Numerical simulations of a single particle for CO2 capture based on MgO sorbent

Abstract

To obtain a deeper understanding of the mass transfer between MgO-based sorbent particles and gaseous reactants (CO₂), it is essential to investigate the mass transfer characteristics of a single moving sorbent particle since most previous researches focused on the removal efficiency of the whole flow field and ignored the behavior of individual particles. Currently, most studies assumed that the reactant (CO₂) concentration across the particle surface is uniform based on the average concentration within the grid, while the reactant concentration on the particle surface changes as the particle moves. In this study, the gas-solid mass transfer between CO₂ and a moving MgO-based particle was investigated. The results indicated that the motion state and velocity of the particles significantly impact the CO₂ removal dynamics and noticeable differences in the CO₂ concentration gradient could be observed around the particle. Increasing the reaction temperature, enhancing the CO₂ mass fraction at the inlet, appropriately increasing the gas velocity, and selecting an appropriate particle size can significantly enhance the reaction rate, thereby improving the CO₂ removal efficiency. The correction formula for surface CO₂ concentration and mass transfer reaction rate was also proposed based on the particle's velocity and direction of movement. Based on the correction formula, more detailed guidance for optimizing reactor design could be obtained and the findings provide theoretical guide for designing CO₂ removal reactors.