Ca–Cu looping process for CO2 capture from a power plant and its comparison with Ca-looping, oxy-combustion and amine-based CO2 capture processes

This study reports the technical performance of an advanced configuration of the calcium looping (Ca-looping) process, called Ca–Cu looping, for the reduction of CO2 emissions from a subcritical CFB power plant with a net output of 250 MWe. In this new process concept, the thermal power requirement in the calciner is satisfied using a chemical looping combustion cycle. Thus, the power consumption associated with the air separation unit that is required in the conventional Ca-looping process scheme can be eliminated. The reference power plant has also been modified to integrate oxy-combustion, Ca-looping and amine scrubbing technologies for comparison. The fully integrated process flowsheets have been simulated using Honeywell's UniSim Design Suit R400. For a more accurate prediction of the CO2 capture efficiency in the carbonator of the Ca–Cu looping process, the experimentally obtained cyclic activity of a novel copper-functionalised, calcium-based composite sorbent has been implemented yielding a rigorous carbonator model. The process simulations also include a comprehensive analysis of the CO2 compression and purification unit as well as a heat exchanger network optimized using pinch analysis for the recovery of excess heat from the high temperature gas and solid streams available in the Ca-looping and Ca–Cu looping processes. Compared to the energy penalty of 10.5 percentage points for a conventional amine scrubbing configuration, the Ca–Cu looping process evaluated in this study achieves the same overall CO2 capture efficiency with a significantly reduced energy penalty of 3.5 percentage points; the lowest value for all CO2 capture architectures assessed here.