US1930045A - Combustion apparatus - Google Patents

Description

Oct. 10, 1933.

R. A. FORESMAN ,930j,045

COMBUSTION APPARATUS Original Filed Feb. 4, 1929 2 Sheets-Shea?l l llli lil mi Oct. 30, 1933. R. A. 'FORESMAN COMBUSTION APPARATUS Original Filed Feb. 4, 1929 2 Sheets-Sheet 2 Patented Oct. 1U, 1933 UNITED STATES COBIBUSTION APPARATUS Robert A. F'oresman, Moore, Pa., assignor to Westinghouse Electric &. Manufacturing Company, a corporation of Pennsylvania Original application February 4, 1929, Serial No.

337,445. Divided and this application November 29, 1930. Serial No. 498,929

7 Claims.V

My invention relates to combustion apparatus and more particularly to Stoker-fired furnaces having clinker pits for receiving and disposing of the refuse discharged from the stoker, this application being a division of my copending application, Serial No. 337,445, filed February 4, 1929 and assigned to the Westinghouse Electric 8i Manufacturing Company.

As is well known, a clinker pit comprises front, back and end Walls, and grinder rolls are disposed in the lower portion of the pit and serve as a means for supporting the ash within the pit and also for gradually removing the ash from the pit. The function of a clinker pit is to provide a continuous ash discharge for the furnace and, at the same time, prevent the infiltration of outside air, which latter may seriously interfere with the combustion conditions in the furnace. The seal against outside air is usually provided by operating the rolls so that a layer of cool ash lies directly adjacent the grinder rolls.

There is a substantial amount of combustible in the material which is received by the pit from the Stoker. It is, therefore, necessary that a controlled amount of air under pressure be admitted to the interior of a pit to effect complete combustion of the combustible therein. In fact, the clinker pit is considered by engineers to be active grate surface.

In clinker pits heretofore known to me, it has been the general practice to form the front and rear walls of movable cast iron plates or aprons, so that, if large clinkers form in the pit they can be removed by moving the aprons to one side and pulling the clinkers out with hooks, or the like. These walls are made in section with spaces between the sections to provide for expansion and growth. The maintenance cost is high for the reason that high and low-pressure areas 40 develop in the pit, due to the Varying character of the material therein and the conditions set up by combustion; and, if a low-pressure area happens to occur adjacent one of the spaces between sections, the high-pressure areas will cause the burning gas to pass through the spaces and burn out the wall at that point. Furthermore, the air supplied to the pit for supporting combustion of the material therein leaks out through the spaces between sections to such a degree that both the now and the pressure of the air within the pit varies at different points and thereby results in the improper combustion of the material and the formation of large clinkers.

In some of the smaller furnaces where the com- 55 bustion rates are relatively low, Ait is known to provide clinker pits with walls of brick. The brick walls are, of course, gas tight and cheap to manufacture. Heretofore, however, this type of construction has been considered impractical for the larger furnaces. The high combustion rates and furnace temperatures in the latter ,type of furnace 'result in clinker adhering to the brick walls, thereby interfering with the proper downward movement of the material in the pit. Also, in the larger furnaces, the brick walls become overheated and in extreme cases, burn out.

According to the present invention,l I provide a clinker pit having walls formed of asuitable ceramic heat-resisting material, for example, fire brick, and provide means for maintaining the exposed surfaces of this wall in a relatively' cool' 70 condition so as to protect the same from the'heat of combustion and to prevent the adherence" of clinker thereto. I also provide improved means for supplying air to the interior of the pit so as to effectively burn out the combustible in the A material within the pit. Further, I provide an improved means for covering the top of the clinker pit front wall which prevents wear to the wall and at the same time provides a bearing support for the rear end of the moving grate which usually forms a part of the Stoker.

It is therefore an object of this invention tol provide an improved form of clinker pit which is extremely durable and efficient and which can be manufactured at a relatively low cost.

A further object of this invention is to provide an improved form of wall construction for a clinker pit which is maintained at all times in a relatively cool condition.

. A further object is to provide an improved cap or cover for the front wall of the clinker'pit which functions to protect the top of the wall, acts as a bearing support for the rear portion of the stoker, and provides for the admission of air and water into the pit. Q

A further'object is to provide an element for rigidly anchoring the front wall of the pit, which also functions as an additional means for admitting air into the interior of the pit. p

These and other objects are effected by my invention, as will be apparent from the following description and claims taken in connection'with the accompanying drawings, forming a part ofV this application, in which:

Fig., 1 is a longitudinal sectional View through my improved form of Stoker-fired furnace;

Fig. 2 is a fragmentary sectional view taken on the line II-II of Fig. 1 and illustrates the inner face of my improved clinker pit front wall;

Fig; 3 is a fragmentary sectional View illustrating the lower end of the stoker and the clinker pit front wall;

Fig. 4 is a detail elevational view lShowing the metal cap which covers the top of the pit front wall;

Fig. 5 is a sectional view on the line V-V of Fig. 4;

Fig. 6 is a detail elevational view of my improved wall-anchoring and air supply casting; and, Y

Fig. 7 is a sectional view taken on the line VII-VII of Fig. 6.

Referring now in detail tothe construction illustrated, the reference numeral 10 indicates a furnace, in its entirety. The furnace comprises walls 11 defining a combustion chamber 12. A downwardly-inclined progressive-feed StokerY 13 is disposed within the lower portion of Ythe combustion chamber and comprises a multiple-retort underfeed sectionV 14 and an undulating overfeed grate section 15. A clinker pit 16 is disposed at the discharge end of the overfeed grate l5.

An air chamber 17 is disposed beneath the -qstoker and a partition 18 having a damper-con- "trolled opening 19 divides the chamber into a front chamber 20 beneath the underfeed section 14 and a rear chamber 2l beneath the overfeed section 15. Air under pressure is delivered to the es front chamber by a duct 22. The air flows upv wardly from the chambers 20 and 21 and through the stoker to support the combustion of the fuel carried thereon.

As is well known, coal is fed from the hopper @-123 and into the end of each retort by a main ram 24. The coal is fed along the retort and upwardly over the sides thereof and onto airemitting tuyres by a secondary ram 25. The action of the secondary rams is also such as to .--gcause a general downward movement of the fuel 46" bed onto the overfeed grate section.

The overfeed grate section 15 comprises a series of grate members 26, 27, 28, 29, and 30 pivotally connected together in end-to-end relation M and extending in the direction of fuel feed. The grate members provide, under all conditions of operation, an unbroken, fuel-supporting surface and are -operated in such a manner that they both agitate the burning material as it cornes from the underfeed section, positively move the Vrburning material thereover, provide for the admission of air for supporting combustion to the fuel bed, and ylastly eject the burning material and ash into the clinker pit.

The grate member 26 is pivotally supported at 'its upper or forward end to a suitable stationary portion of the stoker structure. The grate member 30 is slidably supported at its lower or rear end by the front wall of the clinker pit.

The grate members 26 and 28 are provided at 6o their rear ends with downwardly-extending lugs 31 and 32, respectively. These lugs are pivotally connected to the upper ends of driving links 33 and 34. The lower ends of the driving links are pivotally connected to the opposite ends of a rocker arm 35 keyed to an oscillating power shaft 36, which latter extends transversely of the rear air chamber 21 and is supported by bearings 37 carried by suitable supporting beams 38. The

beams 38 are supported at their ends by transversely-extending I-beams 39 and 40, which latter are a part of the main supporting structure for the furnace.

The grate members 27 and 29 are provided at their rear ends with downwardly-extending lugs V 41 and 42, respectively, and these lugs are pivotally connected to the upper ends of floating supporting links 43 and 44. The lower ends of the supporting links are pivotally connected to suitable supporting shafts 45 and 46, the latter being mounted in suitable stationary supports.

An oscillatory movement imparted to the power shaft 36 results in an up-and-down movement of the driving links 33 and 34 and, as the latter are connected to grate members 26 and 28, the overfeed grate section will also move up and down at the points of connections with the links. This up-and-down movement will result in the bodily movement of the grate members 27, 28, 29, and 30 in the direction of fuel feed. The floating links 43 and 44 and the slidable support for the rear end of the grate member 30 permit such bodily movement.

The up-and-down movement of the grate members provides for the thorough agitation ofthe fuel bed, and in conjunction with the bodily movement, provides for the positive progression of the burning fuel and ash to the clinker pit.

The clinker pit 16 is disposed to receive the burning material and ash discharged from the overfeed 'section 15 and operates to burn out the combustible in the material and remove the ash from the furnace. The clinker pit comprises immovable and gas tight front, end, and rear walls 49, 50, and 51, respectively. Clinker grinder rolls 52 are disposed within the bottom of the pit and serve to support the material within the pit and to grind out the ash into a Water filled ash pit 53 disposed therebelow. The water positively seals the pit against both the exit of air therefrom and the infiltration of air from the outside, thus eliminating the necessity of carrying a head of cool ash adjacent the rolls. The upper level of the water is adjacent the center line of the rolls thereby positively maintaining the rolls in a cool condition.

. The walls of the clinker pit are provided with smooth inner surfaces so as to offer the least possible resistance to the downward movement of the material therein. In order to prevent the adherence of clinkers to the front and rear walls ofthe pit and also to protect the same from burning out, both of these walls are positively cooled.

The rear wall 51 is composed of a plurality of water tubes 54 with cast iron blocks 55 engaging the tubes at the clinker pit side thereof and providing a smooth, contacting surface for the material in the pit. The lower ends of the tubes are connected by a suitable header 56 extending transversely of they rear of the furnace. Water circulating through the tubes 54 results in the absorption of suicient heat from the refuse in the pit to maintain the wall 50 in a cool condition.

If desired, air for supporting combustion may be introduced into the pit through the rear wall 50. As shown, an air manifold 57 extends transverselyV of the rear wall and air under pressure is supplied from the front air chamber 20 to the manifold 57 by means of a suitable conduit 58. The air flows from the manifold 57 into the pit through suitable openings (not shown) provided between the refractory blocks 55.

The front Wall 49 of the pit comprises a body portion 60 Ypreferably formed of a heat-resisting ceramic material, for example, fire brick, a cap or cover portion 61 supported upon the top of 3 1 Y The cap or cover portion 6l for the front wall of the pit is composed of a plurality of two-part' cast-iron sections disposed in side-'by-side' relation along the top of the brick work of the wall. (See Figs. 3, 4, and Each section comprises a body member 64 resting on the top of v the wall and a top or cover element 65 bolted to the'body' 64.

The interior of the body is hollowed out toprovide a chamber 66, and a passage 6'7 is provided through which air may ow from theair chamber 21 into the chamber 66. Water is supplied to the chamber 66 through the passage 6'? means of pipe 68 connected to a suitable water supply pipe or header 69. `The water collects in the chamber and overiiows through openings 70 provided on the underside of the cover 65 and onto the inner surface of the brick. Air also flows through the openings 70 into the clinker pit to support the combustion of the material therein. The openings are so numerous and spaced sufficiently close together that the water therefrom covers the front wall of the clinker pit in the form of a sheet, thereby maintaining the front wall in a cool condition so as to protect the same and to prevent the adherence of clinker thereto.

The cover 65 is inclined downwardly and the top surface thereof performs an additional function of a bearing support for the rear end of the last grate member 30 of the overfeed section. It is to be noted, at this point, that the cap 61 has a four-fold function, viz., protecting and covering the front wall of the clinker pit, furnishing air for combustion to the material within the pit, furnishing water for cooling and protecting the front wall of the pit, and lastly serving as a bearing support for the rear end of the grate member 30.

The wall tie member 62 has two functions, viz., anchorin 7 the front wall, and supplying additional air to the pit. The member 62 is composed of a plurality of two part cast iron sections (see Figs. 3, 6 and 7). Each section comprises a bottom member '71 and a top member 72. The top member '7l is provided with a chamber 73, passages 74 leading into the chamber from the air chamber 2l and passages 75 leading from the chamber '73 into the clinker pit, the hollow chamber 73 and the passages 74 and '75 serving as a means for supplying additional air from the air chamber 21 to the clinker pit. The bottom member 7l is provided with a lug '76 to which is secured the tie rod 63. which latter is connected to the I-beam 40.

In operation, the material is delivered to the clinker pit by the overfeed grate section, and the combustible in this material is effectively burned out due to the gas-tight clinlrer pit walls, the water seal at the lower end, and to the admission of air under pressure through the wall. The exposed surface of the brick front wall of the pit is always maintained in a cool condition by the sheet of water, consequently, there is very little likelihood of clinkers adhering thereto, or of the wall becoming overheated and burning out. Furthermore. the cap 6l and the tie member 62 provide simple, cheap and durable means for performing the several functions heretofore explained.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as arey specifically set forth in the appended claims.

fwhat I` claim ifs:

' 1. In a furnace, the combination withla progress-ive feed Stoker; of a cliiiker' pit disposed to receive the burning material and refuse'froin the stoker and having an immovable, gas-tight front wall formed ofY heat-'resisting' ceramic material and having a substantially planar interior surface; and a series of hollow castings forming a capY for the front wall and having in the elink-er pit sidethereof a series of openings communicating with the hollow interior thereof, and means for supplying water to the interiorv of the casting s'c thatthe waterV will flovvjout of the openings and cover the front falce of the wall in a sheet.

In a furnace, the'com'bination with a Stoker including a movable overfeed grate at the rear or discharge end thereof, of a clinker pit having its front wall constructed of ceramic material, a metal cap for the wall and having its upper surface inclined to provide a bearing for the rear end of the moving grate, said cap being provided with a chamber and having passages leading from the exterior of the pit to the chamber for supplying air and water to the chamber and passages leading from the chamber to the interior of the pit for permitting the air and water to enter the pit, the air being for the purpose of supporting combustion and the water for cooling theinner surface of the front wall.

3. In a furnace, the combination with a progressive feed Stoker having supporting structure and including a movable grate at the discharge end thereof, of a clinker pit disposed to receive the refuse and burning material from the Stoker and including an upright, continuous, and rigid front wall comprising a body portion formed of ceramic, heat-resisting material, a metal cap portion at the top of the ceramic body portion and forming a support for the rear end of the grate, and a tie element anchored within the ceramic body portion at a point between the top and bottom of the wall and including means providing for rigidly securing the front wall to the supporting structure of the furnace.

4. In a furnace, the combination with a progressive feed stoker having a supporting structure and including a movable grate at the discharge end thereof, a clinker pit disposed to receive the refuse and burning material from the stoker including an upright, rigid frontwall comprising a body'portion formed of ceramic heat-resisting material, a metal cap portion at the top of the ceramic body portion and forming a bearing for the rear end of the grate, the cap portion being provided with a chamber in the interior thereof and passages from the chamber to the clinker pit Czl and means providing for supplying air and water to the interior of the chamber, and a tie element anchored within the ceramic body portion at a point between the top and bottom of the wall and including means providing for rigidly securing the front wall to the supporting structure of the furnace.

5. In a furnace, the combination with a progressive feed stoker having a supporting structure and including a movable grate at the discharge end thereof, of a clinker pit disposed to receive the refuse and burning material from the stoker and including an upright rigid front wall comprising a body portion formed of ceramic heatresisting material, a metal cap portion at the top of the body portion and forming a bearing for the rear end of the grate, and a combined air supply and wall tie element anchored within the ceramic body portion at a point between the top and bottom of the Wall and havinga passage therethrough for supplying air to the interior of the pit and including means providing for rigidly securing the front wall to the supporting structure of the furnace.

6. In a furnace, the combination with a Stoker including a movable overfeed grate at its rear or discharge end and a clinker pit for receiving the refuse and burning material from the Stoker and including front, rear, and end Walls, of a hollow box-like casting at the upper side of the front wall of the clinker pit and having a downwardly and rearwardly-inclined upper surface upon which the rear end of the overfeed grate is supported for movement and passages establishing communication between the lhollow interior of the casting and the interior of the clinker pit, and means for supplying air and Water to the interior of the casting.

7. A metallic cap for the front Wall of a clinker pit comprising, a body member having a chamber formed in the interior thereof, and a cover member detachably secured to the body member and having an inclined exterior face, the cover having spaced projections formed on its interior surface adjacent the lower end thereof and cooperating with the body member to provide passages connecting the chamber with the exterior of the cap.

ROBERT A. FORESMAN.

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