二氧化碳在双极膜电渗析系统中溶解吸收过程的研究

在二氧化碳捕集、利用和封存（CCUS）技术中,海水固碳技术绿色环保、安全可靠,具有很好的发展前景。其中,双极膜电渗析法海水固碳技术的关键之处在于二氧化碳在系统中的溶解吸收。考察了结晶器中添加晶种、通气体系成分、模拟烟道气流量、双极膜电渗析装置的电流密度对海水固碳过程中二氧化碳溶解吸收效果的影响,结果表明：系统外加晶种、模拟烟道气作为通气体系时更有利于二氧化碳在双极膜电渗析系统中的溶解吸收,促进碳酸钙生成。在上述基础上,随着模拟烟道气流量的增加,二氧化碳的比吸收速率降低,二氧化碳在溶液中大部分转化成碳酸氢根,碳酸根和碳酸钙的生成速率则会降低;随着电渗析装置电流密度的提高,碳酸氢根、碳酸根和碳酸钙的生成速率均会随之提高。该研究为酸性气体在双极膜电渗析系统中溶解吸收和矿化利用提供了指导。

Study on process of CO2 dissolution and absorption in bipolar membrane electrodialysis system

Seawater carbon sequestration technology is considered as a green,environmental-friendly,safe and reliable technology among CO₂ capture,utilization and storage（CCUS） technologies,which has good development prospects.The key of seawater carbon sequestration technology is the dissolution and absorption of CO₂ in the bipolar membrane electrodialysis system.The influence of seeding in the crystallizer,the composition of the ventilation system,the simulated flue gas flow and the current density of the bipolar membrane electrodialysis device on the CO₂ dissolution and absorption effect was investigated.It was found that the external crystal seeds and the simulated flue gas was beneficial to the dissolution and absorption of CO₂ in the bipolar membrane electrodialysis system,promoting production of CaCO₃.Based on the above,with the increase of simulated flue gas flow,the specific absorption rate of CO₂ was decreased,and most of CO₂ in the solution was converted into HCO₃^-,while the generation rate of CO₃^2- and CaCO₃ would be reduced.With the increase of current density in electrodialysis unit,the generation rate of HCO₃^-,CO₃^2- and CaCO₃ was increased accordingly.This study provided a guidance for the application of acid gas in dissolution,absorption and mineralization in bipolar membrane electrodialysis system.