CHEM designs and manufactures Evaporative Forced Circulation Crystallizers, which are also known as Circulating Magma Crystallizers or Mixed Suspension-Mixed Product Removal Crystallizers.

Where high rates of evaporation are required, where there are scaling compounds, where crystallization is achieved in inverted solubility solutions, or for relatively high viscosity solutions, the forced circulation crystallizer is the best choice. Its most frequent use in the continuous processing of such materials as sodium chloride, sodium sulphate, sodium carbonate monohydrate, citric acid, monosodium glutamate, urea and other similar crystalline products.

The system comprises of a crystallizer vessel and an external pumped circulation loop which usually includes a heat exchanger. The liquor inside the system is maintained in homogenous suspension to ensure a good crystal growth. Supersaturation of materials having scaling and salting tendencies is controlled by the design of the circulation rate, so that a very small temperature rise across the heat exchanger is produced. The temperature difference between the steam and liquor is correlated to prevent boiling within the tubes or in the tube boundary layer. After the recirculation and distribution of heated liquor on the surface, boiling takes place in the crystallizer vapour head. This ensures soft boiling thus minimizing the chances of wall scaling or salting.