GB520868A - Improvements in or relating to furnaces, ovens and the like - Google Patents

Abstract

520,868. Furnaces for heat treatment. MACDONALD, J., and G. W. B: ELECTRIC FURNACES, Ltd. Nov. 2, 1938, No. 31767. [Class 51 (ii)] In a furnace in which the charge is heated or cooled by air or gases circulated between the furnace wall and liner defining a charge-receiving-space and thence through the liner, the path of the air or gases around the charge is restricted by a plate or plates extending across the chamber and defining a space enclosing the charge and approximating to the section of the charge. Fig. 1 shows an electric furnace with heating elements 3 arranged in the space between an outer wall 1 and liner 2 through which space air or gas is circulated by a fan and also through the chamber enclosed by the liner and containing the charge supported on trucks 6. The path around the charge is restricted by plates 8 which may be supported on members 9, 10 and turned about their outer-edges. The plates may be fixed at their outer edges to shafts which may be rotated to turn the plates into upper and lower positions. In a modification the plate may extend across the whole width of the. chamber and be supported in grooves. A cross section of a vertical furnace is shown in Fig. 3 with plates 18 restricting the space within the chamber 15 enclosing the charge 17. The plates are slidable in grooves 19. The space between the plates and liner is closed at the ends so that the air or gas passes only through the space enclosing the charge.