Sugar factory cases - using the ColourQ
"Centrifugals throughput increased by more than 4% "
"To safely increase the centrifugal filling without risking production of out-of-specification sugar and avoiding excessive water consumption, online and real-time colour information is essential"
"Detection of one centrifugal-overfill with massecuite going to the drier more than pays for the instrument"
(ACS, Hillsboro, USA)
“Payback period measured in weeks instead of years”
(SLS, Marseille, França)
Optimisation in Refinarias de Açucar Reunidas, Portugal
During over 12 years of operation at the Refinarias de Açucar Reunidas, the on-line ColourQ instrument has proved to be an invaluable tool for reducing refining costs. It is reliable, maintenance costs are low and the instrument itself requires little attention. Payback time is quick, even for a refinery with a small capacity - the total cost of the equipment is a small percentage of the savings achieved. Apart from allowing fast optimisation of centrifugals, the ColourQ has been helpful for detecting problems with spray-bar ejectors, basket screen blockages and crystallisation problems. Modelling the refining process showed that savings in the pans and centrifugals account for approximately 75% of total savings, recovery 20% and the remaining process 5%. An increase of 1 IU in average sugar colour has the following benefits: a 0.5% reduction in massecuite volume to the centrifugals, 0.4% less sucrose in the molasses, and a 3% reduction in the amount of recycled sugar (from recovery). This also means there is a potential to increase refining capacity, depending on the refinery bottleneck.
Chorão, J. M., (2012). A refiner´s experience of on-line colour measurement. International Sugar Journal, 114, (1367), 804-809.
Optimisation in Harwood Mill, Australia
Manildra Harwood Sugars has installed Neltec ColourQ instruments in both the mill and refinery of the company´s combined facilities on Harwood Island, Australia. An article about the mill instrument has described how reductions in the amount of wash water reduced sugar melting in the centrifugals and increased pan yields (King, 2009*). The amount of massecuite required to produce 100 tons of crystals fell from 200 tons to 195 tons. The reduced melting of crystals reduced the purity of the runoff. This reduced purity was maintained all the way through the next steps in the process, leading to better molasses exhaustion. The molasses purity was reduced from 44 to 41º. In addiction, the uniform quality of sugar from the mill reduced the colour load on the refinery and allowed a higher throughput in the decolourisation plant. The mill staff also found a way to infer the raw sugar pol from the measurements, thus getting real-time results for both pol and colour.
King. S. Marron M. (2009). Proceedings of the Australian Society of Sugar Cane Technologists, Vol 31.
Optimisation in the Aarberg Factory, Switzerland
In 2005 Aarberg sugar factory had been using a Neltec ColourQ instrument for years and applied it to adjust the centrifugals so they provided good, uniform performance. However, close examination of the results revealed that the colour of the sugar produced was lower than the target (19 IU). The overachievement was just one or two IU, but calculations showed that large savings could be achieved from further optimization through automatic control of the wash water. After implementing a control system the expected results were realized. Large energy savings were obtained and more than 4 % of the sugar house capacity was freed to produce more sugar. The resulting stability of the production is illustrated by the tiny standard deviation (SD, just 1.03 IU) relative to the centrifugal batch colour target of 19 IU, calculated for all 45586 batches produced during November 2005 (Nielsen, 2008). The figure below shows the colour, charge by charge, of the sugar leaving the centrifugals during a very stable period, from 15:00 on 11-11-2005 to 06:00 on 14-11-2005. During these 63 hours the SD relative to the target was 0.32 IU, and 95% of all charges had colour within + or - 1 IU of the target. The graph shows that the instrument provides better than 0.1 IU precision.
Diringer, T. and Nielsen, B. (2012). Collecting and using accurate real-time process information to troubleshoot and prevent problems in the sugar factory. Association Van Hook Symposium, Reins, France.