Modeling and simulation of CO2 separation from CO2/CH4 gaseous mixture using potassium glycinate, potassium argininate and sodium hydroxide liquid absorbents in the hollow fiber membrane contactor

Abstract

The emission of CO2 greenhouse gas is one of the most momentous causes of environmental problems such as global warming. Hence, the sequestration of CO2 acid gas from gaseous streams is considered as a mandatory process to control the detrimental impressions of CO2 emission. In the present investigation, a mathematical modeling and a two dimensional comprehensive simulation is developed with the aim of evaluating the removal performance of CO2 acid gas from CO2/CH4 gaseous mixture. As the novelty, potassium argininate (PA), potassium glycinate (PG) and sodium hydroxide (NaOH) are used as promising liquid solvents in the hollow fiber membrane contactor (HFMC) and the best absorbing agent for capturing CO2 is introduced. The validation of model predictions is implemented based on the comparison of simulation results of CO2 and experimental data using sodium hydroxide (NaOH) in a wide range of absorbent temperature and liquid velocity. Comparison of experimental data and simulation results for CO2 flux in wide ranges of absorbent (NaOH) temperature and absorbent velocity illustrates excellent agreements with average deviations of less than 4% and 3.7%, respectively. On the basis of simulation results, potassium argininate (PA) shows higher CO2 separation efficiency compared with the other liquid solvents. The order for CO2 separation rate is PA > PG > NaOH. The results imply that increment in the operational parameters such as porosity, module length and liquid absorbents velocity positively affect the separation percentage of CO2 while, increasing in gas velocity, membrane tortuosity and initial concentration of CO2 deteriorate the separation efficiency of CO2, considerably.