Thermodynamic analysis of KCS/ORC integrated power generation system with LNG cold energy exploitation and CO2 capture

In this paper, an integrated power generation system of Kalina cycle system (KCS) and organic Rankine cycle (ORC) with LNG cold energy exploitation and CO2 capture is introduced. The composite circulation system can fully recover and use the medium and low temperature waste heat to reduce the greenhouse gas emissions. To evaluate the system performances, the thermodynamics model was established and the system was simulated by using Aspen HYSYS software. Thermodynamic analysis has been performed to study the effects of turbine inlet temperature, NH3 mass fraction, evaporation pressure and CO2 capture pressure on the KCS/ORC integrated system. The optimal conditions were also investigated and identified. Exergy analysis of the components operated on KCS or ORC has also been demonstrated. The results showed that the optimal values of the network output, thermal efficiency and CO2 captured quantity of the system were respectively 394.685 kW, 53.25% and 0.3 t/tCO2 (0.6 t/tLNG), while the evaluation indexes of the power recovery efficiency and exergy efficiency were respectively 36% and 41.42%. The exergy loss efficiency of each component was examined. It was indicated that the whole system has significant advantages in waste heat recovery.