New technology for process control during the Crystal Growth Acquisition from 4K Video Monitoring and Image treatment

This article describes how a batch pan microscope using image processing can play an important role at different stages of the process.

Image processing techniques are widely applied in many sugar factories trying to optimize their massecuite production. Smart pan microscopes are now being used in factories in Europe and worldwide. How does the Crystobserver® help sugar plants to monitor the boiling phase? To what extent does video monitoring assist the operator to check syrup quality? What relevant information do the operators get at seeding and graining phase? And how do they use them to improve quality and efficiency?

The article describes the different information given by image processing. Aim of this work is to highlight the advantages that real time acquisition and 4K video monitoring bring every day to sugar factories. The data presented below are from customers’ experiments showing the significant results achieved using on-line Crystobserver®.

The Crystobserver® is mounted directly on a flange welded onto the pan wall. A controlled LED light source backlights the crystals moving inside the pan.

Very sharp images of the crystals are continuously sent to a computer in control room where dedicated software applies specific algorithms to each image and calculates, among other parameters, the Coefficient of Variation (CV), the Mean Aperture (MA) of the crystals and the number of fines in Real-Time. Adjustable thresholds on different variables are used to detect and trigger alarms on non conformities such as: presence of contaminants, creation of false crystals, bad crystal size at a given time, etc…

The statistical data (CV, MA, number of fines, etc…) provide the operator with useful information at different steps along the process. It allows for an accurate characterization of the different parameters influencing the process and for the set up of recipes to stabilize the crystal growth and produce homogeneous crystals with the correct predefined size.

We have summarized some key uses of our device that gives an insight into the benefits obtained for driving a vacuum batch pan, example for 2 cases. For further details, please contact support@dnstechno.com

In a sugar plant where seeding is manually made, on a customer request, the software has been modified to suggest the best cycle during cooking cycles comparisons. This “golden strike” will be a valuable and useful example for the operator.

The lines in red on the graphs are the references for the MA, CV and % of fines.

Many Crystobserver users set fines size < 50 µm, the size is defined by the user.
Fines detection only starts 10 minutes after graining to make sure seeds are not considered. When fines are detected, some operators quickly modify the pan parameters to remelt these new nucleations. They can observe it directly on time thanks to 4K cameras.

In the example below we can observe a strike where the fines have been remelted by water injection (third image from the right)

To conclude, the Crystobserver® is a useful tool for grasping and understanding how the process parameters impact the massecuite production. It helps the operators to control better those parameters in a timely manner, to stabilize their production and enhance the massecuite quality.
Thanks to years of cooperation with faithful customers, we keep on developing digital image processing techniques to enhance the Crystobserver® performances and abilities.
Digital Image Processing techniques have already contributed to a significant step forward in the understanding of the crystallization process and future advances will undoubtedly bring more benefits to the sugar industry.