GB314104A - Improvements in or relating to underfeed mechanical stokers - Google Patents

Abstract

314,104. Thornton, A. A., (Parker, M. E.). March 19, 1928. Mechanical stoking. - Relates to underfeed mechanical stokers employing a fuel-feed screw and is described in connection with a hot water or steam system for heating buildings. The feedscrew working in a conduit 19 delivers fuel upwardly into a fire-pot 16 surmounted by sloping tuyere walls the space around which is in communication with a conduit 101 supplied with air under pressure by a fan 98. According to the invention, in order to prevent back flow of gases through the fuel conduit, air under a higher pressure than the blast is supplied to the fuel conduit by a pipe 106 which is tapped into the fan casing at a point of maximum pressure. The feed screw is driven through a variable-speed gearing forming the subject of Specification 314,324 and having combined with it the safety shear-pin driving-connection forming the subject of Specification 314,323. In addition the motor 95 is controlled jointly by a room thermostat 113 and a boiler-temperature thermostat 109. Thus, in operation, when the motor has been stopped the supply of heat will continue for a time from the boiler without further fuel supply while at the same time possible damage due to solidified clinker on an automatic start with the fire gone cut, is prevented by the safety shear-pin in the gear-box. The sloping tuyere walls have spaced vertical rear members 24 and top edges grooved at 35, Fig. 3, for engagement by L-section securing girders 33 and they rest on a T-beam frame 21 mounted in brickwork. The tuyeres themselves are of converging-diverging form.