pH Measurement in Sugar Refineries

BACKGROUND

About 60 – 70% of sugar comes from sugar cane and 20 – 30% comes from beets. In order to extract sugar from raw sugar canes and from beets, a sugar refining process must take place. However, this process involves multiple steps, many which rely heavily on pH control to ensure the final product is quality processed sugar.

 

The production of sugar is separated into three processes: 1) sugar beet processing, 2) sugar cane processing, and 3) raw sugar refining. Some general steps include: harvesting, cleansing, extraction, purification/clarifying, evaporation, crystallization, refinery, and packaging. Throughout these steps, pH control is a critical part in making sure the sugar is processed correctly.

 

When the sugar is harvested, it must be cleaned to ensure that no soil, bugs, or any other unwanted chemicals contaminate the sugar. Slightly acidic solution is used to wash sugar canes; this cleans the sugar canes while not causing any damage to them. Because the washing and sorting step of the sugar process is important, keeping the pH at the right level is essential to helping provide pure sugar.

 

During the clarifying portion of sugar production, lime (Calcium Oxide) is used to manipulate acid and base levels of pH. Liming, also known as milk of lime—which is suspended particles in water—raises the pH of solutions. This part of the sugar process is significantly important because the quality of the sugar is directly affected by the pH level. By using lime to adjust the pH levels, multiple things can be prevented: lime will neutralize acids in sugar cane and beets which will prevent starch from forming, turn organic acids into removable salts, and keep other particles suspended which will make for an easy filtration and removal. The filtration happens during the carbonation process.

 

During this step in the sugar process, any lime that was used on the sugar cane and/or beet must be removed. If not properly removed, scale buildup may occur during the succeeding steps. Adding carbon dioxide to the mixture will cause the lime to become limestone (calcium carbonate) through precipitation. Carbon dioxide also helps with catching impurities during precipitation. It is beneficial to add carbon dioxide at every few steps to avoid precipitation that may occur. Along with carbon dioxide, pH should also be measured during several steps of the sugar refining process.

 

After the sugar cane or beets have been washed, it is pressed to extract the juice. Sugar is made through the sulphitation process. Also, the color of sugar is one of its most important aspects. The sulfitation process makes sure the sugar has the pure white color many markets demand and customers expect. To intensify the flavor and texture of sugar, sulfur dioxide is added. The sulfur dioxide lowers the pH level of sugar to about five or six. By doing this, sugar crystals are prevented from sticking together which is caused by having too much moisture.

 

However, the sulphitation process creates a very acidic environment for the sugar cane and beet juice. To control the acidity, milk of lime is used to change the pH value by raising it a few pH levels. Using milk of lime however can cause problems for electrodes if the electrodes are not regularly washed. Sensorex can provide the right products for sugar refinery applications such as the S8000 Flat Surface pH sensor platform.

 

The new S8000 Next Generation flat surface self-cleaning modular pH and ORP platform is an excellent choice for the multiple processes in sugar refineries where pH measurement is critical. 

 

The S8000 platform features a multi-use pH sensor: the S8000CD. The sensor features an enhanced double junction ERP reference system combined with our high temperature polymer gels to provide a dependable service life in difficult as well as light duty applications. The modular concept allows users to configure and re-configure the system for use in both in-line and submersion applications. Optional electronic modules enhance the versatility of the measurement system.

 

Sensorex’s S8000 modular pH system offers solutions to a wide variety of pH measurement applications. The S8000CD modular flexibility allows the same sensor to be mounted in-line or submersion along with the option of with or without temperature compensation. There is a choice of optional unity gain or differential amplification when mounting the sensor, and even an option of a 4 – 20mA output. 

 

The S8000CD flat surface pH electrode is based on a modular concept design to save you time and money. It can be tailored to meet your application’s specific needs. Save money by only paying for the features that your application requires.