GB437426A - Improvements in and connected with ovens and furnaces for heat treating metal and other articles - Google Patents

Abstract

437,426. Muffle - furnaces. LUCAS, E. E., Mount Works, Wharton Street, Nechells, Birmingham. May 3, 1935, No. 13244. [Class 51 (ii)] Air, preventing admission of.-In a muffle furnace, more particularly adapted for the heat treatment of metals, a screen of combustion products is passed vertically upwards across the mouth of the muffle through the space 8 between the end of the muffle and the furnace wall 9. In the construction shown the floor flues 2 are fired by burners 1, and the products pass along one or both sides of the muffle to the top flue 5, and thence down the back flue 6 to a flue 7, communicating at the front with the space 8, which leads at its upper part into the exhaust flue 10. The walls of the space 8 below the level of the muffle floor, or above the level of the roof, may converge as shown at 8<a>, and an adjustable block 12 may be provided to control the crosssection of the gas screen. Part of the gases from the flue 7 may be byepassed direct to the flue 10 through damper-controlled side flues. The muffle opening may have a depending lip 3<a>, preferably tapered, along its upper edge. Modifications are described in which the floor flues are fired from the front through sleeves spanning the flue space 8, and in which combustion is effected in the back flue, the products passing to the top flue 5 and thence down the sides to a floor flue. A recuperator may be fitted in the exhaust flue.