Optimization of Stage Numbers in a Multistage Fluidized Bed Temperature Swing Adsorption System for CO2 Capture

Abstract

A dual loop multi stage fluidized bed process for continuous temperature swing adsorption (TSA) of CO2 is investigated using a thermodynamic process model. The operating case is chosen in accordance with a typical post-combustion CO2 capture process, i.e. 90% CO2 capture rate from a gas stream with 10 vol% CO2 content. Steam is used as the stripping agent on the desorber side. Adsorption thermodynamic data for an amine functionalized sorbent material are employed based on adsorption isotherm data from the literature using the Langmuir model. The optimum stage number on both adsorber and desorber side are investigated with respect to achieve high energy efficiency of the separation process. This means that a low stripping steam demand and a low solids circulation rate are desired. The results show that both solids circulation rate and stripping steam demand are low for configurations with multiple stages for both the adsorber and the desorber. The effect of additional stages is high at the beginning (especially up to three stages) and fades with the number of stages. It can be concluded for the chosen separation task and sorbent that a system with five stages on each side could represent a good compromise between effort and efficiency. Further work will focus on more detailed modeling and on experimental evaluation of the discussed process.