means 4arranged in the lean gas offtake line from either of the said retort members or by pressure control ow involving kthe use of regulating valves hereinbefore mentioned. l

apparatus construction in which a group of four uniformly spaced carbonizing retorts is supported in the upper part of a gas generator housing hasfprove'n to besvery efcient and gives a very high carbonizing capacity per unit of time per square foot of metal heating surface employed. The process is preferably carried out with effective `retort temperatures of from 1050 F. to 1500 F.

At temperatures much in excess of 15o0 F., while i the rate of carbonization is accelerated, there is a tendency toward cracking of the tar vapors,

'-which'interferes with the production'of primary tar andv reduces the tar residue credit, both from theA point of yield and quality. On the other hand at temperatures substantially below 1050 F., the carbonizing capacity of the assembly is materially reduced, when using the'above-mentioned preferred thickness of coal or a thicker layer thereof, until a point is reached at which the number `of retorts required in order to permit the Inordery therefore to'compensate for any nous and the non-luminous or obscure radiationsfrom the incandescent generator fuel bed; and the area of that portion of the tubular retort surface lwhich is exposed directly to such radiated heat is preferably the maximum which is consistent with the maintenance of a suitably thin fuel layer in the carbonizing zone.

Fig. 4 clearly illustrates the rapidly increasing rate at which fuel is carbonized when exposed to heat in the low temperature carbonization range, in layers 5" in thickness or less. The particular values for temperatures of 1050*F. to 1400o F. and 1500" 1'". are shown. Ordinarily in carbonizing fuel in annular layers over a water gas generator, certain diiiiculties are encountered where fuel layers of over 5" in thickness are employed, due to the excessive retort space required to carbonize the necessary amount of fuel 'to serve the generator fuel bed, and to the resultant excessive cost of the apparatus assembly.

Fig. 5 illustrates the effect upon the carbonization capacity of a retort assembly due to varying the carbonization temperatures employed. rIhis effect is separately indicated for fuel layers respectively 3 and 5" in mean thickness, between temperatures of l05 and 1800" F. However, at temperatures below l050 F. the carbonization capacity of the retorts, when using the optimum thickness of coal layer, -3--, is reduced to a point wherethe number of retorts required in a self-contained gas generator set is excessive and imposes objectionable structural limitations.

Among the important features of the present invention is the flexibility of control which it permits of the B. t. u. value of the gases formed by the gasification of fuel. In addition to the coal gas produced by the fuel distillation the gases produced in the generator in each cycle of the process may be collected separately or the said gases or any desired portions thereof may be mixed to give a gas of the desired B. t. u. value. Moreover the heating value of these gases can be increased as desired by carburetting selected portions of the gases passing from the generator as previously described. Predetermined portions of the gases are preferably burned in the upper portion of the 'generator andin the regenerator, and the resultant products of combustion, or part thereof, may be mixed with the unburned portions of the gases and carried to storage.

By the use of my invention as hereinbefore described I am able to effect the various objects thereof and to provide for the efficient concurrent carbonization and gasification of bituminous fuel and the like in a serni-continuous succession of operations, at the same time recovering a high B. t. u. coal gas and a second combustible gas mixture of determinate B. t. u. value, together with primary tar, ammoniacal liquor, and the like. The invention is susceptible of modification withlin the scope of the appended claims.

I claim: l. The process of producing a combustible gas and concurrently carbonizing fuel in relatively thin stationary layers which comprises passing a fluid through an incandescent fuel bed and concurrently passing the resultant highly-heated least a portion of the heat for carbonizing the said fuel. f

2. The process of concurrently producing coinl bustible gas and carbonizing fuel in thin layers which comprises passing air through an incandescent fuel bed, passing the resultant highlyheated blast gases' along and in indirect heat exchange relationship with a column of fuel arranged in a thin layer above the said fuel bed, thereafter passing steam through the said fuel bed and then passing the resultant water gas thus formed longitudinally of and in indirect heat ex'- change relation with the said column of fuel in. the same direction'with respect theretoras that steam and passing the superheated steam along the fuel column in indirect heat exchange' rela tion therewith, the direction of l flow of the Ysaid superheatedsteam along the fuel column being in a direction opposite to that of the previous flow of the blast gases and the water gas, and recovering the various combustible gases produced. 3. The process of distilling and gasifying solid fuel which, when carried out ina water gas generator having one or more annular retorts suspended within the upper portion thereof, com

prises the steps of heating a column of the fuel to be carbonized while disposed in a thin layer within a retort, by meansof hot gases moving 'in indirect heat exchange relation with the said column around and on all sides of theretort, and

supplying controlled amounts of secondary air at predetermined pointslengthwise of the said retort and adjacent vthe fuel column therein in such manner as to `control the temperature gradient in the column of fuel irrespective of the relative distance of each portion of the column from the source of the hot gases.`

4. rhe'process for distilling and gasifying solid umn being heated indirectly fromV points` on opposite sides of the thin layer to produce a higher temperature at the lower portion of .the fuel column than at the upper portion thereof, and subsequently flowing hot gases along the said column downwardly from a point adjacent the upper endv thereof to equalize the temperature existing atV the two ends of the column and provide for a uniform carbonization of the fuel.

5. In the semi-continuous process for distilling solid fuel in a column of thin annular crosssection and forv gasifying the carbonized product by means of heat recovered from a combustible gasmaking cycle, applied indirectly through inner and outer walls enclosing a carbonizing zone, the step of controlling the distribution of heat tothe respective surfaces of the annular layer to control the relative proportion ofthe carbonization effected atthe respective inner and outer surfaces of the annular column.

e. In the semi-continuous process for distilling and gasifying Asolid fuel, the step of applying` carbonizing heat to the solid fuel in an enclosed column of thin annular cross section by hot gases moving upwardly along on both the inside and outside of the annular column out of contact with the fuel, and controlling the thickness of the fuel layer to provide a greater thickness thereof sate for the effect of the higher temperature of- .the said gases at their point of first contact with the column, thereby facilitating a uniform time Yof carbonization of the fuel throughout thelength vofthe column.

7. The semi-continuous process for concurrentlycarbonizing nely divided fuel in an elongated column of relatively thin annular cross sec- .tionand for gasifying the carbonizecl product I which comprises blasting air through an incandescent fuel bed to form highly heated blast gasses, passing said gases in indirect heat exchangerelation with a column of rfuel of annular cross section above but out of contact with said fuel bed While dividing the volume of the said t 'l as to pass predetermined' proportions thereof re-l highly heated gases so as to pass predetermined proportions thereof respectively adjacent the inner and outer surfaces of the annular column, and subsequently dischargingthe carbonizedfuel onto the said fuel bed. l

8. The processas defined in claim 7 including the step of burning predetermined portions of the .said blast gases at selected points adjacent to the outer surface of the annular fuel column Ato indirectly heat the portions of the fuel remote from the said incandescent fuel bed to substantially the sameA temperature as that portion of the fuel column nearest to the said bed. y

9.,'Ifhe semi-continuous process for concurrently carbonizing and gasifying fuel which comprises blasting air through an incandescentfuel bed and passing the resultant highly heated blast gases in indirectheat exchange relationship with at least one column of fuel of relatively thin annular cross section, 'thereafter n passing steam through the said fuel bed and passing the result-V ant highly heated water gas in indirect heat exchange relation with the 4fuel being carbonized, the lovverl part of the fuel column being subjected to a higher temperature than the upper part of the said solumn in each ofthe said heatexchange steps, and thereafter passing superheatedsteam in indirect heat exchange relation With the column of fuel rbeing carbonized in the direction oposite to the flow of the said heating gases along the'said column for effecting a uniform carbonizat-ion throughout the length of the fuel column, and discharging the carbonized fuel onto the incandescent fuel bed for use in a subsequent gasification step and for supplying heat for carbonizing subsequent charges of fuel.

. which comprises blasting air through an incan- 'descent fuel bed to form highly heated blast gases,

passing the said gases in indirect heat exchange relation with the inner and outer surfaces of a column of fuel of annular cross section above but out of contact with said fuel bed While dividing the volume of the said highly heated gases so spectively along the inner and outer surfaces of the anular column, and adjusting the rate of flow of heat to the said inner surface of the fuel column throughout the carbonization by heat storage and heat transmitting bodies. K

11. The process ofconcurrently producing a combustible gas and of carbonizing solid fuel which comprises successively passing air and steam through an incandescent fuel bed while dividingV and passing portions of the 'resultant highly-heated combustible gases along and in indirect heat exchange relationship respectively with each of the lateral surfaces of a column of fuel arranged in a thin annularlayer above the -said fuel bed, -thereafter passing superheated Ysteam along and in indirect heat exchange relationship with the said column of fuel in` a direction opposite to the direction of flow of the aforesaid highly heated combustible gases, then passing the said superheated steam through the fuel bed to produce a combustible gas,radiating heat to the said fuel column from the incandescent fuel bed during each of the above steps,

recovering the various combustible gases produced, and discharging the carbonized fuel onto the said fuel bed.

12. The process as defined in claim 11 in which the effective heat transferred to the fuel column by the said combustible gases and superheated steam is in the range of from 105()D F. to 1500 F.

13. The process as defined ingclaim 1l in which .the saidcolumn of fuel being carbonized is in a.

thin annular layer havingk a mean thickness of from 11/2 inchesto 5 inches. e

14. The process of distilling and gasifying solid fuel disposed in a thinstationary layer, which comprises passing a combustion-supporting fluid through an incandescent fuel bed, and concurrently passing regulated portions of the resultant highly-heated combustible gases in indirect heat exchange relation respectively along both -the outer and inner surfaces of a column of fuel arranged in a thin annular layer adjacent to but `out of contact with the saidfuel bed, the said hot gases serving to supply at least a portion of the heat for uniformly carbonizing the said fuel.

15. The process of concurrently producinga combustible gas and of carbonizing solid fuel, which comprises passing air through anincanvdescent fuel bed, dividing and passing regulated portions ofthe resultant highly-heated combustible gas along and in indirect heat exchange relation with the respective inner and outer surfaces of a column of fuel disposed in a thin annular layer above the said fuel bed, burning a selected portion of the said combustible gasvduring such passage and utilizing heat produced thereby for carbonizing the said fuel, carbureting another portion of the said combustible gas, utilizing potential and sensible heat of the first-named portion of the combustible gasfor `supporting the carburetion of the last-named portion of the said gas, and recovering thecarbureted combustible gas.

16. The process of concurrently producing a combustible gas and of carbonizing `solid fuel, which comprises passing air through an incandescent fuel bed, dividing and passing regulated portions of the resultant highly-heated combustible gas along and in indirect heat-exchange relation with the respective surfaces of a column of fuelV disposed in a. thin annular layer above the said fuel bed, burningy a selected portion of the said combustible gas during such passage and utilizing heat produced thereby for carbonizing the said fuel, carbureting another portion of the said combustiblel gas, utilizing potential and sensible heat of the first-named portion of the combustible gas for supporting the carburetion `of the last-named portion of the said gas, recovering thev carbureted combustible` gas, thereafter passing superheated steam along and in indirect in a direction opposite tothe directionyofiiovw of the first-named combustible gas, then passing the said superheated steam through the fuel bed to produce a second combustible gas, recovering the latter, and radiating carbonizing heat to the said fuel column from the incandescent fuel bed during the respective steps of passing air and steam in the said heat-exchange relation with the fuel column.

17. The process of concurrently producing a combustible gas and of carbonizing solid fuel, which comprises passing air through an incandescent fuel bed, dividing and passing regulated portions of the resultant highly-heated combustible gas along and in indirect heat-exchange relation respectively with each of the surfaces of a column of fuel disposed in a thin annular layer above the said fuel bed, thereafter passing steam through the fuel bed, thereby producing a second combustible gas, dividing the last-named combustible gas and passing regulated portions thereof along and in indirect heat-exchange relation with the respective surfaces of-the annular fuel column, then carbureting a selected portion of the last-named combustible gas and supporting the said carburetion by heat regenerated in the process, passing superheated steam in indirect heat-exchange relation With the said fuel column in a direction opposite to the flow of the lastnamed combustible gas, and then passing the superheated steam through the fuel bed to produce a third combustible gas, and recovering the various combustible gases produced during the respective steam treatments.

18. The process of concurrently producing a combustible gas and of carbonizing solid fuel,

which comprises successively passing air andv steam through an incandescent fuel bed While dividing and passing regulated portions of the resultant highly-heated combustible gases upvsubsequent carburetion of the combustible. gases produced in the process, thereafter passing superheated steam downwardly along and in indirect heat-exchange relation With the said co1- umn of fuel and thence through the fuel bed to produce a combustible gas, carbureting the respective combustible gases produced during the steam treatments, recovering the same, and periodically discharging the carbonized fuel upon the said fuel bed. i

19. The semi-continuous process for distilling and gasifying solid fuel in which the latter during distillation thereof is disposed in a column of thin annular cross-section, which comprises 100 heating a column of the solid fuel to be carbonized, While disposed in a thin annular layer, by means of hot gases moving longitudinally of and in indirect heat exchange relation with the said column through each surface of the said layer, and burning controlled amounts of the said hot gases at selected points spaced length- Wise of and adjacent the fuel column in such manner as to control the temperature of the fuel at such points in the column irrespective of the relative distance of these points from the source of the said hot gases.

ALFRED JOHNSON.

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