P-DCB Crystals
The growth in consumption of polyphenylene sulfide (PPS, an engineering plastic primarily used in electronic component manufacture) has fueled the demand for high-purity para-dichlorobenzene (p-DCB). The smallest amount of impurities in the starting monomer can significantly affect the quality of the final product. Purification can be established by e.g. distillation, however the close boiling points of the main impurities ortho- and meta dichlorobenzene requires a large number of trays
Suspension based melt crystallization is an attractive alternative for purification of isomers like e.g. para-dichlorobenzene (p-DCB). The energy of crystallization for p-DCB is close to a factor 3 lower than the heat of evaporation, facilitating significant energy savings.
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Compared to the batch wise operated static or dynamic layer crystallization, the suspension based melt crystallization process features continuous operation at also significant lower energy consumption. Crystal growth rates are over a factor 1000 lower, ensuring gentle formation of ultra pure crystals.
As a solid liquid separator, GEA Messo P.T. applies washcolumns which can efficiently separate the pure crystals from the mother liquor. In the wash column, the pure crystals are rigorously washed with their own melt, eliminating the use and related recovery of a separate wash liquid. A wash column has low operating speeds which results in a proven long lifetime of the moving parts.