Effect of Operating Parameters and Moisture Content on Municipal Solid Waste Pyrolysis and Gasification

Pyrolysis/gasification-based waste-to-energy (WtE) techniques, comprising partial oxidation of waste and subsequent syngas combustion, show potential benefits over direct incineration. To facilitate their development under the specific conditions of China, pyrolysis and gasification of typical municipal solid waste (MSW) are investigated in a fluidized bed reactor. The effect of the equivalence ratio (ER), reaction temperature, and moisture content on MSW conversion is studied. A rising ER increases the syngas yield but decreases the syngas heating value. The combustible gas yield is strengthened at lower ERs and later drops when the ER exceeds 0.4 as a result of the continuously enhanced oxidation reactions. A higher temperature favors pyrolysis reactions but causes an evident decrease in the syngas heating value during gasification. When the ER is at 0.4 and the temperature is at 650 °C, an optimum operating performance is obtained under the specific input simulated MSW (S-MSW) and test conditions, with an energy conversion efficiency of 68.5%. Under such a circumstance, the further increase of the MSW moisture content is effective for stimulating H2 production; nevertheless, the quality of syngas degrades, and the energy conversion efficiency declines. The appropriate MSW moisture content is found to be lower than 20–25%. Besides, emiessions, such as heavy metals and dioxins, are also compared to conventional incineration to verify the environmental feasibility of gasification.

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