US2396888A - Combustion apparatus - Google Patents

Description

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CMBUSTION APPARATUS Filed Sept. 30, 1941 4 Sheets-Sheet l vci; scHoLl.

COMBUSTION APPARATUS Mmh 19, 1946.

Filed Sept. 30,'1941 4 Sheets-Sheet 2 March 19, 1946.` c. sHoLL coMBUs'rIoN APPARATUS 4 sheets-sheet '3 Filed sept. 3o, 1941 March 19, 1946. c? SCHOLL couaUsT'IoN APPARATUS Filed sept. '39, 1941 4 sheets-sheet 4 Patented Mar. 19, 1946 wat COMBUSTION APPARATUS clark s011011, springfield, ohio, assignor to The Steel Products Engineering Company. Springfield, Ohio, a corporation of ho Application September 30, 1941, Serial No. 413,025

(Cl. 11B-45) 13 Claims.

This invention relates to combustion apparatus and more particularly to stokers.

It is a principal object of the invention to provide a stoker of simple and effective construction providing for the combustion of solid fuel under predetermined conditions such that objectionable coke or clinker formation is reduced or eliminated and the ash is produced in the form of powder or particles of small size in which it can be readily handled and removed.

It is a further object to provide such a stoker device in which there is a predetermined regulation of the quantity of air supplied throughout the combustion zone so as to properly control the combustion and assure complete combustion while avoiding excessive temperatures which would otherwise result in the fusing of the ash in large masses of clinker.

It is a further object to provide an underfeed Stoker in which the section of the body of burning fuel is of predetermined shape and depth and in which combustion air is introduced throughout the burning fuel body in correlated relation d with respect to the depth of the fuel body to obtain substantially a uniform and complete combustion at all rates of fuel supply.

It is also an object to provide an underfeed retort in which the combustion chamber is Zoned around the periphery thereof as to air supply and each zone is separately supplied from a plenum chamber so that proper air supplyv is maintained throughout the body of burning fuel notwithstanding locally occurring variations in the thickness of the fuel bed.

It is a further object to provide acombustion device of this character in which combustion air is supplied at relatively low velocities and low pressures in predetermined space distribution over and into the bodyof burning fuel assuring a maintained distributed supply of combustion air at low velocities and pressures to avoid high temperature combustion and the resultant fusing of the ash into large clinkers.

It is a further objectto provide a combustion device of this character in which the ash as received in nely divided particles is removed continuously from the combustion zone and deposited in a suitable ash receptacle.

Other objects and advantages will be apparent from the following description, the accompanying drawings, and the appended claims.

In the drawings, A

Fig. 1 is a plan view of` a stoker installation made in accordance with the present invention;

Fig. 2 is a side elevational view of the same mechanism;

Fig. 3 is a plan view looking down on the retort of the present stoker construction with certain of the parts being broken away to more clearly disclose the construction;

Fig. 4 is a vertical sectional view through the retort on the line 4-4 of Fig. 3;

Fig. 5 is a view partially in elevation and partially in vertical section showing the ash worm and the drive mechanism for effecting actuation thereof;

Fig. 6 is a detail View showing the construction which provides for the drive of the ash conveyor ring;

Fig. 'I is a detail view in section on the line l-l of Fig. 3 showing the provision for discharging the collected ash onto the ash conveyor;

Fig. 8 is a detail view showing the drive connection for effecting the oscillatory movement of the ash ring; and

Fig. 9 is a broken plan view of the 'ash conveyor ring.

In the eld of stokers, particularly those for the domestic or household heating system, it has heretofore been proposed to provide a device em bodying a retort and an ash removal arrangement for removing the ash to a place where it can be properly received and disposed of. In the past considerable diiiiculty has been experienced in the actual operation of such devices in part by reason of the failure of the retort to properly burn the fuel under the wide range of loadv conditions necessarily encountered, and the resulting objectionable formation of coke trees because of incomplete combustion, or the formation of large clinkers by reason of combustion taking place at excessively high temperatures. In some cases it has been proposed to introduce mechanism for breaking or grinding up these formations, but in most cases they have not proven entirely satisfactory in operation since substantial power is required to break or grind up clinkers to a small enough size for handling in the usual conveyor, and the heavy forces involved required correspondingly heavy and expensive constructions.

In accordance with the present invention, a construction of Stoker is provided inwhich the combustion conditions are maintained under predetermined control for all rates of combustion and throughout the entire body of the fuel bed, so that objectionable formation of coke trees or clinkers does not take place. The body of fuel in the retort is of predetermined shape such that combustion air is introduced thereinto from all sides and under such circumstances that there is practically no portion of the body of burning fuel which is not properly and adequately supplied with combustion air. The fuel bed is limited in cross section and is readily accessible to the combustion air throughout its section.

Where the combustion air is supplied to the fuel bed at a relatively high pressure, a portion of the fuel bed which Ibecomes thin tends to cause a lesser resistance to the flow of air, with the result that it becomes cumulatively thinner, resulting in a tendency to burn through locally with the production of local high temperature combustion forming clinkers and at the expense of complete over-all combustion. In thepresent construction, the combustion air is supplied to the body of fuel from a plenum chamber in which a substantially constant pressure is maintained, and from that chamber the combustion air is introduced into the body of fuel through the tuyre openings at a plurality of spaced zones Yor sections. Each such supply is independent of the others and the tuyres are separated into independent sections by solid tuyre members preventing air flow from one section to another. The aggregate of the tuyre openings in each section is greater than the area of the opening from the plemun chamber into that section, and, a pressure drop occurr from' the plenum chamber to each of such sections, so that even in the event that the fuel bed should burn through in one spot, combustion air will continue to be supplied independently into the body of fuel at each of the remaining sections. Thus the tendency for such condition to become cumulatively worse is effectively overcome', and it is practically `impossible for a localized condition of this character to occur to the extent that it will interfere with the continued supply of combustion air to the entire body of burning fuel.

Being supplied at relatively low pressure and limited velocity, the combustion takes place more uniformly throughout the retort, with the substantial elimination of objectionable coke trees resulting from incomplete combustion, and with similar substantial elimination of such high temperature combustion as to result in the production of objectionable clinkers. The ash is formed primarily as a powder, or in particles of relatively small size, the ash" remaining primarily in an unfused condition, or if some fusing does occur, it is limited in extent, and the resulting fused particles are small in size and capable of being handled by an ordinary screw conveyor. Similarly as a result of the introduction of the air under predetermined conditions of pressure and space distribution, the production of :dy ash is limited, and cleaner and more efficient combustion conditions are maintained. While suitable for the combustion of different types of solid fuel, the present invention has been particularly developed for the burning of bituminous coal, and

tube I3 which is open lalong its entire upper extent as shown so that fuel can pass thereinto along the entire length of the bin and be conveyed forwardly and into the closed conveyor section i4 located exteriorly of the bin wall. The construction of this bin feed portion of the conveyor is preferably as disclosed in applicants copending application Serial No. 354,599, led August 28,' 1940, now Patent No. 2,369,370, granted .on February 13, i945, and assigned to the same assignee as this application.

Thefeed worm for supplying the fuel into the retort is shown at I6, and located in non-axial relation with respect to the bin worm l2. The

adjacent ends of these worms are received Within a transfer chamber shown at Il to which the fuel is delivered by the bin worm and from which mechanism indicated at 22. From this mechanism for purposes of illustration, will be described more particularly in that relation.

Referring to the drawings which disclose a preferred embodiment of the invention, a bin l0 is shown which is adapted to receive a quantity of the solid fuel to be burned. It will be understood that the invention is equally suitable for use with a hopper type Stoker, and that the showing of the bin feed type is merely illustrative. Extending into the bin and suitably supported upon brackets il from the bottom thereof is the bin end of the feed worm l2.V It is suitably sup ported, preferably in an open slotted conveyor drive shafts extend on opposite sides and cariy sprocket Ywheels 23 and 24 suitably connected as lby means of sprocket chains to driven pulleys 25 and 26, provided respectively for the drive of the bin worm I2 and the feed worm I6. Further details of such drive and construction of transfer chamber are as shown in applicants copending application kSerial No. 297,247, filed September 30, 1939, now Patent No. 2,364,166, and assigned to the same assignee as this application.

IThe feed worm I6 extends into the lower portion of a retort 30 which has an upwardly curved wall 3| to supply the fuel delivered by the worm upwardly into the combustion zone. The wall 3l is completely closed and is preferably formed integrally with the casing 32 to provide a plenum chamber 33 into which the blower 2l discharges through the air supply conduit 34.

The tuyres 36 are positioned above the casing section 3l and as shown are preferably arranged to provide a combustion space 31 substantially C-shaped in cross section. The tuyres 38 immediately overlying the end of feed worm I6 and the upwardly inclined supply passage extend inwardly so as to break up the circular section of the combustion space, and to form it as an arcuate space with means for introducing combustion air into both the outer andinner portions of such space. Preferably as shown projecting or nose portions of tuyres 38 do not extend upwardly as far as the tuyres 36, but at their rearward or outward portions 39 they do extend to substantially the same level as the remaining body of tuyres.

It has been found that with this construction because of the varying depth of the body of fuel and its resistance to the passage of air thereto,

the greatest quantity of combustion air should be introduced into the combustion space in that portion immediately opposite tuyres 38 or at the exterior surface of the body of burning fuel, that lesser quantities of air should be introduced into the combustion space at either side of tuyres 33, and that the smallest quantity of air should be introduced through tuyres 38 themselves to be supplied to the interior surface of the fuel body. In this way, proper quantities of air are supplied to the various sections of the fuel bed to eectively complete combustion therein at predetermined and regulated rates of burning.

For the purpose of establishing a plurality of air sections from which air may be' supplied at proper predetermined pressures, solid tuyre sections 40 are introduced at the boundary of each of the sections. In the arrangement shown, four such solid tuyre sections are provided, establish--l ing a front zone 4| into which air is introduced at the highest pressure, two side zones 42 into which air is introduced at an intermediate `pressure', and the single rear Zone 43 into which air is introduced at the lowest pressure.

Each of the tuyres is arranged with a series of vertically stepped air introducing apertures 45 on its vinner portion, providing for introducing air into the main combustion space, and likewise is provided with a vertically extending rib 46 separating the inner air apertures from an outer series of Yapertures 41. These outer apertures extend in similarly and reversely stepped relation at the outer periphery of the tuyres, and are preferably substantially smaller in their total cross sectional area of outlet than the openings 45. Likewise, the total area of the outlet apertures 41 is in excess of the area of the apertures 48 through the partition wall 46 so that a pressure differential will be maintained at all times between the air discharged from the two series of openings.

' In order to provide for the independent control and regulation of the combustion air, each of the plurality of sections 4|, 42, andV 43, is independently connected with plenum chamber 33. An adequate supply of combustion air is maintained in the plenum chamber by the blower, and thus an assured supply of combustion air to each of the plurality of sections is maintained, so that even in the event of the resistance of the fuel bed dropping down materially ,in one of those zones, the resistance afforded to the flow of air into that zone is such that it does not exhaust the pressure of the plenum chamber, and a proper and substantially uniform supply of pressure air continues to be maintained into each of the remaining zones.

In order to provide for the regulated introduction of the combustion air into the several zones, a bottom plate 50 is provided on which the tuyres are adapted to rest, and this plate is provided with a series of arcuate slots, indicated at 52 and 53. Slot 5| is the largest in cross section, and is located in that portion of the plate within zone 4|. The two slots 52 are of intermediate cross section and are located in the combustion Zones 42, respectively. Slot 53 is the smallest in section and is located in section 43 of the combustion zone.

In order to provide for regulation in the quantity of air supplied from the plenum chamber, an adjustable plate 55 is provided and received within the casing 3| in position immediately below plate 55. This movable plate 55 has a similar series of apertures therein of the same corresponding size and shape as apertures 5I, 52 and 53, and adapted to register respectively therewith. An adjusting rod 56 extends through the wall of the chamber 3| and is arranged to be moved by the operator to rotate plate 55 and to thus vary the degree of registration between corresponding apertures. As will be obvious, such adjustment thus regulates, in a similar and corresponding manner, the total effective opening into the several air zones, and thus provides for regulating the pressure in the tuyre sections with respect to the pressure existing in the plenum chamber. Preferably the maximum degree of opening possible is sufficiently limited with respect to the capacity of the plenum chamber and of the blower that even in the event of a marked reduction in the resistance of the fuel bed occurring in any one section, the pressure in the plenum chamber is not materially reduced, and consequently combustion air continues to Vbe supplied substantially uniformly to the remaining portions of the fuel bed.` In actual operations, this larrangement has been found to be productive of highly satisfactory results, substantially eliminating the uneven combustion conditions resulting from changes in the air resistance of the fuel bed, and providing for complete combustion taking place under regulated temperature conditions such as to avoid objectionable formation of either coke trees or clinkers. As a specific example of pressure conditions which have been found to give highly satisfactory results, a pressure of .90 inch of water was provided in the plenum chamber 33, .65 inch in section4l, .55 inch in sections 42, .40 inch in section 43 and .15 inch in the space beyond partitions which supply combustion air to the air apertures 41. It will be understood that these figures are illustrative only and may be varied with changes in thev shape of the combustion space, thefdepth of the fuel bed at each section, etc.

Combustion continues with the air being sup- K plied through air apertures 45, and after the fuel passes over the top of the tuyres, with the air introduced, at lower pressures, throughV air apertures 41. By'the time the fuel has travelled over the tuyres, its combustion at the desired controlled Vrate has been substantially completed, and only the ash, in a condition of relatively finely divided particles cr powder remains. Such ash is discharged upon the ash ring 65, which is arranged in the form of a grating having a series of apertures of predetermined limited size therein. The ash rin'g is suitably supported for movement upon an upstanding flange 6| spaced from and parallel withthe outer wall portion 62. rl'he space 63 between these walls 5| and 62 constitutes an ash chamber into which the particles of ash small enoughfto drop through the apertures in the ash ring may fall and as shown is of limited vertical extent so that the entire ash space is located above the level of the feed Worm I6. If any excessively large clinker formation does take place, such clinkers are not permitted to drop into the ash space, but are held on top of the ash ring where they can be removed through the' furnace door. l

In order to provide for movement of ash ring 6I) and the continuous removal of the collected ash from the ash space 63, suitable drive and conveyor mechanism is provided. As shown, a drive socket 1|) is provided at the end of the bin worm 2, and extending from the opposite side of the'transfer chamber |1. An ashconveyor shaft 1| is suitably connected to this socket by a universal connection 12, and carries thereon a barrel cam 13. A cam follower 14 is carried on a pivoted lever arm 15 which extends upwardly and is provided with an operating pin 16 extending into anelongated slot 11 formed in a link member ll-8. An adjustable bolt 19 is threaded in the link at one end thereof and extends into the slot, being adjustable to vary the effective length of the slot.

yThe pin 16 is adapted to bear against one end of the slot in one direction of movement and against theend of the bolt 19 in the other, the adjustment of the bolt thus providing foran adjustable clearance and a regulation of the extent of reciprocating movement of the link under the action of the lever.

The link 18 is attached to a connecting rod 80 which extends into the retort, and which carries at its inner end an operating shoe 8 formed with opposed flanges 82. The ash ring is provided witha depending lug portion 83 adapted to be freely received between flanges 82'so that upon reciprocation of shaft 80 under the action of the drive described immediately above, the ash ring will be given an oscillatory movement. Since this drive is actuated from the reduced speed worm construction as described, it will be clear that the cycles of operation of the ash ring take place relatively slowly, and that the extent of the-oscillatory movement thereof will vary in accordance with the adjustment of the threaded bolt 19.

Pivotally attached to the lower side of the ash ring 60 isa pivoted and weighted lever 85, such lever being formed with a downwardly extending pawl 86. As shown in Fig. 3, such lever is suitably shaped to conform generally to the arcuate shape of the ash ring, and such as to be received within the casing wall 62.

Rotatably mounted upon the bottom wall 90 of the ash space 63 is an ash conveyor ring 9|. The ring 9| is shaped generally similarly to the bottom wall portion 90, that is, both sections are dished to tend to work the collected ash material radially inwardly toward inner Wall 6|, the provision of lower scraper surfaces 9|a facilitating such action. The ash conveyor ring 9| carries ratchet teeth 92 on its upper outer surface, these teeth being located in the line o f action of pawl 8B. The teeth are inclined in one direction and extend substantially vertically in the other, so that in response to oscillatory movement of ash ring 60, the pawl will engage the teeth to cause concurrent movement of the ash conveyor ring in response to one direction of movement of the ring 60 but will be lifted out of engagement and not cause return movement ofthe conveyor ring 9|, in response to reverse movement of ring 60. Thus by this means the oscillatory movement of ring is converted into a ycorresponding intermittent but unidirectional rotational movement of ring 9|.

As the ash falls into the ash space S3, it is gradn ually conveyed around through the space by means of ring 9|, to the point of discharge from such space. As shown in Figs. 3 and 7, a stationary scraper blade 95 is mounted in the .ash space and is inclined with respect to the direction of movement of the ash ring so as to tend to scrape the ash thereon radially inwardly and toward the discharge outlet 96. The inner wall portion 6| is depressed as shown at 91, to form this opening, which leads downward and into ash conveyor tube 98, located parallel with and in substantially the same horizontal plane as the-feed worm I6.

The ash conveyor worm is shown at |00, extending through the tube 98, comprising a forward feeding flight portion for the removal of the ash from the discharge space 96. The worm is actuated by the shaft 1|, being located in proximity thereto and preferably being formed as a part thereof, and hence is driven through the speed reducing mechanism as described above and at the same speed as the feed worm and in correlated feed relation with respect to the drive mechanism for operating the ash ring.

The ash is fed forwardly through the tube 98 to a discharge opening |02, beneath which a reverse ilightiportion |03 is provided for preventing continuedy forward feeding of the ash. The combined action of flights |00 and |03 causes the lifting of the ash upwardly through the discharge opening, the ash being suitably received within a container shown at |04. This container preferably is of suitable size for receiving and retaining a proper accumulation of ash, and is, provided with an inlet opening in one corner of its bottom Wall, in alignment with the discharge opening |02. Preferably a suitable bracket |05 is provided for receiving the flanged edge |06 of the container in operative position, providing for ready re- :moval thereof. Likewise an adjustable gate |01 is located above the bottom opening of the receptacle and arranged to be closed by a manually operable handle |08 extending above the receptacle so that when it is desired to remove and dump the receptacle, the gate can be closed with the receptacle still in position, thus preventing any undesired loss or dropping of the ashes duringremoval.

The invention thus provides a highly satisfactory and yet simple construction of Stoker device providing for the controlled introduction of combustion air in predetermined space distribution and under predetermined conditions of regulated and maintained pressure. Such air is introduced substantially uniformly into the entire section of the combustion zone and under such conditions that it is not possible for locally occurring `changes in the air resistance of the fuel bed to affect materially the supply of combustion air to the remainder of the fuel bed. As a result, the combustion air is supplied under relatively low pressure, and with complete combustion being assured so as to avoid the formation of coke trees, .the avoidance of high temperature combustion is likewise assured with resulting freedom from clinker formation. It is thus possible to provide for the simple and effective removal of the ash in essentially the form of powder or small parti cles and without the necessity of grinding or reducing large size clinkers to a form suitable for handling.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, lit is to be understood that the invention is not limited to-this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

l. Combustion apparatus of the character described which comprises a generally circular retort for the burning or solid fuel, means located around the periphery of the retort for introducing air intol the burning fuel at relatively low velocity and in predetermined maintained dis-4 tribution around the periphery of the body of burning fuel to avoid formation of clinkers and leaving the ash in a finely divided form including a plurality of tuyres for introducing combustion air into the body of burning fuel, means for dividing said tuyres into a plurality of independent sections forming separate air introducing zones spaced around the periphery of said body of fuel, a plenum chamber, means for separately introducing air from said plenum chamber to each of said air zones, said independent air supplies providing a plurality of maintained supplies of combustion air spaced around the combustion zone independently of locally occurring variations in the air resistance of the fuel bed.

2. Combustion apparatus of the character described which comprises a generally circular retort for the burning of solid fuel, means for introducing air into the burning fuel at relatively low velocity and in predetermined maintained distribution around the periphery of the body of f burning fuel to avoid .formation of clinkers and leaving the ash in a nely divided form including a plurality of tuyres located around the peripheryof the body of fuel for introducing combustion air into the body of burning fuel, means for dividing the air passages of said tuyres into a plurality of independent sections forming separate air introducing zones spaced around the periphery of said body of fuel, a plenum chamber, means for separately introducing air from said plenum chamber to each of said air zones, means for separately regulating the quantity of air introduced into each of said air zones and providing a pressure drop between said plenum chamber and each of said air zones, said independent air supplies providing a pluralityv of means for dividing the air spaces of said tuyresinto a plurality of independent sections around the periphery of the fuel bed, a plenum chamber for supplying air into each of said sections, and restricting means for eiecting a pressure drop from said plenum chamber into each of said sections to assure continued supply of air from said chamber into all of said sectionsv notwithstanding the occurrence of variations in the fuel bed resistance in any of said sections.

` 4. Combustion apparatus of the character 'scribed comprising a retort for the burning of solid fuel, a feed worm for supplying fuel upwardly into said retort, a, plurality of tuyres for introducing combustion air to the burning fuel, means for dividing the air spaces of said tuyres into a plurality of independent sections around the periphery of the fuel bed, a plenum chamber for supplying air into each of said sections, restricting means for effecting a pressure drop from said plenum chamber into each of said sections to assure continued supply of air from said chamber into all of said sections notwithstanding the occurrence of variations in the fuel bed resistance in any of said sections, and means for controlling the pressure drop into each of said chambers.

5. Combustion apparatus of the character described comprising a retort for the burning of solid fuel, a feed worm for supplying fuel upwardly into said retort, a plurality of tuyres for introducing combustion air to the burning fuel, means for dividing the air spaces of said tuyres into a plurality of independent sections around the periphery of the fuel bed, a plenum chamber for supplying air into each of said sections, restricting means for effecting a pressure drop from said plenum chamber into each of said sections to assure continued supply of air from said chamber into all of said sections notwithstanding the occurrence of variations in the fuel bed resistance in any of said sections, and means for causing a different pressure drop into said sections in predetermined relation to the thickness of the fuel bed upon said respective sections,

.6. Combustion apparatus of the character described comprising a generally circular retort for `the burningof solid fuel, a plurality of tuyres arranged to form a combustion zone substantially C-shaped in cross section, means for supplying fuel to said retort in the direction toward the open end of said C-shaped combustion zone, means for dividing the tuyeres into a plurality of separate air introducing sections around the periphery of said combustion space, a, plenum chamber, means for supplying air from said plenum chamber to each of said sections independently of the others, meansfor regulating the quantity of combustion air supplied into the several sections of said tuyresmto provide va greater air supply to the exterior and a lesser air supply to the interior of said body of fuel in accordance with the thickness of the fuel bed upon said sections, and means for causing a pressure drop in the pressure supplied to Vallof said sections from said `plenum chamber to Vassure ycontinued supply to each section notwithstanding the occurrence of pressure variations in any of said sections.

7. Combustion apparatus of the character described comprising a generally circular retort for the burning of solid fuel, means for introducing fuel into said retort forburning therein an arcuate `shaped fuelv body, means for supplying fuel to'said retort, a, plurality of tuyres arranged to Asupply combustion air into the interior and exterior of said arcuate shaped tbody of fuel, means for dividing the tuyres into a plurality of separate air introducing sections around the periphery of said combustion space, a plenum chamber, means for supplying air from said plenum chamber to each of said sections independently of the others, means for regulating the quantity of combustion air supplied into the several sections of said tuyres to provide a greater air supply to the exterior and a lesser air supply to the interior of said body of fuel in accordance with the thickness of the fuel bed upon said sections, and means for causing a pressure drop in the pressure supplied to all of said sections from said plenum chamber to assure continued supply toA each section` notwithstanding the occurrence of pressure Variations in any one of said sections.

8. Combustionapparatus of the character described comprising a generally circular retort for the burning ofsolid fuel, a plurality of tuyres arranged to forma combustion zone substantially C-shaped in cross section, means for supplying fuel to said retort towardthe open side of ysaid combustion zone, means for dividing the tuyresinto a ,plurality of air introducing secy tions around the periphery of said combustion space, a plenum chamber, means for supplying air from said plenum chamber to each of said sections independently of the others, means for regulating the quantity of combustion air supplied into the several sections of said tuyres in accordance with the thickness of the fuel bed upon said sections, means for causing a pressure drop in the pressure supplied to all of said sections from said plenum chamber to assure continued supply to each section notwithstanding the occurrence of pressure variations in any of said sections, and means for regulating the pressure supplied to each of said pressure sections. i

9. Combustion apparatus of the character described comprising a generally circular retort for the burning of solid fuel, means for supplying fuel to said retort, a plurality of tuyres for introducing combustion air into the combustion 6 2,396,888 space, said tuyres having both inner and outer 12. Combustiorilapparatus 'for the burning lof 'air lllliIOdulIlg apertures,` means for dividing solid fuel and for-'removing thesh by mnsof said tuyres into a plurality of separate air ina feed worm towhieirthe ashsubstanuauyfiee troducing sections spaced around the periphery of clinkers isA suppliedin'substatially theicoijiof said combustion space, a plenum chamber, dition in which itris'lfo'rrhed during combustion means for separately supplying air from said and through whichthefashiis-transferred to a chamber into each of said tuyre sections, means point of delivery outside ofsaid apparatus,- said for separately regulating the pressure in each apparatus comprising a retort 'for the burnmg of said sections to supply the proper quantity of of the solid fuel, a feed worm for supplying? fuel combustion air in accordance with the depth of l0 into said retort, a plurality of tuyres for 4introfuel bed upon each section, and means for addducing combustionair tothe burningfuel., means tonelly regulating the Supply of combustion air for dividing the air spaces of saidV tuyeresinto a, to said outer series of air apertures, respectively, plurality or independent sections around theipeto provide for air introduction therethrough at riphery of the fuel bed, aplenum'chamber, means lower pressures than through said inner series for separately introducing air Vfrom said plenum of apertures. chamber to eachof said sections, said separate air 10. Combustion apparatus of the character desupplies providing a plurality of maintained sup.v Seribed Comprising e generally circular retort, plies of combustion air spaced around the 'com-V a plurality of tuyres arranged to form a subbustiori zone independently ofn locally occurring stantially C-shaped combustion space, means for variations in the A'air resistance Vof the Vfuel bed Supplying solid fuel to said retort toward the to provide for combustion of said fuel under c on- Open side of said combustion space, means fOI ditions controlled to produce the ash infinely dividing said tuyres into e plurality 0f Separate divided form and substantially free of large elinkair introducing sections for introducing combusersv Vsuch that it is capable of being handled ldition air into both the exterior and the interior rectly by said ash feed worm. f- Surface of the body 0f fuel in Said Space, a ple- 13. Combustion apparatus for the burning of num Chamber, means fOr Supplying air freni Seid solid fuel and for removing the ash by `means plenum Chamber Separately into each of said of a feed Wormkoperating in a closed Yconveyor tuyre sections, means for regulating the air preS- tube to which the ash substantially freeef elink- Sure Supplied to said sections to introduce the ers is supplied in substantially the condition in highest pressure into the exterior portion of said which it is formed Vduring combustion and C-shaped space, an intermediate pressure into the through which the ash is transferred tofa point sections at either side of said exterior portion, and of delivery outside of said apparatus, said apthe lowest pressure into said interior portion of paratus comprising a retort for the burning of the said space. solid fuel, a feed Worm for supplying fuel into 11. Combustion apparatus of the character desaid retort, a plurality of tuyres for introducing scribed comprising a generally circular retort, combustion air to the burning fuel, means for a plurality of tuyres arranged to form a subdividing the air spaces of said tuyres into a plustantially c-shaped combustion space, means for rality of independent sections around the periphsupplying solid fuel to said retort toward the 40 ery of the fuel bed, aplenum chamber, means for open side of said combustion space, means for separately introducing air from said plenum dividing said tuyres into a plurality of separate chamber to each of said sections, said separate air introducing sections for introducing combusair supplies'providing a plurality of maintained tion air into both the exterior and the interior supplies of combustion air spaced around the surface of the body of fuel in said space, a plecombustion` zone independentlyof locally occurnum chamber, means for supplying air from said ring variations in the air resistance of the fuel plenum chamber separately into each of said bed to provide for combustion of said fuel under 'Guyl'e SeClJiOIlS, means for regulating' the air of conditions controlled to produce the ash in finely said pressure supplied to said sections to introduce divided form and substantially free of large elinkthe highest pressure into the exterior portion of ers such that it is capable of being 4handled `disaid C-shaped space, an intermediate pressure rectly by said ash feed Worm, and means for deinto the sections at either side of said exterior livering said ash substantially in its originally portion, and the lowest pressure into said interior formed condition from said combustion zone to portion of said space, and control means for insaid ash worm to be removed thereby. creasing ordecreaslng the supply of combustion 1 Y y air to all of said sections. CLARK SCHOLL.

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