GB603588A - Improvements in or relating to the regulation of the water level in steam generators - Google Patents

Abstract

603,588. Fluid-pressure servomotor-control systems. SULZER FRERES SOC. ANON. Aug. 10, 1945, No. 20531. Convention. date, Sept. 9, 1944. [Class 135] [Also in Group XIII] A fluid-pressure servomotor-control system for a method of regulating the water level 8 in a water tube boiler of the type having an upper drum 7 and an economizer 14, comprises a throttle 33 situated in the steam exit line 39, the pressure on each side of the throttle being applied respectively to opposite sides of a diaphragm 27 connected to a piston 26 controlling communication between an oil pressure line 21 and oil inlet and outlet lines 24 and 25 respectively. Hence an increase in the quantity of steam for draw-off purposes in line 39 lowers the pressure in the chamber below diaphragm 27 which descends and causes piston 26 to do the same, whereby pipe 21 is put into communication with oil outlet pipe 25, and allows a spring 18 to force piston 19 to the right to open a valve 13 on the supply line 11 to the economizer. The increased flow in this pipe causes the increased pressure across a throttle 36 to actuate a diaphragm 28 to cause piston 26 to take up an equilibrium position. The direct supply to the drum via pipe 6 is controlled by a valve 4 operated by a float 10 in the drum. In a modification, the valve 4 is additionally operated by a fluid-pressure servomotor system similar to that operating valve 13. The valves 4 and 13 may be actuated by pneumatic or electrical means, and the respective pistons in the servomotor systems may be influenced by the intensity of the fire or the quantity of combustion air or flue gases.