GB669870A - Improvements in and relating to apparatus for raising and forcing liquids by steam or gas pressure - Google Patents

Abstract

669,870. Automatic liquid-level control systems. CHAPMAN, HAYWOOD & CO., Ltd., and PICCARDO, C. Aug. 15, 1950. [Aug. 15, 1949], No. 21171/49. Class 38 (iv). [Also in Groups XIII and XXVIII] In apparatus for raising or forcing liquids from one or more closed vessels by direct air, gas or steam pressure under the control of valves operated according to the liquid level in the vessel or vessels, the control valves are operated by electrical means energized through circuits which are closed by liquid level responsive devices at minimum and maximum liquid level in the vessel or vessels, the minimum level circuit including a resistance which is short-circuited by the maximum level circuit whereby the electrical means can only be actuated when the vessel is full and can only be released when the vessel is empty. Water is delivered by gravity from a feed water tank 3 of a boiler plant to a lifting vessel 2 and is raised therefrom by steam pressure, through a valve 7 and pipe 6 to a feeding vessel 1. The water is delivered from the latter by steam pressure and gravity, through a pipe 8 and valve 9 to the boiler. The supply and exhaust of steam through a pipe 19 leading to the vessel 1 is controlled by a control valve 17, and through a pipe 14 leading to the vessel 2 by a control valve 10, 11. The control valves, which place the vessels alternately in communication with a steam pipe 15 and an exhaust pipe 20 leading to the tank 3, are actuated by diaphragms 21. The upper surfaces of the diaphragms are permanently subjected to steam pressure through liquid columns 23 and their lower surfaces communicate through liquid columns in pipes 24 with a chamber 25 which is permanently open to steam pressure through a pipe 26 and which may be exhausted to atmosphere, through a pipe 27 controlled by a pilot valve 28 so as to effect a downward movement of the diaphragms and consequent actuation of the control valves. The pilot valve is raised by a solenoid 30, energized through a transformer 35 and rectifier 36, and controlled by upper and lower float switches 31, in the vessel 2, and a relay 38 energized through a rectifier 37, and controlled by upper and lower float switches 31 in the vessel 1, so that the vessels are alternately filled and emptied. The circuit of the lower float switch in each vessel includes a resistance 41, 45 which is short-circuited by the circuit of the upper float switch when the latter is closed. In another embodiment a single vessel is used and controlled in a similar manner to the vessel 2. In other embodiments the control valves are three or four-way semi-rotary valves actuated by diaphragms or pistons and controlled by solenoid operated pilot valves.