Batch crystalliser for prodn. of large crystals - with the soln. in vertical tubes externally cooled

摘要

A crystalliser has a nest of vertical tubes fixed between tube plates in a shell, which can be closed at the base. Soln. to be crystallised is filled into the interior of the tubes, and coolant applied outside the tubes. Agglomerates of crystals form within the tubes; at the end of a batch residual mother liquor is allowed to run out and the crystal agglomerates are freed from the tube walls by passing warm water outside of the tubes. The agglomerates are broken up by a breaker in the base of the vessel and discharged as a mass of individual crystals. The crystalliser is used for the prodn. of large needle- or rod-shaped crystals, partic, of the optically active Menthols. Large crystals are normally grown in batch agitated cooled vessels, and compared with these the device described offers uniformity of control of heat removal, small labour requirement, no breakdown to fine crystals such as is caused by agitation or pumping.