GB1049831A - Improvements relating to a method of and apparatus for producing low pressure steam - Google Patents

Abstract

1,049,831. Heating steam boilers by steam or hot water. JOHN THOMPSON WATER TUBE BOILERS Ltd. Feb. 10, 1964 [Feb. 15, 1963], No. 4873/63. Heading F4A. In power station boiler plant operating at steam pressures of from 1600 to 3500 p.s.i., low pressure superheated steam for soot blowing, fuel oil heating and atomizing, steam pipe tracing and other purposes is generated by H.P. saturated steam or high pressure, high temperature water extracted from the boiler by feeding the steam or water successively through superheating and steam generating tubes of a L.P. steam generator and returning the condensed steam or lower temperature water to the H.P. steam generator. The L.P. generator, Fig. 1 (not shown), consists of a horizontal, cylindrical vessel 1 having water heating coils 2 disposed in its lower part, the coils being connected between headers 4, 5. The vessel 1 is surmounted by a steam dome 6 containing a bank of superheating coils 8. High pressure steam enters the coils 8 at 9 and is condensed therein, the condensate flowing through a line 10 to the header 4 and successively through the coils 2, the header 5, coils 15 in a drains cooler 11 and a control valve 20 to pass to the main turbine feed heating train of the H.P. boiler. Feedwater Which may be impure, for the L.P. boiler is preheated in the cooler 11 and flows into the vessel 1 at a rate to maintain a level 23 therein. The water is evaporated by the coils 2, the steam being superheated in the dome 6 and discharging through an outlet 7. The setting of, the condensate outlet valve 20 is controlled by the steam pressure in the vessel 1 as sensed at 22 to maintain a flow through the coils 2 such that the pressure of the L.P. steam remains constant. In a modification, Fig. 2 (not shown) H.P. water is fed to the L.P. generator from the outlet of the circulating pump of a forced recirculation H.P. boiler, the water at a lower temperature returning to the H.P. steam and water drum.