GB245827A - Improvements in and relating to tunnel kilns - Google Patents

Abstract

245,827. Wilputte, L. Oct. 13, 1924. Tunnel kilns.-The heating or cooling of goods in a tunnel kiln is effected by passing heating- gases or air across the corresponding zones with a direction of flow which is approximately horizontal and is the same at all points in the zone. As shown in connection with a twin tunnel in which two lines of trucks move in opposite directions so that heat is transferred from cooling goods in both end sections to the freshly-charged goods. The kiln consists of a number of structurally independent sections a or a<1>, each section a of the main heating zone having at each side a pair of regenerator chambers E, F for gas and air respectively, while the sections a for the combined preheating and cooling zones have only air regenerators G. The chambers E, F are connected at their upper ends to flues E<1>, F<1>, which deliver to vertical flues D in communication with the tunnel through ports D<1>, and at their lower ends through flues E<2>, F<2> to longitudinal mains K, KA, serving alternately for supplying air and exhausting waste gases. The flues F<2> are permanently in communication with the mains through valve boxes HA having air inlet valves H<3>, while communication between the flues E<2> and the mains can be cut off by valves H<1>. Gas is supplied to the chambers E from a main 0 through branch pipes O<1> fitted with stop valves P and controlling valves O<2>. In operation gas and air are preheated in the chambers E, F at one side of the kiln, combustion is effected in the tunnel, and the products are withdrawn through the opposite regenerators, the direction of flow of the gases being reversed at intervals. The supplies of gas and air are controlled by damper blocks R in the flues E<1>, F<1>, and their distribution in a vertical plane is controlled by throttling-bricks inserted in the ports D<1> and manipulated through access openings A<15>. The regenerator chambers G in the combined preheating and cooling sections of the kiln serve to extract heat from air which has passed through the tunnel and to deliver it again to the entering cold air, thus minimizing the danger of injury to the goods by exposing them to unduly low temperatures during cooling. To equalize the heating of the freshly-charged goods in the two phases of operation gas is continuously supplied through pipes O<3> to the regenerators at the preheating sides of the end sections of the tunnel. In one phase combustion takes place in the regenerators, and in the other in the flues G<1>, D. In a modified construction in which air heating regenerators only are provided in the high temperature zone the flues D serve as combustion flues. When the kiln is constructed to accommodate a single line of trucks flues are arranged so that air which has passed through the regenerator chambers and across the tunnel portion of the cooling-zone, can be similarly passed between the regenerators of the preheating zone. Reference has been directed by the Comptroller to Specification 498/81.