US2550807A - Tunnel kiln - Google Patents

Description

6 Sheets-Sheet 4 V .L l ////U/////////W////////////////// l l l l l INVENTOR. Wil/iam L. Hun/@Jn W. L. HANLEY, JR

TUNNEL KILN May 1, 1951 Filed Feb. 19, 1947 7 2,550,80 w L.. HAN'LEYJR May a May l, 1951 w. L. HANLEY, JR

TUNNEL KILN 6 Sheets-Sheet 6 Filed Feb. 19, 1947 JNVENToR. Wi /liam L. Hdn 165,3?.

Patented May 1, 19h51 TUNNEL Kim- William1LeHai1ley,-Ji'., GreeimiichefGionns;asa

vSignum-.1o1Hanley#Company, Inc., a corporation` Appliat Ftm'ryis, 1947, serialvNo. 729,558 Y 29. claims; (c1. 25-142) Thisr invention is* concerned with: improve@ mentsA in brick-and tileekilns of the `tunnel type',`

ascommonly employed forI 'theA heat 'treatr'nent of such ware.

This invention relates totunnel kilns or4 'ovensespecially designed fornringlclay products such* as bricks, nre brick,l tile-'andther like; either of" the-glazed or unglazed^types- As is us`ual1in-the use of tunnel kilns; thev/aretofbe red'isrmoved progressively Veither continuouslyorV 'intermite-4 tently, through the kiln-fromfits entranceto its exit at a controlled-speedtoeffect'therequiredheat treatment thereof. TheWare-is placed-upon cars vor trucks which-hare in end wend-contact toform a continuous Vlineof trucks; 'entirely-nh ing the kilnthroughoutits length. These trucks 3 are progressed intermittently or continuouslyv throughY the kiln by `intermittently or "continu--l o'usly pushing freshly-loaded cars through the entrance-end ofthetunnely thereby moving the` entire line, 'so that-a truck Aon which the Ware t and Ycooled lto avv safe temperature forfexpo'sureto the ati'nosphe-re;A at the'ltime of dischargefrom*- thekiln.

In accordance with thisinventi'on; the kiln --isf' effectively divided longitudinally-into -aplurality of;zones, in each of which the temperature-fand'I atmospheric conditions can be ycontrolled `from end'to end to effect avery accurate Land emcient heat treatment of- `the Ware. Fundamentally;

the kiln herein disclosed may be-longitudinallyv divided from its entrance to itsvexitxendinto `a low. pre-heat zone,v ahigh pre-heat zone,` ahntzoneand acooling: zone;

O'ne object of this invention is to: provide "a physical structure wherein these-'four zones may* be effectively established-and maintained under very accuratelyz'controlledconditions. and,A Wheream in, Within each vzone both atmosphericandftem-i perature conditions can be controlledis'oasto'. effectively establish `within eachv zoneion'e- Orl-more subsidiary zonesof different temperature-andatmospheric conditions;

Another object of'thisinventionisfto previden-` method -Wherein efficient iheattreatment offwar ofthislkind, involving'ithe stablishmentef d-ifl-n c ferent-and closely controlled; atmos'phericzantlfwg Fgure ista-thorizontal: crossgseetinallview? '21, temperature conditions; asf between; zones; of@ treatmentz. and:withinueaclnzone, vx/hereby; any number of efficient and teiective,processinggcyclesft cam-beprodcedg.

Another obctfofrthefimzentionis: t0DrGydea tunnel kiln and methods of operating it wherein; amaximumiutilization of ga-11 ;:,heat putj into the processeis obtainedr A-,.:stillz.fnrtherA object off the l iru/ention` is to prox/ide1.a;kilrrstructnrek ,nich-isreadilyadaiitel;g with minor alterations.- `Qrzfthe continueustreat 3 mentzof :glazedgor unglazedL- warein eithersmall orgl ge size I Y :important.,r obieeteoffzlh@ invention, hotly from a structural and operan ingvievvpo inti is the. pmvisionofuneans fortransfelringpthehgh temperature@ maints voff cembustonipfromthe not. zonen. di ctly into.- hez-hligh .1 -nrefheat Zone; fori heatinathe wareby; c eetecontact o f .the products offcombuetiornthereyvith,L andfcr directly; trans.- ferrfine z1 heseeproductsoffcmbution somewhat, cooledwtogthe lempgrheatf-,zona rv'for traurisferof1 heat'lbyvradiationmo ther :green ware without d iQ-L retgcontact therewith. Aslafurther; factor. f' efficiency, vtheseflegrodtictsl of combustion aethn t transferredatoftheldriers, where the :'freslily.mold'fVA edigreen L warey ,is dried: i n preparation t for intro-f ductionfinto; e tunneI llilrisy AnotherI .object :of: thisf rinventio'ii is'l Y th i5' 'ff vision 5 of apparatus-.arid operations't whereby the Afired-1wareis cooledlunderclosly controlled (sn-`V ditions through the.;k variou Other andfmorefd'etaild objects-.of the invenL non `wm ,be arnptubern;f raingtheL description ,whim follows wherein theembodimentselected forlill tration in-,thidlfaWlSisdefibdli hflllit l.

.This invention resides vvsulosta'all'y. 1n the ,omf., bination,l constructionrarrangement, relative 16.-,- cation@ o f `1'J a1 ts steps,=and series ofV steps",y allk as. hf-reinafter,fl yg disclosed.

Figurer;v 2V 'isfy a horizontal crass sectional; view;` 'takenlon the1ines;-2. :fof Figures;5.andgi,showyV ing the;adjacent;,portions-vof the; highipregheati zonefandithelhotjzon.;

. 3 taken on the line 2-2 of Figure 8 of the indirect hot zone; line 3-3 of Figure 9 of the direct re zone; and line 4-4 of Figure 10 of the cooling zone;

Figure 4 is a horizontal cross sectional view taken on the line 4--4 of Figure 10 showing the cooling zone and the tunnel exit structure;

Figures l, 2, 3 andfl when arranged end to end in that order illustrate-a horizontal cross sectional view throughout the length of the kiln taken at the various levels indicated above;

Figure 5 is a vertical cross sectional View taken on the line 5-5 of Figure 2;

Figure 6 is a vertical cross sectional view taken on the line 6-6 of Figure 1;

Figure 7 is a vertical cross sectional view taken on the line 1-1 of Figure 1;

Figure 8 is a vertical cross sectional view taken on the line 8-8 of Figure 2;

Figure 9 is a vertical cross sectional view taken on the line 9-9 of Figure 3;

Figure 10 is a vertical cross sectional view taken on the line Ill-I 0 of Figure 3;

Figure l1 is an enlarged vertical longitudinal cross sectional view taken on the line II-II of Figure 1;

Figure 12 is a vertical longitudinal cross sectional view taken on the line I2-I2 of Figure 2;

Figures 11 and 12 when placed end to end in that order represent a single vertical cross sectional view of the high pre-heat zone; and

Figures 13 and 14"taken'together are horizontal cross sectional views similar to those of Figures 1 and 2 of a modied structure in which no tube section is employed. y

As will be well vunderstood by those familiar with the kilns of this type, the construction usually employs a suitable foundation and an overhead structural steel framework, for'supportingv the kiln housing proper. The housing is constructed of brick and-cementing materials, and those parts thereof which come in contact with the high temperature gases are constructed of refractory brick and cements. Little further references to these materials is deemed necessary in view of the fact that from the nature of the structure and its intended use, as will appear hereinafter, the kinds of materials suitable at the various structural locations will be known.

' The car receiving end of the kiln and the low pre-heat section thereof, sometimes referred to hereinafter as the pipe section, are generally indicated at Ill in Figure l, while the high preheat section is indicated at I I in Figures 1 and 2. The hot or firing zone is indicated at I2 in Figures 2 and 3, the cooling section at I3 in Figures Sand 4, and the delivery section, which may be considered to be the terminal end of the cooling section, is indicated at I4 in Figure 4.

The receiving end consists of a double Walled housing 21, which can be closed, upon introduction of each car, by means of a readily movable door, not shown.' The double walled housing, as well as the remainder of the kiln structure, is supported on a suitable foundation F on which are mounted, in the usual manner, a pair of car truck rails R, over which the cars C carrying the ware W tobe treated may roll through the tunnel formed by the kiln.

The remainder of the kiln lhousing K, as illustrated, is built up of brick of suitable types as previously mentioned. The low pre-heat section I0 is arranged as a longitudinal continuation of the double walled housing 21, and is built with a greaterwidthrasshown in Figures 1 and 7. to

are longitudinally divided into separate chambers. These ducts may be divided into chambers by means of cross walls as diagrammatically illustrated in Figure 1, in which blowers 23 are mounted. These blowers are provided with driving shafts 24 to be driven by motors, such as the motor M illustrated in Figure '7. Each of the chambers, formed in the ducts 2li, communicates with the space between the headers i3 and I9 by means of passageways 2|, only one or" which appears in Figure 7, because, as is clear from Figure l, the section of Figure 7, is taken on oppo site sides of the center of the tunnel at different longitudinal points. The blowers 23 are set into the ducts 20 so that their suction sides are respectively open to the chambers, into which the ducts are divided, as shown in Figure 7. The discharge sides of these blowers open into another pair of longitudinal ducts 25, which are sectionalized by cross walls so that the ducts 20 and 25 have the same number sections. The sections of the ducts 25 are provided with a series of discharge slits 26 which are shaped, as clearly shown in Figure '7, so as to direct the air discharging through these slits in an upward direction more or less tangentially to the arch of this section. As the slits 26 do not extend throughout the length of each section but they too are sectionalized, they appear only at the lefthand side of Figure 7, for the same reason that the passages 2| for both sides do not appear in that gure. Each of the compartments of the ducts 20 are provided with passages 22 connecting them with the atmosphere. These passages can ibe dampered to permit the introduction of controlled quantities of tempering air, when required, as will be explained later.

Special attention is drawn to one important improvement in kilns of this type as represented by the structure described above. It will be noted that the blowers 23 and their driving equipment are mounted at floor level and at the sides of the kiln so that they are easily and conveniently accessible Afor repair and replacement. These blowers can be standard commercial products designed to withstand the temperatures encountered and the kiln is arranged as clearly shown in Figures l and 7 so that they can be slipped into place at the sides of the kiln to eiect by such placement direct interconnection between the ducts 2t and 25. This represents a very practical feature in the maintenance of the kiln. Another important advantage of this arrangement is present in the fact that these fans and their operating equipment are placed at the cooler level of the kiln which contributes to longer life with less maintenance. An overall advantage of this arrangement lies in the fact that in the case of breakdown of one of the fans it can be quickly replaced by a spare fan without shutting the current down and allowing it to cool as is the case with some prior kilns. Attention is also directed to the fact that in the arrangement disclosed these fans are placed at both sides of the kiln andthe duct system is sectionalized so that cirestupor-r is..'connected. Although .notrshowm the .delivery` side. cf the blower ;;2.9.=is :usually -aconnectedpby meansof la. duct to thezdrying.;ov,ens, .inzwhichithe fresh moldedgreengoods are preliminarily dried, y

inpreparation for introductioniinto theliilnt dteferring `to Figureatheres shown a :pair .of high temperature blowers 3l, provided withoperating `shafts `3 2 .to -bedriven :by y means .0f-:motors not. shown. The dischargeisides of thesejblowersl are connected to zazpair of. ducts `.which extend longitudinally of the high.preheatsection .ll in the, side `walls of this section, as is ,clear from Eigures 5 and 6. Built into the sidewalls isa longitudinally inclined 'division wallv A:34 .which extends upwardly ff-rom `the -blowers 3| -to the headers .lfsee .Figures .l1 and12. These walls 3.4l invrthis position divide these ducts into two passageways .33 and36 of .gradually changing erossectionalarea. ,The passageways 33 fare of gradually diminishing cross .sectional ,area from thehlowerszl tothe headers I9, while thepassageways 3 6 .are of gradually `increasing cross sectional area in thesame direction. The inner wallcf each of these .ducts forms :the dening wall for lthe car tunnel in ,the section H, as is Clearfrom :Figures- 5 ,and \6. This 'wall :is vprovidedrwith afseries of longitudinally spacedopenings .35, near the tunnel arch, Ywhich establish cQmmunication between the passageways -33 and the tunnel proper. similarly, there ,are formed at the bottom of these walls at longitudinally spaced fpoints a plurality .of iopeningsl Vestablishing communication between the ,passageways 36 iand the tunnel proper. Each passageway 33 :is izprovided at .several .spaced points with branch pipes. 39, whichl connecty with pipe headers` 3.8,extending longitudinally of the kiln. By this arrangement tempering air can befed at `a pluraltyof Vpoints to temper the ilueggas delivered by the fans 3l .so :aste flatten 44outfthe heat-.curve in this section of the kiln, if desired. -Thelower de ning wall of eachof thepassages .35,- -is inclined-upwardly so .as to dischargegases `.from the .passaeeways 33wtangentia11y .of :the Vtunnel auch. HSome or all of :the passages '(31 fare provided with damoerstl and damper .operating levers 4l, operable from the/exterior-of thekiln forcontrolling, at various longitud,inalpoints` the rate-.of ow of gases through` the Apassages 3l. A;s wl1-appearmore clearly hereinafter, thepassages 35 serve to-dischargegasesginto the tunnel proper, while vpassages 3l provided exhaust passages through .which these -gases are rwithdrawn into the passages 36.

lyvreference .to Figure 11, `it ywill be seen that the passages 36 o pen directly into .the -tubes .-l-l.

'The yintake ports .of the blowers SI-ccmmunicate wtha pair of ductsZ formed in .andretewards the .bottom -of the side walls .of the `hot zoneior ringsection `I2 ofthe kiln. Theseiducts extend throughout the Alength offthis` section-of the-kiln. This ,section may be .divided ,into two `.Sub-.sections in thesense .that the; fuel burners tion,- Afare .arranged --tot-effect :indirect and direct r-in'g; ein* thatsequence. uAs shown in Figure'8, asseries .of burners f43f are .mountedon each iside otheitunnel-propenonly oneappearinginligure because, as nin :the :case -lof Figurer?, the .cross section ori-opposite sides -of lthe center -line `is =at two different-longitudinal points. v.'Ih'eseiburners are of the type for burning gaseous fuel, i which burns, `lin v-.anmpen name; 1in.an=upward1yxtending passageway, the-inneriside'of'which is 'formed' by; a sbaile rwalllM. Thepassage opens lupwardly ina :direction fta'ngential l tof-the .arch of the tun-1 nel, as shown, so the :hot .gaseous Yproducts .of combustion fare discharged lupwardly' against I'the tunnel .arch. 'The "burners #43 lare arranged-fat spacedzlongitudinalfpoints, =see-Figuresf2 Afand-3,; in opposed pairs. `At intermediate points, fthe ducts fdare .connected to the tunnel-proper-fo'y means :of .'passagesd, controlled byedamp'ers +46 and` operating .lever-S141. 'The construction'fo'f Eigurei Eis .that -of the -sub -section vin which -lindirect ring iis effected. rIhe description Vof fthe structure o'f .this invention :has 4proceeded far enough to Lm'ake fit :apparent to those skilled iin the v`artfthatLit isfa'daptable to the use-of-anytype ofxf-uelsuitable for .the ring of -clay'fproducts as,'for.example, coal,r oilrandithe'like.

The construction of Figure -9 iis .in -the subsection at :which :di-rect :firing occurs. v In this case, :as illustrated,I the-fuel burners 43 4`are-arrangedso :that the :flame l directly limpinges upon the iware. The burners l"113', "as -is clear lfrcm Eigurei, are :arranged in transversely .aligned pairs whichA does Ynot :appear from Figure L9, `be causeffan oiset cross section -like those' previously described is shown. staggered with yrespectfto theseburnersfareiadditional passages dfbymeans of swhich the ytunnel `proper-is connected 2to the ducts/14.2. As ebefore, .the dampersll and V'control levers'di'l '.areprovided.

At this point it may be noted thatth'e structure selected for illustrating ithe invention Vherein -is imma specialized Iring lprocedure which is Lnot Aof general application. In the Lmore normal Vfiring procedure the .direct -ring sub-section just describediwould not be used. '-Inlthe-particularfprecess: =forawhich this J kiln =wasdesigned fthe direct' ring-'sub-sectionis employed'fto evenup the-temperature .as between the topand the *bottom yfof the'car stacks. Thus,=byfdirect -r'ing the -temperature at Vthe bottom .of the-stacks y may be brought uptothe :temperature atthe top `of 'the the zinner faces of :which-:lie in the plane of Ithef restricted connecting section 100, -prevously=de scribed. Thus, the cooling vsection Yis-eilec'tively subdivided :intera plurality of compartmentsisolated rom each other, when the loaded carsare inthis'portion of the tunnel. Each of these com- Dantments is-provided with a passageway 99 con.- nected `.to longitudinally vextending warm v-ai-r supplmpipesll which areaconnectedto the outlet of -fansa The inner ends v,of the/passages open. j through :slots j5| .to :the `interiortheitllnrltp.

proper. Formed in the side walls, near the foun-v dation level, are the longitudinally extending ducts 50, which are connected at each of the compartments referred to above with the interior of the tunnel by means of the passages 52. These passages 52 are controlled by means of dampers 53 and operating levers 54 as shown. The intake side of each of the blowers i8 is connected by means of couplings '59 with the ducts 5G. These blowers Vare driven by means of motors, not shown, connected to the blower shafts 49. The discharge ports of the blowers 48 are connected'to conduits 96 for warm air recirculation -in the cooling zone sections; and part of this air may be delivereclto the drying ovens, vas a source of heat to dry the freshly molded green goods, supplied,

as pre-heated air, tothe burner nozzles, or used for any other purpose for which this air is useful.

,The terminal end I4 of the cooling section may serve as a seal through which the loaded cars move in a relatively close fit to the discharge end |6 of the kiln, which may be provided with a movable door, not shown. By making the section I4 long enough in relation to the fit which the loaded cars have therewith the openingof the door at the end I6 will not permit of the entry of air in suicient quantity to upset the closely controlled cooling cycledesirable for most effective economical operation.

ln the operation of this kiln, in accordance with the methods of this invention, the pre-dried green ware is introduced, a truckload at a time, into the tunnel kiln throughthe entrance l5. The initial starting period represented by the time it takes to fully load the kiln is of no consequence in the normal operation of the kiln. It will be assumed, therefore, that the entire tunnel is occupied by a line of cars, which are in end to end contact from the entrance end to the exit end. The heat treatment of a freshly introduced car will be followed as representative of all other cars during normal operation.

The door'at the entrance end l5 is opened and a mechanism, not shown, causes a car loaded with greenware to be slowly forced into the kiln. At this time the door at the exit end is also open, since the introduction of one car causes the ejectionof one car (fully processed). In the usual operation the cars are introduced singly, at spaced intervals, so that the movement of the line of cars is, in effect, intermittent. As soon as the car is fully introduced into the housing 21, the door at the entrance end is closed and, likewise, as a car has been ejected, the door at the exit end can be closed.

The hot gaseous products of combustion, which between the ware W which is preferably stacked on the cars C in two transversely spaced columns, as illustrated in Figure 6. As is usual, these columns are arranged so that each article is exposed as much as possible to direct contact with the hot gases. Therefore, the articles are stacked in labyrinth style to form an openwork lattice through which the gases may circulate. The gases after contacting the ware are withdrawn 8. through the ports 31 which connect with the passageways 36, in turn connected with the tubes l1. The passages 36 in effect are suction passages since they communicate through the tubes |1,

I the double walled housing 21, passage 28 with the intake of the suction blower 29. By placing the exhaust ports 31 at the bottom of the passages 3S, the hot gases are caused to circulate in contact with the ware W throughout all portions thereof, so that the lower parts of the ware stacks are properly heat treated. By adjusting the dampers in the passages 31, any desired rate of gas flow at di'lerent cross sectional regions of the tunnel can be effected, so that the rate of heating 'j of the ware, as it progresses through the high pre-heat section, for example, gradually increases, insuring that the ware in leaving this zone will leave it at the proper pre-heat tem-` perature.V v

The heat curve in this section can be flattened out, if desired, by the introduction of cool air through the ports 39, see Figure l2.

' of the blowers v23 and the sectionalized construction of the ducts 20. Each of the duct sections is provided with a passageway 22 having a damper 22 by means of which the air may be tempered by allowing entrance of relatively cool outside air therethrough. Here again, various ternperature conditions can be maintained at Various cross sectional regions of the low pre-heat zone. The air circulating around the pipes |1 is recirculated, and its rate of circulation can be controlled in one practical manner by varying the relative speeds of the motors M. The air is discharged through the slits 2B in a generally upward direction and in passing over the hot tubes |1 is heated to the desired temperature. This heated air circulates through the warestacks and down between them by being directed not only onto the sides of the stacks but onto the top by the tunnel arch and down between the stacks due to the natural circulatory flow created by the relative arrangement of air supply slits 26 and exhaust passages 2|.

The products Vof combustion still further cooled then ow through the double walled housing 21, where the freshly introduced goods is initially warmed up by the radiation of heat from the inner walls of the housing 21.

In the low pre-heat section those types of ware, that is, particularly glazed ware or face brick and tile, are raised to the proper pre-heat temperature under conditions where the sulphur and other deleterious content of the ware that is driven off in the high pre-heat zone is removed from contact therewith, preventing contamination of the ware.

The hot products of combustion are generated in the firing zone by the burning of the fuel in the burners 43. The burning fuel does not directly impinge upon the ware by reason of the bridge walls 44. The hot products of combustion, however, are discharged into the tunnel proper so as to insure, as nearly as possible, uniform ring of the ware. The gases are guided by the tunnel arch down between the ware stacks,

. tarantino? 9 and .these eases .iare'fwthdrawnfxnear -theibottom gof" the stacks through .the passages 1.45 1i-tothe A,suction lducts-.132 fsoxthat all Itrtskr of-.the .stacks are-heated.

AIn the' direct .burner .fsub-:sectionmas is clear from xFigure-9,-thefiiames* generated bythe -burn- .-.ers 43 directly im-pinge-Tupon-the sides-of `the ware--columnsas .distinguished from the previous sub-section, where suc-h @mpi-agement is pre- .vented. Thus, .atTthe-endof the heating cycle and. for a. relativelyshort '.-period of timey the ware `.is subjeetedto -thgdrect action loflthe burning -fuel whereby the ten-ip eraturefof the ware `inthe `.stacks is evened up, .as previously explained. As .previously explained, .all .ofathe .products of wcombustion. of. the tiring-,zene :are withdrawn through .the Yduets 42 fby.V the .,high-,telnperature blowers 3 I The ,cars then-:move inte. the-coolingaone `which V,is effectively sub-.divided Ahymne.baillewvalls 55 into aseries of chambers -.in.tvhic.l:ltherci-rculating ,atmosphere can bemaintainedatvarious temper- ,.atures, and ...generally Speaking, vat..succeed-ingly .1o-wer temperatures, .Wherebyany desired .cooling cycle may. be carried. out. -As .,.is ...well `.known in `-this art, therey .are .particular ktemperature gradients .to be .maintained and.. critical.. temperature points .through ,which. the ...ware `must .be carried. during. cooling, t0'- Prevent undue, .shrink- ...age .and distortion ,of the ware.. .due .to too i rapid cooling. By` .this .arrangement ...the quantity ofA air and its temperaturentering the V.compart- .Jnent is such .that ,a..prede.termined accurate 4LaIIiQllntof 4heat can .be vWithdrawn .fromthe ,ware ,."to ,L attain these ,criticalgtemperature condi-tions at various. succeeding .time intervals,l so that. the .ware .will be cooledin accordance -With..prede termined ,and `known .desirable conditions. .It is 'also possible to insure ,that the jwareby the time it reaches theexit 16, willlbgeata safe .temgperature for. `eiqzlosuretothe.. atmospherewithout damaging effect. lndeedjtis usually desirable 'that the .Ware come fram. thjeqkiln .at .a .temperature at whichit can be handled; whchondition can readilybe.attainedwith this uarrangement -of all heat puifirito` the system" is elected .and that, for example-ijn the case of .',Clmtaminatihg A`atmospheres,-such as are'generated in the high `pre-heat and hotjzlones, the remaining heat of r-contamination oi??` the wareiby reason of` the'evo- -lution of poisoning gases in the high prefh'eat ygzone, fis prevented-so ithatlbuti a` :single pre-heathgzonevis-.necessary `lnft-hat case the muflle comprising the 'pines' tIlyof the. low prevheat zone can vbeeliminated, and :what was previouslythe high pre-heat zone can be merged `or expanded .A intoa Single pre-heating zone. JIn 'that jeasethe of the relatively ,expensive 4,m-ufile.

l ..45 In'review it `will beseenthat Very efcient -use -zone fwithout rstrequiring .van :intermediate which. are often dictated .bythe physical-chemical /nature of the clay` from `.whicl'i ther products uare. molded.

It should be pointed. outthat the kiln herein disclosed: as `zwellias the method cf` operatingv it described abovef-isoispecial valuefin. the .firing 0f glazed clay` products: andsfaee abriclc. andV tile. .Howeven inthe oiunglazedpnoducts,such

Yaas.: common brick, .the dangerpot .discoleratiqnand with any-desiredfprerequisite fconditionsfsomeof In .the .ring ofsometypes. of wareas Edistinguished from the specialized. situation `for which. the .structure .of .Figures .-1 to-12, inclusive, .was devised, itis practical to substitute r,for the tube section vcomprising the Vlowure-heat .section a .lowpre-heat .section-of modified construction as shown in Figure 1.3. -Thissection .is illustrated in Figure 13 as the generalassembly indicated .by the -referencenumeral'10V-and replacesy the section leof `Figure 1, '.Inlcons'truction the 4section ,l-U" is .a substantially..;exact Vduplicate .of the high preeheat section .show-n in .Figures,.1.and :2,

.and `sectien .lll .is .illustrated in Figures 1.3and E14 tofshoyv .its relationship to the :new section llfl) Structurally.,. section ...l 0?-v comprises a ghousing.,K

of. refractory. materia1hav ing.ducts 33 and '36) 4in the side A. fwalls thereof The righthand ends ofthe ducts arefconnec'ted to the .outlets..of

blowers A34a having the .operating-shafts V3 2. The

inlet sides `of thesehlowers are connected to. the

lefthand endsof the ductstof thehignpreheatsection Il. The ducts33 .areof .gradually decreasing-...cross sectgn. towards Ithe .left o f ,sec-

ton. lll' just las `lthey...are in. the case of. section l l and illustrated in Figures .11`and,12. Similarly, the ,ducts 36'ar,e of gradually. increasing cross section lin the. samedirection .and resultlfrom .an

.inclined baule .Wall .34 corresponding, taithe ,bae

wall 34. Along the side of the passage 33 which Mde 1"inesthe. tunnel propenat the top are. thel inlets 3.5. correspondingto ,the inlets ,35x .o:E Figures `11 and 12 and..similarly,alongthe samewallat .the-bottomlthereof. are-.thelpassages 3.1L

IIt .will .loe ,.seen .then .that .structurally this 4Fmodified..1o-' v-.pre,heat section .10' lisV lquite the 4same in.constriuction,.as the highpre-heatsection-lil. .lnthernodied structure thereiis interposed. betweenthese two i. sections. the `blowers 1 3 I la. sa that ,the .i hot. .gases ...withdrawn from. .the

ducts `3.6 .are delivered :into the Aducts v33 and .fultimately .fpass ,from-.there into the tunnel through` theports .35?. From this tunnel they are ...Withdrawn through. the.I ports 31. into. ducts 36..and.from.ther e they. travel through the space ..2-1 formed by. the ,.double :walls at the. ,entrance tend. of the Y.kiln intoduct 281. and thence .,to f the ,blower .219 asbefore. V

In this arrangement. it. will be.- seen. that the initial or lowpreeheatstageof the processie carried eut fby .the direct contact of. the. heated .gases deliveredl from the. section l I into-.the section HL'. This. distinguisheswfrom the .arrange- -gnentpreviously describedwherethese same gases were ...used to. heat i air by heated .transference y through a .conducting Vv vall which .air in. turn circulated `irnecntact `.with .the fresh .incoming .Ware to give. ititsinitial .pre-heat.

u `Irwin new pe apparent" to theseA 'skilled vin the art that the subject matter of this invention in bothits structural and operational character- `isti ':s"is`capable of embodiment'in other physical "forms and uses and modifications Yin other ways" without departing from the novel subject matter herein disclosed. I do not, therefore, desire to be'strictly limited to 'the disclosureherein employed in an illustrative sense but only as required by the claims granted me.

What is claimed is: n

1. In a tunnelkiln, the combination comprising an elongated refractory housing forming a tunnel through which stacks ofrware to be heatv treated may move, said housing including a preheating section and a iiring section having fuel burners, means Vfor directing the products of combustion of said burners into the tunnel kiln into contact with theV ware in the firing r` section, means for laterally withdrawing substantially all of said products of `combustion from the tunnel kiln at the ring section, and mean-s for laterally discharging said withdrawn products of combustion under pressureY into the tun- Y nel kiln at the preheating lsection into contact' with the ware therein. ,Y

2. In the combination of claim 1, rsaid last two means including high temperature blowers and ducts formed in the housing walls for withdrawing the products of combustion from .the tunnel kiln at the ring section and discharging them into the tunnel kiln at the preheating section at longitudinally spaced points.

3. In the combination of claim 1'said fuel burners being divided into longitudinally spaced groups, means for directing the llames from some of said burners so as to directly impinge these ames upon the lower portions of the ware stacks, and means for preventing flames of the remainder of the burners from directly contacting the ware while directing the .products of combustion downwardly onto the upper portion of the ware stacks.

4. In the combination of claim 1, means in said ',firingsection for causing the products of combustion to circulate downwardly onto the ware.

5. In the combination of claim` 1', means in said firing Ysection for causing the products of combustion to circulate downwardly onto the`VV of combustion from the tunnel kiln of the firing Ysection Vbeing distributed to eiect withdrawal in the region of the bottom of the ware stacks at longitudinally spaced points, and individually adjustable means for controlling the withdrawal of the products of combustion from the tunnel Y kiln of the iiring section at diierent rates at said longitudinally spaced points.

7. In the combination of claimV 1, said housing including a cooling section, the walls of the tunnel in the cooling section having a plurality of pairs of longitudinally spaced and transversely aligned baille Vwalls effectively forming separate compartments in cooperation with the ware, and means for circulating cooling air in said compartments at'diierent temperatures.

Viso

8. In a tunnel kiln, an elongated refractory housing forming a passageway through which ware Vcars having the ware stacked thereon may be moved, said housing loeingl sub-divided into a low pre-heat and a high pre-heat zone and a firing zone, a plurality of burners for directing products of combustion into said firing zone, means for directing the products of combustion in a circulatory motion downwardly onto the ware stacks, means for withdrawing the products of combustion laterally from the ring section at the bottom of the ware stacks, means for discharging these products of` combustion directly into the high pre-heat section including ports in the housing for directing the products of combustion into the passageway at a plurality of longitudinally spaced points near the top, means for withdrawing the products of combustion from the high pre-heat section at the bottom of the ware stacks at a plurality of longitudinally spaced points, a heat exchanger in the low pre-heat section lthrough which the products of combustion pass and means for creating a plurality of eilectively isolated parallel paths of Aair circulation over said heat exchanger and into contact with the ware stacks in planesat right angles Ato the path of movement of the ware stacks.

9. In the combination of claim 8, said last means including Control meanswhereby different temperatures may be maintained in said parallel paths of air circulation.

10. In the combination .of claimV 8, said last means comprising longitudinal ducts in the wall of the low pre-heat section of said housing, means 'for sub-dividing said ducts and individual means for circulating air through said ducts sub-divisions into heat exchange relation with said heat exchanger and the ware.

11. In a tunnel kiln refractory housing forming alow preheat section through which ware stacks may be moved, means for passing heated gases through said section along conned paths, means for causing a continuous circulation of air in heat exchange relation with said last means, and means for discharging such air after absorp- -tion of heat from said rst means downwardly onto the ware stacks in a series of longitudinally aligned parallel paths in planes at right angles with the path of movement of the ware stacks, and means for maintaining the air in said parallel paths at different temperatures.

12. In the combination of claim 11, saidV last means including means for introducing cool air in controlled amounts into said parallel paths.

13. In a tunnel kiln the combination comprising an elongatedrefractory housing forming a tunnel through which products to be heat treated move, said housing including' a ring section having fuel burners and a preheating section having a heat exchanger therein, a pair of ducts in each side wall thereof, one duct of each pair lying in a plane above the other duct of that pair, the lower duct of each pair being near the base of the housing, means for connecting the upper duct of each pair with the tunnel of the preheating section so as to discharge air upwardly onto said heat exchanger, the lower duct of each pair being connected to the tunnel at the preheating section below the heat exchanger, and air circulating means interconnecting the lower duct of each pair with the upper duct of each pair respectively, whereby air is circulated from the Vlower ducts to the upper ducts to cause the air discharged onto said heat exchanger to circulate 14,"1Inifithe :combination :ofoclaim 13, fs'aid; air circulating:meansV lyingafintrecesses in'they outer rside .walls l of .saidy housing ALat'-substantially the it .bottom level thereof.

Vl5.' InYa'tunnelkiln. a refractory housingiformgaseouslproducts .ofcombustion at a--.plurality of longitudinally spaced points in said section, means for directing the products of combustion from some of said generating means so as to directly mpinge them on the adjacent ware, means for directing the products of combustion from the others. of said generating means upwardly to the top of said tunnel and downwardly opt0 the ware, and means for withdrawing the products of combustion from the tunnel of the ring section at a plurality of longitudinally spaced points in differently controlled amounts near the bottom of the tunnel.

16. In a tunnel kiln, a refractory housing having a high pre-heat section forming a passage- Way through which ware to be treated may be moved in stacks, means for supplying hot gases to the passageway thereof comprising pairs of ducts in the side walls thereof, the ducts of each pair being arranged one above the other, the walls forming the passageway, a plurality of longitudinally spaced ports connecting the upper duct of each pair with the passageway and ports in said walls connecting the lower duct of each pair with said passageway and means for causingv hot gases to move through the upper ducts of each pair into said passageway and from said passageway into the lower ducts of each pair.

17. In the combination of claim 16, means forindependently varying the size of the ports of one ofthe ducts of each pair to produce differenttemperature conditions longitudinally of the passageway.

18. In the combination of claim 16, said first ports opening into the passageway near the top of the ware stacks and said second ports opening into the passageway near the bottom of the ware stacks.

19. In the combination of claim 16, said upper v ducts of each pair being of gradually diminishing cross sectional area in the direction of gas flow and the lower ducts of each pair being of gradually increasing cross sectional area in the direction of gas flow.

20. In the combination of claim 16, said housing having a low pre-heat section, and a heat exchanger in said low pre-heat section in direct communication with the lower ducts of each pair.

21. Inthe combination of claim 16, said housing having a low pre-heat section, and a heat exchanger in said low pre-heat section in direct communication with the lower ducts of each pair, and means for causing the circulation of air in closed circuits rst in heat exchange relation with said heat exchanger and then with the ware.

22. In the combination of claim 16, said heusing having a low pre-heat section, and a heat exchanger in said low pre-heat section in direct communication with the lower ducts of each pair, and means for causing the circulation of air in closed circuits rst in heat exchange relation with said heat exchanger and then with the ware, said last means including ducts in the housing wall having a plurality of sets of openings ar- .-frangdt toffdischarge 'gases into:fsaidz--passgcway into hea-tgfexchange. 'relation I.with-3; said :theatsexchanger-while'. moving in a '(direction toward said passageway.

23. In the-combination of claim 15, said last .-..rneahs -v including ducts in the housing wall, a

high preheat section also formed-by-.saidhousing, and means for directly transferring the products of combustion from said ducts directly intothe tunnel of said preheat section. '"24.- Ina tunnelv kiln the combination comprisling a refractory housing forming Aa Vtunnel through which ware stacks may be passed, the entrance end of said tunnel forming a preheating section, ducts in said housing at the preheating section for supplying heated gases to the tunnel at that section and removing them therefrom, said ducts being sectionalized, power driven blowers in each section of said ducts arranged at the sides and at the bottom of said housing and directly accessible from theexterior thereof.

25. In the combination of claim 23, said blowers including housings which can be set into openings in the sides of the housing to effect interconnection of said ducts.

26. In a tunnel kiln, a refractory housing forming a tunnel through which ware stacks may be moved on cars, said housing including a cooling section, means for introducing air into the tunnel kiln of the cooling section under pressure at a plurality of longitudinally spaced points, said last means being spaced laterally of the ware so that the incoming cooling air is warmed by admixture with the atmosphere in the tunnel kiln of the cooling section before it strikes the ware,

and means for withdrawing the air from the tunv nel kiln of thecooling section near the bottom of the ware stacks at a plurality of longitudinally spaced points.

2'7. In the combination of claim 26, said last means comprising ducts for introducing the cooling air into the tunnel of the cooling section at a plurality of longitudinally spaced points, whereby the cooling air is caused to circulate transversely of the tunnel in a plurality of substantially isolated bodies to maintain different temperature conditions in the tunnel.

28. In a tunnel kiln the combination comprising a refractory housing forming a tunnel through which products to be heat treated are moved, said housing including a ring section having fuel burners and a preheating section having at least one pair of ducts in the side walls thereof, each connected with the tunnel by lateral ports, one of said ducts being atA the base of the housing and the other near the top, and circulating means for withdrawing the products of combustion of said fuel burners from the tunnel of said firing section into said lower duct and for discharging said products into said top duct, said products moving from said top du-ct through its lateral ports vinto the tunnel at the preheating section.

29. In the combination of claim 28, a second preheating section having at least one pair of ducts in the side walls thereof and connected with the tunnel by lateral ports, one of the ducts of that pair being at the base of the housing and the other near the top, and circulating means for withdrawing the products of combustion from the duct at the rst preheating section into the lower duct of said second pair of ducts, and discharging them into the top duct of the second pair,

Vwhereby said products are discharged into the tunnel at the second preheating section.

WILLIAM L. HANLEY, JR.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number ils Number 16 Name VDate Robertson Dec. 30, 1924 Straight Feb. 9, 1926 Richardson Sept. 14, 1926 Booth Jan. 8, 1929 Bergman Feb. 5, 1929 Meehan June 17, 1930 Ogden June 24, 1930 Prouty et a1. June 14, 1932 Ladd June 4, 1935 Ladd Jan. 5, 1943

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