US1923541A - Gas generating apparatus - Google Patents

Description

Aug. 22, JOHNSON GAS GENERATING APPARATUS Original Filed June 19, 1929 3 she t -sheet l INVENTOR ALFRED -JOHN6ON BY 2 ATTORNEY Aug. 22, 1933. JOHNSON 1,923,541

GAS GENERAT ING- APPARATUS Original Filed June 19. 1929 3 Sheets-Sheet 2 INVENTOR ALFRED JOHNSON ATTORNEY Aug. 22, 1933. A, JOHNSON GAS GENERATING APPARATUS Original Filed June 19. 1929 3 sh t -s t 5 I200 I400 MEAN MiTAL TEMPERATURE-W 0 0 0 m m k 4 7 MEAN THICKNESS 0F FOEL- INCHES I INVENTOR ALFRED JOHNSON ATTORNEY Lil Patented Aug. 22, 1933 ii-siren stares GAS GENERATING APPARATUS Alfred Johnson, West Island, N. Y.,

assignor New Brighton, Staten to Combustion Utilities Corporation, New York, N. Y., a 001'- poration of Maine Original applioationJ-lunc 19, 1929, SerialNo.

Divided and this application August 22, 1931. Serial No. 558,663

19 Claims.

The present invention relates-to processes and apparatus for the distillation 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 gasiflcation of the residual coke in a semi-continuous succession of operations in an integral unit having a carbonization zone of limited annular cross section positioned in the upper end of a gas generator casing directly above the fuel bed of the latter.

This application is a division of my copending United States application Serial No. 372,112, for Process for distillation of carbonaceous fuels filed June 19, 1929.

The advantages to be gained by the carbonization of fuels in thin layers are now ,well known. It has been determined that the rate of fuel carbonization by external heating-particular1y when employing temperatures within the low temperature carbonization range,is substantially inversely proportional to the square of the thickness of the fuel layer being carbonized;--for example a fuel layer 3 in thickness, when heated to a given temperature from each of the sides of the acid layer, will carbonize in one-quarter the time required under similar conditions for carbonizing a 6 layer of fuel.

Carbonizing processes as at present commonly 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 difiiculties, 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 plastic sticky mass at an intermediate stage of the carbonization and to adhere to the walls of the coking chamber.

Accordingly, it has heretofore been standard practice to carbonize arelative thick 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 moved onto the generator fuel bed. Because however of thevery slow rates at which thick layers of solid fuel can be heat-treated to yield a properly carbonized product, it has been necessary in the past either to undertreat the fuel so that it was not complete ly carbonized, or alternatively to seriously reduce the carbonizing capacity of the installation by prolonging the carbonizing time of the charge.

of cycles, the preferred modifications of Among the principal objects of the present invention are to provide in an improved manner for the rapid uniform carbonization of ,a column of fuel; to provide for the uniform carbonization of such a column of fuel by indirect application of heat froma heating fluid flowing lengthwise of the column; toprovide in an improved manner for regulating the temperature along a column of fuel arranged in a thin layer and heated indirectly while held in place; to provide for the carbonization of coal in thin annular layers on water gas and/ or producer cycle. These and other important objects will be clearly indicated in the course of the following description, 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, a plurality of which are suspended in a vertically-disposed, heat-insulated gas generator directly above the fuel bed of the latter. water gas generator or a producer gas generatorl The carbonization of the fuel is effected with the annular space confined between the concentric inner and outer walls of each of the said annular retorts. Heat for the carbonization is transmitted 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 with the said walls of the annular retorts, as will be more specifically described hereinafter. p

The rate of carbonization of the fuel has been greatly accelerated according to the present invention by exposing a relative thin annular coluinn of the fuel to carbonizing heat applied preferably simultaneously to two opposite sides thereof. In practice the thickness of the 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 directly onto the fuel bed of the-gas generator by suitable means. The coke is then gasified in the said The gas generator may be either a generator onstandard water gas cycle or producer gas cycle, or upon a slightly modified series which are hereinafter set forth.

To offset or neutralize the effect of the uneven vertical distribution of heat along the respective comprises afurther stage of indirectly heating the annular column of fuel being carbonized by means of highly superheated steam passed in downrun contact with either the inner or the outer walls of each retort, but preferably with both of them, the said superheated steam transferring functions both as a carbonizing' agency and as a means for equalizing the retort 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 lastnamed or downrunsteam cycle.

Undesirable variations in temperature between the lower and upper ends of the carbonizing retorts also can be prevented in large part by the successive addition of secondary air around the outer walls of the retorts at suitable points spaced vertically of the retorts. J The'amounts of such air preferably are socontrolled as to effect the combustion of predetermined proportions of the gases issuing from the .fuel bed at different elevations lengthwise of the. generator housing.- This further increases the temperature of the .-,5" 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 thefuel where the said vertical temperature 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 the coal layer in the lower portion of the annular carbonizing 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 layer at the respective upper and lower portions of the fuel column is preferably lid adjusted in accordance with the above-mentioned relationship between the thickness of the fuel layer and the time required for its carbonization. To further facilitate the rapid carbonization I of 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 along in contact with the inner wall of the retort, and to transfer such heat to the layer '-='of fuel being carbonized. This refractory material is very efficient as a heat-absorbing and transfer means when employedin the manner indicated, as shown by the fact that the portion I of the carbonization effected. by transfer of heat from the inside surface of the annular fuel layer when the refractory filling material is not employed, amounts to less than. one-half of the portion of the carbonization effected by heat transferred 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 respective inner and outer walls of the retorts is preferably balanced in accordance with the total larger scale, showing the upper end of the generator housing andcertain of the parts associated therewith, portions thereof being cut away, and other portions being shown in section;

Fig. 3 is a horizontal section of the apparatus taken along the line 3-3 of Fig. 2 looking in the direction of the arrows; 1

Fig. 4 is a chart which indicates the relationshipbetween the carbonizing capacity of the retort and the thickness of the layer of fuel being carbonizedwithin 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 existing'betwee'n the carbonizing capacity of a retort and the temperature at which the carbonization is carried out,for definite thicknesses of fuel layers.

In thedrawings l0 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. The side wall 11 is suitably constricted at an intermediate pcrtion thereof to form a lower portion 15 of reduced cross section. A grate 17 of usual construction is positioned in the bottom of the generator 10 above the. base 12, the generator also being provided with-the usual stoke holes 19-19 in its'side walls adjacent the grate. Any type of grate, as for example, a non-clinkering grate, may be substituted for that shown.

For introducing air under pressure into the lower portion of the generator casing, a pipe 21 controlled by valve 23 extends through the side of the generator below the grate 1'7 and is con nected with a suitable. source of air under pres sure.

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. The depending tubular members 29 preferably taper outwardly in a downward direction, and have 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 crosssectional diameter of. the said member for each 8 feet of the length thereof.

The upper end of each of the retort members 29 extends through thegenerator top 14 and to a point substantially thereabove, and each is provided with a flanged cover plate 31 having a therein, and having a second aperture 35 located therein near the peripheral margin of the cover downward within the retort member 29 to a point adjacent the lower surface of the generator top relatively large, centrally-disposed aperture 33 14, so as todefine anannul'ar space between the passageway leading from the interior of the re-.

tort to the said aperture. Other radial members 40, 40 divide the remainder of the annular space between the curtain 37 and the retort29 into a plurality of parts.

Each of the tubular retort mehbers 29 has disposed therein and concentric therewith a gen erally 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 suitable resistant metal or alloy such as hybnickel, and is adapted for limited vertical movement longitudinally of the concentric 1118111- ber 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 latter engages the, bottom margin of the member 29 and forms a substantially gas-tight seal for the bottom of the annular chamber defined between the pair of concentric retort members 29, 41. The construction of the concentric retorts 29, 41 is preferably such that the annular fuelreceiving space defined therebetween is less than 5" in effective annular width, and the preferred optimum'width of this annular space is approximately 3".

Each of the retort members 41 is substantially constricted adjacent the upper end of the retort member 29 to form an upper-end 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 by acap 46. The upper portion of each member 41: is operatively secured to a housing member 47-.o'f acushioning or shock absorbing device, a second member 49 of the said device being adjustably securedto the piston 51 of a hydraulic cylinder 53 which is utilized for An elongated slot or opening 59 is provided in the upperconstflcted portion of each of the inner retorts 41 at a point above the top plate 31.

, A hollow T-shaped casting 61 surrounds the portion of the member 41 having the said slot 59 therein, and provides an annular chamber adapted to be in free communication with the interior of the member 41 only when thelatter is in its uppermost position. The interior of themember 41 is adapted to be, in communication with the upper end of'the annular fuel space when the former is in its lowermost position. A stuillng box associated-with eachtop plate 31 furnishes a gas-tight seal between the interior of casting 61 and the annular fuel space and comprises a housing 68 in which is mounted a metal collar or seal ring 69 provided with a plurality of grooves in its inner peripheral surface, each adapted to accommodate a contracting piston ring 71 for cooperation with the adjacent surface of the inretort member 41. A set screw or the like 3 cooperates with the housing 68 to prevent movement of the collar 69 with respect to the inner retort member. a

The upper end of the T-shaped casting 61 has an opening therein through which the constricted upper end portion 45 of the inner retort member is adapted to extend. A stuffing box 75 hopper 91 is centrally mounted upon the super-' The hopper 91 is provided with a gas-tight closure member93 andis divided into structure 55.

three superposed compartments 95, 97, 99, by a pair 01" vertically-spaced funnel shaped partitions 161, 103, each open at the lower end. Leading from a conical mid-portion of the bottom of the hopper 91'are a plurality of feed lines 167, 107 adapted to convey fuel to each of the annular spaces between the inner and outer retort members 29, 41. Each of the fuel feed lines 107, 107 hasa suitable gas tight valve 109, 109- therein-and the lower end of each line 107 is branched adjacent the generator top to form fuel feed pipes 111, 111, which open into the upper end or one of the annular retort spaces through v openings in opposite'sides of "the cover plate 31 between the metal curtain 37 and the outer retort wall 29. For conveying fuel from the storage compartment 95 into the compartment 97 at a uniform rate, a positive f ed mechanism is provided comprising a screw conveyor 113 mounted upon the upper portion of member 101 and driven from a suitable source of powerthrough pulley 115 and belt 117. The funnel shaped member 103 has a central opening located directly above the midportion of the bottom of the hopper 91.

The upper closurernember 93 of the hopperis controlled by a hydraulic cylinder 127 functioning in the manner shown, through a bell crank 129. V 7 l v 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 checker-work 135 A of a heat refractory material, the said passageway 131'being provided with acut-oii valve 132. The lower end of the said regenerator is connected'with a Waste heat boiler or economizer 137 by means of a passageway 139 having therein a shutoff valve 145. The gas outlet end of the economizer cornmunicates'with a stack 141 provided-with a hydraulically-operated draft regu lator or closure 143.. The lower end of the regenerator is also directly connectedwith the stack 141 by means of a pipe 147 having valve 149 desired.

The upper end of the regenerator 133 is contherein, for by--passingthe economizer 137 when I a lean gas tuye're'155. Oneend of the latter is point between .the said casing and the valve 23.

The other end of the ,tuyere 159 is connected with 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 stack 141, with the pipe 159.

For introducing steaminto'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 steampipe 167 with that portion of pipe 21 between the generator 10 and the valve 23. V

For distributing secondary air into the genera-' tor casingimmediately above the fuel bed and at 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 133,1--a branch conduit 177 controlled by valve 179 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 131 with a vertically-disposed manifold 183. The latter is connected respectively by valve-controlled pipes 135, 187, 189, with each of a plurality of vertically-spaced bustle-pipes 197, 199, 291, surrounding the generator casing. Each of the said bustle-pipes has leading therefrom a plurality of radially-disposed valve pipes 203 provided with suitable air injecting nozzles 205 extending throughthe 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 extendsinto the casing 10 at approximately the same elevation as the lower ends of the retort 29, and another set of nozzles extends through 1 the casing at approximately the same elevation as the mid-portion of the retorts 2 9.

For removing the gases and vapors as they are formed in the annular carbonizing space between v the respective pairs of retort nlembers, 29, 41,

during the carbonization of the fuel therein, each cover plate 31 has mounted thereon a'header or casting 267, connecting the said annular fuel space through a valve pipe 209 with a bustle-pipe 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 thereev through for. condensing tar, and the like present in such vapors. A steam pipe 217 extends into each of the fuel feed lines 137 immediately below the valve 199 therein;.and a steam pipe 219' extends into the upper portionof the space confined between each of the'tubular curtains 37 and each retort member29. Steam is preferably introducedinto the carbonizati'on zone through the steam lines 217 and 219 for the purpose of preventing the distillation. gases from rising into the feed lines 107 and into the curtain 37 where tar andthe like mightbe condensed and deposited. I

For carburetting the blue gas made in one of the cycles of the process according to one modification a pipe 221 leadingto a source of liquid hydrocarbon or other fluid carburetting medium has anend thereof opening into the. upper portion of the regenerator 133, the said pipe being preferably provided with a spraying or atomizing nozzle or the like 223.

While the invention is susceptible of wide modification, depending on whether it is desired to produce coal gas, blue gas, a mixture of coal gas and water gas or a carburetted water gas,the

following example is given solely to illustrate a. preferred application of the process in'the production of amodified blue gas. Assuming that the generator is provided with 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 eachpair thereof, a blast of air is introduced through pipe 31 below the grate 17 and is passed through the burning fuel'in the base of thegenerator, 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 part of the gases as they leave the fuel bed to assist in raising the temperature of the said gases to approximately 1900 this being the preferred temperature for the 'gasesxemployed in heating the refractory material positioned within the inner one of each pair of concentric retort members.

The productsof the primary air blast are then The resultant products of combustion of this portion of the lean gas are conducted. downwardly through the regenerator and from there they maybe led through the waste heat boiler and through the stack to the, atmosphere. The balanceof, the lean gas'fiowing'in pipe 155 is conducted through valve' 157; through a lean gas cooler to a lean gas holder onto a common mixing holder.

Another portion of the gases leaving the generator fuel bed pass upwardlyaroundthe outer] retort'rnember 29, giving up their heat through the said retort walls to the fuel being carbonized.

Thesecooled gases after such heat exchange flow with the blast gases entering the latter from the lean gas line 155 and may be burned with the latter for the purpose of heating-the checker work in the regenerator 133. the hot blast gases from the generator through passageway 131 into I the upper part of the regenerator where they mix pass upwardly in the gas generator, predetermined amounts ofair are introduced into and mixed therewith at a plurality of points spaced vertically of the generator, for the purpose of maintaining the various portions of the outer retort walls at the desired temperature and for uniformly carboniaing the fuel. At this point in the process the air blast'is discontinued, valves 23, 191, 193, 195, 143 and 1'79 being'closed, and the uprun make cycle is begun. Steam is admitted into the lower part ofthe gen erator 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 flue gas being conducted along each refractory-filled 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 tuyere 155 to the primary lean gas coolers and thence to storage. It may be stored in a separate holder from the producer gas previously conducted through the pipe 155, or it may be mixedwith the portion of the primary blast gases that were taken to storage during the first cycle of the operation. A second predetermined por tion 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 generatorthrough the passage 131 and the pipe 151 to the tuyere 155 where it mixes with the blue gas passing upwardly through the inner retort member and is conducted therewith through the lean gas coolers to storage.

During this uprun make cycle the fuel bed is rapidly cooled and the proportion of the heat radiated to the retort members from the incandescent fuel bed falls off appreciably. In order to maintain a satisfactorily uniform coking temperature vertically along the fuel column during this cycle, sufficient air preferably is intro,- duced through the pipes 203 to burn predetermined portions of the said blue gas so as to maintain the hot contacting with the inner and outer wails of the annular fuel column at the detemperature during such contact. the uprun cycle has been in operation for the desired length of time, it is terminated by closing the steam valve 1'75, the various valves .191, 193, 195 in the air line, and valve 157.

A downrun cycle is now started during which is admitted through line 167 into the lower n of the regenerator, the valves 145 and 149 ely connecting the bottom of the regenwaste heat boiler and with the closed, and the valve 165 in conduit 159 being opened. The steam is drawn upwardly through the regenerator, at the same time being highly superheated by heat transferred thereto from the highly heated checker work. The thus steam is thereafter divided if and as M d into two portions. One of the said portio...s passes through the passageway 131 into the upper part of the generator casing, and descends After generator fuel bed in a manner to offset the heating of the lower portions of the-respective retort members to higher temperatures than the upper portions thereof by the heat radiated from the fuel bed 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 through the pipes 151 and 155, the junction box 65 and the slots 59, and into the inner one of each of the pairs of concentric retort members. The said superheated steam then flows downwardly through the said members, giving up its sensible heat to the refractory fillings thereof, and it thereafter passes through the hot fuel bed 220. The blue gas thus formed by thereaction of this steam with the highly heated fuel is conducted through conduit 159 to the primary lean gas coolers and thence to storage. f

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 gases carried thereby are preferably conducted either to lean gas holders or exhausted to 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 annular 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 gas holder or a commonstorage holder.

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 11 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 functions as a support for the fuel 'column when it is in its upmost position, and .it I

also acts as a valve to prevent substantial pro portions 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 flaredbot-' tom thereof assists in breaking up large lumps of coke falling 'upon it during the dischargin'g process.

The retort pairs are preferably filled in succesgenerator is drawn into the fuel bed 220 and does not interfere with the process.

Lean producer gas and the like are prevented from flowing through the space lying between the two concentric retort members during the ime that the inner member is lowered for discharge of coke, due to the fact that the slot 59 thenis positioned below the seal ring 69. During this time valve 209 is closed to prevent the stage by. stopping the conveyor 113.

passage of lean gas into the rich gas bustle-pipe 211. When the inner retort member is again raised to its former position with its flared lower margin in sealing contact with the lower margin of the outer retort member, the slot 59 again permits communication between the inside of the inner retort 41 and the junction box 65, and concurrently breaks communication between the latter and the annular fuel space; The said annular fuel space is thereupon again charged with fresh'fuel from the fuel hopper by the operaing pipes 107 into the retort offsets any tendency for distillation gases to collect in these pipes. The current of stream introduced into the upper portion of each retort between the inner retort member 41 and the metal curtain 37 prevents the accumulation in the space of distillation gases which might deposit therein objectionable materials such as tar.

According to a modification of the process in which a carburetted combustiblegas is produced,

the uprun make cycle is so controlled that the gaspassing upward through the generator is at least in large part conducted into the regenerator by properly setting or closing the valves 157 and 158, and'opening the valvesl53 and 154i,

the said gases then being conducted downward through the highly heated checkerwork in the regeneratoni Simultaneously a spray of suitable carbureting fluid'such as a hydrocarbon oil or the like is introduced into the upper portion of the regenerator and if necessary is vaporized and fixed at the temperature existing therein. The enriched blue gas is conducted from the lower end of the regenerator direct to the pipe 141 and, through branch 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 oftar and the like condensing-in the flues thereof.

In like manner the last portion of the hot producer gases formed in the generator during the blast cycle may be carburetted'by spraying a ca'rburetting fluid into that portion thereof which is passed downward through the highly heated checkerwork in the regenerator. The introduction of air to the regenerator through the air pipe 1'77 is preferably discontinued prior to the introduction of the carburetting fluid into the said gases. 7

Instead of conducting all of the gases formed in the generator 10 during the uprun make cycle through the regenerator, which herefacts as a carburetor, a portion or an of the gases passing throughthe inner retort members of each pair may be conducted direct to lean gascoolers and to storage with or without portions of the gases leaving the generator through the passageway .31, by suitable adjustment of the check valves 154 and 158.

approximately no additional cost.

Although both the inner and the outer retort members of each concentric pair are preferably fabricated from the same kind of heat resistant metal, it is within the scope of the present invention 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. In order therefore to compensate for any unbalanced elongation of the inner retort members under the effect of theirown 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 extreme-upper end of the inner retort may be threaded externally for cooperation with threads formed upon the interior of, the lower end of the housing member 47. Other similar means for accomplishing the same 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 and lowering of the inner retort member without undue jarring and injury to the apparatus. 1

It will be obvious thatother methods of charging coal into theretort may be substituted for that specifically shown and described. It is also within the spirit of the present invention to make the outer retort member cylindrical while employing a reverse taper on the inner retort member so that the sides of the latter slope inwardly in a downward direction, or if preferred both inner and outer retort members may be slightly tapered.

By employing a cylindrical inner retort member, and providing the outer retort with an outward and downward taper, it is possible'to vary the thickness of the annular 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 it is possible to appreciably increase the carbonization capacity of retort-s of the type here shown and described at The relative proportion of the carbonizing heat distributed along the respective surface of the inner retort and the onterretort wall may be controlled by suitable vacuum-producing means arranged in the lean gas 'offtake line from either of the said retort members or by pressure control flow involving the use of regulating valves hereinbefore mentioned.

An apparatus construction in which a group of four uniformly spaced carbonizing retorts is supported in the upper part of a gas generator housing has proven to be very efiicient 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 105 v to 1500 F. At temperatures much in excess of 1500 F., while the rate of carbonization is accelerated, there is a tendency toward cracking of the tar vapors, which interferes with the production of primary tar and reduces the tar residue credit, both from the 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 athicker layer thereof, until a point is reached at which the number of .retorts required in order to permit the continuous operation of the generator introduces many structural difficulties.

It is within the purview of the present invention to utilize for carbonizing the fuel both the luminous and the nonluminous or obscure radiations from the incandescent generator fuel bed; and the area of that portion of the tubular retort surface which 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 valves for temperatures of 1050 F. to 1400 F. and 1500 F. are shown. Ordinarily in carbonizing fuel in annular layers over a water gas generator, certain difliculties 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 carbonizing temperatures employed. This effect is separately indicated for fuel layers respectively 3 and 5" in mean thickness, between temperatures of 1050 F. and 1800 F. However, at temperatures below 1050" F. the carbonization capacity of the retorts, when using the optimum thickness of coal layer, 3", is reduced to a point Where thenumber 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 and in 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.

I claim: 1. Apparatus for concurrently carbonizing and gasifying solid fuel which comprises a vertically disposed generator housing, air and steam lines leading into the lower portion thereof, a plurality of pairs of concentric hollow tubular members mounted in the upper part of the generator housing and forming a plurality of carbonizing retorts of relatively thin annular cross section, a removable bottom closure for each of the said annular retorts, .a' regenerat'or, means for connecting the inner member of each pair of retorts with the regenerator, means for connecting the upper portion of the generator housing with the regenerator, and means forcontrolling the relative amounts of heating gases passing into the regenerator respectively through the inner retort members and through. the generator housing.

2. Apparatus for the concurrent production of combustible gas and a carbonized solid fuel which comprises a vertically-disposed generator housing having a grate, air and steam lines leading to the said housing below the grate, a plurality of pairs of spaced-apart, concentrically arranged tubular members mounted in the upper portion of the housing, each pair of members de fining between them an annular space, "neans for longitudinally moving one of the said tubular members of each pair, means associated with the last-named or movable member and cooperating with the other of the said tubular members to form a bottom closure for the said annular space when the movable tubular member is in its uppermost position, the concentric members being spaced closer together at their upper portions than at their lower portions, means for in-' troducing fuel to be carbonized into the annular space between each of the pairs of concentric retorts, and a plurality of conduits for separately conducting hot combustible gases along within the inner of the concentric members and along the on er surface of the outer of the concentric members and for conducting the said gases to storage.

3; Apparatus for the concurrent production of combustible gas and a carbonized solid fuelwhich comprises a vertically-disposed generatorhousing having a grate, air and steam lines leading to the said housing below the grate, a plurality of pairs of spaced-apart, concentrically-arranged tubular members mounted in the upper portion of the housing, each pair of members defining between them an annular space, a removable bottom closure for the said annular space, means for longitudinally moving one of the said tubu lar members of each'pair, and yielding means rality of pairs of. spaced apart, concentricallyarranged tubular members mounted in the upperportion of the housing,.:each pairof members defining between them an annular space,

actuating means for longitudinally moving one of thesaid tubular members of eachpair, means associated with the last-named or movable member and cooperating with the other of the said tubular'members to forma bottom closure-for the said annular spacewhen movable tubular member is in its uppermost'position, and adjustable means associated with the said movable tubular member for moving the latter 1ongitudinally of the said actuating means for in- .suring a substantially gas-tight seal between the lower portions of the two concentric niernbers when the movable is in its upper-' comprises a vertically disposed generator hous-' ing, air and steam connections leading thereto, a plurality of pairs of concentric tubular members mounted in the upper part of the generator housing and forming a plurality of carbonizing retorts of relatively thin annular cross section, the bottom margin of one of each pair of the concentric members being flared to form a bottom closure for the annular chamber defined by the said pair of concentric members, means for moving one of the concentric tubular members of each pair longitudinally of the other, and a plurality of vertically-spaced groups of fluid inlet pipes opening into the generator housing,

at least some of the said groups being disposed adjacent the tubular members.

7. Apparatus for the concurrent carbonization and gasification of solid fuel which comprises a vertically-disposed generator housing, air and steam connections leading thereto, a plurality of pairs of concentric, hollow tubular members:

mounted in the upper part of the said generator housing and defining a plurality of carbonizing retorts of annular cross section, one of the tubular members of each pair having its lower margin fiaredto'form a bottom closure for the annular retort defined by the respective tubular members of that pair, means, for vertically moving one of the tubular members of each pair to selectively bring the flared bottom margin of one tubular member into contact with the bottom edge of the concentrically disposed tubular member so as to form abottom closure for the'car bonizing retort or to move the flared bottom out 7 of such contact to permit discharge of carbonized fuel from the retort into the lower part of the said housing, a regenerator and automatic means associated with the inner one of each pair of tubular. members for establishing communication between the interior of the said inner member and selectively with a lean gas holder or with the regenerator only when the'said flared bottom margin of one of the said members is inraised position in contact with the bottom edge of the other member of such pair.

8. The apparatus as defined in claim 7 includ-, ing means dividing theinner one of the concentric tubular members of each pair into a plurality of superposed compartments, each of said compartments being provided with refractory filling-bodies.

,9. Apparatus for concurrently carbonizing and gasifying solid fuel, comprising a vertically-di posed generator having a grate therein, air and steam lines leading to the generator below the grate, a pair of concentric hollow tubular mem: bers mounted in the upper part of the generator and forming the respective side walls of a carbonizing retort of relatively thin annular cross section, means for longitudinally moving one of the said tubular members, a bottom closure for the retort secured to one of the tubular members and adapted to close the retort atrthe bottom only when the said-movable member is in its up-' permostposition, and means adapted when the said movable tubular member is in its uppermost position to directly connect the space within the inner tubular member of each pair selectively with a regenerator and with-lean gas storage.

10. Apparatus for concurrently carbonizing and 'gasifying solid fuel, comprising a verticallydisposed generator having therein a grate, air

and steam lines leading to the generator below the grate, a pair of concentric-hollow tubular members mounted in the upper part of thegen-. erator and forming the respective side walls of a carbonizing retort of relatively thin annular cross section, an adjustable bottom closure for the retort spaced above the grate, fluid inlet means in the upper part of the annular retort adapted to prevent accumulations of tar and the like within the upper end of the retort, and means for introducing solid fuel into the retort and for uniformly distributing such fuel therein.

11. Apparatus for concurrently carbonizing and gasifying solid fuel, comprising a verticallydisposed gas generator having a grate therein, air

the curtain and the said inner member, an inlet for solid fuel connected with the retort between the said curtain and the. outer-member of sach pair of tubular members, and means connected with the upper part of theretort for conducting rich gas therefrom.

l2. Apparatusv for concurrently carbonizing and gasifying solid fuelwhich comprises, a vertically disposed generator having a grate, air and steam lines leading-to the generator below the grate, a pair of concentric hollow tubular mem bers mounted in the upper part of the generator and forming the respective side walls of a carbonizing retort of'relatively thin annular cross-sec--- tric tubular members and adapted to establish 1 communication between the interior of the said inner member'and theregenerator when the said tubular member is in its uppermost position, a valve-controlledgas ofitake connected with the said annular retort, means for introducing steam into the lower portion of the regenerator, and a rich gas oiftake leading from the lower portion of the regenerator. I

13. Apparatus for concurrently carbonizing and gasifying solid fuel whichcomprises, a ver-' tically'disposed generator having a grate, air and steam lines leading to the generator below the grate, a pair of concentric hollow tubular members mounted in the upper part of the generator and forming the respective side walls of a carbonizing retort of relatively thin annular cross-section, means for longitudinally moving oneof the said tubular members, a bottom closure for the retort secured to one of the tubular members and adapted to close: the bottom of the retort when the movable member is in its uppermost position only, a regenerator, valve controlled means connecting the upper part of the generator housing with the regenerator, a valve-controlled conduit connected with the upper part ol the regenerator, means associated with the last named conduit and with the inner of the pair of concentric tubular members and adapted to establish communication between the interior of the said inner member and the regenerator when the said tubular member is in its uppermost position, a valve-controlled gas offtake connected with the said annular retort, means for introducing a carbureting fluid into the regenerator, means for'introducing steam into the lower portion of the regenerator, a rich gas offtake leading from the lower portion of the regenerator, and means for introducing secondary air into the i generator at vertically-spaced points above the grate therein.

14. Apparatus for concurrently carbonizing and gasifying solid fuel which comprises a vertically disposed gas generator having a grate therein, air and steam lines leading to the generator below the grate, a pair of concentric hollow tubular members mounted in the upper part of the generator and forming the respective side walls of a carbonizing retort of relatively thin annular cross section, means for longitudinally moving one of the said tubular members, the bottom 010- sure for the retort being secured to one of the tubular members and being adapted to close the bottom of the retort when the movablemember is in its uppermost position only, a regenerator, a valved-controlled conduit connecting the upper part of the generator with the regenerator, other means associated with the movable tubular member and adapted to establish communication between theregenerator and the interior of the movable member only when the latter is in its uppermost position, a valved-controlled rich gas ofitake leading from the carbonizing retort, and a valve-controlled rich gas offtake leading from the lower portion of the regenerator.

15. Apparatus for concurrently carbonizing and gasifying solid fuel which comprises, a verticallydisposed generator having a grate, air and steam lines leading to the generator below the grate, a pair of concentric hollow tubular members mounted in the upper part of the generator and forming the respective side walls of a carbonizing retort of thin annular cross-section, means for longitudinally moving one of the said tubular members, a bottom closure for the retort carried by one of the tubular members and adapted to close the bottom of the retort only when the movable member is in its uppermost position, a regenerator, valve-controlled means connecting the upper part of the generator with the regenerator, a valve-controlled conduit establishing controlled communication between the interior of the said movable member and the regenerator when the said member is in its uppermost position, a valve-controlled gas offtake connected with the said annular retort, means for introducing a carbureting fluid into the regenerator,

means for introducing steam into the lower portion of the regenerator, rich gas ofitakes respectively leading fromlthe lower portion of the ator, valve-controlled means connecting the u'pregenerator and from the base of the generator, and means for controlledly introducing secondary air into the generator at vertically-spaced points tubular members, a bottom closure for the retort carried by one or the tubular members and adapted to close the bottom of the retort when the movable member is in its uppermost position only,

a regenerator, valve-controlled means connecting the upper part of the generator directly with the regenerator, means cooperatively associated with thesaid movable memberand adapted to establish regulated communication between the regenerator and the interior of the movable memher only when the latter is in its uppermost position, a valve-controlled rich gas offtake leading from the carbonizing retort, a valve-controlled gas off-take leading from the lower part of the regenerator, means for introducing secondary air into the generator at vertically-spaced points above the grate therein, and means for introduc ing secondary air into the upper part of the. regenerator.

17. Apparatus for concurrently carbonizing and gasifying solid fuel, which comprises a vertically-disposed gas generator having a grate therein, air and steam lines leading to the generator below the grate, a plurality of spaced pairs of concentric hollow tubular members mounted in the upper part of the generator, the

ing the respective side walls of a carbonizing retort of thin annular cross-section, means for independently longitudinally moving one of the said tubular members of each pair, a bottom closure for each retort controlled by one of the tubular members forming the same independently of the other retorts adapted to close the bottom of such retort when the said movable member is in its uppermost position only, a regenerper part of the generator with the regenerator, means cooperating with the movable tubular member of each pair thereof and adapted to establish controlled communication between the regenerator and the interior of the said movable member only when the latter is in its uppermost position, valve-controlled rich gas offtakes leading from each carbonizing retort, and a valvecontrolled rich gas oiftake leading from'the lower part of the regenerator. V e

18. Apparatus for concurrently carbonizing and gasifying solid fuel; which comprises a verticallydisposed gas generator having a grate therein, air and steam lines leading to the generator below the grate, a plurality of spaced pairs of concentric hollow tubular members mounted in the upper part of the generator, the

tubular members of each of the said pairs forming the respective side walls of a carbonizing retort of thin annular cross-section, means for independently longitudinally moving one ofithe said tubular members of each pair, a bottom closure for each retort controlled byone of the tubular members of each of the said pairs formtubular members formingthe same independently of the other retorts and adapted to close the" bottom of such retort when the said'movable member is in its uppermost position only,.a regenerator, valve-controlled means connecting the upper part of the generator with the regenerator, means cooperating with the movable tubular member of each pair thereof and adapted to conduct regulated portions of hot gases from the interior of the said movable member selectively to the regenerator and to a source of lean gas storage only when the said movable member is in its uppermost position, a valve controlled rich gas offtake leading from each carbonizing retort, a valve-controlled rich gas oiftake leading from the lower portion of the regenerator, means for introducing a carbureting fluid into the regenerator, and means for introducing secondary air into the generator at vertically-spaced points above the grate therein and longitudinally of the said retorts.

19. Apparatus for concurrently carbonizing and gasifying solid fuel which comprises, a vertically-disposed generator, air and steam lines leading to the lower portion thereof, a plurality of pairs of concentric hollow tubular members mounted in the upper part of the generator and forming a plurality of carbonizing retorts of thin annular cross-section, a removable bottom closure for each of the said annular retorts, a regenerator, means for separately connecting the inner member of each pair thereof with'the regenerator, means for connecting the upper portion of the generator with the regenerator, means for controlling the relative proportion of hot gases passing to the regenerator respectively through each of the inner tubular members and directly from the generator, a gas ofitake connected with the lower portion of the regenerator, and a plurality of controlled verticallyspaced fluid inlet pipes opening into the generator adjacent the tubular members.

ALFRED JOHNSON.

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