A Study On Fundamental Issues Of Carbon Dioxide Absorption Using Mixed TETA-MDEA Aqueous Solution

Aqueous solution of N-methyldiethanolamine (MDEA) has been extensively used to remove H2S from natural gas, however there is exsiting a problem of slower absorption rate when it was used to remove CO₂ from natural gas and other gases. An effective way to solve this problem is to add some activators into the aqueous solution of MDEA. Previous study concluded that a TETA-MDEA-H₂O mixed amine solution could overcome the problem and the solution also can provide advantages of large CO₂ loading, low desorption energy and others. However, there is not any information on desorption kinetics of CO₂ from the TETA-MDEA -H2O solution and the influence of impurities possibly existing in the solution on its CO₂ absorption and desorption performance so far Therefore a study on fundamental issues of carbon dioxide absorption using mixed TETA-MDEA -H2O solution has been conducted in this paper, and it may provide a technical support for design and optimal operation of industrical CO₂ absorption processes.CO₂ desorption rates from the mixed TETA-MDEA aqueous solutions with three different compositions were measured using a dynamic method. Based on the desorption mechanism and experimental data, a simplified CO₂ desorption rate equation was developed. Average relative error between the predicted and experimental CO₂ desorption rates is less than 10%, and the equation can provide useful information for design and optimal operation of commercial regeneration units with the mixed TETA-MDEA aqueous solution.Influence of impurities possibly existing in aqueous solution TETA-MDEA on its CO₂ absorption and desorption performance , foaming and foam-breaking performances of TETA-MDEA desorption solution were also experimentally studied in this paper, the impurities including solid particle, inorganic salts and organic compounds. The results can provide useful information for commercial applications of the TETA-MDEA solution.