The largest beet sugar provider in the United States was able to use a custom thermowell to more accurately measure temperatures and increase the efficiency of its sugar molasses production. American Crystal Sugar Co., Moorhead, Minn., selected the Worm flexible temperature sensor manufactured by Moore Industries, North Hills, Calif., to handle the sticky situation.
During the final steps of production of beet sugar, a mixture of sugar crystal and syrup called massecuite is centrifugally spun in a perforated cylindrical basket. This separates the molasses syrup and any non-sugar elements from the sugar. American Crystal was having difficulty accurately measuring the temperature of the molasses using a standard thermowell with a rigid sensor.
American Crystal cited two reasons for the difficulty with obtaining an accurate temperature measurement.
- With a standard thermowell and rigid sensor, only the tip of the thermowell could be inserted into the molasses, which runs about 1.5" deep at the bottom of a horizontal pipe. A large amount of steam from the molasses surrounded the thermowell, reducing its responsiveness to changes in temperature.
- The steam essentially acted as a conductor that heated the rigid stainless steel sensor inside of the thermowell. This meant that the thermowell was measuring the steam temperature rather than the molasses temperature.
American Crystal was able to solve the problem using the custom thermowell with a flexible temperature sensor inserted into it. The end of the thermowell is bent at an angle, allowing the 1" long flexible sensor to lie directly in the molasses. A spring keeps the Moore sensor firmly in place inside the thermowell.
The custom thermowell eliminated the problem of the steam temperature influencing the temperature readings. This meant more accurate readings were obtained that allowed American Crystal Sugar to respond quickly to changes in temperature. For American Crystal, this has translated to more precise control of the water and steam used in the centrifuge and the ability to separate more sugar from the molasses.
A full case study, “Measuring Molasses with a WORM,” is available online.