Performance evaluation on co-gasification of bituminous coal and wheat straw in entrained flow gasification system

Co-gasification of coal and biomass can reduce the CO2 emission and the consumption of fossil fuel. Kinetic analysis and products distribution evaluation are essential to the gasifier design and operation optimization. In this paper, the thermal behavior on co-gasification of a kind of bituminous coal blended with wheat straw was investigated by the thermal gravimetric analyzer and distributed activation energy model. Gaseous products evolution during co-gasification was explored by entrained flow gasification system. The influence of gasification temperature (1100-1400 °C), biomass mixing ratio (0, 0.25, 0.5, 0.75, 1), and oxygen/carbon ratio (0.35-0.65) on H2 and other gaseous products was considered. The result indicated that the adding of wheat straw promoted the gasification performance. The value of Tgin (initial gasification temperature) and Gi (gasification reactivity index) increased as the increasing mass ratio of wheat straw. The distributed of gasification activation energy showed positive synergistic effect. The value of gasification activation energy gradually decreased from 193.58 to 100.62 kJ mol−1, 115.11 kJ mol−1, 129.57 kJ mol−1 as the mass ratio of wheat straw increased from 0.25 to 0.75. The content of H2 and CO increased with the rising of gasification temperature, and the content of CO2 and CH4 showed the opposite trend. At the same time, cold gas efficiency (CGE) increased with the raising of gasification temperature, indicating that the improvement of gasification temperature is beneficial to the improvement of co-gasification gas quality. The content of H2 and CO2 also increased the growth of wheat straw mass ratio. Synergistic effect of gaseous distribution was also observed, especially in 50% of biomass ratio. As the increasing of oxygen-fuel ratio, the content of H2 and CH4 decreases gradually. Synthesizes each kind of condition with the operation condition of gasification equipment and the quality of gaseous products, the gasification temperature of 1300 °C and the oxygen-fuel ratio of 0.45 were the optimum operating parameters for co-gasification of bituminous coal and straw. This research can provide basic information for process design and parameter selection of co-gasification.