Abstract: The distribution of adsorbent particle sizes typically has a significant impact on adsorption performance. Most fixed-bed adsorption studies adopt the assumption of average particle size to simplify the adsorption model, but this does not eliminate the deviation between experiments and simulations caused by particle size distribution in practice. In this study, the population balance equation (PBE) and fixed-bed adsorption kinetics model were combined to simulate the adsorption process in a fixed-bed reactor, modeling the distribution of adsorbate uptake over time on adsorbent particles of different sizes. We integrated and optimized the PBE and fixed-bed mass transfer model in the algorithm, and the resulting combined model adopts a variable time step size, which can achieve a balance between computational efficiency and error while ensuring computational convergence. By slicing the model in the spatial dimension, multiple sets of PBE can be calculated in parallel, improving computational efficiency. The adsorption process of single-component and multi-component CO₂/CH₄/N₂ on 4A zeolite without binder was simulated, and the influence of adsorbent particle size distribution was analyzed. Simulation results show that the assumption of average adsorbent particle size, which was commonly made in published work, will underestimate the time required for adsorbates to break through the fixed bed compared with the assumption of uniform adsorbent particle size. This model helps to consider the impact of adsorbent particle size distribution on the adsorption process, thereby improving the prediction accuracy of adsorbent performance.

Key words: Population balance equation, Particle size distribution, Fixed-bed adsorption

摘要： The distribution of adsorbent particle sizes typically has a significant impact on adsorption performance. Most fixed-bed adsorption studies adopt the assumption of average particle size to simplify the adsorption model, but this does not eliminate the deviation between experiments and simulations caused by particle size distribution in practice. In this study, the population balance equation (PBE) and fixed-bed adsorption kinetics model were combined to simulate the adsorption process in a fixed-bed reactor, modeling the distribution of adsorbate uptake over time on adsorbent particles of different sizes. We integrated and optimized the PBE and fixed-bed mass transfer model in the algorithm, and the resulting combined model adopts a variable time step size, which can achieve a balance between computational efficiency and error while ensuring computational convergence. By slicing the model in the spatial dimension, multiple sets of PBE can be calculated in parallel, improving computational efficiency. The adsorption process of single-component and multi-component CO₂/CH₄/N₂ on 4A zeolite without binder was simulated, and the influence of adsorbent particle size distribution was analyzed. Simulation results show that the assumption of average adsorbent particle size, which was commonly made in published work, will underestimate the time required for adsorbates to break through the fixed bed compared with the assumption of uniform adsorbent particle size. This model helps to consider the impact of adsorbent particle size distribution on the adsorption process, thereby improving the prediction accuracy of adsorbent performance.

关键词: Population balance equation, Particle size distribution, Fixed-bed adsorption