CO2 Capture Using Monoethanolamine in a Bubble-Column Scrubber

A continuous bubble-column scrubber, capturing CO2 gas by monoethanolamine (MEA) solution in a pH-stat operation, is used to search for optimum process parameters by means of the Taguchi method. The process variables are the pH of the solution, gas flow rate, concentration of CO2 gas, and temperature. From the measured outlet CO2 gas concentrations, the absorption rate and overall mass transfer coefficient can be determined with the support of a steady-state material balance equation as well as a two-film model. According to the signal-to-noise ratio, the significance sequence influencing the parameters and optimum conditions can be determined. CO2 concentration and pH value proved to be decisive parameters, while temperature and gas flow rate were minor. Five sets of optimum conditions were obtained and could be further verified by empirical equations.