Numerical study of SNCR application to a full-scale stoker incinerator at Daejon 4th industrial complex

Considering the rapid variation of waste composition and the more severe regulation trend of pollutant emission in this country, the importance of the development of a reliable computer program for a full-scale, stoker-type incinerator cannot be emphasized too much especially in the view of proper design and optimal determination of operating condition of existing and future constructed facility. To this end, a comprehensive, numerical model related with the process of the waste-off gaseous combustion with the capacity of 200 tons/day is successfully made. This includes development of several phenomenological models such as municipal waste-off gaseous reaction, NO pollutant generation and destruction in turbulence-related environment. Especially, in this study a number of sound assumptions have been made for the NO reaction model, 3-D geometry of incinerator and waste-bed model to achieve the efficient incorporation of the empirical models and enhancement of the stability of calculation process. First of all, the turbulence-related, complex combustion chemistry involved with NO reaction is modeled by the harmonic mean method, which is given by the relative strength of the rates of chemistry and turbulent mixing. Further, the 3-D rectangular shape of the incinerator is simply approximated by a 3-D axi-symmetric geometry with equivalent area. And the modeling of complex waste-burning process on moving grate is described by a pure gaseous combustion process of waste off-gas. The program developed in this study is successfully validated by comparing with the experimental data such as temperature and NO concentration profiles in the incinerator located at 4th industrial complex of Daejon, S. Korea. Using the program developed, a series of parametric investigations have been made for the evaluation of SNCR process and thereby evaluate various important design and the operating variables. The major parameters considered in this parametric study are heating value of municipal waste, the injection location and amount of reduction material, and the proper length of insulating castable. In general, the calculated results are physically acceptable and fairly consistent.