Investigation of Mass Transfer Characteristics of SO₂ Absorption into NaOH in a Multichannel Ceramic Membrane Contactor

Abstract

A ceramic membrane with multichannels generally has a higher specific area and larger throughput compared to that with a single channel, which is beneficial to the industrialization of ceramic membrane contactors for SO 2 absorption. In this work, the mass transfer performance of SO 2 absorption into NaOH solution was investigated at various gas and liquid operating conditions in a membrane contactor packed with a 19-channel hydrophilic membrane. The results showed that increasing the NaOH concentration can offset the effect of membrane thickness. To analyze the mass transfer process, a 3D mass transfer model was developed to simulate the concentration distribution of the components. The simulated SO 2 fluxes were consistent with the experimental results. Additionally, the mass transfer model was applied to optimize the structure of channels in multichannel ceramic membranes. The operational mode of the multichannel ceramic membrane is optimized by blocking some inside channels to reduce the mass transfer resistance.

Reusability of Discarded Tubular Ceramic Membranes for CO2 Removal: A Case Study for Membrane Circularity

“…A high NaOH concentration provides a high [OH], a higher reaction rate, and mass transfer as shown in eqs –. Membrane channels have low mass transfer resistance and can increase the mass transfer coefficient of channels with increasing NaOH concentrations . The results of the current study were in line with other studies in which increasing the absorbance concentration from 1 to 2 M provided almost total removal of CO 2 : ,, …”

“…At a Q g of 600 mL/min, the saturation point was reached at 270 min, followed by a significant increase in CO 2 concentration. This is due to the fact that the gas phase boundary layer becomes thinner as the feed gas rate increases, and the overall transfer coefficient increases until the gas resistance is ignored …”

“…The CO 2 removal efficiency (η) is one of the most accurate indicators for evaluating the performance of MC, which can be calculated according to eq : η = Q normalg , in × C normalg , in − Q normalg , out × C normalg , out Q normalg , in × C normalg , in where η is the CO 2 removal efficiency (%), C g,in and C g,out are CO 2 volumetric fraction (%) in feed and outlet gas, respectively, and Q g,in and Q g,out are flow rate (m 3 /h) of feed gas and outlet gas, respectively. CO 2 mass transfer flux ( J CO 2 ) is another important parameter and was calculated by eq : J CO 2 = Q normalg × ( C g , in − C g , out ) × 273.15 0.0224 × T normalg × A where J CO 2 is the CO 2 mass transfer flux (mol/m 2 s), Q g is the gas flow rate in MC (m 3 /h), C g,in and C g,out are CO 2 molar concentrations (mol/m 3 ) in feed and outlet gas, respectively, T g is temperature value (K), and A is the contact area of gas and liquid (m 2 ).…”

Selective Sulfur Dioxide Absorption from Simulated Flue Gas Using Various Aqueous Alkali Solutions in a Polypropylene Hollow Fiber Membrane Contactor: Removal Efficiency and Use of Sulfur Dioxide

“…When DI water was used as an absorbent, as reported in the results for general SO 2 removal experiments, the removal rate rapidly decreased from the beginning of the experiment, and then showed a removal rate of 50% or less in less than 30 min [ 16 , 32 , 33 , 46 , 47 ]. The tendency for various types of absorbents in this study is not much different from those in the previous studies.…”

Superhydrophobic Surface-Constructed Membrane Contactor with Hierarchical Lotus-Leaf-Like Interfaces for Efficient SO2 Capture

“…The massive emissions of sulfur dioxide (SO 2 ) have adverse influences on the ecological environment and human health. − In past decades, numerous researches have been focused on the absorption of SO 2 gas by employing gas–liquid membrane contactor technology, which displays the green and efficient industrial application prospect, avoiding the flooding, bubbling, gas–liquid entrainment problems. − The investigation of acidic gas capture by membrane contactor can be classified into various categories: membrane design, , transfer mechanism, , absorption liquid, optimized operating process, , process simulation, etc. , To obtain the excellent acid gas absorption flux, a membrane contactor designed with a hydrophobic property is essential to keep absorbent liquid from immersing into the pores of membrane contactors. − Therefore, a hydrophobic membrane material, such as polytetrafluoroethylene (PTFE), polypropylene (PP), has been used to prepare porous membrane contactors for desulfurization. − …”