GB1396145A - Pulverised fuel delivery method and system for a blast furnace - Google Patents

Abstract

1396145 Automatic process control BABCOCK & WILCOX CO 29 Aug 1972 40058/72 Heading G3R [Also in Division F4] A system for feeding pulverized fuel to the tuyeres 41 of a blast furnace, comprises three tanks 31 A-C, which are connected in turn to a conduit 33 supplied with compressed air to deliver pulverized fuel to the tuyeres in accordance with the quantity of hot blast fed to the furnace. The tanks 31 A-C are fed from a storage tank 23, receiving pulverized coal and fires from a cyclone 17 and filter 27. A pulverizer 14 is fed with coal from a hopper 11 and hot combustion gases from a chamber 16. A feeder 12 between the hopper 11 and pulverizer 14 is controlled to maintain a required weight of coal in the bins 31 A-C and 23, and the air supply to chamber 16 is controlled in correspondence to the coal-feed. Signals from load cells corresponding to all the tanks 31 A-C and 23 are summed and the signals representing the weights in tanks 31 A-C are differentiated so that a polarity discriminator enables the state of the tanks to be determined. The required flow of coal through the system is determined in accordance with the rate of flow of air through the bustle pipe 51 feeding the blast furnace tuyeres, and a coal demand signal is compared with a signal from the polarity discriminator representing the flow of coal from the system and the datum used to determine a pressure to be maintained in the tanks 31 A-C feeding the furnace. Each tank 31 A-C is pressurized with inert gas from a source 50 to supply fuel to the line 33, maintained under pressure while full of coal as a standby, or connected to the supply tank 23 to be refilled. Pressure equalization valves 55 A, B, C between the tanks 31 A-C and tank 23, coal outlet valves 35 A, B, C and coal inlet valves 32 A, B, C are controlled by a device receiving weight signals from the tanks 31A-C so that, on reaching a minimum weight content of coal, the tank in use is disconnected from the pressurizing supply and the furnace coal feed line 33, and connected to the reserve tank 23 to be refilled, and the full tank, which is already under pressure is connected to the coal feed line 33. The tanks 31 A-C should be refilled at a greater rate than the maximum coal output rate, so that the tank being refilled is disconnected from the reserve tank 23 and brought to pressure before the tank then connected to the pressure is empty. The flow of carrier air in the line 33 is controlled in accordance with the coal demand rate derived from the air flow in the bustle pipe. Inert gas is fed to the reserve tank 23 and tanks 31 A-C to maintain the coal in a fluidised state during storage.