The Application Of Thermal-Calculation Methods In The Design And Syngas Prediction Of Entrained-Flow Coal Gasifiers

A novel thermal-calculation method for membrane wall entrained-flow coal gasifier based on the equilibrium model was proposed in this study, and the method takes into account the heat transfer of the gasifier. The equilibrium model was established by the Gibbs free energy minimization method to avoid solving the intermediate chemical reaction process. The concepts of effective radiation heating area of furnace and flame center modification factor were introduced into the thermal-calculation method. This study not only analyzes the influence of oxygen-to-coal and water-to-coal ratios under normal operating conditions, but also investigates the impact of structural characteristics of a membrane wall entrained-flow gasifier on gasification characteristics. The model was effectively used to predict the syngas composition, the syngas temperature at the outlet of the chamber, and the energy distribution of the gasifier. The syngas composition and heat loss of gasifier obtained by thermal-calculation method are in good agreement with the experimental data of industrial-scale plants. The results show that the oxygen-to-coal ratio significantly impacts the syngas composition and heat loss than the water-to-coal ratio. Increase in the effective radiation heating area of furnace results in the decrease in the syngas temperature at the outlet of chamber, thus reducing the heat loss of flue gas and improving the heat absorption of the membrane wall tube. However, simultaneously, it can also reduce the CO concentration in syngas. Reduction in the flame center modification factor is helpful to increase the CO concentration; however, it also causes colossal heat loss of flue gas.