CO2 Gasification of Municipal Solid Waste in a Drop-Tube Reactor: Experimental Study and Thermodynamic Analysis of Syngas

A gasification-based waste-to-energy technique has been considered as a promising alternative to direct incineration. With the potential benefits of reducing the greenhouse gas emission and producing syngas, CO2 gaisification of municipal solid waste (MSW) was studied in a drop-tube reactor. Process parameters, including the temperature and CO2/MSW mass ratio, were investigated. On the basis of the experimental results, energy and exergy analyses were conducted to evaluate the thermodynamic quality. Results indicated that the temperature had a significant impact on the syngas composition, while the effects of the CO2/MSW mass ratio were not so profound. The tendency of the syngas composition revealed that the Boudouard reaction, water gas reaction, and free radical combination reaction were the most influential reactions in the gasification process. Energy and exergy analyses showed that the total energy and exergy values of syngas increased with the rising temperature, whereas they declined initially and then rose with the increase in the CO2/MSW mass ratio. The detailed energy and exergy distributions of the syngas component were different at various temperatures and CO2/MSW mass ratios. As a result of the remarkable difference between physical energy and exergy of sensible heat, the exergy value of syngas was much lower than its energy value. It followed well with the energy value.