System analysis of natural gas combined cycle (NGCC) integrated with kinetics-based chemical looping syngas production

In this paper, we proposed an oxy-fuel natural gas combined cycle with carbon capture integrated with chemical looping (CO2/H2O) dissociation unit (CL) that produces syngas and fed back to the power plant to gain the efficiency point that is being lost due to carbon capture. The chemical looping CO2/H2O dissociation would produce syngas (CO and H2 with methane reduction step in the redox cycle) from the recycled exhaust gas for additional power generation within the power plant. For developing an industrial scale CL unit, we developed the kinetics for methane reduced ceria and CO2/H2O splitting in an isothermal tubular micro-reactor for an operating temperature range of (900-1100oC) for different methane concentration and similar temperature and concentrations were adopted for oxidation which yielded to Avrami-Erofeev: AE3 model for both redox reaction with different reaction constants. A moving bed reactors system is developed representing reduction and oxidation reactors of CL unit and developed kinetics is hooked to the model in Aspen Plus with user-kinetic subroutine written in FORTRAN code. The CL model developed is integrated with the power plant layout proposed and investigated considering the effect of thermodynamics and the kinetics of redox reaction. It is found that the maximum non-stoichiometry (δ) reached during reduction is 0.29 instead of 0.5 when considered thermodynamics. The chemical looping unit efficiency obtained is 42.8% when considered kinetic-based CL unit compares to 64% for thermodynamic based CL unit. However, the electrical efficiency of the layout lowered as 50.9% for kinetic-based CL unit than 61.5% for thermodynamic based CL unit. Results also show that even with the redox kinetics, a decrease in energy efficiency penalty from 11.3% to 3.8% is observed yielding significant benefit of the proposed layout.