混合醇胺水溶液 MEA/MDEA 之三成分交互擴散係數之量測研究-根據泰勒分散法

Abstract

The objective of this study was to measure the ternary diffusion coefficients of aqueous blended alkanolamine systems monoethanolamine (MEA) + N-methyldiethanolamine (MDEA) + water using the Taylor dispersion technique for temperatures 30 to 50 oC. The ternary diffusion coefficients are reported for solutions containing the total amine concentrations, 2, 3, and 4 kmol•m-3 for various amine concentration ratio. The corresponding mutual diffusion coefficients of aqueous MEA and aqueous MDEA solutions were also measured. In a Taylor experiment, a delta function of solution is injected into a laminar carrier stream of reference fluid which flows in a long capillary tube. The injected solutes spread out as they flow along the tube. The concentration profiles of dispersed solutes are determined by a differential refractometer. A regression procedure is used to calculate the ternary diffusion coefficients from the refractive index profiles. The main diffusion coefficients (D11 and D22) and the cross coefficients (D12 and D21) are reported as function of temperature and concentration of alkanolamines. The dependence of the diffusion coefficients on the compositions and the temperature were discussed. Based on the theoretical model, the calculations of the main diffusion coefficients (D11 and D22) and the cross coefficients (D12 and D21) from the activity and the partial molar volume of components were also reported. A fairly good result was obtained between the calculated and the measured values of ternary mutual diffusivity.