GB711457A - An improved method of and apparatus for controlling the temperature of superheated steam and the temperature of reheated steam in a steam generating unit - Google Patents

Abstract

711,457. Water-tube steam boilers: superheating and reheating. BABCOCK & WILCOX, Ltd. Nov. 28. 1952 [Nov. 29, 1951], No. 30265/52. Classes 123(2) and 123(3) A steam boiler comprises a furnace 10 which is lined with steam-generating tubes and is fired by horizontal rows of burners 12 ... 15 disposed within a wind-box 18, the gases from said furnace flowing through an outlet 150, locating a secondary superheater 144 ... 146, to parallel convection passes, namely, primary superheater section passes 72, 74 and a reheater pass 80 having their outlets fitted respectively with dampers 94, 102 and 114. Ducting 231, with a damper 244 and including a fan 236, is provided for recirculating gases from the boiler flue 232 back to the furnace 10, and a spray attemperator 124, preferably of the kind described in Specification 656,551, with water-supply control valve 130 is fitted in the superheated steam outlet pipe 122 and a similar attemperator 160 with valve 164 in the pipe 173 leading to the inlet leader 110 of the reheater. The fuel supply to the burners is controlled by a damper, not shown, and a secondary supply of air to the windbox by a damper 22. The several dampers and the valves 130, 164 are operable by motors such as 94A, 102A, 114A, 132, 166, 246 controlled by electric switches which have forward, reverse and stop push buttons and are disposed adjacent a steam pressure gauge, superheat and reheat temperature indicators, and steam and air flow measuring devices. At normal loads, superheat temperature is controlled by the attemperator 124 and reheat temperature by regulation of the gas flow through the pass 80. At lower loads gases from the flue 232 are recirculated through the furnace 10, and at higher loads the reheat attemperator 160 is brought into operation.