GB577520A - Improvements in or relating to de-aerators for boiler feed water - Google Patents

Abstract

577,520. Feedwater supply systems. BOBY & CO., Ltd., W., and BOBY, W. V. May 30, 1944, No. 10414. [Class 123 (ii)] In a boiler feedwater de-aerator 10 which is supplied with sufficient steam not only to raise the water therein to its boiling point but to give an excess flow adapted to entrain and carry off the released air and other non- condensible gases, this excess steam being condensed in a preheater 17 which is provided with a gas outlet 18 and through which a fuel or make-up water supply from a pipe 21 passes before entering the de-aerator through a pipe 22, the steam supply is automatically controlled by a valve or valves 12, 14 in the inlet pipe 11 in accordance with the pressure or temperature in the de-aerator, acting through a pipe line 15, and the delivery of excess steam to the preheater in accordnace with the temperature. of the latter as determined by a thermometric device 20 which acts upon a valve 19 in the supply pipe 16 thereto. The steam supply may be taken from one or two stages of a turbine 13, and preferably the valves 12, 14 are so arranged that the valve 12, for example, is opened to its maximum extent before the valve 14 opens. A by-pass 23 is also associated with the valve 19 to ensure a minimum flow of steam and gases to the preheater when this valve is closed completely following, say, an excessive rise of temperature in the preheater due to a failure in the water supply thereto. The main supply of steam may, additionally, be subjected to control in accordance with the temperature in the preheater through a thermometric device 25, 26 acting upon valves 24, 27 in series with the valves 12, 14 respectively, and a second valve 28, controlled by the pressure in the de-aerator, may be provided in series with the valve 19 in the pipe 16.