Fuel combustion and gas flow characteristics of the municipal solid waste incinerator

Abstract

For the combustion performance to achieve the low pollution, it is essential to understand the combustion and gas flow characteristics of the incinerator combustion chamber. Numerical simulation has been frequently applied and has provided a comprehensive set of information on the flow field. However, the waste bed has been usually treated as an inlet condition based on an arbitrarily assumed combustion profile, which has limited the usefulness of predicted results. Thus, it is necessary to develop an improved simulation method that extends the capability of the numerical simulation applied in incinerators. In this study, the combined simulation method(CSM) was proposed, which incorporated the gas flow simulation with a waste combustion model to consider the waste combustion and its interaction with the gas flow region. When coupled with CFD, the bed model provided inlet conditions of the gas flow field on the waste bed which corresponded to the radiative heat flux onto the bed received from CFD. For this purpose, a mathematical model was constructed to predict the waste bed combustion. The waste bed was treated as a packed bed of homogeneous fuel particles. Comparison with the batch type reactor experiments showed that the model provided the macroscopic phenomena of the waste bed combustion and the release of the combustion gas. Test simulations using CSM successfully predicted overall physical processes of the waste bed combustion and its interaction of heat and mass transfer with the gas flow fields for test cases having different design and operating conditions. Such interaction was identified as an important factor of the combustion chamber, which affected the results of both regions. Additionally, quantitative evaluation of the predicted gas flow field as the combustion performance was summarized. Though current numerical simulation, including the CSM, has not fully validated, its results contain useful information on the gas flow field. By definin...