Influences of syngas pretreatment on the performance and energy distribution in an IGCC power plant

Raw syngas pretreatment mainly includes cooling and cleanup and has significant influences on the performance of integrated gasification combined cycle (IGCC) power plant. This investigation sets up IGCC system model based on coal water slurry gasification by using Thermoflex software, aiming to survey how syngas quenching, syngas cooling temperature variation and syngas hot desulfurization will affect the performance as well as energy distribution of an IGCC power plant. The validity of IGCC model was verified by simulating the well-known commercial Tampa Polk IGCC power plant via comparing calculation results with reference data. Then four cases of IGCC power plants adopting different raw syngas pretreatment conditions were simulated based on the verified Tampa Polk IGCC model. Calculation results indicated that, comparing with base case, syngas quenching and an increase of 50 °C in syngas cooling temperature both caused larger energy loss by syngas condensate water, leading to 7% and 0.4% decrease in power plant net efficiency. On the contrary, syngas hot desulfurization promoted gas turbine power output and prevented energy loss by syngas condensate water, resulting in a rise of net efficiency by 1.3%. Based on detailed energy distribution analyses, it is concluded that a reasonable syngas pretreatment route should be essentially beneficial to reduce exergy loss caused by irreversible heat transfer processes during syngas cooling and cleanup.