PULVERIZED COAL COMBUSTION DEVICE

摘要

PURPOSE:To increase a hot air temperature to such an extent as required by coals containing high moisture without increasing a heating area of an air preheater by a method wherein a part of preheated air outputted from the air preheater of a pulverized coal firing device is circulated to an inlet side of the air preheater. CONSTITUTION:Air of which pressure is raized by a primary air blower 2 is heat exchanged with discharged gas by an air preheater 3 and then the heated air is supplied to a pulverized coal device 4. Pulverized coal mixed with primary air is supplied from the pulverizes 4 to a burner. Air supplied by a forced draft fan 1 is preheated by the air preheater 3 and supplied to a burner as a secondary air. A circulation system 5 is provided for branching a part of the hot air from an air duct system 1A connecting the air preheater 3 with a burner and returning it to an inlet side of the primary draft from 2. With this arrangement, the temperature of cold air at the inlet port is raised and at the same time the temperature of hot air at the outlet port is also raised, resulting in that it is possible to cope with a condition that a higher hot air temperature as in a coal containing high moisture is necessary.