Influence on gaseous pollutants emissions and fly ash characteristics from co-combustion of municipal solid waste and coal by a drop tube furnace.

Co-combustion experiments of municipal solid waste and coal were carried out in a drop tube furnace at high temperature 1300 °C. The effect of different simulated municipal solid waste (SMSW) added proportion (0, 7.5, 15, 20 and 25 wt%) in the blend fuels on the characteristics of gaseous pollutants emissions, e.g. CO, HCl, SO2 , NOx , and heavy metals, and fly ash were studied. The results indicated that CO and CH4 emission concentrations were at a low level under all conditions. With the increasing proportion of SMSW, the combustion efficiency decreased slightly, the HCl emission increased obviously at 25% conditions while at lower proportion conditions the change was not significant; the NOx emission concentration showed a tendency to rise first and then decrease, while the SO2 showed an exactly opposite trend; besides, Fe, Cl and S content in the fly ash increased obviously. Under all experimental conditions, only a small amount of heavy metals were emitted in the flue gas while most of the heavy metals were retained in the fly ash. The leaching results showed that Ni leaching concentration was beyond the national standard which means the fly ash needs further treatment before they can be disposed of by landfill, while the HCl, NOx and SO2 emissions can easily reach the national emission standard under the desulfurization and denitrification system operating conditions in real power plants. These findings are helpful for the further development of co-combustion with renewable energy in coal-fired incinerators, yet more investigation on heavy metal emission in fly ash is still required to be further conducted in the future.