K_La Determination Using the Effectiveness-NTU Method: Application to Countercurrent Absorbers in Operation Using Viscous Solvents for VOCs Mass Transfer

Abstract

In this study, the Effectiveness-NTU method, which is usually applied to heat exchanger design, was adapted to gas−liquid countercurrent absorbers to determine the overall mass transfer coefficient, KLa, of the apparatus in operation. It was demonstrated that the ε-NTU method could be used to determine the KLa using the Henry coefficient of the solute to be transferred (HVOC), the gas flow-rate (QG), the liquid flow-rate (QL), the scrubber volume (V), and the effectiveness of the absorber (ε). These measures are calculated from the gaseous concentrations of the solute measured at the absorber inlet (CGin) and outlet (CGout), respectively. The ε-NTU method was validated from literature dedicated to the absorption of volatile organic compounds (VOCs) by heavy solvents. Therefore, this method could be a simple, robust, and reliable tool for the KLa determination of gas−liquid contactors in operation, despite the type of liquid used, i.e., water or viscous solvents.

Keywords

• absorption
• mass transfer
• heat exchanger
• scrubber
• effectiveness-NTU method