GB750071A - Expelling water from the tube systems of steam generators - Google Patents

Abstract

750,071. Emptying steam boilers. SULZER FRERES SOC. ANON. Aug. 30, 1954 [Sept. 16, 1953], No. 25084/54. Class 123(2). The water contained in a once-through tube system of a steam generator, for example in all of the tubes of a forced through-flow boiler or in the superheater or economiser tubes of a convection circulation boiler, is expelled therefrom and the tubes dried out when the generator is shut down by driving a vapour or gas through the tube system in the reverse directon to that taken by the working medium during normal operation. Fig. 1 shows a steam plant consisting of a forced through-flow generator 4 supplying steam through an outlet valve 6 and pipe 7 to a turbine 11 which exhausts into a condenser 10 discharging condensate into a reservoir 12. A pump 1 supplies feed water from the reservoir through an inlet valve 2 to the tube system of the generator. When the boiler is shut down, the fire is extinguished, valves 2, 6 are shut and a valve 8 in a pipe 9 connecting the feed pipe to condenser 10 opened. Steam is produced in the tube system on reduction in pressure therein and forces all or most of the water therein into the condenser. If the steam produced is insufficient to expel all the water, steam can be blown in through a pipe 13 from another boiler 16 or air from a compressor 17 or an inert or corrosion-preventing gas such as nitrogen or ammonia from cylinders 18 may be used, only one of these expedients being provided in any one plant. Where steam has been used to expel the water the tubes are afterwards dried out by blowing air through the system.