Comparison of IGCC (integrated gasification combined cycle) and CFB (circulating fluidized bed) cogeneration plants equipped with CO2 removal

The introduction of CO2 removal processes causes usually generation of waste heat. As the temperature of waste heat carriers is usually moderately high (ca. 100 °C), there is a potential possibility for using them in district heating systems. The main goal of present paper is thus the energy and CO2 emission analysis of CHP (combined heat and power production) plants equipped with CO2 removal and utilizing waste heat generated within the plant. First case is dealing with the CFB (circulating fluidized bed) plant equipped with post-combustion chemical CO2 absorption. The second case is dealing with an IGCC (integrated gasification combined cycle) equipped with the pre-combustion CO2 removal by physical absorption. Both plants have been modeled on the Thermoflex software. The reference, CFB-based CHP plant without CO2 removal has also been modeled. The obtained results indicate that IGCC plant has better thermodynamic indicators than CFB-based unit. Moreover, the CO2 emission considering system interconnections within the electricity production network is negative for both plants equipped with CCS (carbon capture and storage). The highest exergy efficiency is achieved for the reference CFB plant. The decrease of exergy efficiency caused by CO2 capture and compression is ca. 8 percentage points, but in case of IGCC CHP plant the exergy efficiency is only 3 percentage points lower than for the reference system.