New Process Control During The Crystal Growth: Real Time Image Analysis, Comparison of Strikes, Communication With Plant PLC/DCS and Cost Savings

This article describes how a batch pan microscope using image analysis 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®.

Figure 2. Four Crystobserver® installed in Japan, Hokuren group instead of old analogue cameras
Figure 3. Interface 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 % 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, % of fines, number of crystal, 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.

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.

New instrument using image processing techniques:
Non conformities on-line analyzer, the Spotobserver®

Using a very high resolution sensor and a reliable LED lighting system ATEX certified, the analyzer Spotobserver® performs an accurate acquisition and highly sophisticated image treatment in real time. The Spotobserver® detects black spots sizing from 250 μm x 250 μm and above on dry sugar surface. Even in the cases where the images cover the entire flow of sugar over the full width of the conveyor, the system is still based on a sampling analysis as the particles hidden under the surface are not seen.

The system also counts and sorts the black spots according to configurable distribution classes. It triggers alarms on the number of detections and /or on their size, with possible statistical calculations over a predefined period.

The alarm can be used to divert the off-spec and avoid contaminating the final product. The main display shows the video of the sugar surface in real time and the image of the last detection or any image chosen on manual request.

100% of the data and alarms are stored for a complete traceability of the production issues. Overall sugar quality is improved.

Third SpotObserver® purchased by TEREOS, France SpotObserver®

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in the Sugar Industry since 1990
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