NOx Formed Specialty of Biomass Fuel in HTAC

Abstract

High Temperature Air Combustion (HTAC) is appropriate to biomass fuel combustion, but the problem of NOx emission should be played attention. Temperature field in furnace is uniform with HTAC, and there is no higher temperature point, so it can reduce NOx formation. If HTAC combines with low-oxygen combustion, emission of NOx is further restrained. The rules of NOx emission for Biomass fuel: sawdust, rice husk combusting with high temperature air are discussed in 600–1200°C air temperature and 10%–21% oxygen content in air and about 1000°C furnace temperature, especially the influence of parameters such as air temperature and oxygen content in air and water content of biomass fuel is researched. The main results are: (1) since the fixed carbon in rice husk is higher than in sawdust, deoxidisation is more marked and NOx release in rice husk combustion is 20% less than in sawdust combustion in experiment. (2) Oxygen content in air has a great influence. Low-oxygen Combustion has a low NOx emission, which is lower than 150ppm in experimental condition. (3) Water content in biomass fuel has a great influence too, the more of water content, the less of NOx engendering among 7%–46% water content. There are two reasons, first one is water in biomass have depressed the temperature in flame, second is water can react with carbon in high temperature to form a deoxidising environment in furnace, especially in high-temperature Low-oxygen Combustion, the phenomenon is much in evidence. Base on experiments, the results confirmed that HTAC could do a low NOx combustion with biomass fuel.