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

Carbon dioxide (CO₂) is considered to be the major greenhouse gas contributing to global warming. While reducing fossil fuel consumption may provide the ultimate answer to CO₂ emission problems, one of the short-term solutions is the separation and subsequent disposal of the CO₂ from power plant and industrial flue gas streams. A novel, energy-efficient CO₂ 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 CO₂ concentrations indicate that the CO₂ 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% CO₂ are predicted.