US2375771A - Furnace - Google Patents

Description

Mayl 15, 1945. l E. w. DANY Er Al;v 2,375,771

' FURNAGE Filed Dec.- 24, 1941 3 Sheets-Sheet 2 INVENTORS ELMEQ W. DANY BY PAU/ 5. GBL/55e TToeA/E v5.

May 15, 1945. E. w. DANY ETAL FURNAGE Filed nec. Y24, i941 5 sheets-sheet s INVENTORS ELMEB W. DANY PAUL 5. GBUBEE.

PatentedMay 15, `1945 Elmer W. Dany, Brecksville, and Paul S. Gruber,

Cleveland, Oho, assignors .to Ferro Enamel. Corporation, Cleveland, Ohio, a corporation of VApplication December 2 7 Claims.

` Thisinvention relates to furnace construction, and more particularly to certain improvements in fuel-fired, muilie furnaces of the typeY common- "ly used in porcelain enameling on metal and in numerous other heating operations where ware is conveyed through a furnace in a more or less continuous manner.

j Although the furnace illustrated `and described herein is particularly adapted for porcelain enameling, it will be understood by those skilled in the art that the` features disclosed herein are readily adaptable to furnaces intended for annealing or other heat treating operations. A very efficient and successful form of continuous furnace is the so-called U-type in which the furnace structure'is open at one end and closed at the other end and means are provided for transporting ware into and out of the furnace in `a U- shaped path.` In this form of furnace the heating 4zone is disposed at the closed end of the U, and

the cold incoming ware enters the open end of the furnace and moves close to, but in the opposite t direction from, the heated outgoing ware. `Thus the entering ware is preheated `by the heat given off from the Ioutgoing ware. Furnaces of thetype referred to herein have been heated by electrical heating means, by radianttubes disposed along the walls of the furnace, and by mufes, in which fuel such as gas or oil is burned, disposed along I the Walls of the heating zone of the furnace. `My `present invention relates to improvementsl in mulile furnaces as distinguished from the electrically heated or radiantr `tube heated types of furnace.

In prior mufile furnaces with which we are lfamiliar the heating or burning section hasbeen `heated byV mufe chambers disposed inthe oor i andside walls of the furnace. The entire heating `zone has been open from one side wall muffle to the other and the heat input capacity has been limited by the area ofthe bottom and side walls of the heating section.` Our presentnvention contemplates the provision of a heated muflle dividing wallfpreferably centrally arranged between the side walls of the heating section and extending part or all of the distance between the floor and roof ofthe heating section. We are aware that U-type furnaces of the electrically heated and radiant tube heated'classes have been proposed in. which a `dividing wall, which supports heating elements, is` installed in the closed end ofthe furnace. The present invention, how- `ever,possesses` certain definite advantages over i such electrically or radiant tube heated structures l asgwill appear more fully later. y j i 4, 1941, semina.:424,228l

` It is an object of our present invention to provide a fuel-fired furnace of the type described havinga relatively large heating capacity fora ter muffle andfrom said center muie in'heat exon line 3-3 of Figure 1.`

given furnace'volume; Other objects of my invention include; the provision of a U-type' furnace of the muilletype having means forautomatically supplying the greatest amount of Aheat tothe ware as it enters the heating sectionof the furnace and a lesser amount of heat to the ware as itleaves the heating section; the provision of a ULtype furnace havinga heated intermediate wall in the heating" section; the provision of a centrally disposed muifle in the heating section .of a' fuel-fired furnace 'togetherwith effective means for conveying products of combustion to said cenchanging relationship to ware entering the :furnace; the provision of a furnace having side -muies and a center wall muille;` and meansfor 'controlling the relative proportion ofl heating effected by the various muflles; the provision, in a cross-fired muflle type furnace having a heated center wall, of means for independently control- 'ling' the flow of heated gases through the zcenter wall portion; the'provision of improved means for regulating the heat distribution in a 4mufile type furnace; and the provision of an extremely-simple, rugged, efficient, high capacity'heating furnace of the typedesc'ribed.

The above and othei` objects of my invention will appear from the following description of one embodiment thereof, reference being hadto the;

accompanying drawing'sin 'Which- Figure 1 is an illustrative horizontal cross-sec tional view of a U-type furnace incorporating my improvements, the central portion of the preheat-` -ing and cooling zone of the furnace being broken i away for purposes of more compact illustration.

Figure l is takenon line l-I of Figure 2.

Figure 2 is a vertical longitudinalsectional -view takenonline 2-2 of Figure 1. u

Figure 3 is a Vertical cross sectional vieW taken Figure 4 isa fragmentaryivertical cross seci tional' View taken -on line 4-4 of Figure 1- `and .illustratingthe gas passages at the exit end of the I center wall mule.

. Figure' 5 is a vertical `longitudinal sectionalview Figure 6 is a vertical crosssectional view take l on line 6-6 of Figure -1-. i i l ,Y

Figure rI is a vertical cross sectional view showing the damper controls of the flue outlets, taken on line'l-'I of Figure l.

,'Ijhe furnace which We haveillustrated in the V 15 at the endof `the tunnel il bustion fromthe burner .8 yshown in Figure 3 can- 1 `drawings is of the U-type and has a cross-fired heating zone. However, we do not wish to limit our invention either to a cross-fired furnace or to a U-type furnace as various features of our improved construction are readily adaptable to other furnace designs.` In Figure 1 the heating section or zone lof the `furnace extends from the closed end wall I Ato the end walls 2 of the side muiiies. The side walls of the preheating and coolingsection of the furnace are indicated at 3 and 4, and, as is best seen in Figs. 2 and 3, the roof 5 of the furnace is provided with a continuous U-shaped slot 6 through which ware suppOrting bars extend.' The path of this slot is indi-cated in Figure 1 by a dot and dash line 1, and the ccnveyor'mem'- bers and bars are not illustrated because they are well understood and form no part of the present invention. supporting elements which extend through the slot 6 and carry the ware are preferably mounted on an endless chain which .goes in the direction :of the arrow ,in Figure 1. Ware is .loaded onto the conveyor at the `open end (the right hand end in Figure l) of the furnace, vand moves into the heating zone where it `turns through an angle of 186 vand then passes on out in closely spaced Arelation to the incoming ware. As the heating and cooling zone is preferably .open across its entire width, a free transfer of heat from the hot outgoing ware to the cold incoming ware is obtained. The cross-fired heating arrangement which we have illustrated includes four 4burners 8 located on 'one side 'of the furnace below the level of the floor il thereof, and three burners I0 located on the opposite side of the furnace and in .staggered or oifset `relation to the burners il. Each of .the burners 8 directs its name and products of combustion into a transversely extending tunnel Il belowthe floor v9 'fof the burning section of vthe furnace, and each .of the burners II] directs its flame and'products :of combustion .into a transversely extending tunnel .-IZ, also' located below r'the oorofthe furnace. These tunnels are separated bytransverse'walls I3 which extend .across the bottom of the 'heating section of the flunaceand also form supports for .the refractory floor plates forming the floor 9 :of the furnace heating section.

As may be clearly seen lin Figure 3, .the products `of combustion .from 'each 'burner 8 Y pass through jthe .corresponding tunnel. I i below the furnace door 3, and :thenmove upwardly into the side muilie chamber'd through an open passage Products of comnot enter `tlxe side munie' 16, however, lbecause ofthe ibaiile' member l1 which shuts oi rcommunication between the .tunnel .II and the .side muille #6, i

"The mufes I4 and I6 preferably extend along lthe full length of the side 'wal-ls' of the lheating chamber, and .are provided with inner, relatively thin, refractory walls Maand 16a. In each of the muniesv 2M and 1G we'preferably provide verticaliy :extending 'pilas-ters for assisting in the desired distribution of heat through the muiiles. In mufile I4 these pilasters are seen at t8, V19 and 19a, the pila-ster 1I8 extending up relatively `close to the top of the mufilelchamber, and the pilasters II'Q and AIISIaL 4'being 'of' successively decreasing height. Similar pilasters 2D, 23| and 22are' disposed A'inthe side munie i6. 'will appear later, the' fic-w of gases 'through the side muilles 'III land I6 is from the closed end ofthe furnace `toward the Aopen end (left to `right in Fig-s. l and 21), and

It will suflice to point out that the' a the pilasters just referred to assist in maintaining this flow in the desired manner whereby more uniform heating of the walls I 4a and IBa is ob tained.

The intermediate or center wall mufiie is generally indicated at C, and comprises side walls 23 and 24, end walls 25 and 26, and atop portion 2'I.y The side walls 23 and 24 'are' supported onl suitabley base blocks 28 and 29 which span the transverse walls I3 and are supported thereby.

. The wall C has its left hand end (Fig. 2) spaced from the closed end I of the burning chamber the side walls of the furnace.

The interior of the center muille C com-municates with the transverse tunnels I I rand I2, which it overlies, by means of the cpeningsll. We preferably install pilasters 3I, 32, 33, y34 and. 3 5 in the munie-C. These pilasters are .supported on the walls I3, and are .stepped down, as seen. in

Figure 24, from the highest pi-iaster 3l to thelowest piiaster 35 adjacent the exit end of the center muilie.

Products of combustion from the tunnels II .and 12, over which the muffIeC is disposed, may pass upwardly into the muiiie C throughzthe passages l3i). Pilasters 3I, 32, 33, 34 and V35 cause the pro-ducts V'of combustion to sweep over the entire inner area of the mulc C and assist .in effecting even heating of the walls of the mufe. As

the products of combustion approachy thek end i wall .25 they are directed downwardlyby this wall and pass out the muiiie wall .C through .theautlet :opening 36 which, as is best seen in Figure 4, Aopens into the endportion of a .duct 4BTI which in turn .extends longitudinally beneath the floor 38 of the preheating and coclingchamben y The products of combustionv which venter the side mufiies I 4 and i6 4move toward thexopenend of `the furnace and `pass `:downwardly :through :openings :39 yand 40 (Fig. 1) into 'the end portions of ducts 4I and 42, which also `extendnbeneath the floor 38 ofthe preheating and cooling section. vThe ` ducts 31, 4I and 42 preferably extend substantially' the full length of the preheating and coolingsection of the furnace and when they approach the vvopen end of the furnace they are turned at right angles, .as clearly seen inFig- 'ure 1, and connect with the stack 43 locatedat one sideof the furnace. Independently adjustable dampers '44, 45 and'46 are provided for -the flues 31, M land 42 respectively. vBy adjusting these dampers the relative Asizes of' the outlet openings of the nues 31., 4I .and 42 may beadjusted, and thus the draft on eeen of the-munies l I4, I6 and `C may be regulated. y

For example, `if'it is desired to increase-the yquantity of heat :applied to the center 4muiiie LC, the damper 44 maybe opened without changing the position of the dampers 145 .andv 46.

Thiswill result 'ina greater proportion of the hot 'products` .'rnisjnexibuity of control ofthe munies isjextremely advantageous as it isfrequently"desirable to vary the heat input to the ware at different'` parts of the burning zone. My center wall `mufile provides aforni of automaticmeans for applying heat to the ware without any complicatedfcon'- trolssuch as 'are necessary `with electrically heated furnaces.` Aswthe unburned ware' enters the` burning, section,` heat given off from the wall) 24 and fromthe wall lBa will'` rapidlyraise the temperatureof the ware. The resulting cooling ef;-

`fecton the walls 24 will call for mere heaty fromA the products of combustionwithinithevmuille, and thus the temperature will be maintained at v the .necessary value. As the ware leaves the burningzone and .passes between the walls 23 and I4, however, it'has been heated to its desired temperature, and thus there is not as great a flow of heat from the walls 23 and'l4a to the wareas there was from the walls Ita and 24.` Thus the greatest heat is automatically applied to the incoming ware where it is most desirable.

By adjusting the dampers 44, 45 and 46, as explained above, heat may be applied uniformly to both sides of the ware and the` temperature at` the various points in the heating zone may be maintained within the desired limits. Further more, as` all of the products of combustion pass out beneath the iioor of the preheat and cooling zone, an efficient heat transfer is obtained which serves to assist in preheating the incoming cold ware. width of ducts 31, 4| and 42 as extending across substantially the full width of the preheat and cooling section, it will be understood that these ducts may, if desired, be positioned beneath only the portion of floor of the preheat and cooling rsection over which the cool entering ware passes.

It will further be understood that the structural arrangements of brick, refractory elements, etc., illustrated herein is more or less diagrammatic, and that modifications and variations in the structural features may be made without departing from the precepts of our invention. The features of our center wall or island type mule and independent control of the heat applied thereto may be taken advantage `of in the so-called counter-flow furnaces, `or in other types Although we have illustrated the total 2 of straight-through furnaces, as distinguished from the U-type of furnace which we have illustrated. i

Although we have described the illustrated ern` bodiment of our invention in considerable detail, it will be understood by those skilled in the art that numerous variations and modifications may be made in the form and arrangement `of the parts. We do not therefore wish to be limited to the particular furnace structure herein shown and described, but claim as our invention all embodiments thereof coming within the scope of the appended claims, l

Weclaixn:

1. In a furnace of the `type described, a heating section, transversely extending tunnels beneath the floor of said heating section, burners adapted to direct their products of combustion into said tunnels, muiles in the sidewalls of said heating section, a centerwall munie disposed between said side wall munies in said heating section, means for establishing communication between one`of said side wall mufes .and some of said tunnels and between the other of said side wall` muilles eommunication'i between" said `center wall "munie and "at least" ceram of 1 each of said manen,` e

preheating section connecting-toone end of said heating section@independenty` ducts extending from said side wall lmuilles and rsaid 'center wall muflie in heat transferring relation to 'said'pre-l heating section, stack means providing an outletA for vsaid,` ducts; and lindependent means. for regulatingtlieflowof gases through each yof said duets# I l 2; Ina U-type furnaceh'avinghan opnendfand a "fclosed end, a heating A"section l adjacent said closedend, apreheating and cooling section be# tween said' heatingfsectionand said open end,

wan mufnes mi 'ppcsite sides; ofsaid 1haaingfseel tion, an ,interrnediateV muiiiefin said,y heating section between `said wall Amuffles and spaced'froni vsaid closed 'fend of l said'fur'nace, a combustion tunnel extending 'l transverselyf of said `heating section below saidrnuilles, gas conducting connections from said tunnel into one of said wall muflles and into saidintermediate muffle, duct means extending belowsaid preheating and cooling section for conducting gases away from said one of said wall muiiles and said intermediate mufe, and means forv apportioning the flow of gases between said munies.

3. In a U-type furnace having an open end and a closed end, `a heating section adjacent said closed end, a preheating and cooling section between said heating section and said open end, wall muiiles on opposite sides of said heating section, an intermediate muiile in said heating section between said wall muiiles and spaced from said closed end ofl said furnace, a combustion tunnel extending transversely of `said heating section below said muiiles, gas4 conducting connections from said tunnel into one of said wall` muilles and into said intermediatemuilie, a second combustion tunnel extending transversely of means for controlling the flow of gases through Asaid muilles.

i 4. In a fuel fired muffle furnace, a plurality of oppositely and alternately disposed transversely directed burners, transversely disposed combustion tunnels for said burners separated by parallel walls supporting the floor of said furnace, side muffle walls supported at the ends of said tunnel walls defining side muffies communicating with alternate tunnels at the ends opposite said burners respectively, central mufe walls sup--` ported on` said tunnel walls inthe mid-portion of said furnace defining a central muiile communieating with each of said tunnels, exhaust passages leading fromsaid mufles, pilasters of varying heights supported by said tunnel walls Vdisposed in said mufliesfor distributing-` the flow of gases from said tunnels to said passages` within said Inules, and meansfor apportioning the flow of said gases between the several munies.

5. In a fuel fired munie furnace, aplurality of transversely directed burners, transversely disposed combustion tunnels for said burners separated by load bearing walls, sidemuille walls supported at the ends of said tunnel wallsdefining side muflies communicating with said tunnelsl at the ends thereof, central muflle walls 'supy ported on said tunnelwalls in the mid-portion of ,others oflftunnelsy meansV for establishing tun-nel, side munies suppgiftedA above and VaizQthie .engs- .of sa'idvtunnels and extending 'transversely thereof, @een .side munie oommunicating with one bun-nel "et fthe..1er-urlepileele.,lille burnerJ a central muiiie .disposed above said tunnels and between said side' inutiles and extending .substantially par ail-lei with sai-idside munies, said .central .mume eemmunieelins Witllbeth .Seid tunnels, exhaust nasseges .leading ,from each .-.of .said munies sep.-

erelelu. eue-means, .fer eeulrelllue the new ,er gases A tl1r1euel1-said .exhaust passeges whereby tie apportion the heat between said' munies. 7. In a fuel fired munie furnace, e pair of .teensveitsely .disposed 'Combustion tunnels. burners .disposedin K. the .ends .of .said tunnels, side` ,munies supported above and at the Jelldvsof `saisi tunllle and .extending `tiunsversely thereof,V each. side munie .communicating with only .one .combustion tunnel et. .one end thereof, e ceutifalmume ldis,- Dosed aibove said tunnels endbetween [Seid ,side ,muilies and .extending substantially pagelle), with said ,side mumes, said central militie communi;- oting with both ,said combustion tunnels, ex; haust passages leading from .each ,of seid 13iL11i1es seperately, .and meansY .for .controlling thelfiow of l eases through .leach uof ,seid .exhaust passages dependent1y.

PAUL s.

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