I have experience in industrial scale sugar crystallization. Agglomeration (formation of conglomerates) in the vacuum pans is a basic problem, too. The main causes of conglomeration are: high supersaturation and bad massecuite circulation in the pan. If solubility of the dissolved material increases with increasing temperature (like in the case of sugar), supersaturation will be decreased and it will reduce conglomeration. There is no single instrument to monitor supersaturation on-line, it can only be calculated. The SeedMaster Instruments manufactured by K-PATENT Oy, Finland are able to provide on-line data on it to be used for the advanced automatic control of sugar crystallization.
Thank you for your input and I understand from your answer that it can be controlled by heat cool technique or slow cooling of supersaturated solution.