GB110918A - Improvements in or relating to Tunnel Ovens. - Google Patents

Abstract

110,918. Dressler, C. Aug. 11, 1916. Tunnel kilns.-In a kiln or oven having longitudinally arranged combustion flues as described in Specifications 18114/10, 8228/12, 8505/13, and 18821/13, the high-temperature zone of the kiln is prolonged by introducing fuel and air into the combustion flues at different points along their length. The combustion points may be close together, so that a substantially uniform high temperature is maintained over a length of the kiln, or they may be spaced so that the goods pass successively through zones of high and lower temperatures. In one form, shown in Fig. 1, the combustion flue is divided longitudinally by a partition b, and the two chambers c, c<1> thus formed are supplied with gas through dampered ports d, d<1>, situated at different points in the length of the kiln, and with air either through separate inlets e, e<1>, or through a common inlet at the rear of the port d'. The products of combustion from the two chambers mix together in the undivided portion a' of the combustion flue. The combustion point of the inner of the two chambers c, c<1> is preferably nearer to the inlet end for the goods. The partition b may be flanged to provide strength, and the joint between it and the roof of the combustion flue may be made by sandy clay to allow for expansion. In a modification, the partition b extends only a short distance to the rear of the gas and air inlets d, e, and the chamber c is there closed by a transverse partition. In other constructions, one of the chambers is formed by an internal flue, or the two chambers may be end to end in the flue, and the gases from the rear chamber are led to the commmon portion a' by a bypass. In the construction shown in Fig. 8, gas is supplied through ports d to a number of separate combustion chambers, the roofs of which are arranged stepwise to allow air from the flue u to enter through ports e. The products of combustion pass into the flue through lateral openings v. In other forms, gas, or air, or both are admitted at different points along an undivided flue.