Addition of Calcium Compounds Improve the Yield of Hydrogen and Retention of Chromium Metal during the Gasification of Simulated Waste

This study explored the constituents of syngas and the distribution of chromium metal when different calcium compounds (Ca(NO3)2, CaCO3 and CaO) were used as additives. In this experiment, artificially simulated waste was taken as the biomass for gasification and chromium metal was used as the heavy metal in the simulated waste. The syngas composition, the yield of H2 and the retention of chromium metal were analyzed. Results showed that all the three calcium compounds could increase the proportion of H2, but that there was no significant difference between them. The contents of chromium in the bed materials with different particle size were measured and displayed that the concentrations of chromium were higher in the bed materials with particle diameters above 1.00 mm and below 0.35 mm. Under the operation temperature of 700°C, the calcium compounds retained the highest content of chromium metal, for it evaporated only a little under this low temperature. Therefore, adding calcium compounds into the fluidized bed during the gasification of the waste could enhance the yield of H2 in the syngases and increase the content of retained chromium metal in the sand bed.