Mass-Transfer Characteristics and Optimization of a Hydrophilic Ceramic Membrane Contactor for SO₂ Absorption

Postcombustion SO₂ capture-from a high-volume flue gas-calls for a separator which should possess a high gas/liquid ratio concurrently without causing liquid flooding and entrainment. This study aimed to evaluate the feasibility of a hydrophilic ceramic membrane for SO₂ separation by investigating the mass-transfer characteristics of SO₂ absorption into NaOH coupling with a tubular Al₂O₃ membrane. We first established a numerical two-dimensional model to simulate the SO₂ absorption process with respect to the available experimental data. Then, we analyzed the mass-transfer characteristics by simulating the distributions of SO₂ and OH^- in the membrane contactor and estimating the resistances of SO₂ transfer in different phases. Simulations showed that the SO₂-NaOH reaction was quite rapid and mostly occurred in the gas/liquid interface, leading to a minor membrane-phase resistance. Furthermore, effective NaOH concentration lines under several key membrane parameters and operating conditions were proposed to facilitate the design of a membrane contactor.