Carbon and nitrogen balances for pyrolysis of methane fermentation sludge (MFS) using super-heated steam
2010
Qian, Q., Tokyo Univ. (Japan). Inst. of Industrial Science | Mochidzuki, K. | Sakoda, A.
Utilization of biomass as alternative fuel sources has gained an increasing interest. The biomass with high nitrogen content, however, would cause atmospheric pollution during their conversion and energy application, the objective of this study is to convert a high nitrogen content waste, methane fermentation sludge (MFS) into char using superheated steam pyrolysis (SSP). The carbon and nitrogen mass balances in the SSP process were investigated and the potential application of the derived char as a solid fuel was discussed. The results show that the input and output of C and N agree well at 300 and 350degC but deviate from each other at 400degC. The dehydration and deamination essentially occur at 300degC, whereas tars and lower class hydrocarbons are dominantly formed at 400degC. Nitrogen prefers to convert into NH4-N rather than to reform as NO2-N, NO3-N or organic nitrogen, showing that SSP is an environmentally friendly way for the conversion of high nitrogen-contained biomass. The HHV of char derived at 300degC is 15.8 MJ/kg. It decreases to 13.3 and 11.4 MJ/kg at 350 and 400degC respectively. For a solid fuel, high H/C with low O/C and N/C ratios is always desired. Accordingly, the MFS-derived chars obtained at above 350degC by SSP can be potential solid fuels used by mixing with other coal.
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