A Study on Formation Behavior of Hazardous Nitrogen Compounds in Gasification Processes of Animal Biomass

Abstract

Gasification and power generation from biomass such as livestock wastes has possibility to contribute to solve energy and environmental problems. But some biomass has high fuel nitrogen content, which may cause the emission of fuel-NOx. There are few reports on the behavior of nitrogen contained in biomass during the pyrolysis and reforming process. In this study, we investigated the behavior of nitrogen content in chicken manure and meat-and-bone meal during the gasification and reforming processes. The release behaviors of gas-N such as NH3, HCN and N2 and Tar-N and Char-N during the pyrolysis process within the temperature range from 873 K to 1173 K were examined using an up-draft fixed bed gasifier. In the pyrolysis process, more NH3 was observed from chicken manure and more HCN was observed from meat-and-bone meal, which is due to the difference of nitrogen composition in those fuels and of the conversion from tar-N or char-N to gas-N. We also investigated the nitrogen behavior in the reforming process within the temperature range from 973 K to 1173 K. In the reforming process, NH3 was decomposed to N2, but HCN was not. And tar-N produced from meat-and-bone meal was converted to HCN during the reforming process. From these results, to decrease the harmful nitrogen compounds such as NH3 or HCN, higher temperature reforming is desirable in the case of chicken manure, and lower temperature gasification to leave nitrogen in the char is desirable in the case of meat-and-bone meal.