Reducing the rate of scaling in evaporators in the sugar making factories using anti-scalants

Abstract

This research project was aimed at lowering the rate of scaling in the evaporators in the sugar manufacturing industries particulary SCOUL using anti-scalants. The significance of this research was to create a basis for the use of anti-scalants in inhibiting the scaling ions in the clarified cane juice. This was to lower the concentrations of the scaling ions particulary Ca 2+ and Mg 2+ present in the cane juice to undetectable limits which would greatly lower the rate of scale formation in the evaporators. This would help reduce the maintenance costs incurred by companies during clean-up of evaporators to remove the scales and it would also provide the company with more time to utilize for production since the clean-up sessions would be reduced as well. This analysis was limited to testing the removal of Calcium and Magnesium ions from the clarified cane juice using two anti-scalants of EDTA and polyacrylic acid. The clarified cane juice was sampled from the clarifier and the scale samples were obtained from the evaporators after a clean-up session. These samples were prepared and analysis was carried out on them to determine their composition. The scale inhibitors were purchased from Ramed Chemicals Limited in Kampala. The cation and anion compositions of the clarified cane juice and scale samples were identical and found to be Ca 2+ , Mg 2+ , SO 4 2- , PO 4 3- , C 2 O 4 2- , CO 3 2- , NO 3 2- . When the clarified cane juice was treated with EDTA, the Mg 2+ ions were completely inhibited but the Ca 2+ ions were not inhibited by the EDTA. When the clarified cane juice was treated with polyacrylic acid, the Mg 2+ ions were inhibited to some extent and the Ca 2+ ions were inhibited completely by polyacrylic acid. When the clarified cane juice was treated with a combination of EDTA and polyacrylic acid, both Mg 2+ and Ca 2+ ions were inhibited beyond detectable limits. In conclusion, the combination of EDTA and polyacrylic acid was effective in inhibing the scaling ions Ca 2+ and Mg 2+ .