DUST COAL BOILER, DUST COAL COMBUSTION METHOD, DUST COAL FUEL THERMAL POWER GENERATION SYSTEM, AND WASTE GAS PURIFICATION SYSTEM FOR DUST COAL BOILER

摘要

This invention provides a dust coal thermal power generation system, which can significantly reduce emission of NOx in a boiler, and can eliminate the provision of a denitration apparatus. When the denitration apparatus is not provided, the capability of removing mercury in a boiler waste gas is deteriorated. A waste gas purification system for a dust coal boiler, which can prevent this unfavorable phenomenon, is also provided. There is also provided a dust coal boiler comprising a furnace for burning dust coal, a burner for supplying dust coal and air for combustion into the furnace and burning the dust coal in an insufficient air state, and after-air port provided on the downstream side of the burner for supplying air for perfect combustion. In this case, the air ratio in the furnace is brought to 1.05 to 1.14, and the residence time of the combustion gas form the burner provided on the uppermost state to a main after-air port is brought to 1.1 to 3.3 sec. Preferably, water is previously mixed into the air supplied into the after-air port to increase specific heat. Further, dust coal carrying air and air for combustion in the burner are partially previously mixed together before jetting into the furnace. The waste gas purification system comprises a dust coal boiler, an air heater provided on the downstream of the dust coal boiler for heating the air for combustion in the dust coal boiler by heat exchange with the boiler waste gas, a dedusting apparatus, and a desulfurization apparatus. The system further comprises at least one of a halogen gas supply device, a catalyst device for oxidizing a mercury gas and a mercury adsorbing agent blowing device to oxidize mercury in the waste gas.