Investigations of an air-blown integrated gasification combined cycle fired with high-sulphur coal with post-combustion carbon capture by aqueous ammonia

This work deals with CO2 capture plants for an advanced air-blown gasification-based combined cycle where a coal with high sulphur content, which is really relevant for the coal market, is used as feedstock. The sulphur removed as H2S from the coal-derived gas enters a wet sulphuric acid process. Later, the resulting acid is used to control ammonia slip in a post-combustion CO2 capture plant based on ammonia scrubbing and designed for a reduced energy demand. Thus, limiting the energy impact of the CO2 capture technology will improve the power plant efficiency, according to a presumable lower cost of the generated electricity, as a high-sulphur coal is used as fuel input. In detail, a cooled ammonia-based process is found to be more attractive than a more conventional chilled ammonia-based solution: in case of 90% of CO2 avoided, the overall power plant efficiency is equal to 41.7% and the SPECCA (specific primary energy consumption for CO2 avoided) as low as 2.3MJ/kgCO2. Moreover, the calculation results show the SPECCA for CO2 avoided ranging from 80% to 90% is almost constant, even though the power plant efficiency increases if lower levels of CO2 capture are considered.