Thesis for the Degree of Master of Science


Year 2002
Marko Forsell

Instrumentation audit of sugar manufacturing process

In this thesis the generally used measurement techniques in sugar plants are explored. Also, the physical and chemical properties of sugars and polyols are studied. The unit processes of sugar manufacture are introduced. The objective of this thesis is to build a comprehensive discourse about the measurement techniques and why these techniques can be utilized in sugar plants. The chemical phenomena that occur in the processes can be understood on the basis of the properties of the components.

The literature part of the thesis reviews the characteristic properties of saccharose, glucose, fructose, xylose, xylitol and lactitol. The chemical background of the chromatographic separation, the evaporation crystallation and the hydrogenation as unit processes of sugar manufacture are examined. Refractometry, polarimetry, pH, density, conductivity, mass flow and volume flow measurement are introduced here. Of infrared applications, FTIR, NIR and Raman spectrocopies are studied in more detail.

In the applied part of the thesis, refractometers, a density meter and a radioactive density gauge were tested. The tests were carried out in the chromatographic separation pilot plant in Kantvik (Finland) and in the xylose production plant in the crystallation process in Lenzing (Austria). In the separation pilot plant, the meters were tested with different feed solutions and different parameters. The meters are compared to the reference values measured in the laboratory. Also, the correlation functions based on the mathematical least square method is developed.

Based on the results from the tests, decision-making concerning the measurement instruments for different applications in future projects will be easier. In the betaine solution separation process, the density-based dry substance meters do not operate properly. The refractometer is more stable and operates more accurately in betaine separation. With impure molasses solution, the prism of the refractometer can become dirty and therefore cause inaccuracy in the measurement. In the end of the crystallation process, the efficiency and operability of the refractometer and the radioactive density gauge decrease substantially.

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