US1652570A - Tunnel kiln - Google Patents

Description

Dec. 13, 1927. 1,652,570

I I w. L. HANLEY. JR

TUNNEL KILN Original Filed Oct. 6. 1923 3 Sheets-Sheet 1 lllllll4 Dec. 131M727.

w L. HANLEY. JR

TUNNEL KILN- Original Filed Oct. 6. 1923 3 Sheets-Shut 2 Dec. 13,1927. 1,652,570

W. L. HANLEY. JR

TUNNEL KILN Original Filed Oct. 6. 1923 3 Sheets-Sheet 3 annexe! Patented Dec. 13, 1927.

UNITED, STATES PATENT OFFICE.

TUNNEL KILN.

Application filed October 6, 1923, Serial No. 666,880. Renewed March 11, 1927.

My invention consists in the novel features hereinafter described, reference being had to the accompanying drawings, which show one form of tunnel kiln embodying my invention, selected by me for purposes of illustration, and the said invention is fully disclosed in the following description and claims.

My invention relates to tunnel kilns or ovens designed more particularly for firing coarse clay products, such as bricks, firebrick, tile, etc., although my invention is applicable .to kilns for firing other classes of goods where found desirable and advantageous. In the operation of tunnel kilns, the goods are moved progressively, either continuously or intermittently and usually are carried upon trucks or cars, the movement of the goods being effected in a direction longitudinally of the kiln and causing them to pass through zones of different temperatures so that the goods being in a green or unfired'condition, when they enter the kiln, 'shall be completely fired and cooled to substantially such a temperature that they may be handled at the time they reach the delivery end of the tunnel. Such kilns are divided longitudinally in a plurality of zones which may be described briefly as, first a preheating zone in which the goods are raised to somewhere near the temperature of firing, second the firing zone in which the goods are completely fired during their passage longitudinally thereof, and third the cooling zone in which the fired goods are gradually depriied of their excess heat and broughtto a sufiieiently low temperature to enable them to be handled. It has been customary in the construction and operation of these kilns to efiect the combustion of the fuel within combustion fines or passages ex tending through the firing ZOIle of the turn nel. in which the greatest amount of heat is radiated and the products of combustion are conducted through similar fiues through the heating zone to the entrance end of the tunnel, for the purpose of preheating the goods. In the COOliIlg zone at the other end of the tunnel, the fired goods are cooled by means of air drawn into the tunnel itself or through suitable flues provided in its walls or within the tunnel to abstract the excess heat from the tired goods and this heated air is in some instances employed in the combustion lines, and in other instances is withdrawn for other purposes. The construction of this type of kilns is extremely expensive in its initial cost, and also in its upkeep and operation. It necessitates practically the use of gaseous fuel, and where this is not readily available. it necessitates the erection and upkeep and the continuous operation of a producer gas plant, which is in itself extremely costly and requires a high degree of skill for its, efficient operation. The kiln itself is expensive on account of the extensive flue construction, much of which is require to be of very high fire resisting material, and this flue construction is difiicult to keep in repair. Repairs to the flue construction are also exceedingly expensive inthatithe necessitate the removal of the goods and the cooling of the entire kiln structure, to enable the workmen to enter and make the necessary repairs. Furthermore it is necessary to maintain and operate powerful'air forcing apparatus to secure the circulation of the products of combustion through the flues in the firing zone and preheating zone, and additional and separate air forcing means for passing the cooling air through the cooling zone. All of these considerations have made it almost, if not quite, prohibitive to employ this type of kiln for the firing of coarse clay products which, on account of their extremely low sale price, must be handled continuously at the highest possible volume and at the lowest possible costs, both as to initial cost and upkeep and daily operating expenses. Efforts have been made to reduce the expense-of these tunnel kilns, but they have usuallv been in the direction of reducing the initial costs in connection with the other items above mentioned. For example, it has been proposed to construct what may be termed twin kilns or double tunnel kilns, in which two exterior ,walls are employed, with a central wall, thus doubling the capacity at some what less than double the cost of construction. But the slight economy involved in disposing of one lateral wall, necessitates the greatly increased initial cost of the kiln in order to provide two tunnels. It has also been proposed to operate the cars in a twin tunnel kiln in opposite directions in the two provide a kiln having provision for the simultaneous treatment of goods carried therethrough on two lines of trucks or cars movmg in opposite chrections, the cars loaded with goods passing through a single tunnel at each end of the kiln structure, and through separate firing zones adjacent to the portion of the kiln located centrally thereof, longitudinally, the heat for the firing zones being furnished by direct firing from a plurality of furnaces arranged on opposite sides of the centrally located firing zones, saidfurnaces being operated under conditions ,permitting their accurate control as to the temperature within all parts of the firing zones, the products of combustion being withdrawn, preferably by suction from the firing zones, and conducted away for the purpose of further use in preliminary drying rooms, or

otherwise, the fired goods on leaving the separated firing zones in opposite directions and passing through the end portions of the kiln on their way to the delivery end, transferring their heat to the green goods moving in the opposite direction within the same tunnel, either by direct radiation, or pref- V erably by continuous circulation of air transversely of the tunnel and upon and through the heated and cooled goods therein, so as to cool the heated goods progressively, while progressively preheating the entering goods.

In this arrangement or construction, it will be observed that there'is a very greatdecrease in the initial cost of construction, as the greater part of the kiln is composed merely of parallel exterior side walls, and

a single crown or roof portion. Moreover direct firing, by which is meant that the products of combustion from the furnaces come directly into contact with the goods to be fired, results in great economy of fuel.

The fuel most available at the point where the kiln is located can be utilized whether gas, oil, wood or coal, and its combustion can be readily regulated by means of suitable dampers and other controlling mechanism.

Aga-in, the only air forcing devices needed are those for supplying air to the furnaces and withdrawingthe products of combustion, as the air within the two end portions of the kiln merely acts to assist in transferring the radiated heat from the fired goods to the green goods, and may be used continuously over and over again. It will also be seen that the products of combustion in the firing zones being positively withdrawn therefrom by suction, will not be carried lengthwise of the furnace into the end sections thereof, and this suction may be so regulated in connect-ion with the air forcing means supplying air to the furnaces, as to withdraw only the "products of combustion, or if desired to withdraw some of the air fromthe end portions of the kiln also, which would result in the admission of cool air at the extremities of the kiln.

It will also be noted that all longitudinal flue constructions through those portions of the kiln at opposite ends of the firing zones are omitted, thus effecting a great saving in initial cost and upkeep, and in efiiciency of operation.

Referring to the accompanying drawings,

. Fig. 1 represents diagrammatically. a top plan view of my improved tunnel kiln.

Figs. 2 and 2 represent a horizontal sectional view of the kiln, portions being broken away.

Fig. 3 represents a vertical cross section of the kiln through the firing zones on the line 33 of Fig. 2.

Fig. 4 represents a similar section on the line 4-4 of Fig. 2,

Fig. 5 is a section through one of the end sections of the kiln, both of which are of light construction, on the line 55 of Fig. 2.

Fig. 6 is a similar section, illustrating a slight modified construction.

Referring to the drawings, A, represents the duplex firing chamber of my improved kiln, which is located centrally with respect to the length of the kiln, and is provided at each end with a unitary cooling and preheating chamber, one of which is indicated at, A, and the other of which is indicated at, A The duplex firing chamber is illustrated in section in Figs. 3 and i. It comprises two exterior walls, 1, l, a central partition wall, 2,- and separate crowns, 3, 3, of any usual or preferred construction, forming two tunnels, ffff, separated by the partition wall, 2, each of which constitutes a firing zone. At the outer side of the tunnels of each of the firing zones are located a plurality of furnaces, 5, for the combustion of any desired character of fuel, that is to say, gas, or oil, wood, coal, etc. The fuel may be supplied continuously in anv desired or appropriate manner, according to its character, and I have not undertaken to illustrate the particular means for supplying the fuel, which may be a suitable stoking arrangement in the case of coal, operated either by hand or power, or suitable injector nozzles in the case of liquid or gaseous fuel. The necessary air for combustion will be supplied in any desired manner. I haveil lustrated in Figs. Qand 2 a pair of air lOJ forcing devices, 66, for this purpose, connected by pipe, 7, with the various furnaces, under the control of valves or dampers, 8, so that the supply to each furnace may be regulated and adjusted.

In order to distribute the'products of combustion from the furnaces as uniformly as possible throughout the goods and secure the even firing of the same, each tiring zone is provided with a vertical deflecting wall or bridge wall as it is sometimes called, indicated at 9, which extends upwardly from the back walls of the furnaces, tapering toward the top, and the upper portion is preferably curved or inclined inwardly towards the chamber occupied by the goods, as indicated at 10. The deflecting walls are each provided on their inner faces adjacent to the bottom of the contiguous goods space, with outlet or eduction ports, 11, at the inner ends of transverse passages, 12, extending through the wall and each communicating at the outer face of the wallwith a pipe or passage, 13, so that the products of combustion from the goods space may be withdrawn through the transverse passages, 12, and pipes, 13, from the interior of the firing zone. This leaves the portions of the deflecting walls, or bridge walls, between the adjacent eduction ports and passages flue less, or in other words, of solid construction, as shown in the drawings, without any longitudinally extending passages therein. This is important as the bridge wall is subjected to intense heat on both sides, both on the side adjacent to the inlet passage for the products of combustion from the furnace, and on the side adjacent to the goods space of the firing zone, into which these products of combustion are discharged. By making the deflecting wall, or bridge wall, flueless, as shown, except for the eduction ports and the eduction passages, and by locating the collecting fine or header outside of the kiln chamber, the bridge wall is enabled to withstand the intense heat to which it is exposed, without disintegrating or becoming injured, while the presence of a collecting flue or flues, in the deflecting wall, or bridge wall, would reduce the thickness of the wall at points adjacent to said flue, or flues, and render the entire wall liable to injury and disintegration under exposure to the intense heat on both sides thereof. In this instance I have shown the horizontal flues arranged between adjacent furnaces and extending from the firing chamber to the outsidevof the tunnel kiln chamber where they are connected with a suitable suction device, such as, for example, a common exhaust flue or collecting flue, 14, which may be connected with an exhaust fan or other exhausting mechanism (not shown), by means of which the products of combustion arewithdrawn from the interior of the firing zones and conducted elsewhere for further use. F or example, they may be carried and delivered to a preliminary drying room or chamber, in which the green ods are preliminarily dried before beingintroduced into the kiln. I prefer to provide each of the fines, 13, with a controllin damper, 15, which may be of any preferre or usual construction. I have simply indicated in the drawing an ordinary form of butterfly valve or damper but a sliding valve, or any other type of damper may be conveniently used. By means of the dampers, 15, and the dampers, 8, itwill be seen that the temperature within each of the firing zones can be readily regulated. Each of the exhaust lines or passages, 12, 13, will naturally withdraw the products of combustion from the adjacent furnaces on either side and by properly adjusting the several dampers in the different pipes, 13, the control of the firing zone throughout its length can be accurately secured, to maintain any desired heat curve. For example, I find it convenient to maintain a temperature of approximately 1400 F. at the entering end of each of the firing zones, and of approximately 1900 F. at the opposite end of each of the firing'zones. These temperatures however, can be readily varied as circumstances may require, by the means before described. It will be understood that each of the firing zones is provided with longitudinal rails, indicated at 1616, extending t-herethrough for supporting the wheels of the trucks or cars, indicated diagrammatically at 17. The superstructure of these trucks is preferably built up of layers of fire resisting material supported upon the metallic frame-work ofthc truck, in a well known manner. The bricks or other goods to be fired will be piled on the trucks, preferably in parallel stacks, as indicated in dotted lines at 3030 with suitable spaces for circulation between them and downwardly between the stacks. In order to protect the metallic portions of the trucks as far as possible, as they pass through the firing zone, the central partition wall, 2, and the vertical deflecting walls, 9-9, are provided with inwardly extending projections, indicated at 20, and 21, respectively, which extend over the lateral portions of the trucks and tendto prevent the passage of products of combustion down around the wheels and supporting structure of the trucks. The upper faces of the shoulders, 2020, extend downwardly and inwardly, being in this instance inclined. as shown in Figs. 3 and 4, and act as deflecting surfaces to, deflect the products of combustion descending between the center wall, 2, and the adjacent goods on the cars, laterally across the goods space toward the outlet or eduction ports, 11, through the goods, or the lateral passages, 19, in the car superstructures. These deflecting surfaces. of the the adjacent goods space to the outlet or eduction ports, 11.

I also prefer to provide the inner faces of the lateral deflecting walls, 9, with one or more horizontal, inwardly projecting ribs, 22, which project toward the goods carried by the trucks. These horizontal ribs are below the inwardly extending deflecting portion, 10, of the lateral deflecting walls, and cooperate therewith in causingthe products of combustion to distribute themselves through the goods and prevent them from being drawn downwardly adjacent to the deflecting walls, 9. The goods are arranged on the trucks so as to provide a central passage downwardly between them, indicated at 23, and if the goods are coarse clay products, such as bricks, tile, etc., they will be so arranged as to provide lateral passages, so that the products of co1nbus.:ion may become dis tributed throughout the stack or pile of goods on the trucks after leaving the throat formed between the deflecting portion, 10, of the deflecting walls, and the top, 3, of the kiln portion, so that the products of combustion will pass substantially uniformly downwardly through and around the goods and across the bottom of the same through the passages, 19, through the ports, 11, and exit passages, 12, 13, to the outside of the kiln.

It will be noted that I prefer to arrange the firing zones for both lines of cars in alignment with each other, transversely, and located substantially centrally with respect to the entire length of the kiln structure. By this means the heat is concentrated and as the partition wall, 2, is subjected to heat from both sides, there is practically no loss by radiation through this partition wall, as any transfer of heat therethrough would be conserved within one firing zone or the other. At each end of this duplex firing zone, provided a single tunnel structure preferably having only one crown or arch, and no central partition wall, as indicated in Fig. 5. These tunnel portions, r A connect with the central firing zone portions A, and are provided with two sets of rails which are continuations of the rails extending through the firing zones. The lateral walls are provided with inwardly extending projections, 21", similar to the projections, 21, in the firing zone, and between the sets of rails is located preferably a raised platform, 24-, of brick or other fire resisting material, extending slightly above the lateral projections of the truck structure and provided on opposite sides with horizontal inwardly extending ribs or flanges, 25, to prevent the heated air from passing down around the wheels and metallic parts of the trucks. Ihe trucks are illustrateddiagrammatically in the accompanying drawings, and their spewhen in operation, there will be one line of trucks carrying goods which have been fired and are being moved toward the outer end,

and another line of trucks on the other tracks moving in the opposite direction and carrying reen or unfired goods to the firing zone. It will be noted at once that there will he an exchange of heat from the fired goods to the green goods as the fired goods are cooled and the green goods are preheated. It will also be seen that this exchange of heat will take place in such a manner that the fired goods will be gradually cooled and the green goods will be gradually heated. I prefer to make the end sections, AA of the tunnel of such length that in handling any particular goods the fired goods will be sufiiciently cooled to be handl d by the time they are' discharged from the kiln, and this will result in a very gradual heating of the greenor unfired goods from the time they enter the kiln where they will haveopposite them goods which have been very considerably cooled, until they reach the proximity of the firing zone, where they will have opposite them highly heated fired goods which have just left the firing zone, so that by the time the green or unfired goods reach the firing zone they have been brought nearly to the firing temperature. As these conditions will be somewhat modified by the exterior ternperature of the air and other conditions variations in the temperature at which the goods are delivered to the firing zone can be accommodated by proper regulation of the furnaces of the firing zone, as herein before described. For example, if the goods arrive at the firing zone at too low a temperature, the temperature of the firing zone at the initial end of the same can be increased by regulating the furnaces therefor so that by the time the goods reach the hottest portion of the firing zone they will be at the desired temperature. In like manner, if it'is found that the green goods reach the firing zone at a temperature very near the firing temperature, the heat of the furnaces in the firing zone can be slightly reduced to prevent excessive temperatures in the firing zone. It will be understood that in the transfer of heat from the fired goods to the green goods, this will bebrought about by direct radiation and by convection air currents, the circulation of which is illustrated in the drawing by the arrows, in Fig. 3, in which the goods on the truck at the right are the highly heated goods from the firing zone, and those on the left hand truck are the unfired ware which is being preheated. There will be the greatest possible conservation of heat under this arrangement, and as the air within the tunnel sect-ions, Ai r is merely circulated passing upward through the heated goods and downward through the green or unfired goods, it is unnecessary to use air forcing mechanism to secure the desired circulation of air and the same air can be used over and over again.

In handling certain classes of products, it may be desirable to protect them from the effects of direct radiation, and in such case proper.

a comparatively thin longitudinal screen of brick, metal or other suitable material, preferably of brick, may be erected on the platform, 24, as indicated at 26, in Fig. 6. This screen need not extend throughout the entire length of the sections, A, A of the kiln, unless it is desired that they should. In many instances it will be sutlicient to have these screens, 26, extend over such a distance from a firing zone toward the end of the kilns as will prevent the directradiation from the fired goods too rapidly heating the green goods moving in the opposite direction, and in such case at the extremities of the kiln where the fired goods have parted with a very considerable amount of heat, the partition or screen, 26, may be omitted. It will be understood that this partition is not a central wall and forms no part of the kiln In practice, it will not extend to the crown or roof of the kiln, but will leave a considerable aperture, indicated at 27, above it, and the screen, 26, is also provided at its lower end with transverse passages, indicated at 28 in Fig. 6, topermit of the circulation of the convection currents in substantially the'same manner as will take place where the central screen is altogether omitted.

It will be understood that the trucks or other conveying means carrying the goods are advanced either continuously or intermittently, and movable in one direction on one set of rails, and movable in the other direction on another set of rails. Ordinarily this will be conveniently accomplished by introducing a truck of green goods at one end of each set of rails and simultaneously moving the entire line of trucks so as to discharge a truck load of fired and cooled goods at the opposite ends of the kiln.

It will be noted that the construction of my improved kiln is extremely simple and that the location of the furnaces of the duplex firing zone directly opposite each other, and provided with means for accurately regulating said furnaces for the admission of air to the furnaces, and the withdrawal of the products of combustion by suction, both regulated by suitable dampers, gives a very satisfactory control of the heating means for the firing. zone, and with the greatest conservation of heat, as any exchange of heat through the partition wall, 2, will simply transfer heat from one firing zone to the other, and assist in maintaining the desired temperatures. It will also be understood that pyrometers, or other heat indicating means (not shown) can be installed at intervals within the duplex heating, zone so as to facilitate the regulation of the parallel zones to maintain a gradually increasing temperature from one end to the other in opposite directions, as before described. It will also be seen that: the greater portion of the kiln is of single tunnel construction, and as these portions of the furnace are not subjected to as high heat as the firing zone, the construction thereof can be made cheaper and simpler and will be less liable to deterioration than where portions of the cooling zone are directly alongside of a firing zone for goods on another track.

My improved furnace is admirably adapted for the rapid and continuous firing of coarse clay products, such as bricks, tile, etc., but it may also be employed for firing other classes of goods, if desired.

What I claim and desire to secure by Letters Patent is 1. In a tunnel kiln, the combination of a duplex firing chamber having two, firing zones separated by a vertical longitudinal partition wall and provided with rows of furnaces located on opposite sides of the duplex firing chamber, the furnaces of each row' communicating directly with the adjacent firing zone, means for withdrawing the products of combustion from each firing zone, a unitary tunnel section extending longitudinally from each end of the duplex firing chamber, provided with parallel goods conveying means movable in opposite directionsfeach of which passes through one of the firing zones, each of said end sections forming a combined cooling and preheating zone.

2. In a tunnel kiln, the combination of a duplex, centrally located firing chamber, having two firing zones separated by a vertical, imperforate, longitudinal partition wall, and provided with rows of furnaces located on opposite sides of the duplex firing chamber, the furnaces of each row communicating directly with the adjacent firing zone, means for withdrawing the products of combustion from each firing zone, regulating means for independently controlling said furnaces, a unitary tunnel section extending longitudinally from each end of the duplex firing chamber,'two lines of tracks for two oppositely moving trains of cars extending longitudinally through'the entire kiln, each of said tracks passing through one'of said firing zones, each of said end sections forming a combined cooling and preheating zone.

3. In a tunnel kiln, the combination of a duplex firing chamber, having two firing zones, separated by an imperfo "ate vertical, longitudinal partition wall, and provided each with arow of furnaces located adjacent to its exterior wall, and discharging 'into the adjacent firing zone, an eduction flue adjacent to each of said. furnaces and communicating with the ad acent firing zone near the bottom of the same, for with-- drawing the products of combustion therefrom, a unitary tunnel section extending longitudinally from each end ofthe duplex firing chamber, said kiln being provided with two parallel lines of tracks, extending longitudinally therethrough for two oppositely moving trains of cars, each line of tracks passing through one of the firing zones and each of said end section's forming a combined cooling and preheating zone.

7 4. In a tunnel kiln, the combination of duplex firing chamber having two firing zones separated by an imperforate, vertical longitudinal partition wall, a row of furnaces located adjacent to the exterior side of each firing zone, said rows of furnaces being on opposite sides of the duplex firing chamber, the furnaces of each row communicating directly with the adjacent firing zone, a longitudinal deflecting wall in each firing zoneadjacent to the outer wall thereof, and

providing a passage over the top of said dethe firing zones, each of said end sections forming a combined cooling and preheating 5. In a tunnel kiln, the combination of a duplex firing chamber having two firing zones arran ed alon side of each other and separated by an imperforate, vertical, longi tudinal partition wall, a row of furnaces [for each firing zone, located adjacent to the outer side of the same, and communieating directly therewith, said rows of furnaces being disposed oppositely to each other with respect to the duplex firing chamber, a longitudinal deflecting wall in each firing zone, ad acent to the outer wall thereof, providing a passage for the products of combustion from said furnaces over the upper edge of said deflecting wall, said deflecting Well being provided on its inner face with ports, communicating with the adjacent firing zone adjacent to the lower portion thereof, a plurality of transverse eduction Hues communicating with the said ports, for withdrawing the products of combustion of the several furnaces there-- from, dampers for said eduction fines for regulating the several furnaces independently, a unitary tunnel section extending longitudinally from each end of the duplex'firing chamber, two lines of tracks for two oppositely moving trains of'cars extending through the entire kiln, each of which passes through one of the firing zones, each of said end sections forming a combined cooling and preheating zone.

6. In a tunnel kiln, the combination of a duplex firing chamber having two firing zones arranged side by side and separated by an imperforate partition wall, a row of furnaces for each firing zone located on the outer side thereof, said rows of furnaces being located on opposite sides of the duplex firing chamber, a vertical deflecting wall in each firing zone, adjacent to the outer wall thereof, and providing a passage for the products of combustion from the furnaces into the adjacent firing zone on the outer side of said deflecting wall, and ov r the top thereof, an eduction flue adjacent to each of said furnacescommunicating with the interior of the adjacent firing zone at the inner side of said deflecting wall at the lower portion of the firing zone, and provided with controlling means for regulating the adjacent furnaces, a unitary'tunnel section extending longitudinally from each end of the duplex firing chamber, provided with two lines of tracks for two oppositely moving trains of cars, each of which passes through one of the firing zones, each of said end sections forming a combined cooling and preheating zone. v

7. In a tunnel kiln, the combination of a duplex firing chamber, having two firing zones, separted by a partition wall, a row of furnaces located along the outer side of each firing zone, and the furnaces of each row communicating directly with the adjacent firing zone only, a longitudinal deflecting wall within each firing zone forming a passage for the products of combustion between it and the exterior wall of the furnace and over the top of said deflecting wall, each deflecting wall having its upper end portion inclined inwardly toward the goods space therein, and being provided with ports communicating with the goods space of the ad jacent firing zone near the bottom of the same, a plurality of transverse eduction flues extending from said ports to the exterior of the firing zone, and provided each with a damper for regulating the adjacent furnaces, a unitary tunnel section extending longitudinally from each end of the duplex firing zone, and provided with two lines of tracksfor two oppositely moving trains of cars, each line of tracks passing through one of said firing zones, and each of said end sections forming a combined cooling and preheating zone.

8. In a tunnel kiln, the combination of two unitary end sections, each comprising a single tunnel and a central duplex tunnel section, having two firing zones separated by an imperforate, vertical longitudinal partition wall, a row of furnaces located on the outer side of each firing zone and communicating directly therewith, a longitudt nal deflecting wall in each of said firing zones on the outer side of the goods therein, and-providing a passage for the. products of combustion from the adjacent furnaces between it and the outer wall, and top of the firing zone, said deflecting walls being each provided with inwardly extending deflecting portions at their upper ends, extending toward the goods space, and with horizontally disposed ribs below the upper ends of said walls on the side adjacent to the goods space, each of said deflecting walls being also provided with ports communicating with the goods space of the adjacent firing zone, a plurality'of transverse eduction fines extending from said ports through the said deflect-- 'ing' Walls and the exterior wall. of the kiln, and provided with dampers, two lines of tracks extending through the entire kiln, for conveying the two lines of cars in opposite directions, each line of tracks extending through one of said firing zones, each of said end sections being provided with-a central platform between the lines of tracks, the space above said platforms being free for the circulation of air around the goods carried by the cars of both tracks, each of said end sections being of suficient length to permitthe cooling of the fired goods on one line of cars and the transfer of the heat from said fired goods to the incoming goods on the other line of cars.

9. In a tunnel kiln, the combination of two unitary end sections, each comprising a sin gle tunnel, and a central duplex tunnel section provided with a central imperforate vertical longitudinal partition wall, dividing it into two firing zones, a row of furnaces located on the outer side of each firing zone and communicating directly therewith, a longitudinal deflecting wall in each of said firing zones on the outer side of the goods space therein. providing a passage for the products of combustion from the adjacent furnaces between it and the outer wall and top of the firing zone, each of said deflecting walls being provided with eduction ports communicating with the goods space of the adjacent firing zone, eduction fines extending from said ports to the exterior of the kiln and provided with dampers, said central partition wall being provided on each side, adjacent to the lower portion of the goods space, with an inwardly extending rib having a downwardly and inwardly extending deflecting surface for deflecting the products of combustion transversely of the adjacent goods space in a direction toward the eduction ports thereof, two lines of tracks extending through the entire kiln for conveying two lines of cars in opposite directions, each line of tracks extending through one of said firing zones.

10. In a tunnel kiln, the combination of two unitary end sections, each comprising a single tunnel, and a central duplex tunnel section provided with a. central iinperforate "ertical longitudinal partition wall, dividing it into two firing zones. a row of furnaces located on the outer side of each firing zone and communicating directly therewith, a longitudinal deflecting wall in each of said firing zones on the outer side of the goods space therein, providing a passage for the products of combustion from the adjacent furnaces between it and the outer wall. and top of the ring zone, each of said deflecting walls being provided with eduction ports communicating with the goods space of the adjacent firing zone, eduction fines extending from said ports to the exterior of the kiln a: d provided with dampers,said central partition wall being provided on each side, adjacent to the lower portionof the'goods space, with an inwardly extending rib having a downwardly and inwardly extending deflecting surface for deflecting the products of combustion transversely of the adjacent goods space in a direction toward the cduction ports thereof, said deflecting walls being each provided with inwardly extending horizontally disposed ribs below the upper ends of said walls on the side adjacent to the goods space to assist in distributing the products of combustion downwardly through the goods and prevent them from being drawn downwardly adjacent to the deflecting walls. two lines of tracks extending through the entire kiln for conveying two lines of cars in opposite directions, one line of tracks extending through each of said firing zones.

11. In a tunnel kiln provided with a firing zone, located substantially centrally of the length of the kiln and communicating with the end sect-ions of the kiln, of a row of furnaces located at one side of the firing zone and communicating directly therewith, a longitudinal deflecting wall in the firing zone at theside of the goods space adj acent- --to the furnaces providing a passage for the products of combustion from the furnaces between it and the outer walland the top of the thing zone, said deflecting wall being provided with eduction ports communicating with the goods space in the firing zone, eduction flues extending from said ports to the exterior of the kiln and provided -with controlling devices, the walls of said space in a direction toward the said eduction portson the opposite side thereof,

12; In a tunnel kiln, th combination with the firing zone thereof, and goods supporting and conv ying means movable longitudinally thercthrough, of a vertical, longitudinal deflecting wall in said firing zone, providing an inlet passage for the products of combustion between said deflecting wall andthe adjacent side wall of the kiln, discharging over the top of the deflecting wall into the goods space, a row of furnaces for heating said firing zone discharging their products of combustion into said inlet passage, said deflecting wall being provided with eduction ports on its inner face adjacent to the lower portion of the goods space, and eduction passages connected with said eduction ports for conducting the products of combustion away from the goods space of the firing zone, said deflecting wall between said eduction passages being of solid construction and flueless to enable it to withstand the high temperature to which it is exposed on its opposite sidesi 13. In a tunnel kiln, the combination with the firing zone thereof, and goods supporting and conveying means movable longitudinallytherethrough, of a vertical, longitudinal deflecting wall in said firing zone, providing an inlet passage for the products of combustion between said deflecting wall and the adjacent side wall of the kiln, discharging over the top of the deflecting wall into the goods space, a rowv of furnaces for heating said firing zone discharging their products of combustion into said inlet passage, said deflect-ing wall being provided with eduction ports on its inner face adjacent to the lower portion of the goods space, a longitudinally disposed collecting flue located outside of the tunnel kiln chamber, and eduction, passages connecting said eductionports with said, collecting flue for conducting the products of combustion away from the goods space of the firing zone, said deflecting wall between said eduction passages being of solid construction and fiueless to enable it to withstand the'high temperature to which it is exposed on its opposite sides. I 141-. In a tunnel kiln, the combination with the firing zone thereof, and goods supporting and conveying means movable longi tudinally therethrough, of a vertical, longi-*- tudinal deflecting wall in said firing zone,

providing an inletpassage for the products of combustion between said deflect-ing wall and the adjacent side wall of the kiln, discharging over the top of the deflecting wall into the goods space, a row of furnaces for heating said firing zone discharging their products of combustion into said inlet passage, said deflecting wall being provided with eduction ports on its inner face adjacent to the lower port-ion of the goods space, and transversely disposed eduction passages con nected with said eduction ports, and extending substantially horizontally through the bridge wall. and a longitudinally extending collecting flue exterior to the bridge wall and connected with said eduction passages, for conveying the products of combustion of the furnaces'away from the goods space of the firingzone.

15. In a tunnel kiln, the combination with the firing zone thereof, and goods supporting and conveying means movable longitudinally therethrough, of a vertical, longitudinal deflecting wall in said firing zone, and providing an inlet passage for the products of combustion between said deflecting wall and the adjacent side wall of'the kiln, discharging over the top of the deflecting wall into the goods space, a row of furnaces for heating said firing zone discharging their products of combustion into said inlet passage, said deflecting wall being provided with eduction ports on its inner face adjacent to the lower portion of the goods space, and transversely disposed, horizontal eduction passages connected with said eduction ports and extending transversely through the lower portion of said deflecting wall, and through the adjacent exterior wall of the kiln, and a collecting flue located outside of the kiln wall and connected with said eduction passages, the portion of said charging over the top of the deflecting wall into the goods space, a row of furnaces for heating said. firing zone discharging their products of combustion into said inlet passage, said deflecting wall being provided with eduction ports on its inner face adjacent to the lower portion of the goods space, and transversely disposed, horizontal eduction passages connected with said eduction ports and extending transversely through the lower portion of said deflecting wall, and

through the adjacent exterior wall of the kiln, the portion of said deflecting wall between the'transverse eduction passages being solid and flueless to enable it to withstand the high temperature to which it is sub jected on its opposite sides, and independent regulating means for independently controlling the passage of products of combustion through said eduction passages.

17 In a twin tunnel kiln, the combination with a duplex firing chamber located substantially centrally of its length, provided with a central vertical imperforate partition, dividing it into separate firing zones, a row of furnaces arranged on opposite sides of the firing chamber, the furnaces of each row discharging their products of combustion directly into the adjacent firing zone, a longitudinal deflecting wall in each firing zone, adjacent to the exterior kiln wall thereof forming an inlet passage from the adjacent furnaces between it and the kiln withstand the high temperatures to which they are Subjected on both sides, regulating means for said eduction passages, said kiln being provided at each end of said firing chamber with end portions for preheating and cooling, and two parallel sets of tracks for trains of tunnel cars movable in opposite directions, extending through the entire kiln, each set of tracks passing through one only of said firing zones.

18,. In a tunnel kiln, the combination with a duplex firing chamber located vsubstantially centrally of its length, provided with a central vertical imperforate partition dividing it into separate firing zones, a row of furnaces arranged on opposite .sides'of I the firing chamber, :the furnaces of each row discharging their products of, combustion directly into the adjacent firing zone, a longitudinal deflecting wall in each firing zone adjacent to the exterior. kiln wall thereof forming an inlet'passage from the adjacent furnaces between it and the kiln wall and over the top of said deflecting wall, each of said deflecting walls being provided with eduction ports on its inner face adjacent 'to the lower portion of the goods space of the adjacent firing zone, eduction passages extending from said eduction ports to the exterior of the kiln, the port-ions of each deflecting wall between said eduction ports being solid and flueless, to enable them to withstand the high temperatures to which they are .subiected on both sides, regulating means for said eduction passages, kiln being provided at each end of said firing chamber with an unitary end section, each forming a combined preheating and cooling zone, two parallel sets of tracks for conveying tunnel cars in opposite directions extending through the entire kiln, each set of tracks passing through both of said end sections and through one of the firing zones.

19, In a tunnel kiln, the combination with the firing zone thereof,-and goods supporting and conveying means movable longitudinally therethrough, of a vertical, longitudinal deflecting wall in said firing zone'providing an inlet passage for the products 01 combustion between said deflecting wall and the adjacent side wall of the kiln, and discharging over the top of the deflecting wall into the goods space, a row of furnaces for heating said firing zone discharging their products of combustion into said inlet passage, said deflecting wall being provided with eduction ports on its inner face adjacent to the lower portion of the goods space and located at different points longitudinally of the firing zone, and a longitudinally disposed collecting flue communicating with the eduction ports and located outside of the kiln structure defined by the side walls, crown and the floor of the kiln, to enable said deflectingiwall to withstand the high temperature "to which it is exposed on both sides.

-20, In a tunnelkiln, the combination with the firing zone thereof, and goods supporting and conveying means movable longitudinally therethroug'h, of a vertical, longitudinal deflecting wall in said firing zone providing an inlet passage for the products of combustion between said deflecting wall and the adjacent side wall of the kiln, and discharging over-the top .of' the deflecting wall into the goods space, a row of furnaces for heating said firing zone discharging their products of combustion into said inlet passage, said deflecting wall being provided with eduction ports on its inner face adjacent to the lower portion of the goods space and located at different points longitudinally of the firing zone, and a longitudinally disposed colleeting flue communicating with the eduction ports and located outside of the kiln structure defined by the side walls, crown and thfloor of the kiln, to enable said deflecting Wall to withstand the high temperature to which it is exposed on both sides, and independently operable ling means for certain of said eduqiion ports located adj acentthereto and at different points longitudinally of the firing zone for obtaining accurately graduated ratures within and longitudinally of the ing zone.

21. In a tunnel kiln, the combination with the firing zone thereof, and goods (supportand conveying means movable longiin tu dinally therethrough, of a vertical, longitudinal deflecting wall in said firing zone providing an inlet passage for the products of combustion between said deflecting wall and the adjacent side wall of the kiln, and

discharging over the top of the deflecting wall into the goods space, a row of furnaces for heating said firing zone discharging their products of combustion into said inlet passage, said deflecting wall being provided with eduction ports on its inner face adjacent to the lower portion of the goods space and located at different points longitudinally of the firing zone, eduction passages connected with said eduction ports for conducting the products of combustion away from the oods space, a longitudinally disposed col- "ectin flue connected with said )assa es and located outside of the limits of the kiln structure defined by the side walls, crown and bottom of the kiln, and independently operable controlling means for the eduction orts located in certain of said passages at 5 ifi'erent points longitudinally of the firing zone, to assist in obtaining accurately gradthe adjacent said wall of the kiln, and dis charging over the top of the deflecting wall into the goods space, a row of furnaces for heating said firing zone discharging their products of combustion into said inlet 'passage,-said deflecting wall being provided with I tudinally of the firing zone.

eduction ports on its inner face adjacent to the lower portion of the goods space and located at different points longitudinally of; the firing zone, a longitudinally disposedcollecting'flue, eduction passages connected with said eduction ports for conducting the products of combustion to said flue, and means for independently controlling said eduction ports for obtaining accurately graduated temperatures Within and longi- 23QIn a tunnel kiln, the combination with the firing zone thereof, having a goods space and goods supporting and conveying means movable longitud nally therethrough, furnaces'forheating the firingzone, means for conveying the products of combustion to and discharging them into the goods space of the firing zone at different points longitudinally thereof, said firing zone being provided with a plurality of eduction ports lo-' cated at different points longitudinally of the firing 'zone, a longitudinally disposed collecting flue connected with said ports,

and independently operable means located adjacent to certain of said eduction ports at different pointslongitudinally of the firing zone to assist in obtaining accurately graduated temperatures within and longitudinally of the firing zone.

24. In a tunnel kiln, the con'ibination with the firing zonethereof, having a goods space and goods supporting and conveying means movable longitudinally therethrough, furnaces for heating the firing zone, means for conveying the products oflcombustion to and discharging them into the goods space of the firing zone at different points longitudinally thereof, said firing zone being provided with a plurality of eduction ports located at different points longitudinally of the firing zone, a longitudinally disposed collecting flue, transversely disposed passages for connecting said eduction ports with said collecting flue, and independently operable control devices for certain of said ports at different points longitudinally of the firing zone located between said ports and the collecting flue.

25. In a tunnel kiln, the combination with the firing zone thereof, having a goods space and goods supporting and conveying means movable longitudinally therethrough, furnaces for heating thefiring zone, means for conveying the products ofcombustion to and discharging them into the goods space of the firing zone at different points longitudinally thereof, said firing zone being being provided with a plurality of eduction ports located at different pointslongitudinally of the firing zone, 1 a longitudinally disposed collecting flue located outside of the limits of the firing zone as defined by the side walls, crown and the'bottom of the kiln, eduction passages for connecting said eduction ports with said collecting flue and independently operable control devices for certain of said ports at different points longitudinally of the firing zone located adjacent to said ports and between them and the collecting flue to assist in obtaining accurately graduated temperatures within and longitudinally of the firing zone. a A

26. In a tunnel kiln, the combination with the firing zone thereof, having a goods space and goods supporting and conveying means movable longitudinally therethrough, furnaces for heating the firing zone, means for conveying the products of combustion to and discharging them into the goods space of the firing zone at different points longitudinally thereof, said firing zone being provided with aplurality of eduction ports located at different points longitudinally of the firing zone, eduction means connected with said ports for conveying the products of combustion away from the firing zone including eduction passages communicating with said ports and located adjacent thereto,

and a longitudinally disposed collecting flue communicating with said passages, said ports and passages at different points longitudinally of the kiln having different predetermined capacities of withdrawal to as sist in establishing graduated and varying temperatures within said firing longitudinally thereof.

27. In a tunnel kiln, the combination with the firing zone thereof, and goods support ing and conveying means movable longitudinally therethrough, of a vertical longitudinal deflecting wall in said firing zone providing an inlet passage for the products of combustion between said deflecting wall and the adjacent side Wall of the kiln, and discharging over the top of the deflecting wall into the goods space, a row of furnaces for heating said firing zone discharging their products of combustion into said inlet passage, said deflecting wall being provided with eduction ports on its inner face adjacent to the lower port-ion of the goods space and located at different points longitudinally of the firing zone, eduction means connected with said ports including eduction pasages adjacent to said ports, and a longitudinally disposed collecting flue communicating with said passages, said eduction ports and passages having varied predetermined capacities of withdrawal for assisting in establishing graduated and varying temperatures within said firing zone longitudinally thereof.

In testimonv whereof I aflix my signature.

WILLIAM LEE HANLEY, JR.

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