Comparative evaluation of municipal solid waste incinerator designs by flow simulation

Flow simulations have been carried out to evaluate the effects of combustion chamber design and air/combustion gas flow configuration on the overall performance of municipal solid waste incinerators. Computational results show velocity and temperature fields in the entire region of flow passage. Local recirculations and uneven distributions of flow velocity and temperature should be minimized and mixing is to be enhanced. Two parameters are proposed to help quantify the overall flow condition. The degree of mixing of different species, which enter the incinerator from the air and combustion gas inlets, is represented by the mixing parameter α. Here, α is calculated on the nodal points. The probability distribution of α in the entire computational domain is used for comparative evaluation of incinerator designs. The thermal decomposition parameter β is calculated by integrating the kinetic rates along the trajectory of a fluid element. This parameter represents the portion of the unreacted materials among the total pollutants released from the bed. By employing these parameters, various incinerator design alternatives can be quantitatively analyzed from two principal viewpoints, i.e., the effectiveness in mixing and the thermal decomposition of pollutants.