摘要 |
Apparatus and method for the reduction of nitrogen oxides (NOx) in the emissions of a fuel burning fluidized bed combustion system. Using a staged combustion technique, an overfire air inlet is provided in the freeboard zone above the bed. In the first stage, residual oxygen (O2) in the off-gas just above the bed is held in the 0.4 to 0.8% range by the actual coal and air rates. In the second stage, carbon monoxide (CO) and unburned hydrocarbons, both present in the first stage off-gas, are combined with additional air using the overfire air inlet. CO levels in the final effluent are reduced with little or no increase in NOx emissions.
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