Numerical study of steam-air gasification of Kuznetsk coal in entrained-flow reactor

Integrated gasification Combined cycle plants (IGCC) have high efficiency and minimal emissions of harmful substances, which makes them a promising technology for the energy production from coal. However, the cost of energy produced from IGCC remains high, which requires the improvement of IGCC technology. Increasing the efficiency and reducing the material consumption of IGCC is possible due to the addition of steam to the air blast in gasifier. To study the effect of steam addition on the gasification process, a one-dimensional kinetic-thermodynamic model has been developed that takes into account the chemical reaction inside the pores, the distribution of coal particles by size, the change in reaction order of steam gasification of coal, and the recirculation of coke-ash residue (CAR) from the gasifier outlet. Calculations of steam-air gasification of Kuznetsk coal in an industrial two-stage gasifier MHI for two types of coal grinding (ball mill and disintegrator) and three gasifier operation modes: nominal, pyrolysis (maximum recirculation of CAR) and flow (minimum recirculation of CAR) are carried out. Dependence cold gas efficiency of the gasifier from the steam / coal ratio is non-monotonic, associated with a change in the order of the steam gasification reaction. The maximum increase of cold gas efficiency is 0.5–9% abs. depending on the gasifier operation mode.