Title : Non-woody biomass combustion in grate furnaces: Model optimization and parametric analysis
Abstract:
Grate combustion is widely used in biomass utilization due to its strong fuel adaptability. However, accurately modeling the conversion process is challenging due to the complex interactions between drying, pyrolysis, gasification, and char combustion. This study presents a one-dimensional numerical model that describes the conversion of non-woody biomass on a grate. Based on time and space discretization, the model comprehensively considers the conservation of mass, momentum, and energy, as well as the multistage conversion process of biomass in a moving grate-fired bed. This process includes moisture evaporation, volatile matter release, char gasification and combustion, and heat transfer mechanisms. The model also incorporates reaction kinetics and free-board radiation coupling effects to more accurately describe bed temperature distribution and the reaction process. The research focuses on the thermochemical conversion of non-woody biomass fuels in grate furnaces, emphasizing model optimization and sensitivity analysis.
Base on our previous models, this study introduces several improvements. In particular, the radiation model has been improved to account for radiation penetration within the fuel bed rather than being applied only at the top layer. This allows for a more realistic simulation of heat distribution between different layers. This improvement overcomes the limitations of the previous assumption that radiation occurs only in the top layer of the fuel bed, enhancing the accuracy of predicting the internal temperature distribution.
Additionally, a parametric study was conducted to investigate the impact of operating and fuel parameters on conversion behavior. Parameters such as fuel particle size, residence time, and radiation conditions were systematically varied to evaluate their influence on temperature changes, reaction rates, and overall combustion efficiency.
The results provide insight into radiative heat transfer and its impact on the distribution of temperature, moisture content, and char mass fraction along the grate. Additionally, the results of parametric study shows the impact of operating and fuel parameters on conversion behavior. The improved model enhances the accuracy of predicting biomass conversion behavior and can be used as a reference for optimizing operating conditions in future grate furnace applications.
