GB1329578A - Method of heating metal parts particularly steel ingots or the like in soaking furnaces particularly pit type furnaces and a burner arrangement for carrying out the method - Google Patents

Abstract

1329578 Burner arrangement and control for soaking furnace SOC ITALIANA IMPIANTI SpA 13 Nov 1970 [15 Nov 1969] 54210/70 Headings F4B and F4T A burner control system for controlling the heating of steel ingots in a pit type soaking furnace 1 heated by a burner arrangement comprising two coaxial burners defined by air chamber 5 and outer fuel tube 7, and inner fuel tube 8 and intermediate air tube 7 respectively, each burner being provided with respective fuel supply pipes 11, 15 and air supply pipes 9, 14, includes means controlled automatically upon the furnace wall reaching a temperature higher than the surface melting temperature of the ingots to throttle the air and fuel supply pipes to the outer burner causing a consequent increase in pressure in the supply pipes of the inner burner and an increased admission speed of combustion gases into the furnace during the initial stages of the soaking period, thus maintaining or increasing turbulence, initiated by inclined air supply nozzle 10, and uniformity of temperature distribution in the furnace, the ratio of fuel to combusion air remaining constant for both burners. During the soaking period heat is conveyed to the ingots by radiation from the superheated furnace walls, by convection induced by intensive turbulence, and by the direct output from the remaining operational burner which is fuelled by any gaseous fuel or fuel convertable into gaseous form, e.g. liquid or pulverized fuel. Air supply pipes 9, 14 are connected to a common manifold 16 supplied by blower 17 and similarly fuel supply pipes 11, 15 are supplied by blower 19, the supply pipes 9, 11 to the outer burner having electrically operable throttle elements 20, 21 controlled in response to temperature sensor 24. Flow measuring devices 27, 29 and controller 28 ensures a constant fuel/air ratio for combustion. During an initial heating period throttle elements 20, 21 are open and both burners operate at full power. When the walls of the furnace reach the required temperature sensor 24 acts to gradually close throttle element 20, controller 28 consequently and simultaneously closing throttle element 21 to shut down the outer burner, thus creating a pressure rise in the supplies to the inner burner. As the ingot heats and the furnace walls cool a uniform final temperature is established at which control device 26 and sensor 24 act to close throttle element 22 and, via controller 28, throttle element 23 to shut down the inner burner completely and terminate the soaking period.