Please cite this article as: Qi J, Han K, Wang Q, Gao J, Carbonization of biomass: Effect of additives on alkali metals residue, SO 2 and NO emission of chars during combustion, Energy (2017),
AbstractThe effect of additives (NH 4 H 2 PO 4 , CaCO 3 and CaO) on biomass carbonization was studied in the current paper, including residual K and Na in chars, SO 2 and NO emission of different chars during combustion. Experiment was carried on a tube furnace system. The results show that, CaO and NH 4 H 2 PO 4 reduce the alkali content of chars to different degree. Three additives inhibit SO 2 emission from raw and carbonized biomass remarkably, and SO 2 mass emission is lesser than 0.1 mg g −1 . Three additives enhance NO emission at different levels, and NO mass emission is from 1.2 to 3.5 mg g −1 . Both raw and carbonized biomass can be modified by some additives to achieve near zero emissions of SO 2 . Although the additives promote the NO release, the total emission rate (3.8 to 10.1 %) was much lower than that of brown coal combustion, which was reported as 33.5 to 37.7 %. Economic analysis shows that three additives are economy for industry utility. Thus the three additives are good for modifying biomass carbon to attain clean and efficient combustion.