Steady state simulation of coal gasification with radiant syngas cooler based on Aspen Plus

Pulverized coal airflow bed has the advantages of low oxygen consumption, low coal consumption and high carbon conversion rate, and is widely used in industry. Radiant syngas cooler can effectively recover the waste heat of syngas produced by pulverized coal gasifier, which is more economical and environmental friendly in the long run. A steady state model of coal gasifier with radiant syngas cooler(RSC) was constructed using Aspen Plus. Since the temperature of RSC is quite high, the further gasification reaction was considered in this model. Moreover, the heat loss and unburned carbon was considered according to the industrial experience data and the simulation is validated as reliable by industrial operation results. Based on the model, the influences of core operation parameters like oxygen-coal ratio, steam-coal ratio and carbon conversion rate were analyzed to provide a theoretical guidance. The study results show that the effective composition of syngas increases rapidly at first and then decreases gradually with the increase of oxygen-coal ratio, and reaches the peak value when the oxygen-coal ratio is 0.5. When the oxygen-coal ratio is lower than 0.5,the gasification temperature increases slightly with the oxygen-coal ratio and when the oxygen-coal ratio is between 0.5 and 1,the gasification temperature increases rapidly with the oxygen-coal ratio. When the oxygen-coal ratio is higher than 1,the gasification temperature almost remains unchanged. Since the gasification temperature should be higher than ash fusion point to facilitate discharging slag in furnace, the oxygen-coal ratio is suggested to be higher than 0.6. The effective composition of the syngas(CO+H₂) almost decreases linearly with the increase of steam-coal ratio. The effective composition of the syngas(CO+H₂) almost increases linearly with the increase of carbon conversion rate. The gasification temperature decreases linearly with the increase of steam-coal ratio and carbon conversion rate.