Tuesday, May 3, 2011
Effects of mixer type and stirring speeds on initial reaction rates and conversion have been reported in the bioconversion literature, as well as lower initial rates of reaction on scaled-up processes in comparison to similar laboratory procedures. Those findings indicate that scale-up of the early liquefaction stage of viscous high-solids cellulosic material presents transport phenomena challenges. Reliable data on transport phenomena parameters is thus needed to successfully move a bioprocess from the laboratory to the industrial scale. We describe magnetic resonance imaging methods designed for characterization of rheology, diffusivity and mixing in fiber suspensions. The relevance of the MRI methods for scale-up is discussed in the context of the capability to handle kilogram-sized samples, and the measurement of effective diffusivity and mixing variables at length scales and time scales of industrial interest. Also discussed is the suitability of the non-invasive imaging techniques for in-line, on-line or at-line measurements.