Study on Production of Unburnt Gas at The Unsteady State of Combustion Process in A Waste Incinerator

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The concentration of Dioxins and PCBs in a municipal refuse incinerator depends on the concentration of unburnt gas that is produced. The unburnt gas is much generated in an unstable state at the beginning of waste combustion. In a batch incinerator where the operation of start up and shutdown is repeated frequently, the concentration of the unburnt gas will change drastically. In this study, behavior of solid waste combustion and unburnt gas production was clarified through the experiment which uses an electric furnace and an actual batch incinerator. Moreover, the concentration of the produced gas and the temperature in the furnace were simulated based on the waste combustion model and thermal gas flow analysis. The results are summarized as below:1) The weight loss ratio of each waste sample classified into one of the components of domestic waste was analyzed by using TG. After confirming the additive property of the reaction constant, the property of the representative waste on the thermal decomposition and combustion was calculated.2) The solid waste having three dimensional sizes was decomposed thermally or burned in the electric furnace controlled on the condition of furnace temperature, moisture, and apparent density. Then the production of CO were represented as a transfer function having a fourth-order lag element.3) Paper and plastics (PE, PS and PVC) were burned in an actual batch incinerator and then several kinds of gas components were measured continuously. The concentration of chlorinated phenol (CP) was also measured.4) The three dimensional profile of gas flow, gas concentration, and gas temperature was computed respectively through a hybrid simulation based on the waste combustion model and on the thermal gas flow model. Moreover, the gas mixing effect of the secondary combustion chamber was discussed.