Process design and thermal-calculation of a novel entrained-flow gasifier using fine ash as feedstock

Fine ash from gasification is produced in huge quantities, and has the carbon content of around 20---40%. The treatment of fine ash is urgently needed to be resolved. However, large-scale industrial utilization of fine ash has not yet been realized. The ash content of fine ash is 60--70%. The calorific value of fine ash is usually lower than that of coal. The adiabatic combustion temperature of fine ash gasifier is lower than that of pulverized coal gasifier, and the outlet temperature is also lower. This paper pointed out the reason why the outlet temperature of the entrained-flow gasifier was low when fine ash produced by Ende gasifier was used as the gasification feedstock. A novel process of using the entrained-flow gasifier to utilize the carbon in fine ash was proposed. Fine ash in raw syngas was captured by a bag dust collector, mixed with pulverized coal, and transported to the entrained-flow gasifier. The gasification parameters of the process were obtained. When fine ash was used alone as feedstock, it was difficult to reach the required temperature for the discharge of liquid slag. When fine ash and coal were co-gasified, the outlet temperatures were 1461 and 1529 celcius, which could meet the gasifier's safe operational requirements for smooth discharge of liquid slag. The syngas concentrations were greatly affected by the carbon content of fine ash. The results of the current work provide a useful reference for industrial design and application of fine ash in atmospheric entrained-flow gasifier.