Numerical Simulation of Chemical Looping and Calcium Looping Combustion Processes for Carbon Capture

Abstract

Efficient carbon capture and storage (CCS) technologies are needed to address the rising carbon emissions from power generation using fossil fuels that have been linked to global warming and climate change. Chemical looping combustion (CLC) is one such technology that has shown great promise due to its potential for high-purity carbon capture at low cost. Another CCS technology that has garnered interest in recent years is calcium looping (CaL), which utilizes calcium oxide and the carbonation-calcination equilibrium reactions to capture CO2 from the flue stream of fossil fuel power plants. Computational fluid dynamics (CFD) simulations of two CLC reactors are presented in this chapter, along with system level simulations of CaL for postcombustion carbon capture. CFD simulation of a CLC reactor based on a dual fluidized bed reactor is developed using the Eulerian approach to characterize the chemical reactions in the system. The solid phase consists of a Fe-based oxygen carrier while the gaseous fuel used is syngas. Later, the detailed hydrodynamics in a CLC system designed for solid coal fuel is presented based on a cold flow experimental setup at National Energy Technology Laboratory using the Lagrangian particle-tracking method. The process simulation of CaL using Aspen Plus shows an increasing marginal energy penalty associated with an increase in the CO2 capture efficiency, which suggests a limit on the maximum carbon capture efficiency in practical applications of CaL before the energy penalty becomes too large.