High-efficiency water vapor absorption by tri-ethylene glycol combined with methyldiethanolamine

Abstract

• MDEA combined with TEG to improve water vapor absorption. • Effects of gas/liquid flow rates and MDEA concentration were studied. • The effect of MDEA concentration on foaming of solution was investigated. • MDEA had no significant effect on foaming in the experimental condition. • Solution of 10 vol% MDEA and 90 vol% TEG has the highest water vapor absorption. This study investigated methyldiethanolamine (MDEA) effects on gas dehydration using tri-ethylene glycol (TEG) solution in a packed tower. The gas phase has entered the bottom of the contact tower, and it contacted the TEG to separate the moisture after passing through a humidifying tower. The key parameters were the concentration of MDEA in TEG solution, the concentration of water in the solution, and the gas and liquid flow rates. The results revealed that existence of MDEA in the dehydration process did not decrease the absorption efficiency and it even slightly increased the absorption performance of water vapor at some concentrations. The results also showed that increasing the liquid flow rate has a little effect on the absorption efficiency which can be due to the very high solubility of water vapor in TEG. However, the gas flow rate increase reduced the absorption efficiency, which showed that the main mass transfer resistance was in the gas phase. Also, the presence of 5 vol% water in the absorbent solution reduces the water vapor absorption efficiency by approximately 20%. Finally, the effect of MDEA concentration on foaming of solution was investigated, and it was shown that the presence of MDEA had no significant effect on foaming in the experimental condition.