1,015,213. Tunnel kilns. KELLER OFENBAU G.m.b.H. Aug. 3, 1962 [April 19, 1962], No. 29870/62. Heading F4B. Ceramic ware is fired in a tunnel kiln heated by combustion in a space between the cars and the roof and walls of the kiln, the flow of air in counter - current through the kiln being adjusted by setting the flow section of channels extending longitudinally and transversely of the cars, and, except for air introduced with the fuel, no air or gases are withdrawn from or introduced into the kiln between the ware discharge end and the ware entry end. The longitudinal channels 12 and transverse channels on the kiln cars are formed by channel section bricks 9SP1/SP, 911 arranged on the cars, Fig. 4, and flow restricting elements may be placed in the channels. Skirts 13 on the cars dip into sand troughs at the sides of the kiln. The kiln has fuel ports 6SP1/SP in the firing zone, Fig. 1, and outlet flues 7 at the ware entry end communicating with ports at the level of the car platforms. The ends of the cars have overlapping strips 16 and an asbestos gasket 18 co-operating with a flange 17, Fig. 6, and the support structure 22 for tiles to be fired are arranged to form longitudinal channels and transverse firing channels 21, Fig. 11. The amount of air entering the kiln at the ware discharge end is such that the product of its mass and mean specific heat is equal to the product of the mass and mean specific heat of the ware plus an allowance for the cars and furniture. Since no additional air or gases are fed to the kiln or removed from it before the gases reach the flues 7, this enables the greatest possible use to be made of the heat withdrawn from the ware in the cooling zone.
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