Despite improving our knowledge with respect to the physical processes in stirred tanks and application-specific peculiarities, often trial are still necessary for the design of an agitator system.

Production scale plants can than be designed on the basis of lab and pilot scale test results by using the scale-up rules. Lab and pilot test vessels are commonly in the size range of 5 to 100 liters, in some cases with large scale-up factors also larger than 1 m³.

For speciality chemicals and formulated or cosmetic products, the target sizes of the production systems are 1–100 m³, while reactors for mass products and fermenters can reach the range of up to 1000 m³. In ore processing, the vessel sizes are even significantly larger. On one hand, the scale-up must not lead to expensive over-designs. On the other hand, operational safety must be ensured in all conditions.

EKATO has comprehensive know-how to ensure safe and accurate design of agitating processes, taking into consideration empirical values, test results, and numerical simulations.

In order to plan meaningful experiments at lab or pilot scale, it is first necessary to scale down the targeted production scale concept. If possible, this is done with geometrical similarity of all essential components. From the various mixing requirements, the relevant scale-up parameters need to be identified and to be aligned with the test plan. Relevant parameters include gas/liquid mass transfer, a chemical conversion, product homogeneity or the stability of an emulsion. The test results show how these parameters can be adjusted.

In addition to general physical laws, scale-up is based on dimensionless numbers and characteristics as a result from similarity theory. Numerical flow simulation CFD also makes an increasing contribution to the design of production systems because it allows comparative studies of flow processes at different scales. For complex processes and especially continuous operation, the licensor often builds a pilot plant that represents the full scale system with all mass and energy streams. This allows to investigate all scale-up relevant parameters in their interactions and to define them. EKATO provides the components for all basic mixing operations – from an individual impeller and agitator up to complete functional units.

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