Patent GB-234092-A (GB)
Title: Means for automatically regulating the rate of combustion in furnaces or ranges of furnaces
IPC: F23N3/08
Filed: 1925-05-09
Abstract: 234,092. Roucka, E. May 13,1924, [Convention date]. Draught, regulating.-Apparatus for regulating the draught in one or more boiler furnaces in accordance with the steam consumption or load comprises a diaphragm subjected to boiler pressure and serving to actuate a valve controlling the admission of steam to a servo-motor which adjusts the fulcrum of a lever system, or a spring acting thereon, such lever system being subjected also to the pressure of air supplied to or gases in or leaving the furnace and adapted to operate a valve controlling the supply of fluid to a servomotor controlling the flue damper. The pressure in the steam main 22 is transmitted by a pipe 24 to a diaphragm 28 adapted to operate a lever 32, loaded by a weight 34 and spring 36, and connected by a rod 38 to valve gear 40 controlling the admission of steam to a servo-motor 50. The piston-rod 48 of the servo-motor is connected by a chain 42 passing over pulleys 44 to the spring 36 which operates on the lever 32 to restore it and the valve gear to their normal position. The movement of the piston-rod 48 also adjusts the position of a guided roller 59 acting as a fulcrum to a lever 52, one end of which is acted upon by an adjustable spring 60, the other end being connected by a rod 74 to a bell 72 immersed in oil or the like and subjected to the draught pressure on the furnace side of the damper 4, through a pipe 20. The rod 74 is also connected to an adjustable spring 64 and to one arm of a lever 80, the other arm of which is provided with a weight 84 and connected to valve gear 88 controlling admission of pressure fluid through a pipe 18 to a servo-motor 12 having its piston-rod connected to a chain 8 for operating the damper 4. Upon a rise of steam pressure in the main 22 due to decrease in the demand for steam, the roller fulcrum 59 is moved outwardly to a position to the light of that shown in the Figure, and the decreased leverage of the spring 60 allows the external air pressure to depress the bell 72 and actuate through the lever 80 the valve gear 88 to admit steam to the servo-motor 12 to close the damper 4. Upon an increase in the boiler load and corresponding drop in pressure in the main 22, the apparatus operates in the reverse manner to open the damper 4. The piston-rod 48 may be arranged to adjust the tension of the spring 60 instead of the position of the fulcrum 59. For regulating the draught in a range of boiler furnaces, a single diaphragm device 28 and servomotor 50 is employed adapted to operate a number of rollers 59 arranged in series each serving to influence the draught through a lever 52, bell 72 and servo-motor 12 of each individual furnace. The bell 72 may be enclosed and subjected on its upper surface to the pressure in the fire-box so as to control the draught in accordance with the differential pressure between the point where the tube 20 is connected to the furnace and a point in the fire-box, or opposite sides of the bell may be subjected through Pitot tubes to pressures at two points in the air supply beneath the grate or in the smoke flue.