Patent GB-480812-A (GB)
Title: Improvements in control systems
IPC: F22B35/10
Filed: 1936-11-27
Abstract: 480,812. Fluid - pressure servomotor - control systems. BAILEY METER CO. Nov. 27, 1936, No. 32514. Convention date, Dec. 18, 1935. [Class 135] [Also in Group XXXV] A vapour generator of the drumless forced flow type in which liquid under pressure is received at one end and superheated vapour only is delivered at the other, excess liquid being discharged at an intermediate point has the liquid inflow and the supplies of fuel and air for combustion regulated in accordance with the vapour outflow, the air supply being further regulated by the vapour outflow pressure and by a device subject to vapour outflow and air flow to preserve a predetermined vapour outflow-air flow relation. A feed pump 289, a secondary air blower 13, a primary air blower 14, a pulverizing mill 15 and a fuel feeder 16 are all driven by an auxiliary turbine 287 having supply valves actuated by a diaphragm subject to variable air pressure from an auxiliary valve 41 actuated by the pressure differential across a valve 21 in the liquid supply conduit. The valve 21 is adjusted by variable air pressure from a relay valve 47 itself under the control of two auxiliary valves 42, 48. The valve 42 is actuated by a Bourdon tube subject to first stage shell pressure of the main turbine 12. The valve 48 which also controls the diaphragm actuating the separator discharge valve is actuated by a device 29 sensitive to the liquid level in the separator 232 arranged between the generating and superheating sections of the generator. A Bourdon tube 23 subject to vapour outflow pressure actuates an auxiliary valve 69 to control the operation of a byepass valve 22 across the water pump and a pneumatic actuator 38 adapted to operate a butterfly damper in the conduit connecting the secondary air blower to an air heater 20. From the air heater the air flow divides, part passing to the primary air blower and thence through the pulverizing mill to the burner 4, the remainder passing through a conduit 7 to the burner air chamber 6. The conduit 7 contains a regulating valve 19 operated by a pneumatic actuator 39 controlled by an auxiliary valve 71 coupled by a floating lever to the indicating arms of a pair of flow meters 32, 35 sensitive to the vapour outflow and the total air flow respectively. The speed of the fuel feeder is controlled by a variable speed gear electrically regulated under the control of a switch 73 actuated by a pair of diaphragms 74, 75. the diaphragm 74 being subject to the pressure differential across a restriction in the conduit between the blower and pulverizer, while the diaphragm 75 is subject to the pressure differential across the pulverizer. In a modification the various valves and dampers are actuated by actuators comprising a spring-loaded pistons housing a pumps operated by electric motors. The motors are controlled by electron-discharge devices with variable area electrodes acting through relay panels including electron-discharge devices. The actuator and relay panels as well as the auxiliary and relay valves used in the first modification are identical with these described in Specification 481,921. Specifications 425,507, [Group XII], 472,787 ; 475,561, [Group XXXV], 481,994, and 482,611 also are referred to.