Development of a fully coupled bed combustion simulation method for grate-fired furnaces using Fluent UDF

To address the limitations of the traditional FLIC-Fluent coupling method in municipal solid waste （MSW） incineration simulation，specifically， long iteration cycles across multiple operating conditions and significant errors caused by data mapping at the FLIC-Fluent coupling interface，this study developed a fully coupled bed combustion simulation program based on Fluent User-Defined Functions （UDF）. By integrating four modules—dynamic regulation of particle emissivity， zonal motion control of the grate， bed drag shielding， and wall collision-induced fragmentation—the program achieved a fully coupled calculation of solid waste particle movement， bed combustion， and furnace flow fields within a single Fluent platform， serving as a complete replacement for the bed calculation functions of FLIC software. A 750 t/d reverse-inclined forward-feeding grate furnace in a Chinese waste-to-energy plant was selected as the engineering validation object. The model was calibrated using continuous operational data from 12 on-site measurement points. The results indicated that the computational time per operating condition was reduced by 71.4% compared to the traditional FLIC-Fluent coupling method； the relative error between simulated furnace temperatures and on-site measurements was ≤ 4.10%， significantly outperforming the 9.68% maximum relative error of the traditional method. The proposed method provides a reliable engineering simulation solution for optimizing operating conditions and screening blending schemes in the co-incineration of multi-source solid waste.