GB916442A - Improvements in and relating to forced recirculation steam boilers heated by waste gases - Google Patents

Abstract

916,442. Forced recirculation steam boilers. VORKAUF, H. July 3, 1961 [March 15, 1961], No. 23886/61. Addition to 786,412 as improved upon by 913,033. Class 123 (2). The forced recirculation boiler described in the Specification 913,033 is modified in that a pipe is fitted between the isolating valves of each group of tubular elements which is arranged to vent the group automatically to atmosphere or to a vessel at lower pressure when the valves are operated to isolate the group from both the water supply and from the steam and water drum. In Fig. 1, three-way valves 9a and 9b installed in steam and water lines 7a and 7b serve to isolate the tube groups 5a and 5b respectively on the steam side and to provide the connection to a vent pipe 12. Valves 8a and 8b in the water supply pipe are coupled to the valves 9a and 9b so that the tube group can be vented down only when valves 8a and 8b are closed. In an alternative arrangement, Fig. 2 (not shown), a three-way valve is installed in the feedwater line providing the connection to the vent line and a non-return valve serves to isolate the tube group on the steam side.