PURPOSE: To enable production of a minimum unburnt content in ash by means of a minimum mill power, by constituting a pulverized coal combustion device such that coal crushed by a crushing part is separated as pulverized coal by a classifier, and the separated coal is conveyed to a burner.
CONSTITUTION: When fire-retardant pulverized coal is burnt, a unburnt content produced in the vicinity of an exhaust gas passage is increased, resulting in an increase in the metal temperature of a superheater 4. Detection of such metal temperature by means of a temperature detector 6 permits discrimination of burning coal being fire-retardant. In which case, through opening of a damper 23, a flow rate of a slit air F is increased. As the flow rate of the slit air F increases, a bypass amount shown by an arrow mark G increases, and thereby, a time, for which pulverized coal stays in a mill 9, is increased, the grain size of the pulverized coal is decreased according to the staying time, and a unburnt content in ash is decreased. On the contrary, flammable coal is burnt early and therefore, the metal temperature of the superheater 4 is decreased over that in the case of fire-retardant coal. The metal temperature is detected by a temperature detector 6, and this enables to discriminate that coal under combustion is flammable, and in this case, with the damper 23 closed, the flow rate of the slit air F is decreased and a flow rate of a throat air B is increased.
MASAI TADAHISA
MORITA SHIGEKI
MIGAKI HITOSHI
NAKASHITA SHIGETO
