US1591674A - Stoker structure - Google Patents

Description

July 6 1926. y

fR. A. FoREsMAN STOKER STRUCTURE 'Filed `April 18, 1922 til ...63.

I i l I l n n l 5 /Llomsman INVENTOR ATTORNEY Patented July 6, 1926.

UNITED s'rATEs PATENT OFFICE.

ROBERT A. FGRESMAN, OF MQRE,

SYLVANIA.

STOHER STRUCTURE.

Application filed April 18, 1922.

rlhis invention relates to mechanically operator furnaces having a refuse pit for the removal of solid products of combustion, and more particularly to means for treating the residuum of the fuel discharged from the active grate surfaces prior to its removal from the refuse pit. It has for an object to provide an apparatus of the char acter designated which shall prevent the formation of objectionable clinker masses in or above the refuse pit.

The term refuse in the specification and claims of this application is employed in a generic sense to include the residuum of fuel discharged from the active grate surfaces.

ln mechanically operated furnaces of steam power plants in which high furnace temperatures are normally maintained and 3 in which fuels of low fusibility are employed, objectionable clinker masses tend to form over and in the refuse pit, which clinker masses prevent the complete combustion of the unburned content of the refuse, both by occluding the unconsumed carbon and by interfering with the uniform distribution of air through the refuse, and Vunder conditions favorable for the adhesion of clinkers, clinker masses of considerable size form by accretion, which either clog or greatly increase the work of the discharge mechanism, and which not infrequently become of such size as to bridge the refuse pit.

It has heretofore been proposed to break up the clinker masses formed in and above the refuse pit by mechanical means, such 'as moving members operated from the Stoker driving mechanism. These constructions have failed in certain installations employing low grade fuels, since, at best, they merely break up the clinker masses already formed.

It is the purpose of the present invention to overcome the diiiiculties above mentioned, by providing in connection with the pit a construction which prevents the formation of clinker masses in and above the refuse pit. This result is secured by the employment of a specially constructed casting over which a .relatively shallow zone of high temperature combustion 'is maintained in the upper portion et ythe retueeand by the ia- Serial No. 554,518.

jection of streams of an aqueous medium, as., for example, water or steam, into the refuse at a level well toward the top of the pit. The steam, produced by the impingement of the water upon the highly heater refuse, in case water is injectechor, directly injected into the refuse, rises upwardly tl'irough the burning residue and attacks the hot refuse, destroying its adhesive proper'- ties and making it extremely friable. The refuse in and above the pit is thus maintained in a uniformly loose and open condition. in which condition it is readily passed downwardly through the pit and removed therefrom without the difficulties commonly encountered. Y

These and other objects, which will be more manifest in the further description of my invention, are attainedby the employ! ment of the apparatus illustrated in the accompanying drawings in which Fig. 1 is a fragmentary longitudinal sectional view of an underfeed stoker embodying my invention; Fig. 2 is a view, in elevation, of specially constructed air box having provision for carrying the distributing header; and Fig. 3 is a sectional view of the air box shown in Fig. 2. y

, Referring to Fig. 1, I show an underfeed Stoker of the single-end type, having altornate series of tuyeres 11 and intervening retorts 12, the tuyeres being mounted on the air chambers 13 which also serve to form the side walls ofthe retorts 12. At the lower end ofthe tuyeres and retorts are dead plates 111 over which the residuum of the fuel passes from the active grate surface to the refuse-discharge pit 15. The pit 15 entends the full width of the furnace and has at its bottom suitable refuse-discharge mechanism 16, which may be of any well known type.

The front wall of the pit has at its upper portion sectionally-constructed air boxes 20, preferably Vsecured to the air chambers 15 and communicating therewith through openings 21. Each air box section (Figs. 2 and 3) has a cross sectional configuration particularly adapted for securing they advantageous combustion conditions above described. T he., sections may be cast integrally or may be made, for convenience of manufacture andaaemblwot a nuinbcpof ings. iles shown. each section comprises three castings, 225 and Q/l. rihe casting' 22 is in the toi-m ot an obtuse angle and has a vertical tace abut-ting` against a correspondinface of the wind bolil, the other tace 26 lforming tac botto-in of the boay 2U.

The casting 23 is the refusesupporting member of the bor; and has an upper horizontal 'race 28 extendinginwardly beneath and beyond the dead pla-te 14., an inclinedexposed tace 39 sloping oownwardiy and inwardly 'trein the inner edgefo'f the upper tace toward the center of the pit and at a somewhat larger angle ot inclination to the horizontal than that of the inclination o1" the tujyeres. Qn the face 2S) are a plurality of air-delivering apertures 30. 'A curved reentrant 'face 3l extends downwardly from the lowermost edge ot' the fuel-supporting; tace 29.

rlie casting 2 4 is a trianegularly-shaped casting whieh depends beneath the entending tace 29 of the casting- 2li and is provided with a hook 32 eoaeting with a bracket 33 east integrally with the member Q18. The exposed aee oi the cast fj Qfl is substantially vertical, and is preerabl;T slightly curved downwardly and outwardlgT from `the lower edge of the extendingl taee Q9, as

shown. r'he casting` Q #l serves a guide for the refuse, which more readily passes downwardly throneh the pit iecause ot the receding face i Downwardly-extending apertures are also'provided in the Casting,- 24%. The (sa-stings 23 and 2li., when assembled, 'torni between them nn inw; idiy-openi-ngV chamber 88 tor the reception o*u distributing` header 39, which is adapted to discharge iets of aqueous medium through apertures 40 and an opening il between the castings 23 and 24 into the refuse pit. Beneath and substantially in vertical alineinent with the air box 20 are sectional guide plates Apron sections p irotalli1 supported at their upper ends t6 in any suitable manner, as from brackets el?, secured to the 'trame ot the furnace, are disposed beneath the guide plates e2 and cin-operate with the pates l2 to guide the refuse to the discharge meehanism i6. The latter construction forms no part ot the present inxf'ention`r and for this reason a detailed description thereof is deemed unnecessary in the present speeiiieation.

The rear wall of the pit comprises a bridge wall 52 oit refractory material sup-- ported on a hollow base plate 53 which may be mounted o n the framework oit the l'urnace. An air boitV 5ft is disposed beneath the base plate 58 and opposite to the guide plate 42. Apertures on the exposed surface 56 ot the box 54 deliver air to' the combustion Vzone et the pit. n n apron 5? inail respects lle the apron Alti? forms the lowerportion ofthe rear" wall et the pit, It may' be desuL Loenen able to employ sprinkler heads 60 on each side of the pit and immediately above the aprons for thoroughly quen-:ming` the refuse in the bottom ot' the pit, although it is to be in'ideratood that the headers GO are in no wise Jential to the proper tunotioning;l et the apl; compris; ny present invention. manner of operation of the above described apparatus is as follows: The residuuni ot' the burning fuel passes downwari'lly `from the active grate surface, composed of alternate series of tuyres and retorts, rer the dead plates is into the pit l5. .e ssuraing that the furnace is in full operationU the refuse idually rerum/'ed 'trom the bottom ot the pit causes the refuse thereabove to slowly mo e downwardly in the pit. The fuel bed in and over the pit is, howev r, so maintained that there is all times a considerable thickness of residuum over the dead plates l;- and the air boxes 20. Air, preierablj,y under pressure, is delivered into the refuse from the boxes 20 and maintains an active Combustion in the upper portion the pit. l/Vhile the. refuse in its downward passage is being supported on the face of the box 20, and as it passes below the level of the header 39, an aqueous medium7 which may be water, steam, mixture ot water andstean'i, or a mixture out water and air, is injected 'from the headers into the reituse. There results sudden absorption ot the heat ot' the refuse, resulting; in a rapid rie4 in temperature o't the aqueous medium and, in case the water is employed, a copious gene-ration or steam. The aqueous ine-trium upon injection and during its upward passage through the refuse contacts intilnatel;v therewith and acts directly thereon to destroy the adhesive properties of the clinler or slag' content thereof. This action ot the aqueous medium upon the refuse. results in the prevention ot the formation of objectionable olinlter masses in the refuse.

A. wide temperature difference between the highly heated refuse and the injected fluid serves to augment the active interaction between the refuse and the aqueous n'iediinn. It is, consequently, desirable to maintain a higl'i temperature ot the refuse into which the aqueous medium is injected. The water box 2() disclosed herein is, therefore, Constructed to support the refuse upon its upper aoe 29 and at the saine time maintain a high rate combustion thereorer by supply;- ing air under pressure to the refuse supported on the upper tace 29. The heated clinlter or slag' Content ot the refuse has a tendency to agglomerato as it passes over the inner edge or' the aee 29 into the pit. At these points of incipient slag 'ormatioiu the streams of aqueous medium are injected into the heated refuse. There results an intimate Contact and active interaction between the elinker and the aqueous medium which.

` claims.

lVhat I claim is:

l. In a furnace, in combination iii an ash discharge device therefor, a pit adapted to receive the refuse from the active grate siii'- face comprising an air box forming an uppei' portion of one of the side Walls of the pit and having a chambered recess in a Wall thereof exposed to the refuse, and means Within said recess for discharging jets of a cooling fluid into tlie'refuse.

2. In a furnace, in combination, an ash discharge device therefor, a pit adapted to receive the refuse from the active grate surface comprising an air box forming the upper portion of one of the side Walls of the pit and having a horizontally extending recess in the Wall thereof exposed to the refuse, a header disposed Within the said recess and arranged to discharge jets of Water into the refuse.

` 3. In a furnace, the combination with an ash discharge device having a pit to receive refuse from the active grate, of an air box forming an upper portion of the side Wall of the pit, said air box comprising` an exposed declined top Wall provided With air emitting apertures, a re-entrant side Wall lying beneath the top Wall and forming a chamber' for the disposition of a fluid disti'ibuting header, and an angular supporting wall portion cooperating Wit-h said top and side Walls to form a box-like air chamber,

l. In a furnace, the combination With an ash discharge device having a pit to receive refuse from the active grate, of an air box forming an upper portion of the side Wall of the pit, said air box comprising an exposed declined top Wall, provided with air emitting apertures, a re-entrant side Wall lying beneath the top Wall and forming a chamber for the disposition of a i'iuid distributing header, an angular supporting Wall portion cooperating with said top and side walls to foi'm a box-like air chamber, and a guide Wall supported on the side Wall and spaced from and oppositely declined to the top wall.

5. In a furnace, the combination with an ash discharge device having a pit to receive refuse from the active grate, of a sectional air box forming an upper portion of the side wall of the pit, each section of said air box comprising an exposed declined top wall provided With air emitting apertures, a i'eentrant side Wall lying beneath the top Wall and forming a chamber for the disposition of a fluid distributing' header, and an angular supporting wall Yportion cooperating with said top and side walls to forni a box-lil-:e air chamber.

In a furnace, the combination ivitli an ash discharge device having a pit to receive refuse from the activ-e grate, of a sectional air box formino' an upper portion of the side Wall of the pit, each section of said air vbox'comprising an exposed declined top vvall provided with air emitting apertures, a. re-entrant side Wall lying beneath the top Wall and forming a chamber for the disposition of a fluid distributing header, an angu lar supporting Wall portion cooperating with said top and side Walls to foi-m a box-like air chamber, and a guide Wall supported on the side Wall and spaced *from and oppositely declined to the top ivall.

7. In a furnace, the combination with an ash discharge device having a pit to receive refuse from the active grate of an air box forming an upper portion of the side Wall of the pit, said air box comprising a protruding declined top Wall. a receding guide Wall, and means for introducing streams of aqueous medium from the air box into the pit at the juncture of said top and guide Walls.

8. In a furnace, the combination with an ash discharge device having a pit to receive refuse from the active grate, of an air box forming an upper portion of the side Wall of the pit, said air box having a 're-entrant chamber for housing a distributing header.

9. An air box for a refuse pit comprising a fuel supporting portion having a reentrant chamber` therein for housing a fluid distributing header.

lO. An air box for a refuse pit comprising fuel supporting portions having a reenti'ant chamber therein for housing a fluid distributing header, and including a protruding declined top Wall, and a guide Wall joined to the lovver edge lof the top Wall and forming therewith an overhanging ledge.

ll. An air box for a refuse pit comprising fuel supporting portions having a reentrant chamber therein for housing a duid distributing header, and including a protruding declined top Wall and a guide Wall receding from the line of juncture With the top wall.

l2. An air box for a refuse pit comprising an exposed declined top Wall provided with air emitting apertures, a i'e-entrant side Wall lying beneath the top Wall and forming a chamber for housing a fluid distributing header, and an angular supporting Wall portion cooperating with said top and side walls to forni box-like air chamberi 13. An air box for :L refuse pit comp 1isi'ng an exposed declined top Well provided with sir emitting apertures, s re-entrsnt side Wall lying beneath the tog Well end 'tornr ing a Chamber for housingl e fluid dif ibutingheader, une en angular supporting` well portion cooperatinl with said top und side Wells to forni a box-like air chambere und e guide Wall supported on the side Wall and spaced from and oppositely declined to the top Wall.

lll. A sectional air box for a. refuse pit each section comprising un exposed declined top Wall provided With air emitting apertures, 2t re-entrant side Wall lying beneath the top wall and forming e chamber for housing a l'luid distributing header, and an angular supportingwall portion cooperating With said top end side Wells to forni :L box-like air chamber.

15. il sectional air box for e. refuse pit, each section comprising.;- en exposed declined top wall provi-ded with nir emitting apertures, a reeentrent side will lj-,iingi` beneath the top Well und orniing u chamber for housing a fluid distributing lie-lider, an angular supporting Wall portion cooperating with said top and side Walls to forni :i sox-like air chamber, and e guide Well supported yon the side Wall and spaced from and oppositel;7 declined to the top wall.

n testimony whereof, l have hereunto subscribed my name this lil day of April N22.

ROBERT A. FORESlL/lil.

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