| 摘要 |
A boiler (1), in which the secondary air temperature can be efficiently increased for higher thermal efficiency by appropriately reducing the heat transfer area of the boiler while maintaining the heat collection of steam in the whole boiler, is disclosed. In the boiler, a heat exchanger (16, 17) provided in one of two flow paths formed by partitioning a downstream portion of a flow path for exhaust gas discharged from a furnace (23) has a smaller total heat transfer area than a heat exchanger (20) provided in the other of the two flow paths; the exhaust gases discharged from the flow paths to outside the boiler (1) are introduced, without being mixed, into an air heater (2) downstream of the boiler (1); and, in the air heater (2), the heat of the exhaust gases is transferred to the primary air and the secondary air so as to heat combustion air. |
