Computer simulation of a novel circulating fluidized bed pressure-temperature swing adsorber for recovering carbon dioxide from flue gases

Abstract

Carbon dioxide (CO 2) is considered to be the major greenhouse gas contributing to global warming. While reducing fossil fuel consumption may provide the ultimate answer to CO 2 emission problems, one of the short-term solutions is the separation and subsequent disposal of the CO 2 from power plant and industrial flue gas streams. A novel, energy-efficient CO 2 separation process known as the circulating fluidized bed pressure-temperature swing adsorber (CFB-PTSA) is simulated in this work. A hydrodynamic model for the gas and solids flow structure in the riser of circulating fluidized beds is combined with a competitive adsorption model for a carbon dioxide, nitrogen, oxygen mixture on a type X zeolite, as described by the ideal adsorbed solution theory, to predict the reactor performance. Simulations performed at various riser operating conditions and flue gas CO 2 concentrations indicate that the CO 2 recovery decreases with increasing concentration at a fixed solids circulation flux, but the purity of the recovered product increases. Recoveries in the range of 65–88.5% and product purities of 75–90% CO 2 are predicted.