GB572369A - Improvements in or relating to steam generators - Google Patents

Abstract

572,369. Steam boilers. HINDLE, T. Nov. 4, 1943, No. 18293. [Class 123 (ii)] In a flash boiler of the kind described, for example, in Specification 566,955, which comprises an upper economizer section 7, a lower evaporator section 10, and an intermediate superheater section 15, means is provided for preventing the pressure within the boiler exceeding the normal maximum value due to residual radiant heat in the fuel-bed or fire-box when the steam throttle valve 18 in the superheater outlet pipe 16 is closed and deliveries of feed-water, fuel and combustion air are suspended, as described, e.g., in Specification 571,167, [Group XXXV]. Said means include a water storage vessel 1 which is maintained full and at a pressure substantially equal to the boiler pressure by the fuel pump (not shown) and has an outlet 5 leading to the economizer section 7 which is connected to the section 10 by a down-pipe 8 fitted with a spring-loaded check-valve 11. This valve 11 normally prevents flooding of the sections 10, 15 when the boiler is shut down but is adapted to be opened by an electromagnet 12 if the pressure in the superheater outlet pipe 16 exceeds a pressure of, say, 50 lbs. per sq. inch above the normal maximum steam pressure, actuation of said electromagnet 12 being effected by a switch 29 controlled by a pressure element 28 which is connected by a pipe 36 to the pipe 16. The arrangement is such that during operation of the boiler the feed pump forces water through the section 7 to the section 10, the steam from the section 15 flowing through the pipe 16 and throttle valve 18. When the valve 18, however, is shut, and the deliveries of feed-water, combustion air &c. suspended, any abnormal rise in pressure in the pipe 16 will cause the element 28 to close the switch 29 and energise the electromagnet 12 to open the valve 11 and permit a flow of water through the boiler until the pressure in the latter falls, the steam generated in the meantime passing through a pipe 19 leading from the pipe 16 to a dispersion pipe 21 in the tank 1 where it is condensed and the feed-water therein heated as a consequence.