Computational study of fluid dynamics in ACEP

A practical method was devised to predict quantitatively macroscopic backmixing effects on the separation efficiency in a multistage separation process by utilizing a packed column. In this method, the variance based on the statistical variance method was utilized. During steady operation, the variance B arising from macroscopic backmixing within the extra-column lines and equipment can be treated in a similar manner for the separation power as the variance M related to microscopic distribution. Thus, the macroscopic backmixing term I derived from the variance B can be treated like the height of separation unit H derived from the variance M. In equipment design, according to this method, macroscopic backmixing effects on separation efficiency can be quantitatively evaluated by flow patterns obtained through computational analysis of fluid dynamics. Three-dimensional flow in a selector valve, which has a stagnant region as clearance for the rotary motion, was computed by direct integration of the incompressible Navier-Stokes equations using the finite-difference method. The dependency of flow patterns, and the variance of the output signal as a response to delta-function tracer input signal on the channel configuration in the selector valve, were investigated. Also, this dependency was experimentally measured, and the computational results successfully corresponded to the experimental data. It was found that the computational analysis of fluid dynamics can be utilized in the equipment design for the separation process. (author)