A Study on CO2 Absorption in Bubble Column Using DEEA/EEA Mixed Solvent

摘要

Absorption of carbon dioxide in aqueous blends of alkanolamines prepared from renewable resources (DEEA/EEA), which can be produced from green materials, was explored. In addition, the scrubbing factor of CO2-gas in alkaline solution was found to be excellent in a bubble-column, as compared with another scrubber. Thus, a continuous bubble-column scrubber was used in this study. Therefore, a continuous bubble-column scrubber absorbing CO2-gas, using a DEEA/EEA mixed solvent as an absorbent under a pH-stat condition, was used to search for the optimum process parameters by means of Taguchi’s analysis. The process variables included the pH of the solution, gas-flow rate, and concentration of solvent. From measured outlet CO2-gas concentrations, absorption rate, removal efficiency, and overall mass-transfer coefficient could be determined, with the aid of steady-state material balance equation, as well as a two-film model. Additionally, the liquid-flow rate of DEEA /EEA was observed automatically through the action of a pH controller. The data obtained were in the range of 1.26x10-4-11.80x10-4(mol/s-L), 0.0728-0.8395(1/s), and 28-98.66% for absorption rate, mass-transfer rate, and removal efficiency, respectively. According to S/N ratio, the significance sequence influencing the absorption rate was D(pH)>C (gas flow rate)>A(concentration of DEEA)>B(concentration of EEA), while the significance sequence for overall mass-transfer coefficient was A>B>C>D.