High Purity Separation of Eutectic Mixtures in a Continuous Moving Crystal Bed Column Crystallization

Abstract

This paper presents new experimental results on the separation of an o -dichlorobenzene/ p -dichlorobenzene mixture in a continuous moving crystal bed crystallization column under the top-fed operation mode. Local concentration distributions of the binary eutectic mixture were investigated as a function of the feed composition, reflux ratio, crystal bed height, and internal stirring speed. It is demonstrated that the key factor that is decisive to the separation capability of column crystallization is the reflux ratio. The experiments showed that product purities can easily exceed 99.0% over a wide range of feed compositions, 68–94 wt%, reflux ratios, 1.0–4.7, and crystal bed heights, 200–900 mm within a column of 50 cm i.d.