pH Measurement in Sugar Refining

Processed sugar is refined from raw sugar cane juice in a multi-step process. First, pH is used to control the addition of lime slurry to maintain a high pH level, necessary for neutralizing natural acids and precipitating dissolved organics. Next, pH is used to regulate the addition of carbon dioxide feed that removes calcium from the stream and prevents scaling downstream. Finally, pH is used to control the addition of sulfur dioxide, which in addition to acting as a biocide, lowers the pH in the purified juice to values necessary for crystallization of sugar. Solids from the lime slurry and precipitation steps can coat the pH sensor's reference junction and pH glass, causing erratic readings and a shorter sensor life. The Rosemount™ 396P pH sensor with shrouded tip or flat glass option resists the effects of coating to provide an accurate pH measurement. A retractable sensor is also available for easy cleaning and replacement.