38 years ago the first Neltec ColourQ instrument was installed on a vibrating conveyor in the Assens, Denmark, sugar factory. 
First ColourQ version in Assens, Denmark Soon, calibrations were developed to present the real-time measurements in ICUMSA® solution colour units – even if the instrument does not need to touch or dissolve the crystals. Many factories have installed and done extensive instrument testing with satisfactory results. For example, a refinery concluded the instrument did not add any error when compared with lab determination of ICUMSA® solution colour. An extensive test by ICUMSA® in two beet sugar factories confirmed that Neltec’s ColourQ reading had the same validity as the laboratory determination by the ICUMSA® solution colour method.
During the ICUMSA® test, Neltec developed a set of General Guidelines for Validation of Indirect Measuring Techniques. These General Guidelines (available from Neltec) were approved at the ICUMSA® meeting in Warsaw in2016.
New version of the instrument – ColourQ 2200
Since the original version of the instrument was developed, electronics have got much more compact. 
ColourQ 2200 in Aarberg, SwitzerlandNeltec has taken advantage of this in the newer version of the instrument which has all the benefits and accuracy of the first version but is much smaller. In addition, as standard, the instrument now comes with an enclosure, so the cleaning frequency can be reduced.
Due to the excellent accuracy, many factories now use the instrument to control crystal washing time automatically. With this option, the instrument can reduce the amount of water to what is strictly necessary and, at the same time, send an alert if the water consumption gets too high. Furthermore, in a battery of uniform centrifugals, the system will also issue warnings if one or more require significantly more water than the best. Again, this can alert the operator to investigate what causes the higher water need.
Improved separation in continuous centrifugals
Continuous centrifugals are used for massecuites with difficult purging of the mother liquor. Neltec has developed a special version of its colorimeter for use in continuous centrifugals, the ColourQ 1700 CC. When this was first applied, the surprise was how significant the massecuite variations really are. The colour of the crystals leaving the basket can vary by a factor of 3 within 24 hours, even in factories with a uniform continuous crystallization. In a few minutes, the colour often varies by 30%. An operator with many centrifugals to follow has no chance of following these rapid changes and correcting the settings. Sometimes too much ash and colorants go with the crystals back in the process, and at other times too much sucrose is dissolved from the crystals.
Using ColourQ 1700 CC (see start picture: ColourQ 1700 CC instrument on continuous centrifugal) makes it possible to separate difficult massecuites you normally cannot separate in a continuous centrifugal. For easy massecuites, usually separated in batch centrifugals, you now can separate them in a well-controlled manner in continuous machines, too.
Improved separation in discontinuous centrifugals
In batch centrifugals, too, the variation in the massecuite properties makes it difficult to keep the centrifugal settings at optimum. The mother liquor purges fast from massecuite with a small number of fines. Then the space between the crystals is open, and the strong G-factor forces air through the crystal wall. This dries the remaining film of mother liquor on the crystals, making the film difficult to remove when the water is applied. At the other extreme, with many fines, the purging takes much longer and leaves much mother liquor at the time the wash is applied. As a result, the water gets mixed with mother liquor and is therefore less efficient for cleaning the crystals. 
PurgeQ 1200 with transducer and signal conditioning unit
The Neltec PurgeQ 1200 instrument helps the operator determine when the wash should be more efficiently applied. Further, it tells when the high purity run-off leaves the basket. In this way, the valve switching from low to high purity run-off can be controlled. Finally, the instrument can tell when the run-off has been purged, so the spinning can be stopped (and valuable cycle time saved).
Controlling cooling crystallization to get lower CV
Neltec has developed an instrument for the early detection of fines during cooling crystallization. With this information, it is possible to not only monitor but also control the cooling in a way, so the number of fines is reduced, even when the standard liquor varies. For factories producing seed slurry for seeding the production crystallizers, this opens for improving the product CV.
Author: Bjarne Nielsen, Neltec Denmark A/S, Vestergade 35, 6500 Vojens, Denmark; mail@neltec.dk
