Study On The Process Of CO₂ Absorption In Aqueous Ethanolamine Solution In Microchannel

Micro-chemical technology is one of the important directions in the development of chemical industry.As the core of micro-chemical technology,micro-reactor has excellent mass transfer and heat transfer performance.Therefore,micro-reactor has broad application prospects in the chemical and energy fields.However,the research on the gas-liquid two-phase mass transfer process in the microreactor is lacking.In this paper,the combination of on-line measurement technology and unit mass transfer model is used to investigate the effects of gas flow,liquid flow,microchannel geometry,and absorption concentration on bubble length,velocity and mass transfer characteristics under Taylor flow.The experimental systems were CO₂-water,CO₂-MEA aqueous solution,and mixed gas-MEA aqueous solution.For the purely physically absorbed CO₂-water system,the dynamic change of Taylor bubble along the fluid flow direction is studied.According to the bubble cross-sectional shape and the unit mass transfer model,the parameters such as liquid film thickness,gas holdup,bubble volume,specific surface area,and liquid side mass transfer coefficient were calculated.The results show that the length of Taylor bubble decreases first and then stabilizes in the direction of fluid flow,and the experimental results are theoretically analyzed through liquid film leakage flow and liquid bomb internal circulation.Finally,the semi-empirical correlation of the liquid-side volumetric mass transfer coefficient is proposed,which is in good agreement with the experimental values,and the deviation is within±10%,indicating that the correlation is better predictive.For the CO₂-MEA aqueous solution system with rapid chemical reaction,the dynamic change of Taylor bubble along the fluid flow direction was studied.Compared with the purely physically absorbed CO₂-water system,the change in bubble length and velocity was found to be more significant in the CO₂-MEA system.Based on the 43200 data points,the liquid side mass transfer coefficient was fitted,and a good predictive empirical correlation was proposed with a deviation of±10%.Finally,compared with the enhancement factors obtained by the theoretical model and the correlation fitting,the deviations are found to be within±20%and±15%,respectively,and the smaller the enhancement factor,the larger the deviation.For the mixed gas-MEA aqueous solution system with rapid chemical reaction,the dynamic change of Taylor bubble along the fluid flow direction was studied.Compared with the CO₂-MEA system,the change in bubble length and velocity was found to be more significant in the pure CO₂Taylor system.Finally,the effects of gas and liquid two-phase fluid flow and absorption concentration on the removal rate of CO₂ under Taylor flow were investigated.It was found that the removal rate of CO₂ increased with the increase of liquid flow rate and concentration of absorption liquid,and decreased with the increase of gas flow rate.