US2166966A - Stoker furnace - Google Patents

Description

July 25, 1939. E. B. PRiEBE STOKER FURNACE 2 Sheets-Sheet 1 Filed June 26, 1936 ATTORNEYS E. B. PRIEBE STOKER FURNACE July 25, 1939.

Filed June 26, 1936 2 Sheets-Sheet 2 m mm m Yw NP m M m m M T a w. vvm r 5 W Patented July 25, 1939 UNITED STATES PATENT OFFICE 11 Claims.

This invention relates to stoker furnaces,.especially boiler furnaces with progressive feed, such as underfeed, overfeed or chain grate; the

fuel bed advancing towards and upon a discharge I plate or member over which the refuse discharges into an ash pit. In one form of such boiler furnace there is a water cooled rear or bridge wall,- which wall, or the front or fire side of which wall, is located above the discharge plate and which wall terminates above the discharge plate, thereby forming an ash discharge gate or throat through which the bed of refuse is thrust 'or travels 'rearwardly in discharging to the ash pit. The reference to a rear wall is intended to desig nate the furnace wall adjacent the stoker discharge end; in the case of usual stokers it may be the bridge wall, generally exemplified by Priebe and Miner Patent No. 1,633,418 of June 21, 1927, but in the case of so-called Type E stokers it may be-the equivalent side wall, at each of the two sides, constituting in effect two rear walls, and exemplified by Priebe and Miner Patent No. 1,333,952

of December 1, 1931, a division of 1,633,418.

The general object hereof is to improve the efficiency and life of the discharge structure involving the stoker discharge plate and the bridge or equivalent wall above the ash pit. A particular object is to afford effective water cooling of the discharge throat not merely as to the bridge wall front side, but the arch formed beneath it above the plate and pit. A further object is to afford an improved system of cooling tubes for the lower part of a bridge wall and protecting blocks shielding the same from the heat of the fuel bed.

Further objects and advantages will be explained in the hereinafter following description of an illustrative embodiment of the invention.

In the accompanying drawings Fig. 1 is an interior elevation of a stoker furnace embodying the present invention, seen in right hand view; the right hand side of this figure being considered the rear side of the furnace, and the view. being taken partly in vertical fore-and-aft section.

Fig. 2 is a front elevation of the lower part of the rear or bridge wall of Fig. 1.

- Fig. 3 on a larger scale and in front elevation shows a portion of the lower part of the wall, with the covering blocks omitted from some of the water tubes.

Fig. 4 on the same scale with Fig. 3 is a right elevation and section taken on the line 4-4 of Fig.

Fig. 5 is a partial right elevation and section view corresponding in part with 1 but show- 5 ing a modified structure.

In Fig. 1 is shown a boiler furnace containing a progressive feed stoker of conventional type, including for example an underfeed retort stoker 10 along which the fuel bed is advanced toward the rear, as by reciprocating pushers in the re- 6 torts, and beyond the main stoker l0 an extension grate H comprising for example reciprocating grate members which receive the fuel bed by overfeed from the main stoker and continue its travel to the discharge.

The furnace chamber above the stoker or grate is bounded at the front by a wall l2 and-by opposite side walls I3. There is shown, beyond the stoker or grate, a side wall twyer l4 extending substantially higher than theretorts of the stoker. The line l5 may indicate approximately the fuel bed'outline.

At the end of the fuel bed travel the stoker or grate delivers the refuse or ash over a discharge plate or dump member l6, shown of conventional 20 construction. This dump plate is preferably a fixed member, but is mounted upon a shaft I! by which it can be adjusted so as to change the height of the discharge edge of the plate.

The edge of the discharge plate I6 extends 25 over, and discharges into, an ash pit l9 comprised between front and rear walls 20 and. 2|, the pit being closed at the ends and having at its foot any suitable means for progressive or intermittent removal of ashes. I 30 The furnace hereof is preferably, a boiler furnace, and the boiler may be of any type or design. Conventionally it is shown as comprising a low header or drum 23, an upper rear header or drum 24 and an upper front header or drum 35 25. Extending between the drums 23 and 24 is a system of boiler tubes 26, partly indicated, and between the drums 24 and25 are tubes 21, steam being drawn from one of the upper drums as usual. 40

In front of the second or'downflow pass 29 of the boiler is the rear or bridge wall of the combustion chamber, over which the products of combustion travel into the second pass. This upwardly extending or bridge wall may be composed 45 of several cooperating portions. Thus on the foremost series of tubes 26 isshown a system of refractory blocks 30 forming with these tubes a closed wall. Below this closed wall portion 30 is shown a closed refractory wall 3| which extends 50 downwardly and is then turned or curved rearwardly at 32, terminating adjacent to the pit wall '21 and drum 28.

The bridge or rear wall thus defined is shown as cooled by a system of uptake water tubes 34 extending in cooling relation to or in front of the bridge wall, and eifectively forming a part of it. These uptake tubes 34 at their lower ends are extended substantially horizontally as tubes 35 connecting-with a header, as the drum 2], exterior to the ash pit. These tubes, after coming forward from the header 23 through the ash pit wall, or between'it and the bridge wall, extend substantially horizontally above the ash pit, extracting heat from the ash therein, and thence curve upwardly into the uptake tube portions 34 which, near the top of the bridge wall, are curved into slanting extensions leading toan upper header or drum, as the upper boiler drum The lower part ofthe tube system 34, where exposed to the hottest part ofthe flre, is covered wby a system of protecting blocks 31. These are preferably cast iron blocks, either fused or cast directly upon the tubes or else coupled or bolted the eon, but they may be composed of silicon carbide or other heat conducting refractory material. These blocks or coverings 31 are preferably applied in short sections, as usual, spaced for example one quarter inch, thus to allow for expansion or growth and prevent warping of the,

' tubes.

This system of tube-protecting blocksfl is shown as extending down substantially to the bend of the tubes, but not necessarily continued along the horizontal tube portions 35 that are exposed merely to the ash pit. At thefoot of the series of protecting blocks 31 is shown a special block 38 or ",shaped with an angular corner or edge 40 and constituting anose'or gate block, above or opposed to theplate l8 and therewith forming the refuse throat or gate. In Fig.

I 5 the nose blocks 38, or the transverse seriesgo" A convenient construction of nose block' thereof, are shown as applied directly upon the uptake tubes 34. In Figs. 1 to 4 however the special nose block 3!, having the projecting corner 40, is shown mounted or attached upon a special transverse water tube ll extending across the width of the furnace closely below the bend of. the tubes 34. While the special nose block might be cast or fused upon the tubes as in Fig. 5 it is preferably bolted on as shown in Figs. 1 to 4, being thus replaceable when burned away by the heatpf the fire.

mounting, as shown in Figs. 1 to 4 is as follows.

The block 39 is formed to hook under the transverse tube II, for example it may have a face portion and two legs which straddle the trans- -versetube. The tube is thus thoroughly pro- At the back end of thetected from the heat. leg or each leg of the block is shown an extension or bolt 42, and the legs or bolts may be con-: tinued between and beyond the system of uptake F tubes 34. By this arrangement a cross bar may be located back of the tubes 34, the bolts passing through openings in the cross bar, and nuts 44 at .the ends of the bolts serving to clamp together these various elements, the block, the transverse tube, and the uptake tubes. As seen in Figs. 3 and 4 the blocks I! are not merely shaped to straddle the transverse'tube 4|, but at cleaner.

is bent forwardly and then transversely, extending through a side wall It and constituting the tube 4|. The far end of the tube 4i passes through the opposite side wall of the chamber where it has a coupling 41 connecting it with an uptake or extension tube 48, shown as passing back through the wall and rising .vertically to the height of the bridge wall, thence extending at 48 to an upper header or drum, for exampie-slanting upwardly to the front-drum 25.

Referring further to Fig. 5 this shows, as do Figs. 1 to 4, a boiler furnace having a stoker grate l0 whereon the bed I! of fuel and ash travels progressively rearwardly toward a point of discharge into a rear ash pit i9, and having a fixedposition spill-plate it over which. such bed slidingly discharges substantially continuously; into such ash pit; and combined with such stoker grate and spill-plate, the bridge or 'rear wall iii-1| overhanging said spill-plate and comprising a system of separate uptake water tubes 34 in circulation with the boiler, eachextending continuously, first along the under part of the wall spaced above the spill-plate and thence bent curvedly around the lower inner corner of said wall and thence extended upwardly along the inner side of the wall, for keeping cool the wall, and a system of high-heat conductive or metal blocks 31,-etc., covering such uptake water tubes at and near such wall corner,-such tubes being in. cooling relation to such blocks; said spill-plate and said covering blocks at the wall comer being spaced so close together as to define between them an ash discharge throat which is vertically narrow and of short length in' the direction of discharge, through-which throat the bed must be constricted, compressed or squeezed by its continuous forced travel, crowding it through toward'dischar'ge, and the bed must thus traverse the, short length ofthroat-in contact with both the spill-plate below and corner blocks above whereby the bed effectively seals the throat continuously against undue air inflow, and said cornerblocks not only thereby protecting the tubes against undue heat exposure, but also directly.

taking and protecting the tubes against the thrust and abrasion of the traveling bed, and at the same time affording a contact-cooling effect operating to chill the top surface of theadvancing bed, thus congealing any molten material and preventing adhesion and facilitating passage afford an efllcient ash gate or throat serving the objects first above stated. In en'ect'the tubes and blocks constitutes cooled arch or top wall to the discharge gate and to the ash pit. @ach of the tubes It maybe a' single bent tube ex tending from header 2! toheader 2i, and thus is well able to be cleaned by driving through it at suitable periods the usual kind of boiler tube The described arrangement of abridge wall extended above the discharge plate and ash pit admits of the provision of an observation door or window, "and such a door 53 is indicated in Figfi5. By observation through the door If the discharge of refusethrough the gate may be observed, and the discharge plate It may be vertically adjusted to proper position during such ing of the nose block will cause pressure between the nose block and tube ll for intimate contact and heat conduction.

An advantageous bridge wall construction is that shown, wherein the lower part of its inner side is closed between the tubes 34, as at 3|, the tubes here having the face protecting blocks 31, whereas higher up, where the heat is less intense, the structure changes, the tubes here being free and surrounded by the hot gases, the closing of the wall being slightly outwards of the tubes, as at 30; so that in effect the upper parts of tubes 34 constitute a screen, the gases passing between the tubes on their way from the combustion chamber and main pass to the top of the second pass 29 of the boiler.

I claim:

1. In a stoker furnace a discharge plate over which the stoker rearwardly discharges, a rear or bridge wall spaced above the plate to form therewith a throat discharging rearwardly to an ash pit, a system of water tubes in circulation with the boiler extended in cooling relation to the under side of said wall above the ash pit and throat andthence as uptakes in cooling relation to the front side of said wall, and a horizontal water tube in circulation with the boiler and extended transversely along the under side of said wall for transverse circulation above such throat.

2. In a stoker boiler furnace a discharge plate over which the stoker rearwardly-discharges, a rear or bridge wall spaced above the plate to form therewith a throat discharging rearwardly to an ash pit, a system of water tubes in circulation with the boiler extended as uptakes in cooling relation to said wall, and a transverse tube below such uptakes carrying protecting blocks constituting the upper edge of such throat.

3. A furnace as in claim 2 and wherein the blocks protecting the transverse tube protect also the uptakes and the uptakes carry additional protecting blocks thereabove.

blocks engage both the transverse and uptake tubes and have means securing them in position.

s. In a stoker boiler furnace a discharge plate over which the stoker rearwardly discharges, a rear or bridge wall'spaced above the plate to form therewith a throat discharging rearwardly to an ash pit, a system of water tubes in circulation with the, boiler extended under said wall and as uptakes in cooling relatiori'to said wall, a transverse water tube below such uptakes in circulation with the boiler, and a series of blocks constituting the upper edge of such throat, detachably mounted in, protecting relation to the under side of said transverse tube.

7. A furnace as in claim 6 and wherein the blocks are shaped to straddle the transverse tube and have couplings extended between the uptake I tubes and means there securing them.

8. A furnace as in claim 6 and wherein each throat block is shaped to hook over and protect the transverse tube with an extension back between two uptake tubes.

9. In a stoker boiler furnace a stoker grate, and to the rear thereof a discharge plate over which the stoker rearwardly discharges and spills into an ash pit, a furnace rear wall above said plate, a system of uptake tubes in circulation with the boiler and in cooling relation to the under and front part of said rear wall, said plate and wall spaced apart and forming between them an ash discharging throat, and a series of throat-defining blocks in protecting relation to said tubes and forming the ceiling of such throat while said stationary plate forms the floor thereof; and said rear wall comprising also a horizontal water tube in circulation with the boiler, ar-

ranged for transverse flow in protected relation to said protecting blocks.

10. In aboiler furnace having. a stoker grate whereon the bed of fuel and ashtravels progressively toward a point, of discharge into an ash I corner of said wall and thence extended upward-' 1y along the inner side of the wall, for keeping cool the wall, and a system of high-heat-conduc tive blocks covering such uptake water tubes at and near such wall corner, such tubes being in cooling relation to such blocks; said spill-plate and said covering blocks at the wall corner being spaced so close together as to define between them an ash discharge throat which is vertically narrow and of short length in the direction of discharge, through which throat the bed must be constricted and crowded by its continuous forced travel toward discharge and must thus traverse the short length of'throat in contact with both the spill-plate and corner blocks whereby the bed effectively seals the throat continuously against undue air inflow, and said corner blocks not only thereby protecting the tubes against undue heat exposure, but also directly taking the thrust and abrasion of the traveling bed, and at the same time affording a contactcooling effect to chill the top surface of the advancing bed thus preventing adhesion and facilitating passage of the bed through such throat.

11. The combination as in claim 10 and wherein the stoker grate is of a kind sloping downward toward the spill-plate at the rear, and the tube covering blocks at and near the wall lower inner corner are metallic blocks intimately associated with the uptake water tubes, and said blocks are shaped to present a saliently projecting nose which extends across the furnace and defines the upperrside of the throat and receives the thrust of the advancing bed.

ERNEST B. PRIEBE.

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