JPS6410002A - Boiler plant - Google Patents

Abstract

PURPOSE: To reduce thermal stress being generated on restarting and to extend the life of a boiler by connecting the rear-flow-side air-supply duct of an air-flow duct closing damper to the rear-flow-side exhaust gas of an exhaust gas duct closing damper with a connection duct with a closing damper halfway. CONSTITUTION: Closing dampers 5 and 9 are closed during hot panking and closing dampers 14 and 16 are opened. In this case, air entering from a push-in ventilation machine 7 being stopped passes through a connection duct 15 and enters a rear flue 3 from a rear flue lower part 8 due to the suction effect caused by the thermal buoyancy of a high-temperature gas in a chimney 11, flows in the direction of a fire furnace 2 in opposite direction as compared during boiler operation between a group of pipes 1, and passes through a connection duct 17 from a fire furnace lower part 4 and is exhausted through the chimney 11. As a result, the peripheral wall of the rear flue 3 is cooled by a relatively low-temperature air, and on the contrary, the peripheral wall of the fire furnace lower part 4 is heated by air that becomes a high temperature by absorbing heat when passing through a group of pipes 1, thus preventing a temperature difference from occurring at a boundary part 13 between a fire furnace and the rear flue and hence preventing thermal stress from occurring on restarting.