Research of coupling technologies on NOx reduction in a municipal solid waste incinerator

Abstract

The controlling of NOx emission remains the focus and motivates research in municipal solid waste incineration nowadays. The denitrification process in municipal solid waste incinerator based on coupling technologies of flue gas recirculation, over-fired air and selective non-catalytic reduction were conducted by numerical simulation in this work. The effects of different flue gas recirculation ratios, two paths of applying flue gas recirculation and application of coupling technologies on NOx emission and combustion characteristics were studied. The results indicated approximately 23.54% of initial NOx was reduced with flue gas recirculation ratio of 20% (injected through path 1), and the boiler efficiency was increased gradually from 80.16% to 83.78 %, as the flue gas recirculation ratio increased from 13% to 20%. The improvement of NOx removal efficiency was maintained at about 16% when flue gas recirculation ratio was 13% to 20% (injected through path 2). Moreover, the NOx removal efficiency was 33.68% when selective non-catalytic reduction technology was applied separately but increased by 13.51% when over-fired air technology was combined. With coupling technologies applied, the total NOx removal efficiency reached the highest of 76.48%, indicating flue gas recirculation coupling with over-fired air and selective non-catalytic reduction technologies is feasible to achieve lower NOx emission in municipal solid waste incineration.