泰勒分散法量測混合醇胺水溶液 DEA/MDEA 之三成分交互擴散係數

Abstract

The ternary diffusion coefficients of aqueous blended alkanolamine systems diethanolamine (DEA) + N-methyldiethanolamine (MDEA) + water using the Taylor dispersion technique for temperatures 30 to 50 oC were measured. The ternary diffusion coefficients were reported for solutions containing the total amine concentrations, 2.5, 3, 3.5, and 4 kmol•m-3 for various amine concentration ratios. The corresponding mutual diffusion coefficients of aqueous DEA 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 were determined by a differential refractometer. A regression procedure was 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) were reported as functions 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 performed. Fairly good results were obtained between the calculated and the measured values of ternary mutual diffusivity.