SIMULATION OF HIGH-TEMPERATURE STEAM-ONLY GASIFICATION OF WOODY BIOMASS WITH DRY-SORPTION CO2 CAPTURE

Over the lastfew decades, research on the abatement of carbon dioxide (CO2) gas has gained momentum, due to its increasing atmospheric levels. This study investigated thigh-temperature steam only gasification of woody biomass for the production of high purity hydrogen integrated with CO2 capture in a moving-bed gasifier. Extensive process modelling and simulation were performed using the superior solid handling features of the Aspen Plus process simulator software. After validating the model with experimental data from a demonstration plant available in the open literature, a reversible carbonation-calcination reaction of calcium oxide (CaO) with CO2 was added to the system. Sensitivity analyses were conducted to verify the predictive accuracy of the model. The effects of steam-to-carbon (S/C) ratio on the resulting gas composition were thoroughly studied to delineate the complex process of gasification. Beyond the mitigation of CO2 emissions, the introduction of a CaO-based sorbent in the process simulation significantly enhanced hydrogen production by simultaneously promoting the forward water-gas shift reaction and reducing tars through increased tar cracking reactions. The results show that hydrogen of a higher purity was produced with the inclusion of dry sorption CO2 capture in the gasification process. Moreover, the addition of the sorbent increased the higher heating values (HHV) by 3 times and improved the cold gas efficiency by 34 %.