Experimental Investigation into a Pilot-Scale Entrained-Flow Gasification of Pulverized Coal Using CO2 As Carrier Gas

Abstract

Using CO2 as a carrier gas in pneumatic conveying of pulverized coal instead of N2 has been paid more and more attention with the wide application of dry-feed entrained-flow coal gasification technology due to its attractive effects as a reactant. Accordingly, a pilot-scale performance of entrained-flow gasification using CO2 as the carrier gas of pulverized coal was investigated at gasifier temperatures between 1300 and 1400 °C. The differences in solid mass flow rate and flow stability are insignificant in the dense-phase pneumatic conveying between CO2 and N2 carrier provided that the conveying pressure differences and solid velocities in the pipeline are kept constant. Regarding syngas composition in dry basis, there was a desired drop in inert gas (N2) concentration from about 6% to less than 2%, while the CO2 concentration increased by about 4%age points in optimal operation conditions when CO2 carrier substituted for N2. At the same time, gasification profiles in different operation conditions indicated that CO2 carrier can act as an auxiliary gasification agent. Steam as another important gasification agent, however, cannot be completely substituted by CO2 carrier gas.