Patent GB-697644-A (GB)
Title: Improvements in tunnel kilns
IPC: F27D99/00
Filed: 1949-07-07
Abstract: 697,644. Tunnel kilns. CREMER, G. July 7, 1949 [Dec. 27, 1948], No. 18025/49. Class 51(ii) In a continuous tunnel kiln for firing ceramic ware divided into drying, preheating, firing, indirect cooling and direct cooling zones, end doors are dispensed with and axial flow of air through the tunnel in the preheating, firing and indirect cooling zones is prevented by mounting metal slides having flexible seals contacting the walls and roof of said tunnel between any pair of adjacent trucks, providing further flexible sealing units at chosen points on the sides of the tunnel to contact the sides of the trucks and completing the sealing of the tunnel space by providing the trucks with side plates dipping downwardly into sand seals. Each slide 21 Fig. 11 shaped to the contour of the tunnel 2 and provided with metal brush seals 25 on its side and upper peripheries, is mounted between adjacent kiln trucks 28 which are traversed through the tunnel by pusher mechanism 33, passes through the drying zone, Fig. 1, for at least four truck lengths until a slot 20 is reached through which slot the slide is removed and returned to the inlet for re-use. Immediately prior to the slot 20 on each wall of the tunnel is a metal brush seal 34 contacting the side plates of each truck which side plates dip into sand seals 35, the side plates of adjacent trucks being provided with mutually engaging brackets and sockets to complete the seal, Fig. 19, (not shown). In the final cooling section of the tunnel, Fig. 9, further slides 21 are introduced between trucks through a slot 24 and removed through another slot 23 spaced from the former by at least three truck lengths, a further brush sealing unit 34 being provided between said slots. The Specification as open to inspection under Sect. 91, comprises also the subject matter of Specification 697,716. This subject-matter does not appear in the Specification as accepted. Cooling air entering by the exit end of the tunnel, passes by ducts 12 alongside the tunnel roof to metal recuperators 10, 11, Fig. 7, which constitute a rapid cooling zone, passes into ducts 13 having a branch supplying heated combustion air to the burners in the firing zone, Fig. 5 (not shown), through ducts 14 over the preheating zone, Fig. 3 (not shown), and is supplied as drying air through ports 47 in the drying zone, Fig. 1. Finally by means of staggered recesses 32 in opposite walls of the tunnel it passes through the trucks and out at the inlet end of the tunnel. Provision is also made in the cooling zone, Fig. 7, for a water-cooling system 4 which incorporates sets of pipes 5, 6 and 7 in the roof of the rapid cooling section and sets of roof pipes 1 and wall pipes 3 immediately before the slot 24 in a section 9 of the cooling zone in which the profile of the tunnel is enlarged. A further set of tubes may be disposed in the roof of the firing section for the provision of heating steam and refractory screening slides may be movably inserted in front of any of the sets of cooling tubes or the recuperators 10, 11 in order to control the cooling gradient in the tunnel, Fig. 14 (not shown). Combustion gases pass from the firing section to the preheating section from which they are discharged through rows of ports in the side walls connected in symmetrical fashion through collecting boxes and ducts to a chimney to give uniform distribution through the discharge ports.