Numerical analysis on the performance of a 300 MW IGCC coal gasifier under various operating conditions

Abstract To improve availability and lower the electricity production costs in an integrated gasification combined cycle (IGCC) plant, it is essential to minimize operation problems in the coal gasifier. Using computational fluid dynamics, this study evaluated the performance of the coal gasifier at Taean IGCC with 300 MWe capacity both with and without steam in the gasifying agent under loads between 50 and 100%. The swirling flow developed by the horizontally biased coal burners had a huge influence on the particle trajectories, reactions, and temperature distribution. In particular, the gas temperature was higher in the upward swirling flow, whereas the downward flow carrying more particles developed a lower temperature region below the burner level. These phenomena became more prominent at lower operational loads. Despite the design conditions including steam in the gasifying agent, the operation without it was stable at 0.36–1.07% lower cold gas efficiencies with increased heat transfer to the wall. With steam injection, 37–98 °C lower gas temperature and corresponding increase in the slag thickness were expected in the lower part of the gasifier due to an increase of endothermic char reactions by 4.6–7.6%. This could be severe for low-rank coals with higher inherent moisture and lower energy content compared with design coal. Therefore, a low operating load with steam injection requires careful control of slag composition and flowability for prevention of slag discharge problems.