GB319840A - Improvements in or relating to kilns and the like - Google Patents

Abstract

319,840. Carborundum Co., Ltd., (Carborundum Co.). July 3, 1928. Tunnel kilns.-In a tunnel kiln heated by a combustion chamber made of refractory material of high thermal conductivity, which radiates heat and discharges combustion products into the tunnel, as described in Specification 266,140, the combustion is controlled to provide a reducing, neutral or oxidizing atmosphere as may be desired. The kiln shown has a preheating-zone a, low and high temperature zones b, c, a cooling-section d with groups of air flues x, y z in the walls, and a final cooling- section formed by a metal tunnel 37. The partitions between the cooling flues and the tunnel are made of a non-metallic refractory material of high thermal conductivity, such as silicon carbide, and the air heated in the flues is conducted to a roof flue 14 and delivered through damper-controlled conduits 15, 16, 17 to the combustion chambers 6, 4. In the high temperature zone there are two combustion chambers 6 fired from opposite ends at each side of the tunnel, while in the low temperature zone a single chamber 4 of smaller fuel burning capacity than the chambers 6, is provided at each side. The combustion chambers may be constructed as described in Specification 186,639, or may consist of elongated chambers 22, Fig. 7, made of silicon carbide with side outlet passages 23, or of two spaced chambers, arranged either side by side, or in superposed relation, and connected by a passage at one end. The chambers may be built into the kiln structure, or removably supported on benches at the sides of the tunnel, or may be mounted on trucks so that they can easily be withdrawn for replacement. Transverse passages 42 leading to the space beneath the goods trucks 44 are provided to allow a natural circulation of air for cooling the rails and the metal parts of the trucks. Specification 159,522 also is referred to.