Improvements in or relating to the regulation of reheat steam temperatures in boilers

摘要

1,049,280. Regulating steam temperatures. SULZER BROS Ltd. Oct. 29, 1965 [Oct. 29, 1964], No. 45931/65. Heading F4A. The temperature of reheated steam entering a low pressure turbine 19 is controlled by varying the heat exchange between the reheat steam and live steam on its way to a high pressure turbine 12, in a coaxial tube heat exchanger 11 situated in the flue of the boiler. Water from pump 1 is fed through the economizer 3 and evaporator 5 of once-through force flow, force flow or natural circulation boiler 2. The high pressure steam produced is separated from any water in trap 7, and then passed through superheater surface 9 to tube 10, from whence the flow splits into two parts, part flowing through inner tube 20 of coaxial tube heat exchanger 11 to give up heat to reheat steam passing in co-current flow through outer tube 21, and then flowing to tube 14, via superheater surface 13, while the remainder flows directly to tube 14 .through by-pass line 22. From tube 14 the recombined high pressure flow passes through superheater surface 15 to high pressure turbine; 12. The partly expanded steam from high pressure turbine 12 flows for reheating through outer tube 21 of the heat exchanger 11 and through reheat superheater surface 17 on its way to low pressure turbine 19. The temperature of the reheat steam at the inlet to turbine 19 is maintained constant by varying the high pressure steam flow through the by-pass 22 by valve means 23, and by injecting cooling water into the pipe 10, under the action of controller 25 actuated by temperature detector 24. The high pressure steam temperature at the inlet to turbine 12 is maintained constant by injecting water into pipe 14 under the action of controller 31, actuated by temperature detector 30. In modifications the by-passed superheater surface 13 may be situated before the coaxial tube heat exchanger 11, and the water injection into tube 10 may occur after the branching off of by-pass line 22 (Fig. 2, not shown).