Visualisation of dispersion, Dissolution and settling of powders in a stirred mixing vessel by electrical resistance tomography

This paper investigates the mixing of food powders in a batch vessel. The objective is to use the online instrumentation namely the electrical resistance tomography (ERT) and focused beam reflectance measurement (FBRM) to monitor the rates of dispersion, dissolution and settling of different powders. Food process industries are increasingly using non-soluble powders in their recipes. The non-soluble powders with high protein content are difficult to hydrate and it is always desired to know when their hydration is complete. For this reason, it is critical for these industries to be able to measure and know the degree of mixing of powders inside the mixing tanks. The monitoring of the solid-liquid mixing systems is challenging and often ill-defined. In this work, the processes of dispersion, dissolution and settling have been studied experimentally using ERT and FBRM techniques. Both the techniques are used online to continuously monitor the mixing process. The ERT senses the dispersion, dissolution and settling of the powders in the aqueous media while the FBRM is used to capture only the dispersion and dissolution process. The results show that through the combined use of these methods in a solid-liquid stirred mixing tank, it is possible to extract real time information on the powder mixing process.