US1402843A - Boileb - Google Patents

Description

J. DOHERTY.

BOILER CONSTRUCTION.

APPLICATION FILED SEPT 20, 1917- 1,402,843. Patented Jan. 10,1922.

2 SHEETS-SHEET 1.

Jcunea Doll/6kg J. DOHERTY.

BOlLER CONSTRUCTION.

APPLICATION FILED SEPT 20,1917.

Patented Jan. 10, 1922.

2 SHEETSSHEET 2.

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a 11v VENTOR BY a f v A TTORNE Y BOILER tltlllllhTHUflTION.

Application filed. fieptcmher T 0 all whom it may concern;

Be it known that l, dairies Dornurrr, a citizen 01" the United, ir itates, residing at llhicage, in the county of Cool: and State 0:. Illinois, have invented certain new and. useful Improvements in Boiler Constructions; and I do hereby declare the flEOllOWillg to he s :tull, clean and erect description of the invention, such as will ensble others skilled in the art to which it appertains to make and use the same.

This invention relates to coal hurninp; tun naces for steam or hot Water heating, and like uses and more particularly to that type of such furnace in which an. overhead sup ply of supplemental combustion-supporting air is admitted to the fire-hon for perfecting the combustion reuctioin thereby rendering such furnaces capable oil? operation on bituminous coal Without objectionable srnolr and hence with corresponding thermal eficiency. The type of furnace referred to is Wellknown in this art and many ditlerent :t'orins oi it have been heretofore disclosed in pet ents but none of them, so far a I am aware has resulted in a furnace equipment suited to the demands oi? the trade. or capable of the continued efficient service as I here di coveredis possible and practical by the or ganizetion of means hereinaitter disclosed.

My invention consists in the manner or": in troducing and heating the SUPlDlQlYl-Eri al air and in the structure of the air supply duct and its air distributing: orifices and in the relation oi such orifices to the fuel bed and the path of. the fire erases as well in the organization or? these features in the structure of sectional furnaces, all as hereinafter more fully described In the eccompainyin drawing. illu" the preferred form oi the inventioin K 1. is perspective of a sectional Water-heatinp; furnace with the side wall brolren. out and the interior parts shown in vertical and oblique sections.

Figure 2 is a partial face view of the water-curtain section.

Figure 3 is an enlerpged cross-section of the Water curtain, and

Figure 4 a detail showin a portion of the exposed or air-heatine Well. of the air duct.

The furnace illustrated comprises front and rear Water-containing sections 1 and 3 and a series of intermediate watercontein inn; sections 2, all having: the same external contour and adapted to he clamped tightly Specification of Letters Patent.

Patented Jan. Ht, 192%.

isaa'ri.

together, as usual in sectional idirnaces so that the Writer spaces in e: ch section are put in coini'nunication, and the assembled sec tions "form the walls of the fire hex and the usual tlue spaces by means oi? which the reouisite surface is atlordec for transfer of from the tire cases to the Water. For us purpose, the sections constitu..'ng the iront part of the furnace are provided with cross chambers 2 which are desirably T- shaped in cross-section. and form the root or crown of the hex. The furnace section new? in rear ot t ese crown. sections, is provided With a Water-containing; cross member or bottle of considerable vertical dimension so that it depends Well below the crown Wall end terms a Water curtain. marking" the rear limit ot the upper part of the the box. The means for admitting the supplemental air is associated with the lower edge out this Water curtain as presently explained. The cross chainliier members Q of the turnace sections it in rear of the water curtain are spaced ore each other forming: lue speces hetween in through which th re oases rise to the upper iorizontal side lines 4 above the fire n t. ln these side 'tlues gases flow itorweirdly ove the crown Well 2"; indicated the arrows and then turn and pass rear. h the horizontal center flue 8, l and chirnneu not shown. This t is no different from fun lone in. common use and is. the preterred although no; a. necessary arrangement or the tines oi the o ontion.

resent in;

The bottom of the :lirehoi: is formed by a peri orote updraft grate (l which is parallel 7 With the crown well and substantially horizontal. The grate extends to the rear ot' the water-znirtain D and ahuts against or terminutes adjacent to. an uprinht Well B which constitutes an ordinary bridge Wall in the 'ueseut case; its function is merely that of a rctainino Wall tor the bed ot fuel on the grate. The upper front edge of this Wall is shown in the drawing); beve led and the H The coal is supplied through the feed grate in the usual way and this constitutes the main supply of combustion-supporting air. The space in rear of the wall B when that is a bridge wall as shown, serves merely as part of the line space or as a chamber tor the collection of dust.

The lower edge of the water-curtain l) extends transversely and horizontally over the rear part of the grate and :tuel bed, occupying a level which is somewhat nearer to the grate than to the crown wall 2, and in this position, it cooperates with the fuel bed'clirectly below it, to form therewith a somewhat restricted passageway throat thror gl which the lire-box opens into the flue space in rear. Practically all of the fire-gases developed in the furnace flow through this passage which extends across the furnace with practically uniform vertical dimension. The duct A toradmitting the supplemental air is coextensive with the water-curtain, being substantially coincident with its said lower edge and receives air from atmosphere, through appropriate, damper controlled inlet openings 6 in the side legs of its furnace section shown in Fig. 2 and discharges and distrilnites such air through a series of uniformly spaced and downwardly directed exit orifices openinq from the lower side of the duct and theretore'toward the fuel bed. The air flow into and through the duct and its orifices is caused by the chimney suction which sutfices to produce a vigorous discharge through the row of orifices because the air path through the grate is more or less ob structed by the fuel and there is no other equivalent entrance for air to the interior of the furnace, besides which the location of the duct is nearer to the chimney than other points in the lire-box. The single cross-duct supplies all the air that is needed for combustion which does not enter by way of the grate and supplies it at suliicient velocity to cause it to penetrate the throat passage above mentioned and seemingly to impinge against the subjacenl; bed of fuel creating an extraordinary mixing effect and turbulence in the tire gases at that point. which is manifested in practical operation by the de velopment of a sheet of livid white flame extendino; directly from the water-curtain through the horizontal lines of the furnace T his effect is in part the result ot the arrangement of all the air duct orifices in a single transverse plane or zone over the rear part of the Fuel bed and distinguishes my invention from that class 0t supplemental air furnaces in which the supplemental air is introduced through many separated orifices distributed over the whole area of the roo orj sides olthe firebox, as well as from other designs in which supplemental air is admitted without adequate velocity or from orifices too remote from the fuel bed produce the necessary turbulence. Bees admitting the supplemental an in the and at the requisite velocity,

men oncounte the lire gases and .l have a ad that unless lt exceeds a certain cr temperature, its ellect on the cllicicnc c the combustion process will be ii' uind he generally neutral or actually I have further ascertained that critical temperature is not attained hen he air duct is enclosed in water or clteted: in such arrangements the thi oucgh the. duct cdiuiotexceed rely low temperature oi the water 1 and that is much too low to produce Mot-ion rcterrcd to and cannot give the ion cl'licienc v r-rhicli is the object of V 7'. cation. in the other hand. l have -o demonst ted, that any material incso oi the air temperature above said al point is not attended with any cor ouch: benelit to the reaction and is arc'lorc not nec sary, besides which the oi such hi h temperaturcs involves serious diliicultics on account of the rapid disint ratimi by the heat oil the material h the air duct is formed. The desc ibed location of th air duct, close over .c rear part of the luv] bed. is th hottest mace and so b: as T am aware v V .ractory material commercially c, .i ll at can peruizuiculily witbstaml such tcni' eraturc. Previous clliorts to construct ducts in. or near this location. out ol. various kinds of firebriclr have been nosucccss ul on this account and the attempt to remedy the diiliculty by jMlHIltl'lIlSl a larger volume of air through the duct. so a, to lmep the tcnipemture noun. is not practicablc. because an such air flow as would be ell w 'vo tor this purpose robs the Fuel pit air supply and thereby he primary combustion.

these dillicult cs. One oil'- the walls (l of the air duct is arranged so s to be oirectlv oxaposcd tor substai'itiully the whole of its length to the radiant heat of the fuel bed which. as stated, is very intense at this point. and said wall is thereby highly and also un formly hcatcd and transmits its heat to the air flowing inside the duct. The other or opposite w: ll of the duct is shielded 'l'l'oiu the radiant heat and protected :urainst :la' quiring' so high a temperature by virtue oi its proxim ty to the water in the curtain l).

the temperature ol which is of course at all times relatively very low. This side of the duct is therefore kept relativcly cool. The protectioi'i and cooling: elliect ol' tlzc water supplemented by the cooling eh'eet ol' the 1 ,aoas ia incoming air, is found in practice to keep the exposed wall C at such. temperature as to renderit indefinitely immune from thermal. deterioration, while the air flowing behind it acquires a temperature high enough to adapt it for immediate chemical. com" mation with the firegases in ordinary c" tion, and to produce the charact efficient flame effect above referred to. such organization and partial protection and cooling of duct otherwise highly heated for its full length, its combustion-perfecting function is made available in the fullest degree.

The preferred air duct passage as shown in the drawing is formed in part by the metal wall of the water-curtain itself, which is provided along its lower edge with a series of forwardly projecting teeth It, all of substantially equal size and containing water, and in part by the separately made wall member C above referred to, which is of angle-bar cross section and seated upon the tips of the teeth, as indicated in Figure 3, thus forming the duct passage A. with the spaces between the teeth forming the downwardly directed air orifices. The said spaces are about the same width as the teeth so that the air is delivered as closely adjacent and also uniformly spaced, jets or blasts. approximating the form of a continuous sheet of air. The wall U, being structurally separate from the water-curtain wall and longitudinally coextensive with and also being supported intermediate of the ends of the duct upon the water curtain, besides having a simple cross-section, is entirely free to expand and contract under thermal change without injury to itself and without imparting strain to the metal of the watercurtain proper, while neverthless sulfici as stated to establish the requisite tempt ture in the supplemental. air. While I am not able to give the exact value of the critical air temperature which it mentioned above, because of the difficulty of ineasuri m it, it will be sufficient to those skilled in this art to say that it is attained by substantially the extent of wall exposure to the radiant pass off with the flue gases without miningor sufficiently combining therewith.

In connection with the statement above made that the air duct provides for the introduction of all the combustion supporting air except that which enters through the grate, it will of course be understood that in every furnace there is inevitably more or less air leakage especially at the feed door, and that the feed door may be provided, as in the present case, with an air damper for controlling the entrance of outside air above the fuel. th'dinarily, the effect of air admission thorugh such dar :r is to chill or suppress the comb" ton rathu than otherwise, such dampers being princ pally useful when the fire is banked. llnder certain conditi ns and w'th. certain lrlnds of coal a limited admission of air at the feed door may serve to support conituistion, but in any event the amount of air leakage, if any, and the amount admitted through the feed door damper, is relatively negligible as respects its effect on the flow through the cross duct, so that it does not deem the entering velocity of the latter and the mixing effect which is dependent thereon, and it is therefore true that the said duct and the ash pit together admit substantially the whole supply of the combustion support ing air.

The firebox side of the water-curtain above the air duct is faced with refractory material represented in the present case by tiling 5; this refractory surface becoming highly heated is found to lend assistance to the combustion in the fire-box-possibly by the so-called regenerative effect. The water,- curtain is also formed with one or more small apertures E in its upper part adapted to cause a slow withdrawal of gases from beneath the crown wall and for the purpose of insuring the continuous presence of very hot gases contiguous to said wall so as to utilize their heating effect in the crown wall. water.

Claims:

1.. in a furnace of the type described, the combination with a fire-box having a horizontal, perforate updraft grate and a main air supply through the grate, of a transverse baffle wall containing water and coactinp; with the rear part of the fuel bed on said grate to form therewith a. throat passage, means for admitting supplemental heated air to the fire-gas flow in said passage com-- prising an air duct associated in parallel. relation with the lower edge of said wall,

one side of said duct being exposed to the radiant heat whereby it heats said supplemental air, and the other side being shielded therefrom and. subject to the coohn effect of the water in said wall, and means constituting the exit from said duct adapted to direct said heated air crosswise of the flow through said passage, said air duct exit and main air entrance being correlated to produce a velocity of said heated air flow adapting it to mix with said fire-gas flow.

2. In a furnace of the type described, the combination with a fire-box having); a horizontal, perforate updraft grate constituting an entrance for some of the combustion supporting air, of an entrance for substantially all the balance of the combustion supporting air consisting of a transverse air duct extending directly over and spaced above burning fuel bed at the rear part of said and forming with said bed the principal gas flow passage from the fire-box, said duct being associated with means whereby it is protected by water on one sit e and subject to the radiant heat of the combustion on another side, whereby the. air iow therein is heated, and provided with downwardly di rected exit means adapted to cause ininture of said heated air with the flowing through said passage.

3. In a furnace of the type described., the combination of firebox having a ho tal, perforate updraf crate constituting; an entrance for some 0 the combustion supporting air and an entrance for substantially all the remainder of the supply of comb-uslion-supporting air comprising; a row of air orifices extending transversely over and at a uniform distance above the whole fuel bed at the rear part of said e rate and air duct for conducting the air to said .ces 90H? prising; a wall having means spaced above the fuel bed for protecting it by water, and another wall uniformly subjected to the radiant heat of the combustion and serving to heat the air issuing from said orifices.

4. In a furnace of the type described, the combination with a fire-box having; a perforate updraft grate constituting an entrance for combustion-supportine air, of a transverse fire-loox wall containing; water disposed over the rear part of the fuel bed on said grate, means for admitting substantially all the rest of the combustion-supporting air to the fire gas flowing between said wall and fuel bed, comprising a transverse air duct situated directly in front of the lower water containing edge of said wall, one side of said air admittingmeans being exposed to the radiant heat of the combustion and the rear side thereof being shielded therefrom and subjected to the cooling-effect of the water in said wall, and means for directing the heated supplemental air toward the fuel bed and adapted to cause the same to mix with the fire gas fiow beneath said wall.

' 5. In a furnace of the type described, the combination with a firebox having; a perforate updraft grate constituting the main air supply, of a transverse firebox wall containing water and having its lower edge disposed directly over the rear part of the fuel bed on said grate and nearer to the (gratethan to the firebox roof, means for admitting supplemental air to the fire flow beneath said wall comprising a transverse air duct associated in parallel relation with said lower edge, one of the walls of said duct being exposed to the radiant heat of the combustion and another being shielded therefrom and subjected to the cooling; effect of the water in said wall, and a row of air exit orifices in said duct arranged to direct heat ed air j fl the fuel bed, said main and suppleinentzu air ci'itranccs constituting substantially the whole supply of comljuistion supporting" air to the lire-box.

6. in a furnace of the type describml, the combination "ith a firebox having a hurl :aontal perforate updraft grate and a main air supply through the grate, of a transverse water-curtain forming the r r boundary wall of the fire-boat, means rm. admitting heated supplemental air to the tmssagrc ben-ath said water curtain comprising an air duct associated with the lower ed c of said curtain and partly protected tl'icreby :1 5.Iul115-3 the radiant heat and having; an uir-heatingr wall directly exposed to the radiant heat and an exit adapted for directing the heated air from said duct toward the grate.

7. In a furnace of the type described. the combination with a fire-box ha ing a horizontal, perforate up-draft grate and a main air supply through the 1:lflllQ, of a supplemental air admission duct disposed substantially horizontally and transversely over and out of contact with the rear part of the burning fuel bed on said grate and providing fire-gas passage betwcen the same and said bed, said duct being formed by trans verse wall members, one of which is waterprotected and one of which is subject to the radiant heat of the combustion and having downwardly directed exit means adapted to discharge highly heated air crosswise into the fire-gas flow through said passage.

8. In a furnace having a horizontal, perforate rip-draft grate constituting a main air supply, a supplemental airsupply comprising); a transverse air-distributing passage disposed over the rear part of the fuel bed on said grate and open to atmmqahore at the side of the furnace and constituted of separate passage-forming; wall members, means for keeping water in contact with one of said passage forming wall members, the other member being directly exposed to the radiant heat of the combustion whereby it transmits heat to said supplemental air, said passage having air exit means directed toward the fuel bed.

9. In a furnace having a horizontal updraft perforate grate constitutiim' an entrance for pa "t of the combustion-supporting air supply, an entrance for substantially all the rest of said air supply comprising" a transverse, substantially straight. air-distributing passage composed of separate passage-forming members, means for lrcoping water in contact with one of said passage forming wall members, the other member being exposed to the radiant heat, and both of them being disposed directly over the fuel bed, and the passage formed thereby having inlets from atmosphere through the sides of the furnace, in alignment with said passage, and having downwardly direct l air-exit means,

10, A furnace of the type described. coinprising the combination grate, a wat :urtain located above the fuel bed on said grate and provided i rejecting teeth, and a separate member co-acting with sane water-curtain to form an air pas: said passage having entrance means for an: the spaces between said teeth serving 0m distributing outlets from said passage.

11, line furnace of the type described, the combination with a grate, of a transverse, water-containing baffle wall located. above the fuel bed thereon and. forming the rear of the fire-box space, and a separate member mounted on said wall and forming therewith a supplemental air admission duct havair air exit means.

12. In furnace of the type described, the combination with a grate, of water-con taining member provided with toothlilre projections a member of angled crosssection supported by said projections and forming airsdmittinpand a'ir-distrib uting passage,

13. In a furnace of the type described, the combination with a grate and a transverse water-cur ain forming the rear wall of the firebox space and a sep ately formed member supported lIllJGliIlQ etc of its ends on said water-curtain anr ,ssociated therewith to form an air-admitting and. air-distributing cross duct exposed to the radiant heat on one side and protected by the water in said curtain on another side.

14. In a sectional furnace, the combination with front, rear and intermediate water-containing SEC'tlOlT-l all made of similar external contour and assembled to form the furnace body with internal chant bers constituting fine and lire-box spaces, of means carried by one of said intermediate water-containing sections constituting a de pending Water-containing fire-box wall and also constituting an air-coinlucting and distributing passage, said. passage extending crosswise of the furnace above the fuel bed and having an opening to atmosphe-P at its end intersecting the side of said intermediate water-containing section.

15. In a sectional furnace of the type dcscribed, the combination with a series of front watencontaining sections all of similar external. contour assembled. to form the front part of the furnace containing a firebon space and having an up-draft grate, of a water-containin section of similar external contour assembled in rear of said front tire box sections and carrying a depending tran verse water-containing wall situated over the rear part of said grate and a transverse air-distributing passage located above said grate and directly in front of the lower portion of said water-containing wall external L l Wall-ear e part of the 1.

id, in a sectional 'l' n scribed, the conibinu'. wliter-containing lions all of similar ex:- ternal contour assembled to fin-n1 the front part of the furnace and containing and forming a crown wall with horinontal flue spaces above it and a fire-box. space beneath it, and for said space, of an intermediate water-containing and ill ila-s ing section of similar external contour assembled in rear of said series and having its water space extended downwardly to form a water curtain depending below said crown wall and over the grate, air-admitting and air-distributing cross duct having down wardly directed air exit means, the walls of said duct being supported intermediate of their ends on said intermediate or water eurtain section and another water-containing section or sections also having a similar external contour assembled in rear of said water-curtain section to form the rear part of the furnace.

17. in a sectional furnace of the type de scribed, i'vhecombination with a series of front water-containing sections, all of similar external contour, assembled to form the front part of the furnace and containing a crown wall with flue space; above it and a fire-box space beneath it, of a watercontaining and flue-forming section in rear of said series, means wholly carried by said last named section constituting a transverse water-curtain depending below said crown wall and also constituting an air-admitting and air-distributing cross duct adjacent the lower edge of said water curtain.

18, in a furnace of the type described, the combination of a lire-box, updraft grate, constituting the main supply of coinbustion-supporting air, a transverse wateri 0 ill containing baille forming the rear wall of said lire-box having an air duct associated with its lower edge adapted to deliver substantially all of the balance of the air required for combustion into mining relation with the fire gases passing beneath said baths and also having a facing of refractory material on its front surface.

19. A sectional furnace of the type described composed of a front, a rear and several intermediate vi tor-containing sections, all similar external contour and all sseniblcd together to form the furnace with internal parts constituting flue spaces and a fire bOX, and an updraft grate constituting the main air supply to the fire box, in comh a series of bination with a supplemental air admission duet adapted to introduce. substantially all the balance of the air required for combos tion and disposed substantially horizontally and transversely over and out of contact with the rear part of the burning fuel bed on said grate, and providing an open firegas passage between itself and said fuel bed, said duct being formed by transversely extending wall nieinhers, one of which is oonstituted by a water-containing part of one oil said intermediate l'urnaee+eetions and one of which is constituted by a horizontally extending member associated with said intermediate section and subject to the radiant heat of the combustion, said duct having downwardly-directed air exit means adapted to discharge the highly heated sup 'ilemental air crosswise of, and into mixing relation with, the tire-gas flow through said passage. 20

In testimony whereof I afiix my signature.

JAMES DOHERTY.

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