Investigation of CO2 absorption in methyldiethanolamine and 2-(1-piperazinyl)-ethylamine using hollow fiber membrane contactors: Part C. Effect of operating variables

• MDEA/PZEA blended solution was firstly investigated in the membrane gas absorption.
• A comprehensive 2D model for CO2 absorption was developed and implemented.
• The effects of operating parameters on the membrane performance were observed.
• 3D concentration distribution of gas and liquid phases was depicted in this model.
• A turbulent and countercurrent flow gave better CO2 absorption performance.

In order to tackle with the gas emissions from power plants, the membrane gas absorption (MGA) technique has been adopted in the present work. A comprehensive steady-state mathematical model for CO2 transport in a hollow fiber membrane contactor (HFMC) has been formulated and the governing differential equations were solved using the software of COMSOL Multiphysics. A blend of MDEA and PZED was first applied to the membrane gas absorption. The simulated predictions were verified and in good agreement with the recent experimental data reported in literature when in the case of non-wetting of membrane pores. The 3D concentration distributions of gas and liquid phases were depicted. In addition, the effects of operating conditions on the membrane performance such as the serial modules, flow directions and conditions, membrane wetting, and operating pressures were carefully investigated and discussed. It was found that in a system with a turbulent and countercurrent flow, serial membrane contactors gave better removal efficiency. Increasing the pressure and decreasing the wetting ratio promoted the CO2 capture process. Moreover, the absorbent which was fed into the tube gave better absorption performance than that in the shell side. Thus, the current objective of this study is to provide guidelines for estimate of the membrane performance and selection of absorbents and operating properties.