Effect of Operation Parameters on High Temperature Air Gasification

A kinetics model and a experimental rig for high temperature air coal gasification(HTAG) research were set up. The effects of important operation parameters, such as air-coal ratio, steam-coal ratio and specific gasification rate, on gasification indexes were studied through the kinetics model and gasifier. The results show that: the model can accurately predict the gas composition. And when air-coal ratio increases from 1m³/kg to 1.25m³/kg, the syngas yield increases from 2.27m³/kg to 2.82m³/kg, carbon conversion increases from 73% to 94% and gasification efficiency increases from 68% to 82%, but the calorific value changes little. When air-coal ratio is larger than 1.25m³ /kg, the combustion zone extends much because of the excessive air and as a result, the calorific value and gasification efficiency decrease a lot. Thus the proper air-coal ratio should be 1.25m³/kg. With steam-coal ratio increasing from 0.6kg/kg to 0.7kg/kg, calorific value of the syngas increases little at first and then decreases, but syngas yield increases a little, gasification efficiency and carbon conversion change little. When steam-coal ratio is larger than 0.7kg/kg, the gasification temperature decreases and as a result, the gasification condition gets worse. Thus the steam-coal ratio should be 0.7kg/kg. When specific gasification rate increases from 260kg/(m² ldr h) to 335kg/(m² ldr h), carbon conversion, gasification efficiency, calorific value and yield of the syngas change little. When pecific gasification rate is larger than 335kg/(m² ldr h), the contact time of gasifying agent, gasification products and carbon is shortened and as a result, the gasification condition gets worse. Thus the specific gasification rate should be 335kg/(m² ldr h).