| 摘要 |
PURPOSE: A method is provided to prevent corrosion of utility boiler side walls and generally to reduce the rate of side wall corrosion of a coal-fired utility boiler. CONSTITUTION: A method of reducing the rate of side wall corrosion in a coal-fired utility boiler while maintaining reduced NOx emission levels, the coal-fired utility boiler comprising a plurality of walls interconnected to form an enclosure, wherein at least one of the walls includes a plurality of burners for introducing a mixture of pulverized coal and primary air into the boiler, the coal-fired utility boiler additionally comprising at least one overfire air port for introducing overfire air into the boiler; the method comprising: providing a plurality of curtain air ports in at least one of the walls; injecting a stream of pulverized coal and a sub-stoichiometric amount of primary air into the boiler through the burners; combusting the stream of pulverized coal and primary air in the boiler; introducing overfire air into the boiler through the at least one overfire air port, wherein the overfire air comprises between about 5% and about 20% of the total air provided to the boiler; introducing curtain air into the boiler through the curtain air ports, wherein the curtain air comprises between about 5% and about 20% of the total air provided to the boiler; and balancing the flow of air through the overfire air port(s) and the curtain air ports such that the ratio of curtain air to overfire air is small enough to maintain combustion staging and assure NOx emission levels of less than about 0.50 lbs. per 10¬6 Btu, yet is large enough to maintain a fuel mixture ratio of less than about 115% of the stoichiometric ratio in the atmosphere adjacent to the walls.
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