The emissions and control of NO x and N 2O in pressurized fluidized bed combustion

Abstract

Using the Otaniemi pressurized fluidized bed combustion test rig a study has been made of the emissions and control of NO x ( NO + NO 2) and N 2O in different operating conditions for three types of solid fuel (peat, bituminous coal and brown coal). The influence of operating parameters, including bed temperature, excess air level, pressure, etc., were investigated. The results showed that NO x emissions were low and the excess air level was a dominant variable, and N 2O emission was mostly dependent on the burning temperature. Ammonia injection and air staging are effective as NO x reduction techniques. Both techniques can reduce the NO x up to 60% dependent on the fuel type and the amount of ammonia or degree of air staging. The oxygen level and temperature of ammonia injecting position were significant factors in NO x reduction in ammonia injection operations. The N 2O emissions, however, were always increased as a consequence of NO x reductions.