Adsorption modeling of CO2 in fluidized bed reactor

Abstract

A model was proposed for studying the adsorption of CO2 in fluidized bed reactor based on combination of two-phase fluidization with tanks-in-series model. Logical combinations of ideal reactors can be of critical importance in gaining insights into the nature of FBRs and might better be further utilized in process simulation software. Implementation of the tanks-in-series model, in addition, is more consistent with hydrodynamics of the bed compared to one-phase and two-phase models. Considering this model, the fluidized bed was divided into 4 equal-volume stages, in which gas flows as completely mixed flow in emulsion phase and in bubble phase as plug flow. Using experimental data, the number of sections was found as a function of Hata number, superficial gas velocity and minimum fluidization velocity. The experimental results in a laboratory scale fluidized bed reactor with two particle sizes (335 and 605μm) at different superficial gas velocities (0.47, 0.62, 0.79, 0.94 and 1.25m/s) and aspect ratios were used for model validation. Obtained breakthrough curves from modeling were compared against experimental data to verify the validity of the model and acceptable agreement was observed. By fitting the results of the proposed model with experimental data, the reaction constant and Langmuir equilibrium constant were determined to be 0.041/s and 0.019m3/mol, respectively. Increasing the superficial gas velocity and better mixing of adsorbent result in greater adsorption capacity. Moreover, it was observed that smaller particles have higher adsorption capacity due to higher specific surface area and mass transfer coefficient than larger particles. It has also been found that the optimum superficial gas velocity was in the range of 0.62 and 0.79m/s for both particles sizes.