Prediction Methodology of Fuel-NOx Emissions in Gasified Fuels’ Combustion

Abstract

Gasification technologies enable conversion of low-grade resources to clean gases, and can generate electricity through gas turbine. However, gasified fuels contain nitrogenous compounds of NH 3 and HCN that cannot be removed in the case of employing a hot/dry-type synthetic gas cleanup for improvement of plant thermal efficiency and are oxidized into fuel-NOx in combustion processes. Fuel-NOx emissions constitute the majority of NOx emissions in exhaust. In combustion processes of the CO, H 2 and CH 4 mixture fuels, the oxidation characteristics of nitrogenous compounds are different from cases of conventional hydrocarbon fuels, and influenced by fuel constituents and combustion methods. Author had clarified influence of gasified fuel constituents on fuel-NOx emissions through experiment. This paper clarifies that conversion rate of nitrogenous compounds to fuel-NOx is decided by both a CH 4 concentration and primary equivalence ratio in the case of using two-stage combustion, while conversion rate is greatly affected by an H 2 constituent in the case of gasified fuel containing no CH 4. Consequently, a prediction methodology of conversion rate of fuel-N is established in the case of air-staging two-stage combustion.