US553947A - Downdraft-kiln - Google Patents

Downdraft-kiln Download PDF


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US553947A US553947DA US553947A US 553947 A US553947 A US 553947A US 553947D A US553947D A US 553947DA US 553947 A US553947 A US 553947A
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    • C21D9/00Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • F27B3/00Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces
    • F27B3/002Siemens-Martin type furnaces
    • F27B3/005Port construction


(No Model. 's Sheets- Sheet 1.. 5
H. AQWH'EELER. DOWNDRAFT KILN. No. 553,947... Patented P05; 4,' 18.96;
(No Model.) Y 3 Sheets-Sheet 2. H. A. WHEELER. DOWNDRAFT KILN. No. 553,947. 7 Patented Feb. 4, 1896.
"a k g l pi. l N \E N Q w E H PQ q (No Model.) v 3 sheets-sheet 3.
SPECIFICATION forming part of Letters Patent No. 553,947, dated February 4, 1896.
Application filed July 3, 1895. Serial No. 554,898- (No model.)
To aZZ whom it may concern.-
Be it known that I, HERBERT A. WHEELER, a citizen of the United States, residing at the city of St. Louis, in the State of Missouri, have invented new and useful Improvements in Downdraft-Kiln s, of which the following is a specification.
My invention relates to improvements in the utilization of the waste heat in cooling the burned kiln, in greater economy in fuel, and in the construction of the kiln; and with these objects in view my invention consists of the novel devices and combinations hereinafter described and specifically claimed.
In the accompanying drawings on three plates, Figure l is a longitudinal View of the kiln, partly in elevation and partly in section, along the line 1 1, Fig. 2. Fig. 2 is a horizontal View of the kiln, partly in plan and view of the roof-tile covers; and Fig. 5 is an enlarged section of the dampers for control.- ling the waste heat on the line 1 1, Fig. 2.
Similar letters refer to similar parts in all the drawings.
The kiln is what is known as the downdraftrectangular type that is used for burning building-brick, paving-brick, fire-brick, sewer-pipe, terra-cotta, and other clay wares, and in conformity with this class of kilns consists of a long rectangular chamber A with an arched roof B in which is set the brick or ware for burning, with fire-boxes O 0 along each side of said chamber, flash-walls D for carrying the flames to the top of the kiln, open floor-tiles E for allowing the heat to pass through the floor to the flues F under said floor, which convey the products of combustion to suitable chimneys G, and buckstaves H and tie-rods I for binding the side walls J and end walls K in the usual manner.
End doors L give entrance to the kiln for filling and emptying, and roof-ports M permit the inspectionof the brick during the burning and hasten the cooling after burning if opened. to expand without buckling or bulging.
My improvements for the utilization of the waste heat that is lost in cooling of the burned Slots 0 in the flash-wall enable it kiln consists of one or more openings orports N in one or both end walls directly under the crown of the roof, and of a circular or any other convenient shape or size. For clearness only one such port is shown in only one of the end walls in the drawings, but two or more ports can be used, and in both end walls if desired. This port N is connected by pipe or hot-air main P that goes to a suitable exhaust fan or blower, which draws the heated air out of the kiln and throws it into the tunnel-driers or other kilns for drying the brick before burning. This port is closed by two dampers Q and V of special design and construction. One damper, Q, is inside of the kiln and rests on a shelf R that is built out from the end wall. This damper is composed of asbestos boarding, or fire-clay tiling, or similar fireproof material, and sets in front of the port N when it is to be kept closed during the burning of the kiln, and is moved or slid to one side along the shelf R during the cooling of the kiln by means of tongs that are introduced through the roof-slot S. Loose tiles T cover this slot S in the usual manner, which can be moved to one side to give access to the damper Q or to admit air when desired.
The other damper,V, is composed of a heavy sheet of asbestos cloth or of a thin fire-clay tile inclosed in asbestos cloth and hung by an asbestos rope from a small winding-drum and ratchet or winch \V. This damper V works in a special deep slot X, and by the drum W can be raised to close the port N or lowered to more or less completely open it. By using two dampers of refractory material which are operated through slots, the heat can be prevented from escaping through the port N during the burning of the kiln by jamming both dampers tightly against the wall with fire-claywedges, or by daubing them tight with clay before firing the kiln.
By removing damper Q to one side and slightly lowering damper V, so as to uncover the top of the port N, the waste heat when cooling the burned kiln isfirst drawn from along the top of the crown of the roof and away from the hot brick or other ware, which, from the usual settle as the result of burning, are below the port N, and so the brick or ware are not checked or i jured by drawing ICO off the heat, as it is taken from above them. As the bricks or ware grow cooler and can stand the admission of more air and the faster withdrawal of the heat, the damper Y can be further lowered and finally entirely dropped into the lower part of the slot X, when it is safe to throw the port N wide open. the heat is first drawn off at the beginning of the cooling down of the hot kiln, the top of the slot X is left open to allow cold air to rush into the port N to cool the hot gases sufficiently as to not injure the pipe P or the exhaust-fan, the temperature of the kiln is then very high or above a red heat. The slot S is also opened to increase this influx of cooling air, if desired. When this cooling air is no longer needed as the kiln grows cooler,
and during the burning of the kiln, the top of the slot X is covered with tile similar to T. By thus adjusting the lowering of the damper V the heat can be utilized without injuring the brick or ware by too sudden cooling, and by admitting a regulated amount of cool air through the slots X and S by removing more or less of the tile covers the temperature of the withdrawn hot air can be kept sufficiently low as to not injure the hot-air main or exhaust-fan. An additional control over the temperature in the hot-air main P is obtained by putting a valve U at P, the end of the main opposite to the fan, which is left open, and this controlling-valve U is opened more or less as may be required to lower the temperature of the gases as they are drawn out of the kiln by commingling with the cold air admitted by the valve U.
Any number of kilns may connect with the hot-air main P, for which purpose they should preferably be built in a row, or each kiln can have its own independent system of hot-air mains and fans, as may be found desirable,
according to the size of the kilns, arrangement of the plant, and other local reasons.
My improvement for a more economical use of the fuel consists in having the fire-boxes or furnaces C entirely within the side walls J, instead of being more or less on the exterior, and in building them adjacent to one another in pairs, as C and C, with both opening into the same bag or pocket or combustion-chamber Y between the side wall J and flash wall D. By having the fireplaces C and C in pairs and tiring them alternately, the temperature in the combustion-chamber is not much lowered when a furnace is being coaled or cleaned, as the heat of the adjoining furnace maintains the temperature. This results in more perfect combustion and reduces the formation of smoke with the saving in fuel resulting therefrom, while the quality of the brick is very much improved by maintaining a more uniform heat, and no checked brick results, which happens if cold air enters the kiln.
By having the fires entirely inside of the side walls, the great loss of heat by radiation and convection is prevented that occurs when they project out beyond the side walls, as in the usual downdraft-kilns.
My improvements in the construction consists in building heavy primary arches of firebrick a, which are carried on fire-brick side walls b, to carry the side walls J of the kiln, and secondary furnace-arches of fire-brick (Z, carried on fire-brick walls a, which line the furnaces. This enables the independent secondary arches cl and lining-walls e to be repaired and renewed as they burn out from the slagging action of the fire without weakening or affecting the walls of the kiln, as the latter are carried on the primary arches ct and side walls l).
The fire-arch (Z is cooled by leaving a port or airpassage 9 between it and the primary arch u, which will greatly prolong the life of the tire-arch d and introduce hot air into the combustion-chamber Y, which will aid in se curing complete combustion and preventing smoke, with the economy resulting therefrom.
The fire-boxes C and G are closed by a fireclay tile m, which is bound in an iron frame and hung from an overhead pulley n by a counterweight p. This gives a better means of coaling and cleaning the fire by raising the door entirely out of the way and enables the heat to be controlled by partly opening the door from below, which throws the entering cold air over the fire first, thereby preventing smoke and securing more perfect combustion. Hitherto the fire doors have been either hinged or slid sidewise on rollers or a step, which opens the furnace from top to bottom when it is necessary to partly open the door to check the fire. This causes smoke and imperfect combustion, which would not occur if the partial opening was made on a level with the fire, as it then gets heated by passing over the fire, which is secured by my new application of a verticalmoving counterweighted door.
A further improvement in the construction of the kiln is to cover the roof-ports M by a special combination of tiles. Instead of covering the roof-port with a single tile in the usual manner, a primary split tile h and 7b with a small hole 1' in the center is used, and a secondary tile covers this small hole 2'. By this arrangement the settle of the brick or ware is measured through the small hole '6 on removing the coverk, and the large tile h and h make a convenient datum to measure the settle from. This small hole also makes it much cooler and easier for the kiln-burner, allows the escape of much less heat, and results in less frequent cracking of the tile than when a large single tile is used, while by splitting the large primary tile h into two halves, or 7L and h, the tendency to crack is still further reduced.
What I claim as my invention, and desire to secure by Letters Patent, is-
The combination in a downdraft-kiln of one or more ports in the end Walls directly for closing and regulating the covering of the under the crown of the roof, an inside damper resting on a shelf and operated through a slot in the roof, a curtain-damper Working Within a deep slot through said port, said curtaindainper being hung by an asbestos rope, a Winch for lowering said rope, movable tiles slots, and pipes leading from said ports to exhaust-fans, substantially as shown.
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