Insights into a membrane contactor based demonstration unit for CO2 capture

Abstract

A continuously operated CO2 capture unit, based on absorption in a membrane contactor and lowtemperature vacuum desorption, is demonstrated. The major advantage of membrane contactors is their high specific interfacial area per unit volume. The unit is designed to be modular to allow different absorption membrane modules and stripping units to be tested, with the aim of capturing CO2 from simulated flue gases at concentrations down to the ambient concentration. In addition, desorption can be performed under vacuum to improve the desorption efficiency. The experimental unit incorporates comprehensive measurements and a high level of automation, with heat integration and continuous measurement of electricity consumption providing real-time estimates of the energy consumed in the capture process.In preliminary tests, the results of which are described herein, a 3M Liqui-Cel™ polypropylene hollow-fiber membrane module and a glass vacuum chamber were used for absorption and desorption, respectively, along with a potassium glycinate amino acid salt absorbent solution. This solution has high surface tension and is fully compatible with the polypropylene membrane unit used. In preliminary tests, the highest observed CO2 flux was 0.82 mol m -2 h -1 , with a CO2 product purity of above 80%. The calculated overall mass transfer coefficient was comparable to reference systems. The performance of the unit in its current setup was found to be limited by the desorption efficiency. Due to the low desorption rates, the measured specific energy consumption was exceedingly high, at 4.6 MJ/mol CO2 (29.0 MWh/t) and 0.8 MJ/mol CO2 (5.0 MWh/t) of heat and electricity, respectively. Higher desorption temperatures and lower vacuum pressures enhanced the desorption efficiency and reduced the specific energy consumption. The energy efficiency could be improved via several methods in the future, e.g., by applying ultrasound radiation or by replacing the current vacuum chamber stripping unit with a membrane module or some other type of desorption unit.

Gas-liquid membrane contactors for carbon dioxide separation: A review

“…For example, Accurel ® and 3M Liqui-Cel ® are both commercial modules made from PP hollow fibres that have been used for over 20 years for dissolved gas control [85,[121][122][123][124][125]. More recently, postcombustion CO2 separation applications have been developed with Liqui-Cel ® membranes, focussing on the solvent composition, membrane process designs, or membrane surface modifications [126][127][128][129]. However, PP and PE membranes can be chemically degraded during long-term operation in contact with an amine-based solvent [22,130].…”

Real-Time Fault Detection and Diagnosis of CaCO3 Reactive Crystallization Process by Electrical Resistance Tomography Measurements

“…Hydrogen carbonate formation occurs immediately after carbon dioxide dissolution (Equation (2)); hence, the aqueous form of the CO 2 is instantaneously consumed in the solution. Detailed descriptions of the membrane contactor system for the CO 2 capture unit and its integration with a calcium carbonate crystallization process are given in [33,34], respectively.…”

Hollow Fiber Membrane Contactors in CO2 Desorption: A Review

“…The improvement and promotion of carbon capture technologies are required to reduce the globally rising CO2 emissions, which is one of the most harmful gases associated with global warming and other negative climatic effects. 1 Common strategies rely on carbon capture and sequestration (CCS), which is focused on long-term underground CO2 storage in aquifers or other geological formations, 2 and carbon capture and utilization (CCU), which produces products with a high value added, such as chemicals or fuels, from CO2. 3 These are widely considered for mitigating the ongoing rise in levels of atmospheric CO2 attributed to increasing industrial demands of fossil fuel sources due to the increase in population and economic growth.…”