GB746255A - Pulverised coal feeding and pressurising system - Google Patents

Abstract

746,255. Pneumatic conveyers. UNION CARBIDE & CARBON CORPORATION. Aug. 16, 1954 [Aug. 27, 1953], No. 23723/54. Class 78 (1). In apparatus for introducing pulverized material, e.g. coal, from a hopper 10 at atmospheric pressure into a stream of gas, e.g. oxygen, under pressure of the kind in which the material is discharged from the hopper by gastight means, e.g. a rotary bladed wheel 12, falls into a supply chamber 14 and is transferred by a mechanical conveyer operating in a closefitting casing, e.g. a screw 24, to a mixing chamber 30 having an inlet conduit 32 for supplying gas under pressure and an outlet conduit 34, a preselected level of material is maintained in the chamber 14 and the pressure in this chamber is kept at a preselected value above the pressure in the mixing chamber. The level of material is kept constant by a diaphragm-operated switch 16 which through a relay 20 controls the supply of current to the motor 22 driving the discharger 12. A port 64 in the chamber 30 is connected by a pipe 62 to one side of a differential pressure controller 54, the other side of which is connected by a pipe 60 to a port 50 in the chamber 14. The controller includes a mechanism for measuring the difference in pressure between the ports 64, 50 and a switch mechanism adapted to operate one or the other of the motor valves 68, 42 which regulate the flow of carbon dioxide or other inert gas into or out of the chamber 14 when the pressure differential is above or below a predetermined value. If the pressure in the chamber 30 increases, the controller 54 acts through the line 70 to open the valve 42 and inert gas flows into the chamber 14 through the pipes 44, 46, 48 and port 50 until the pressure is built up. When this occurs, the valve 42 closes. When the pressure falls, the controller works through the line 66 to open the valve 68 and inert gas passes from the chamber 14 through the port 50 and pipes 48, 46 and 76 until the pressure is reduced sufficiently. The valve 68 then closes. The chambers 14, 30 are connected by a relief conduit 48, 72 containing a check valve 74 which opens automatically when the pressure in the chamber 14 exceeds the pressure in the chamber 30 by a preselected amount.