Simulation of coal gasification process based on hybrid model

The current gasification mechanism model has large residuals under variable working conditions and the model can only simulate one working condition in a single run and cannot be run continuously to characterize the long-cycle operation of gasifier. This paper firstly used the process simulation software Unisim to establish the long-cycle mechanism model of gasifier based on the reaction kinetics of 3000 t/d coal-water slurry gasifier in Yulin Chemical Co. of National Energy Investment Group. Then, a hybrid model of the mechanism model in parallel with the BP neural network model was developed, and the simulation accuracy of the hybrid model was verified and analyzed. Finally, the application of the hybrid model in gasification index prediction and gasification performance analysis was investigated. The application of the hybrid model for gasification index prediction and gasification performance analysis was investigated. The results show that the simulation error of the single-case mechanistic model for gasification temperature and syngas composition is less than 5%. The long-period mechanistic model can predict the variation trend of gasification furnace temperature, and the correlation coefficient between the simulated and operational values is 0.822, but the simulated values fluctuate greatly, and the relative standard deviation (RSD) of the simulated gasification temperature values is 3.8 times of the operational values. The simulation accuracy of the hybrid model for gasification is significantly better than that of the mechanistic model. The simulation accuracy of the gasification mixing model is significantly better than that of the mechanistic model, with the simulated values matching well with the trend of the operating values, and the errors of gasification temperature and syngas composition are less than 2%. The mixing model still has a high accuracy after the change of working conditions, and the simulation error increases from 2% to less than 4%. As the oxygen to coal ratio increases from 480 Nm³/m³ to 498 Nm³/m³, the gasification temperature calculated by the mixing model increases from 1160 ℃ to 1306 ℃, the CO₂ content in the syngas increases from 18.6% to 19.9%, the CO content decreases from 42.6% to 42%, and the H₂ content decreases from 37.7% to 36.8%, which are consistent with the mechanistic model. The hybrid model has a significant correction effect on the mechanistic model, in which the temperature is corrected by about 38 ℃, and X(CO), X(CO₂) and X(H₂) are corrected by −1, −0.9 and 1.5 percentage points respectively.