US2045920A - Tunnel kiln - Google Patents

Description

me 3Q, i936. Q H, PARMELEE 2,645,920

TUNNEL KILN Filed Feb. 27, 1936 4 Sheets-Sheet l -@O W u m INVENTOR (Uffa/Po /K Evi/##105 ATTORNEY Patented June 30, 1936 narran srargs LMSZ@ PATENT FFQE TUNNEL KILN Application February 27, 1936, Serial No. 66,038

12 Claims.

The general object of the present invention is to provide an improved tunnel kiln of the type in which the wares or goods treated are moved through an elongated kiln chamber by means of 5 a reciprocating ware moving means extending longitudinally of the kiln chamber beneath the Wares, and given up and doWn movements to alternately transfer the Weight of the wares to and from said means, respectively from and to adjacent stationary Ware supporting means, and being moved longitudinally of the kiln in one direction during each period .in which it'supports the wares and thereby giving movement in the same longitudinal direction to the wares, and bef ing given a return longitudinal movement, without corresponding movement of the Wares, during each period in which the wares are supported by the stationary ware supporting means.

In known kilns in Which the goods or wares are moved through the kiln chamber as above described, the movable Ware supporting means Y comprises one or more beams each movably re'- ceived in a corresponding slot formed in the bottom wall portion of a stationary kiln housing or kiln structure proper, such kilns being sometimes and aptly designated as of the walking beam type. My improved kiln differs from previously known kilns of the Walking beam type, in that the kiln housing of the improved kiln including the side, roof, and slotted bottom Wall portion of thekiln chamber, forms part of a movable unit which is given the reciprocatory up and down and to and fro movements required for the intermittent progressive movement of the wares from the inlet end to the delivery end of the kiln chamber. The provision of the above `mentioned movable unit simpliiies and facilitates the construction and operation of the kiln and its adjuncts in .some respects, and facilitates the inspection, repairs, and '-'J` reconstruction, both of the lower portion of the movable unit, and of the stationary part or parts normally extending into the bottom wall slot or slots of the unit, since, when necessary, the movable unit may be raised or lowered by jacks to provide increased access to said slot or slots and stationary part or parts.

To permit the major portion of the movable kiln housing, including the kiln chamber side and roof walls, to be jacked up or lifted entirely above the stationary portion of the kiln structure, I may make provisions for disconnecting from the said major portion, a relatively small lower portion of the movable kiln structure which would otherwise limit the extent to which the said major portion could be elevated. The ability to elevate the side and roof walls of the ykiln above the stationary portion of the kiln structure is especially important in a kiln in which the kiln cham-k ber height is quite small, as it needs to be in some kilns. For example, in gaseousr carbonizing, it has been found necessary in some cases to limit the height to which the wares in a kiln extend above the bottoni of the kiln chamber, to a distance of I2 or less, so asy to avoid an objectionable non-uniformity in thekiln atmosphere at different levels as a result of kiln atmosphere stratification caused by differences in the density of different vapor constituents of the atmosphere.

It is obviously difficult, if not impossible, for workmen to enter and Work in a kiln chamber of the usual construction and such small vertical extent, even though the width of the kiln chamber is many times the vertical height of the latter, vas it may be, so as to give the kiln a suitable large ware capacity without objectionable increase in l20 kiln length. In repairing a kiln of ordinary con struction and having a chamber of such small vertical extent, it would be necessary in many cases to open up the roof ortcrown of the kiln, but With the side and roof walls of the kiln chamber held well above the stationary lower portion of the kiln structure, as herein provided for, the then open underside of the kiln chamber provides ample access to the kiln chamber for repair operations therein. 30

For some purposes, kilns of the Walking beam type are provided with a hearth on which the wares are directly supported and which is interposed between the Wares and the Ware lifting and advancing means, said hearth being composed of plate or slab sections which meet edge to edge and are progressively advanced through thekiln. Such a hearth may be employed in my improved kiln when necessary or desirable, and my improvements include a special hearth construction desirably employed in certain cases@ In-my prior application, Ser. No. 17,420, filed April 20, 1935, I have disclosed and claimed a kilnk of the walking beam type characterized by the fact that the kiln is heated wholly or in part by ,4D means of one or more heating units each comprising an elongated combustion chamber formed in a'beam portion of the kiln structure beneath, and serving either as a movable or stationary support for the war-es. F

The kiln disclosed and claimed in my said prior application was especially devised, and is characterized by its adaptability for use under the special conditions required, or desirable in glazing or glost firing tableware and analogous ce- V ramic articles not enclosed in saggers, but freely exposed to contact with the kiln atmosphere during their passage through the kiln chamber. While capable of use in various forms and for various other purposes, in its preferred forms hereinafter illustrated and described in detail, my improved kiln is well adapted for the above mentioned special purposes of the kiln of my prior application, and a'specic object of the present invention is to incorporate the novel kiln features disclosed herein, in a tunnel kiln utilizing the general principles, and possessing the.

general advantages, of the kiln disclosed and claimed in my prior application.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages, and speoic objects attained with its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.V

Of the drawings:

Fig. l is a somewhat diagrammatic plan view of a tunnel kiln in section on the broken line I-I of Fig. 3, and with parts broken away;

Fig. 2 is a longitudinal section on the line 22 of Fig. 3 of portions of the kiln; v

Fig. 3 is a section on the line 3-3 of Fig. l;

Fig. 4 is a section on the line 4-4 of Fig. I;

Fig. 5 is a section taken similarly to Fig. 3, illustrating a modification;

Fig. 6 is a section taken similarly to Fig. 3 illustrating a second modification;

Fig. 7 is a partial section on the line 1 1 'of Fie` 6;

Fig. 8 is a somewhat diagrammatic plan View of a portion of a kiln provided with a modified form of means for giving the kiln housing longitudinal to and fro movements; and

Fig. 9 `is a partial section taken similarly to Fig. 3, illustrating a third kiln modification.

The kiln shown in Figs. 1 4 comprises .a movable unit including the side walls A' and roof A2 of the kiln, chamber A, and longitudinal beamlike portions A3 forming a slotted kiln chamber bottom wall, and a metallic supporting structure which directly supports the parts A and A3, the parts A', A2, and A3 being formed of masonry, which is refractory, at least, inv the portions thereof adjacent the kiln chamber in the high temperatureportion of the latter. The metallic supporting structure comprises supporting beams B transverse to the length of the kiln and beneath the side walls A and parts A3. The metallic supporting structure also comprises parts, including metallic beams B and B2 extending longitudinallyof the kiln which suitably interconnect the transverse beams B, and comprises vertical buckstay members B3.. v'Ihe latter, are connected at their lower ends to the ends of the beams B and are inter-connected in pairs at their upper ends by tie rods B4. As shown, suitable heat insulating material at the outer sides of the side walls A and above the roof A2, is held in place between metallic sheathing walls B5 at the opposite sides of the kiln and directly engaged and supported by the inner edges of the buckstays B3.

The stationary portion of the kiln structure comprises longitudinal masonry beam portions D beneath the kiln chamber and alongside of, and alternating Vwith the movable beam-like por- Akilns of the walking beam type.

tions A3. The portions D are supported from the kiln foundation C by columns E which are spaced apart for the passage and necessary normal movements of the movable kiln chamber supporting beams B. In the construction shown in Figs. 1-4, there are two movable portions A3 and three stationary beams D.

As shown, each beam B is formed in three end to end sections. Each end of the central section is normally in abutting relation with the adjacent end section, as indicated at B6. Normally each central section of the beam which extends through the corresponding opening in the stationary goods supporting means between the columns E thereof, and beneath the beams D, is rigidly but detachably connected at each end to the corresponding end section by splice plates B7 and clamping bolts B8. When the plates B7 and bolts B? are removed, the side walls A1 and roof A2 of the kiln housing may be lifted bodily upward as far above the stationary portion of the kiln structure as may be necessary or desirable to facilitate kiln chamber repair operation. The set of end sections of the beams B at each side of the kiln are connected to the corresponding subjacent beam B1, and the central sections of the beams B are connected to the subjacent beams'B2. p p

The kiln shown in Figs.` 1 4 includes a kiln chamber bottom wall or hearth formed of refractory Vplates or. slabsF which are rectangular in outline and meet edge to edge to form a continuous ware supporting platform or hearth which isr intermittently advanced longitudinally'of the kiln from the entrance to the delivery end of the latter, slabs or plates F being added to the hearth at the inlet end of the kiln and detached from the hearth at its vopposite end as the hearth is progressively advanced, .as is customary in kilns of the walking type provided with sectional When the movable portion of the kiln strucif ture is lowered, the slabs F of each row are directly supported on the subjacent beam D. and when the movable portion of the kiln structure is elevated, the slabs F are engaged and lifted 01T the beams Dand are then supported by the Jil movable portions 'A3 and the ledges or shoulder projections A4 from the kiln side walls, the slabs FV of each side row being then engaged and supported each at one end by the adjacent portion of the adjacent ledge A4 and at its opposite end by theadjacent portion of the adjacent part A3, and the slabs F of the central row are then engaged and supported each at its opposite ends by the adjacent portions ofthe two beam-like.

:parts A3.

The means employed to givethe movabie kiln unit its rising and fallingand longitudinal to and fro movements, may be of any suitable type and form such as are customarily employed in The particular mechanism, shown in Figs. 1-4, comprises two angularly movable shafts G and GA extending transversely to the length of the kiln beneath the `movable kiln unit andsuitably disposed intermediate the ends of the kiln. The shai t G is Y ments.

Through a crank arm G and link G2 at each CII side of the kiln, angular movements of the shaft G give oscillatory movements to four levers G3 arranged in two pair, one pair at each side of the kiln and comprising two levers at opposite sides of the shaft G. The levers G3 are journalled in brackets G4 mounted on a supporting platform or base CA carried by the adjacent portion of the` foundation C. Through a connecting rod G0,

the oscillating movements of each lever G3 gives similar oscillating movements to bell crank levers G located at suitably frequent intervals along the length of the kiln between that lever G3 and the end of the kiln at the opposite side of the latter from the shaft G. Each of the levers G30 is journalled in an individual bracket G mounted on the foundation C. One arm of each of the levers G3 and G30 carries a roller G7 journalled to turn about a horizontal axis transverse to the length of the kiln. The various rollers Grl are given simultaneously up and down movements by the angular movements of the shaft G and provide movable supports for the previously mentioned longitudinal beams B which directly support the transverse beams B, the beams B resting on and being supported by the rollers GI at all times.

As shown, the shaft GA carries an arm GA', adjacent the center line of the kiln, and provided with an anti-friction roller GA2 at its upper end. The roller GA2 works in a vertical guideway formed in a bracket BG secured to the adjacent transverse beams B (or to the beams B2) The opposing guideway sides BG between which the rollers GA2 t and work, are vertical. In consequence, oscillatory vmovements of the shaft GA give longitudinal to and fro movements to the movable kiln unit.

The parts including the shafts G and GA for giving the movable kiln unit its movements, are so relatively arranged and operated that the movable kiln unit is given regularly recurring cyclic movements, each of which includes four components, namely, an upward component, a horizontal component longitudinally of the kiln chamber in the direction of the arrows applied to Figs. 1 and 2, a downward component, and a horizontal component opposite in direction to the component in the direction indicated by said arrows. The upward component of each cyclic movement necessarily precedes the downward component. The horizontal movement in the direction of the arrows is effected during the period in which the movable unit holds the hearth slabs F above the level at which the slabs engage and are supported by the stationary beams kD. Each return horizontal component of the movable unit movement, or a substantial portion, at least, of that component, must occur during a period in which theslabs F are resting on and supported by the beams D. Since the means employed for giving the shafts G and GA their movements form no part of the present invention, further reference thereto is unnecessary.

The arrows in Figs. l and 2 point toward the delivery end, and away from the inlet end of the kiln, and in each cyclic movement component in the direction of the arrows of Figs. 1 and 2, the slabs F and thereby the wares supported on the hearth, are given a movement away from the inlet end and toward the delivery end of the kiln. Since in an ordinary continuous tunnel kiln the period required for the movement through the kiln chamber of each ware piece is a matter of several hours, and frequently of many hours, the progressive movements of the wares in the direction of the Vkiln maybe and ordinarily will be each of a few inches only, and all components of the movements of the'movable kiln unit may be of very low velocity, so that only a small amount of power isrequired to'move the relatively large'mass to be moved. y

In the kiln shown in Figs. 1-4,`the kiln is heated wholly by means of kiln heating units, associated one with each of the stationary beams D. The-heating unit associated With-each beam D comprises a combustionchamber' d formed in the upper portion of each beam D and extending longitudinally of the kiln through the high temperature and heating up' sectionsl of the kiln, and means for supplying uid fuel and air for combustion to the chamber d in the high temperature zone of the latter and for withdrawing products of combustion from the nue. at one or more points adjacent the entrance end of the kiln.

As shown, three burner pipes 'H are provided for v supplying fuel gas to each Vflue d at suitably dislength of the corresponding beam D, the section "f d of the flue within the cooling zone section of the kiln passing combustion air received by it at or adjacent the delivery end of the kiln to the section ofthe ue forming the combustion charnber d.. The air thus passed through the flue section d assists in cooling the wares passing through the cooling zone of the kiln, and is-thereby preheatedprior to its delivery to the combustion chamber d. i

Each flue, comprising va combustion chamber d and its extension d', may extend from one end to the otherof the'beam D in'which it is formed. Ordinarily,'however, I consider it preferable to close the ends `of the ue as indicated in respect to the right hand end of the extension d shown in Fig. 2, and to supply air to and withdraw products of combustion from the `flue respectively adjacent the deliveryfand entrance ends of the kiln, through corresponding vertical passages in the beam extending downwardly from the flue. Thus as shown, air for combustion and ware cooling purposes is supplied'to the flue extensions d through corresponding kvertical passages d2 adjacent the delivery end of the kiln, and products of combustion may be withdrawn from each combustion chamber d through one or more passages d3. As shown, there are two spaced apart passages d3, similar to the passages d2, and opening from the combustion chamber adjacent, but at diiferent distances from the inlet endof the kiln. Each of the passages d3 communicates at its lower end with piping d4 for-passing products of combustion to a stack or other combustion chamber exhausting device. As shown, air may be supplied to the combustion chamberithrough air inlet passage d5 similar to the passages d2, at one or more points of each combustion chamber intermediate the burner pipes H and the exhausting gas outlet-s d?, the air so supplied serving to temper or regulate the temperature in the portions of the combustion chambers between the passages d5 and the inlet end of the kiln. Dampers d0 may be provided to regulate the flow through each of the passages d2, d3, and d?.

Each burner pipe H is advantageously formed (AFL upward-into the. corresponding combustionachamber d through a; vertical Vpassage D10 formed in the subjacent-` portionof the, corresponding beam D, and. in which-,the` burner pipe is removably held as means including a clamping screw H and. a. collar H2 bolted to the-metallic channel barD11 interposedbetween' the beam D- and the subjacent supporting; columnsE.. As shown, each burner pipe H has its upper or" burner. end H3 transversely bentv and-pointing toward the entrance endof thefkiln'. Ateach endof the kiln chamber a door J isprovided;V and asv shown, a car. orrplatfonnK, movable'into'and out ofthe inletl end. of= the: kihr chamben, and ay similar car or platform', KA-zforsmovement. intoand out of the: deliveryfendlof; the' kiln chamber may be provided for: the introductiono-f slabsections F at the: inlet: end of; the kiln` and for the` discharge ofV slab sections F at thev delivery; end ofv the kiln.

To prevent airl orf-other. gas flow= into the kiln chamber; or gas ow out of'V the kilm chamber throughtheslots'in the bottomiwa-ll: ofv the kiln chamberI.may provide a: sandsealor other suitable sealing means'. for the joint, between thev lowerportion of eachtsidewalliA- andthe adjacent;V beam'` 13;. as. shown.. Sand=seals are shown, each ofi which'` comprises a ilanged metal bar M secure'd to. ther kiln side walll and?. having a depending'ilange extending: into-sandv held by anmetallic trough memberm secured to the adjacent side of. thebeamx D;.asfby rivetingY or welding Vit to the adjacent. edge` oilv the corresponding channel bar D11. With the arrangement shown, the contiguoushearthplate slabscF tend to; prevent gas flow into or out ofi thev kiln chamber through the bottom: wall= slots onopposite sides ofthe. central beaml D3; However; a sanft seali including parts M and m similar to the partsM. and m', respectively; may: be. providedas=shown between .each kiln unit portion Alandtheadjacent beams D, the partsbeing supportedi by the parts A3 of themovablekilnunit'. l

Inv mylsaidprior application I have shown sealing comprising relatively movable coacting metallic parts.. suitable for use in. lieu. of the sand seal means-illustrated herein..

As. willVA be readily.4 apparenti to: those skilled in the art, inthe normalv and: contemplated use of the kiln shown in Figs. 1 4, hearthV slabs F are successivelyinserted. in.. the kiln. at'. the inlet end of the kiln andi successively removed from the kilni at its exity end; Vat intervals. determined by the time required to advance the hearth along the beams Da distanceequal to the slab dimension in the. direction of: the length of the kiln. The wares moved through the kiln are progressively heatedA upasl they pass through the preheating and high temperature section of. the kiln which extends from the inlet end of` the: kiln to the portion of the kiln. containing', the burner pipes H most remote from the entrance end of the kiln. The portion of the kiln' thereafter passecll through by the wares` as they move to the delivery end of the kiln, serves as a cooling zon-e, in which wares are cooled down toa temperature at which they can beA safely moved out of the kiln chamber. In Figs. 1-4, the cooling zone section of the kiln includes cooling flues I and inlet and outlet connectionsI and I2 therefor, which may be of any'usual form. Combustion conditions in the combustion chambers, and cooling conditions in the cooling zone or section of the kiln, may be regulated by damper or analoof a khighly refractory metallic alloygand extends.

gous adjustments in accordance with the usual practice inthe operation of continuous tunnel kilns..

When, as may occur from time to time, it becomes necessary to make repairs to the inner walls of the kiln chamber, it is practically feasible andrelatively easy, after removing the splice plates B7 and bolts B8, to lift all o-f the'movable kiln structure, except the central sections of the beams B, the beam parts A3 and thebeams B2, upward as-far above the tops of the beams D as may be necessary'or desirable to provide suitable access to thekiln chamber through its then open underside. When. the kiln includeshearth plates F as shown anddescribed, all ofthe hearth plates may be removed from the kiln chamber, preparatory to the elevation of the kiln housing, or, at least, the plates in the two rowsadjacent the sidesV of the kiln chamber should be removed preparatory to or during the lifting operation.

'Ihe lifting of the housing may be effected conveniently by means of lifting jacks -placed beneath the beams B1 at suitable intervals along their lengths. Withv the arrangement shown, when the Vsplice plates B7 and bolts B8 are removed, the central sections of the beams B, with the beamparts A3 above them, may be supported through-the beams B2 on the kiln foundation. In thearrangement shown in the drawings, there is only a small clearance between the underside of the beams-B2 and the subjacent portions of the kiln foundation, When the kiln housing is at its lowermost normal orworking level, shown in Figs. 3; and 4. The hereinafter mentioned kiln modications illustrated in Figs. 5, 6 and 9 each includes beams B formed in separable end to end sections as and for the same purpose as the beams B ofthe kiln of Figs. 1 to 4, are so formed. In Fig. 9, the end. sections ofthe beams B are shown as disconnected from, and held some distance above the central sections of those beams.

In the kiln shown in Figs. l-ll, the entire kiln heatingv effect is obtained by the combustion of fuel inA the combustion chambers d below the Ware supporting hearth. When necessary, or desirable, however, other kiln heating means may be employed. Thus, as `shown in Fig. 5, a separate combustion chamber L may be providedY at each side of the kiln chamber. The fuel burned in each combustion chamber L may be supplied thereto by one or more burner pipes HA, which may extend horizontallyY intor the combustion chamber through the outer side of the combustion chamber L. Air for combustion may be supplied to each combustion chamber L through a subjacent flue LA formed in the adjacent side wall of the kiln and extending from the high temperature end of the combustion chamber to the delivery end. of the kiln. Products of combustion may be withdrawn from each combustion chamber L through one or more ports opening into a flue beneath the combustion chamber in alignment with the corresponding ue LA and communicating with a suitable discharge pipe LB communicating with the stack or other exhausting` device associated with the combustion chambers L-. .Except for its combustion chambers L, the kiln shown in Fig. 5 does not differ from that shown in Figs. 1 4.

With combustion chambers formed in the movtionary waste'gas piping'V through flexible con- 'f7 nections. Such flexible connections need not be illustrated, or further referred to herein, however, since they comprise nothing claimed as novel herein, and ilexible pipe connections suitable for the purpose are disclosed in Vmy above mentioned prior application.

As will be apparent, the number of the slots formed in the bottom wall portion of the kiln chamber of a movable kiln unit of the general character shown in Figs. 1 4, may vary with conditions. For example, as is illustrated in Fig. 6, the kiln chamber bottom wall portion of the movable unit may be formed with a single slot, which may be of a width but little less than that of the kiln chamber. The combustion chamber da of Fig. 6 may be provided with air and fuel inlets and gas outlets similar to those employed with the previously mentioned chambers d. As shown in Fig. 6, the roof of the combustion chamber da is formed of relatively thin plates or slabs d10 of refractory material which is corrugated or uted with the corrugation ribs and grooves extending transversely to the length of the kiln so that the slabs although made thin to reducetheir resistance to heat flow, may have suiiicient strength and rigidity to avoid sagging notwithstanding their considerable length, while being thin enough to insure aV suitably good heat conductivity. In order that `the heat conductivityof the slabs d10 may be desirably high, the slabs may be made of refractory material, such as rcarborundum or Sillimanite which when hot, is a relatively good conductor of heat. Such material may also be used in the top walls of the combustion chambers d and the hearth slabs F of the kiln arrangements shown in Figs. 1-5. The kiln shown in Fig. 6 includes side combustion chambers L like those shownin Fig. 5. p

The movable ware supporting hearth shown in Figs. 6 and '7 is formed of slabs FA which differ from the slabs F of the arrangement first described in that they are of box girder type, each slab being formed with one or more, three as shown, channels F', each of rectangular cross section and extending between the two ends of the slab, and opening at its ends into the kiln chamber. The vertical web portions F2 of each slab FA, at the sides of its channels F', conduct heat away from the bottom Walls of the slab and give the slab suitable rigidity even though the temperature in the combustion chamber is high enough to weaken the bottom Wall 'portion F3 of the slab. The provision of the channels F in the slab also permit of a combustion chamber tem-` perature high enough to overheat the bottom portions of the wares on the hearth if the latter were formed of thin slabs of refractory material having good heat conductivity. As shown, the slabs FA of Figs. 6 and 7 are formed each with a tenon at one edge and acorresponding groove at its opposite edge, so that 'the joints ,F4 between adjacent slabs of the hearth are tongue an groove joints.

The special hearth slab construction shownin Figs. 6 and '7, is not restricted to use in a kiln having a single bottom wall slot, but may be used in kilns having a plurality of such slots as shown in Figs. 1 4, and may be used, also, in kilns of the walking beam type in which the kiln chamber housing is stationary as it has been heretofore.

In lieu of shaft GA and associated parts'for giving the kiln housing its longitudinal to and fr0 movements, in some cases I may advantageously employan arrangement including hydraulic cylinders P and'PA at the ends `of the kiln structure, as illustrated diagrammatically in Fig. 8. As shown, the piston rod or plunger of the cylinder P is pivotally connectedto one end of a draw bar or link P2 pivotally connected at its other end to an extension B20 from the adjacent end ofthe metallic under structure of the movable kiln housing, the piston stem or plunger of the cylinder PA being similarly connected to a projection B20 from the other end of the movable metallic under struc-ture of the kiln housing. With the described arrangement, the cylinderP isemployed Vto give the movable kiln housing its movement in the direction of the arrow shown in Fig. 8, and the cylinder PA is employed to give the housing movement in the opposite direction.

lAs diagrammatically shown, the cylinders P and PA may be supplied with oil or other operating fluid pipes Rand RA and a two-way valve or cock Q from a source S of fluid under pressure, connected to the inlet of valve Q by a pipe R. P2 indicates the exhaust or outlet pipe connected to the valveV P, through which uid may be discharged from one of the cylinders P and PA while the other is making its Working stroke. As shown inFig. 8, the valve Q is in the position required for kiln housing movement in the direction of the arrow by the cylinder P.

As will be apparent, when the kiln housing is given its longitudinal movement by a pulling force applied to the advancing end of the. kiln, f `as provided for in Fig. 8, there is practically no` tendency to lateral kiln housing movement and any resultant binding action such as might occur if the kiln housing Were moved by aV pushing force applied to its trailing end or intermediate its ends. The advantage thus obtained with the arrangement sho-wn in Fig. 8, increases as the size of the kiln, and particularly its width, is increased.

When necessary to supplement the` kiln heating effect of the combustion chamber o-r chambersbeneath the kiln chamber, I may use in lieu of, or vin addition to, kthe side Wall combustion chambers L, one or more combustion chambers in the kiln roof. In the kiln shown somewhat diagrammatically in Fig.. 9, there` are four roof combustion chambers Zar in addition tothe twoside wall combustion chambers L, and ve combustion chambers d beneath the kiln chamber.

Each of the combustion chambers la may ex- 5 tend longitudinally of the kiln and be provided with separate' supply and exhaust connections, similar to those provided for each of the side wall combustion chambers L. The kiln chamber of the kiln shown in Fig 9 is relatively wide` and of small vertical extent, and in such a kiln, the side wall combustion chambers are of less importance, and the roof combustion chambers may be of more importance, than inkiln having a.

kiln chamber which is narrower and of greater .best forms :of embodiment or my invention now known to me, it will be apparent to those skilled inthe art that changes may be made in the forms of the apparatus disclosed without departing from the spirit of my invention as set forth in the appended claims and that in some cases certa-in features of my invention may be used to Vadvantage without a corresponding use of other features.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A continuous tunnel kiln, comprising in combination a movable kiln chamber housing unit providing a Wall surrounding a horizontally elongated kiln chamber and formed with one or more slots in the portion of said wall beneath, and extending longitudinally of said chamber, stationary goods supporting means including an elongated part parallel to, land extending upward into each such slot, and means for giving said `unit cyclic movements, each including an upward component, a horizontal component in the direction of goods movement through the kiln chamber, a downward component, and a horizontal component opposite in direction to the first mentioned horizontal component, whereby said unit is adapted to alternately lift wares in the kiln chamber above and return them to a level at which said wares are supported by said stationary means, and to move the wares longitudinally of said stationary means in said direction of goods movement when the wares are above said level, and to move in the opposite direction without a corresponding movement of the wares when the latter are at the'level at which they are supported by said stationary means.

2. A continuous tunnel kiln as specified in Vclaim l, comprising heating means including an claim V1, comprising heating means including flues, one formed in each of the said stationary parts extending upward into a corresponding bottom wall slot of the kiln chamber, and each extending Vfor substantially the full length of the kiln chamber, and including means for supplying air to each said ilue at the end of the latter adjacent the delivery 'end of the kiln chamber, means for withdrawing products of combustion from the flue adjacent the entrance end of the kiln chamber, and means for supplying fuel to 4said combustion chamber intermediate the ends of the kiln chamber. Y

4. A continuous tunnel kiln as specified in claim 1, comprising heating means including an elongated combustion chamber in each said elongated part extending upward into a slot in the bottom wall of the kiln chamber, and one or more combustion chambers formed in an upper portion of the kiln chamber wall, said combustio-n chambers being separate from one another and each extending along an elongated heating up Yand high temperature. section of the kiln.

5. A continuous tunnel kiln as speciiied in claim 1, including a movable ware supporting hearth composed of sections meeting edge to edge, there being a row of such sections extending `longitudinally of the kiln chamber above each `slot in the bottom wall of the kiln chamber with the ends of each section in the row projecting laterally beyond the opposite side edges of -the slot and overlapping the portions of the bottom' wall of the unit at the margins of the slot, whereby when said unit is moved upward, the sections in the row are engaged and lifted by the unit, and when the unitis lowered the sections in the row are engaged andsupported by the said elongated part extending upward into and then projecting through said slot.

6. A continuous tunnel kiln as specied in claim 1, in which the means for giving the movable kiln housing unit its movement comprises meansfor exerting a pulling force on one end of the unit to move the latter horizontally in the direction. to advance said one end of the unit and for exerting a pulling force on the opposite end of the unit to move the latter horizontally in a direction opposite to the rst mentioned direction.

7. A continuous tunnel kiln as specified in claim 1, in which a major portion of the movable kiln housing unit including the side and roof walls ofthe kiln chamber is detachably connected to a bottomV wall portion of the unit,

whereby when said portions are disconnected, said major portion may be moved bodily upward above said botto-n1 wall portion and the stationary goods supporting means to thereby permit access to the kiln chamber through the then open under-side of thelatter.

8. A continuous tunnel kiln as specified in claim 1, in which the movable kiln housing unit comprises a lower metallic portion including beams extending transversely to the length of the kiln, and in which the stationary goods supporting. means is formed with transverse opening through which the central portions of said beams extend, and in which the central portion of each of said beams vis detachably connected to` opposite end portions of said b-eam underlying the side walls of the kiln chamber, whereby when the. central portions of the transverse beams are disconnected from the respectively corresponding end portions of the transverse beams, the portion of the unit including said end portions and the side4 and roof walls of the kiln chamber may be bodily elevated above the stationary goods supporting means to permit access to the kiln chamber through the. then open lower side of the latter. V

9. A continuous tunnel kiln as specified in claim. 1, inA which the movable kiln housing unit comprises a(A lower metallic portion including beams transverse to, and beams longitudinal of the length of the kiln, and in which the stationary goods supporting means is formed with transverse openings through which the central portions of said transverse beams pass, and in which the central portion of each of said transverse beams` is detachably connected tothe opposite end portions of said beam, said end portions underlying the side walls of the kiln chamber and one of said longitudinal beams being adjacent each side of the kiln and beneath and connected 4to the corresponding end portions of the transbeam end portions, the longitudinal beams beneath and. connected to said end portions and the side and. .roof wall of the kiln Chamber, may be moved bodily upward above the said stationary supporting means to permit access to the kiln chamber through the then open lower side of the latter.

10. A continuous tunnel kiln as specied in claim 1, including sand-seal parts carried by said movable unit, and cooperating stationary parts to prevent gas movement into or out of the kiln chamber through the bottom wall slot or slots thereof.

11. A continuous tunnel kiln comprising in combination a kiln chamber having a slot formed in its bottom wall and a beam portion extending upward into said slot, means for giving said bottom wall and beam portion relative cyclic movements, each such movement including an upward component, a horizontal component in the direction of goods travel through the kiln chamber, a downward component, and a horizontal component opposite in direction to the first mentioned horizontal component, a ware supporting hearth comprising slabs arranged edge to edge in a row extending longitudinally of the kiln chamber above the slot, and each having its end portions projecting laterally away from the opposite sides of said slot and being advanced through the kiln chamber by said movements and being formed with one or more open ended channels extending between the ends of the slab, and kiln heating means supplying heat through said slabs to wares thereon.

12. A continuous tunnel kiln comprising in` combination a movable kiln chamber housing unit providing a wall surrounding a horizontally elongated kiln chamber and formed with a slot in the portion of said wall beneath and extending longitudinally of said chamber, stationary goods supporting means including an elongated part parallel to, and extending upward into said slot, a ware supporting hearth comprising slabs arranged edge to edge in a row extending longitudinally of the kiln chamber above the slot and each having its end portions projecting laterally away from the opposite sides of said slot and being formed with one or more open ended channels extending between the ends of the slab, means for giving said unit cyclic movements, each including an upward component, a horizontal opening in the direction of goods movement through the kiln chamber, a downward component, and a horizontal component opposite in direction to the rst mentioned horizontal component, whereby the portions of said unit immediately adjacent the sides of said slot are adapted to alternately engage andl lift said slabs above, and return them to the level at which said slabs are supported by said stationary means and to move the slabs longitudinally of the kiln chamber in the direction of goods movement when the slabs are above said level and to move in the opposite direction without a corresponding movement of the slabs when the latter are at the level at which they are supported by said stationary means, and kiln heating means supplying heat through said slabs to wares thereon. CLIFFORD HUNT PARMELEE.

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