Effect of Diethanolamine (DEA) Solvent Flow Rate on the CO2 Absorption-Desorption Process Using a Hollow Fiber Membrane Contactor

We demonstrate a scalable and energy-efficient hollow fiber membrane contactor (HFMC)-based process using a green solvent for CO2 capture. This process uses a deep eutectic solvent (DES) in an HFMC to provide close interfacial interactions and contact between the DES and CO2. This approach overcomes disadvantages associated with direct absorption in DES and could potentially be applied to a variety of solvent-based CO2 capture methods. Commercial low-cost polymer hollow fiber membranes (e.g., microporous polypropylene) were evaluated for CO2 capture with reline, a prototypical DES. Single-gas measurements showed that the DES-based polypropylene HFMC can capture and separate CO2 while rejecting N2. From a mixed gas containing 50 mol % N2 and 50 mol % CO2, the DES-based HFMC separated CO2 with a purity of 96.9 mol %. The effect of several process parameters including solvent flow rate, pressure, and temperature on the CO2 separation performance was studied. The flux of the recovered CO2 was 67.43 mmole/m2/h at a feed pressure of 4 bar. In situ Fourier transform infrared (FTIR) measurements combined with density functional theory (DFT)-based molecular dynamics simulations revealed that reline absorbs CO2 by physical absorption without forming a new chemical compound, and CO2 separation by reline occurs via the pressure swing mechanism. This research provides fundamental insights about physical solvent-based separation processes and a pathway toward practical deployment.

CFD study of CO2 separation in an HFMC: Under non-wetted and partially-wetted conditions

Global warming, driven significantly by carbon dioxide (CO2) emissions, necessitates immediate climate action. Consequently, CO2 capture is essential for mitigating carbon output from industrial and power generation processes. This study investigates the effect of absorbent temperature on CO2 separation performance using gas-liquid polymeric hollow fiber membrane (HFM) contactors. It summarizes the relationship between liquid-phase temperature and CO2 capture efficiency across various physical and chemical absorption processes. Twelve relevant studies (nine experimental, three mathematical), providing a comprehensive database of 104 individual measurements, were rigorously analyzed. Liquid-phase temperature significantly influences CO2 separation performance in HFM contactors. In particular, the present analysis reveals that, overall, for every 10 °C temperature increase, physical absorption performance decreases by approximately 3%, while chemical absorption performance improves by 3%, regardless of other parameters. This empirical law was confirmed by direct comparisons with additional experimental results. Strategies for further development of these processes are also proposed.

Evaluation of the removal of CO 2 using membrane contactors: Membrane wettability

In this work, carbon dioxide (CO2) loading capacity of methyldiethanolamine (MDEA) solution promoted by potassium lysinate (KLys) was experimentally measured by using a gas absorption setup at different concentrations and temperatures. The CO2 removal efficiency of the MDEA + KLys solution was investigated for a CO2/N2 gas mixture by using computational fluid dynamic (CFD) simulations in a hollow fiber membrane contactor (HFMC). The effects of operating conditions including solvent concentration, solvent flow rate, gas flow rate, inlet CO2 concentration and module length on the CO2 removal efficiency were also studied. The experimental results revealed that CO2 loading capacity increases with increasing KLys concentration in the solution, while decreases as temperature increases. The simulation results indicated that MDEA + KLys solution has higher CO2 removal efficiency compared to pristine MDEA and MEA solutions. The CO2 removal efficiency increases with increasing solvent concentration, solvent flow rate and module length, whereas decreases as gas flow rate increases. The zeolitic imidazolate framework-8 (ZIF-8), as sorbent, was then incorporated into the MDEA + KLys solution and its effect on the CO2 removal efficiency was also examined. The MDEA + KLys + ZIF-8 nano-absorbent showed higher CO2 removal efficiency than that of MDEA + KLys absorbent, where introducing 0.4 wt.% ZIF-8 enhanced CO2 removal from ⁓96% to ⁓99%. The results of this work suggest that both MDEA + KLys absorbent and MDEA + KLys + ZIF-8 nano-absorbent are promising candidates for CO2 absorption processes. However, for practical use as well as a complete investigation, their behavior should be assessed by using other parameters of solvent such as reactivity with CO2, corrosion rate, and regeneration performance.

CO2/N2 separation by glycerol aqueous solution in a hollow fiber membrane contactor module: CFD simulation and experimental validation

This study uses DEA solution to absorb CO2 from the gas flow through the hollow fiber membrane contactors. This study aims to evaluate the performance of hollow fiber membrane contactors to absorb CO2 gas using DEA solution as solvent through mass transfer and hydrodynamics studies. The use of DEA solution is to reduce the mass transfer resistance in the liquid phase, and on the other side, the large contact area of the membrane surface can cover the disadvantage of membrane contactors; additional mass transfer resistance in the membrane phase. During experiments, CO2 feed flows through the fiber lumens, while the 0.01 M DEA solution flows in the shell side of membrane contactors. Experimental results show that the mass transfer coefficients and fluxes of CO2 increase with an increase in both water and DEA solution flow rates. Increasing the amount of fibers in the contactors will decrease the mass transfer and fluxes at the same DEA solution flow rate. Mass transfer coefficients and CO2 fluxes using DEA solution can achieve 28,000 and 7.6 million times greater than using water as solvent, respectively. Hydrodynamics studies show that the liquid pressure drops in the contactors increase with increasing liquid flow rate and number of fibers in the contactors. The friction between water and the fibers in the contactor was more pronounced at lower velocities, and therefore, the value of the friction factor is also higher at lower velocities.

Experimental study on the separation of CO2 from flue gas using hollow fiber membrane contactors without wetting

Fluidized countercurrent solvent extraction of oil pollutants from contaminated soil. Part 1: Fluid mechanics

Theoretical study of CO2 separation from CO2/CH4 gaseous mixture using 2-methylpiperazine -promoted potassium carbonate through hollow fiber membrane contactor

Investigation of carbon dioxide capture with aqueous piperazine on a post combustion pilot plant – Part II: Parameter study and emission measurement

Collision cross section (CCS, Ω) values determined by ion mobility mass spectrometry (IM-MS) provide the study of ion shape in the gas phase and use of these as further identification criteria in analytical approaches. Databases of CCS values for a variety of molecules determined by different instrument types are available. In this study, the comparability of CCS values determined by a drift tube ion mobility mass spectrometer (DTIM-MS) and a traveling wave ion mobility mass spectrometer (TWIM-MS) was investigated to test if a common database could be used across IM techniques. A total of 124 substances were measured with both systems and CCS values of [M + H]+ and [M + Na]+ adducts were compared. Deviations <1% were found for most substances, but some compounds show deviations up to 6.2%, which indicate that CCS databases cannot be used without care independently from the instrument type. Additionally, it was found that for several molecules [2M + Na]+ ions were formed during electrospray ionization, whereas a part of them disintegrates to [M + Na]+ ions after passing through the drift tube and before reaching the TOF region, resulting in two signals in their drift spectrum for the [M + Na]+ adduct. Finally, the impact of different LC-IM-MS settings (solvent composition, solvent flow rate, desolvation temperature, and desolvation gas flow rate) were investigated to test whether they have an influence on the CCS values or not. The results showed that these conditions have no significant impact. Only for karbutilate changes in the drift spectrum could be observed with different solvent types and flow rates using the DTIM-MS system, which could be caused by the protonation at different sites in the molecule.

GTI Energy and Air Liquide Advanced Separations (ALaS) have been developing a novel hollow fiber membrane contactor (HFMC) technology for post-combustion CO2 capture. The process combines advantageous features of both absorption and membrane-based separation processes to separate CO2 from flue gas cost-effectively. The key component of the HFMC technology is the super-hydrophobic, porous hollow fiber, which is made from polyether ether ketone (PEEK). Compared to conventional absorption/desorption technologies, the critical advantage of the HFMC process is the high contact surface area provided by the hollow fibers enabling an increased volumetric mass-transfer rate. In the PEEK HFMC process, the specific surface area has been increased by an order of magnitude over structurally packed or trayed columns, resulting in compact systems with small footprints. A pilot-scale demonstration of the HFMC process on coal-fired power plant flue gas has been performed in Wilsonville, AL at the National Carbon Capture Center (NCCC) treating flue gas from pulverized coal-fired Alabama Power’s Gaston Power Station. A 90% CO2 removal rate was achieved by the HFMC using a 50 wt.% aMDEA solvent during the initial tests with 4 modules and actual coal-fired flue gas at NCCC. The stripped stream from the two-stage flash desorber had a CO2 concentration of >98.6 vol%. Further tests indicated an issue of liquid-side concentration polarization – higher CO2 concentration in the fluid boundary layer (next to the fiber) relative to the bulk flow stream. This issue was resolved by decreasing the aMDEA concentration from 50 wt.% to 35 wt.%. Continuous testing with 28 membrane modules, however, did not match the single module results; the CO2 capture performance declined with time. Quantitative analysis as well as inspection and measurements of the spent modules were conducted to investigate the potential causes. The major issue identified was the tubesheet leaking from patch points and potentially from fiber/epoxy separation. Future steps would include: 1) resolving technical hurdles in materials and manufacturing; 2) increasing the inner diameter of the hollow fibers to achieve a low pressure drop (when flue gas flows through the hollow fibers); and 3) consideration of inclusion of multiple membrane cartridges in one housing. Overall, this project has advanced the HFMC technology to a high TRL level and resolved a number of technical issues (e.g. concentration polarization) that other researchers have not dealt with to date. The project results and publications is a significant contribution to the literature and for other technology developers.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of reduced pressure of oil shale retorting. 2. Oil yieldHyun S. Yang and Hong Yong SohnCite this: Ind. Eng. Chem. Process Des. Dev. 1985, 24, 2, 271–273Publication Date (Print):April 1, 1985Publication History Published online1 May 2002Published inissue 1 April 1985https://pubs.acs.org/doi/10.1021/i200029a009https://doi.org/10.1021/i200029a009research-articleACS PublicationsRequest reuse permissionsArticle Views57Altmetric-Citations7LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts

This paper reports the absorption of SO2 in a transversal flow hollow fiber membrane contactor (HFMC) using water at 27 °C. Experimental results show that gas and liquid flow rates can be regulated independently without causing operational failures in the HFMC. High SO2 removal efficiencies could be achieved at water flow rates from 194 and 463 mL min−1, gas flow rates between 8276 and 18073 mL min−1, and the inlet SO2 concentration of 2000 ppm. The SO2 removal efficiency increased with increasing liquid flow rate and decreasing gas flow rate. The overall volumetric gas phase mass transfer coefficient \( (K_{G} a) \) of the HFMC is in the range of \( 10^{ - 3} \;{\text{mol}}\;{\text{s}}^{ - 1} \;{\text{m}}^{ - 3} {\text{Pa}}^{ - 1} \). It is higher than that of conventional wet SO2 scrubbers although water is used in HFMC while effective alkaline absorbents are used in the compared reactors. It indicates that the HFMC is superior in SO2 absorption over conventional absorbers.