Numerical study on the effective utilization of high sulfur petroleum coke for syngas production via chemical looping gasification

This study aims at investigating the syngas production and sulfur conversion mechanisms during the chemical looping gasification (CLG) process with the industrial by-product petroleum coke (petcoke) as fuel, which is beneficial to the waste-to-energy process. The chemical kinetics including petroleum coke decomposition, char gasification, oxygen carrier reduction and the sulfur species reaction model are incorporated into the dynamic model to simulate a CLG fluidized bed reactor with iron-based oxygen carriers. Results suggest that the model is able to well predict the time-varying concentrations of the syngas products and sulfur-containing gases. The near-zero COS emission from the reactor outlet confirms the previous experimental results and contributes additional evidence that the presence of steam enhances the conversion of COS to H2S. The effects of temperature, steam and N2 flow rates on the petcoke CLG performance are also evaluated. The results indicate that higher temperature and steam flow rate lead to an improvement in the conversion of carbon and sulfur in petroleum coke. However, further increasing the gas flow rates may result in a more intense fluidization state, which might significantly facilitate the OC reduction reactions with flammable gases, thus increasing the CO2 and SO2 production in the petcoke CLG process.