Among the thermochemical conversion technologies, combustion is the only proven technology for heat and power production. In the biomass combustion process, fuel N in biomass can be oxidized into NOx, causing acid rain or smog. The pollutant formation of NOx occurs due to fuel constituents like N, Cl, K, Mg, Na, Mg and Ca. Air staging has been developed as a primary measuring to reduce the NO emissions. The NO reduction potential of 50% to 80 % is mainly depending on the combustion temperature, the air ratio, the fuel and the residence time in the combustion chamber. For the high-temperature combustion investigations of in-furnace DeNOx technology are carried out using air staging in an electrically heated entrained flow reactor. For the investigations to reduce the NOx emissions, torrefied biomass (e.g. alder, spruce, birch) and HTC-coals (consisting of compost, grass clipping and leaves) are used. The investigated parameters are temperature from 900 to 1200 °C, the residence time and stoichiometry in the fuel rich primary zone from 0.6 to 1.15. The experimental results show that the thermal NO becomes important from a temperature of 1200 °C. From a combustion temperature of 900 °C to 1200 °C the NO emissions of HTC- coal increased (at the not staged experiments) by 30 %. Moreover, the effect of air staging in the combustion process was shown to enhance NO reduction over biomass to different degrees. At 1200 °C with a mass flow of 0.8 kg/h and an air ratio of 0.71 in the substoichiometric zone a maximum reduction of NO (75%) can be seen. In addition a strong dependency of the fuel N with the NO emissions is investigated. The burnout values of the cyclone ash reached up to 99.8 %.      «

Among the thermochemical conversion technologies, combustion is the only proven technology for heat and power production. In the biomass combustion process, fuel N in biomass can be oxidized into NOx, causing acid rain or smog. The pollutant formation of NOx occurs due to fuel constituents like N, Cl, K, Mg, Na, Mg and Ca. Air staging has been developed as a primary measuring to reduce the NO emissions. The NO reduction potential of 50% to 80 % is mainly depending on the combustion temperature,...     »