Removal Of Acid Gases (H₂S, CO₂) And Its Characteristics Of Gas-liquid Mass Transfer

There are most familiar acidic gases of H₂S and CO₂ in industrial gas mixtures and off-gases. Acidic gas H2S is mainly from gas mixtures in natural gas processing, hydrogen purification, refinery off-gases treating and synthesis gas for ammonia and methanol manufacturing. Impurities H₂S must be removed from the gas mixtures to meet the requirements of sequential processing or environmental regulation. CO₂ is one of primarily greenhouse gases. CO₂ recycle from industrial off-gases can availably control and diminish greenhouse effect. The technology of absorption of acidic gases into aqueous solutions of alkanolamines has been one of preferred approaches in current various technologies. This work mainly dealt with removal of acidic gases of H₂S and CO₂ and development of high performance complex solutions. Based on gas-liquid mass-transfer theory and different property of gas mixtures contained acidic gases, the processes and characteristics of mass transfer of acidic gases were investigated in packed columns and membrane contactors. This work focused on two sections: 1) selective absorption of H₂S from gas mixtures contained CO₂ into aqueous solutions of blended amines of MDEA-TBEE in a packed column. 2) development of high performance complex solutions including MDEA-based and amino-acid-based complex solutions; mass-transfer enhancement of the complex solutions on absorption of CO₂ in a membrane contactor; effect of the complex solutions on hydrophobic polypropylene (PP) membrane configuration; and characterization of the mass-transfer enhancement and the effect of membrane configuration by mathematic models.High selectivity of blended solutions can bring on decrease of energy consumption and increase of purity of gas products which come from regeneration of blended solutions. So, there is an especial significance in the case of energy sources shortage and huge energy consumption nowadays. Based on reaction mechanism of alkanolamines with acid gases in this work, selective absorption of H₂S from mixed-gas streams into the aqueous solution of blended amines of MDEA-TBEE has been studied using a static and a dynamic evaluation setup, respectively. TBEE, a severe sterically hindered amine, was added into MDEA to form the blended amines. The acidic gases absorption performance into the aqueous solution of blended amines of MDEA-TBEE was compared with that of single amine of MDEA. A variety of effect factors on the performance were investigated by means of evaluation indexes of removal efficiency and selectivity factor. Based on the mass balance, overall mass transfer coefficient, K_Ga was determinated. An approximate model for mass...