GB527765A - Soaking pit furnace and method of controlling it - Google Patents

Abstract

527,765. Ingot-heating furnaces. DEHN, F. B. (Amsler Morton International, Inc.). March 9, 1939, No. 7721. [Classes 51 (i) and 51 (ii)] In an ingot heating furnace of the kind described in Specification 491,814, the thermal input to the furnace is controlled by regulating the fuel supply during the initial stages of the heating cycle in accordance with the temperature prevailing at the top of the furnace and thereafter regulating the fuel supply in accordance with the temperature prevailing at the bottom of the furnace. The thermal input is first manually set at a predetermined rate and when the thermocouple 71 at the top of the furnace reaches the control point a recording potentiometer 51 energizes an electromagnet power unit 49 to actuate a valve 48 in the fuel supply pipe 46 to reduce the fuel supply. When the thermocouples 75, 76 at the bottom of the furnace indicate a predetermined temperature on the controller 52, a switch 77 is operated to connect this controller to the power unit 49 so that the fuel supply is controlled in accordance with the temperature at the bottom of the furnace. The correct ratio of the fuel supply through the pipe 46 and air supply by a blower 30 through pipe 31 is maintained by a regulator 45 which is operated by the differential pressures on opposite sides of orifice plates 60, 63 in the air and fuel supply pipes to control fluid pressure from pumps 56, 57 and pipe line 58 leading to the regulator 45 and from the regulator through pipes 43, 44 to a power cylinder 42 for actuating a valve 41 in the inlet to the blower 30. A regulator 39 is provided for maintaining a constant pressure in the furnace. This regulator is operated by pressure differentials in the furnace pressure sampling tube 67 and in a tube 69 connected to atmosphere and controls fluid pressure from the pumps 56, 57 and main 58 to pipes 37, 38 connected to the power cylinder 36 for adjusting the damper 35 in the stack flue.