Can conversion of the process control system data from discontinuous evaporating crystallizers improve the process monitoring?

Optimization of process control and automation of discontinuous (batch) evaporating crystallizers can be improved by integrating the available data. This study combines PCS data with sampling of the massecuite at multiple time steps to develop a balancing scheme calculating massecuite composition as well as the feed syrup, evaporation and crystallization rates. Multiple approaches regarding the crystal content, purity and saturation coefficient are tested, evaluating the importance of adequate input data. Laboratory validation of the scheme’s results indicates that the calculation of conversion rates is driven almost exclusively by PCS data. The description of the massecuite composition requires a more exhaustive effort. Calculated trends of the feed, evaporation and crystallization rates pass a plausibility test within the context of the observed strike. Although more sophisticated testing is required, the balancing scheme appears to be a valuable tool in monitoring processes more comprehensively to improve process control.