The application of electrical resistance tomography within a vacuum sugar pan in order to better understand its boiling dynamics.

Abstract

This dissertation is concerned with the application of tomography within the sugar industry; in particular non-accessible locations found in a sugar mill. In this study, the focus of research is that of a vacuum pan, and if better understood through tomographical techniques could significantly improve mill efficiency and throughput. The tomography system comprises unique mechanical interfaces, data acquisition modules and software algorithms in order to generate images which reflect the dynamics in the tomographical sensor zone. The distribution of gas (low conductivity) and liquid (high conductivity) within a tube is of main interest in order to understand the boiling dynamics and ultimately pan design. This is attained by determining the internal cross-sectional spatial distribution of conductivity of a number of tubes within the pan simultaneously. Thermal properties of the contents of the sugar pan (a syrup-like substance known as massecuite) at different boiling stages can be estimated based on the tomographical data. Data acquisition is achieved via an in-house designed electronic state machine. A neighbourhood back-projection reconstruction technique was developed in MATLAB in order to generate tomographical images. Results from the system have identified different boiling dynamics which improve the understanding and design of vacuum sugar pans.