Lab trials

Lab trials are still an indispensable part of the methods for the development of impellers and the design of agitators and processes. There is no competition to the numerical methods; both approaches ideally complement each other.

Basic investigations serve to broaden the knowledge about the physical processes in the stirred tank or powder mixer. Newly developed mixing elements must be characterised in terms of their hydraulic performance and in the treatment of the basic mixing tasks. Standardised measuring technologies are used here.

Application-related investigations occupy a particularly wide area. First of all, it is necessary to know the physical properties of the materials to be mixed – in particular under operating conditions (i.e. according to the different process steps). Data for multiphase mixtures or bulk solids are lacking in the literature; here, only measurements provide clarity.

Viscosity is the most important material property in mixing technology. It not only affects the power consumption of the stirrer but also the blending behaviour, the dispersing capacity, and the heat transfer. EKATO has the necessary measuring technology in its laboratories: rheometers for the determination of viscosities, for particle and drop size distributions, microscopes for the evaluation of crystal morphologies etc.

Lab trials are often performed with model fluids. This allows the simple and rapid comparison of different stirring arrangements and apparatus concepts for a particular application. This includes the determination of mixing times or the mass transfer capacity in gas-liquid processes. The residence time behaviour in continuous systems can also be readily optimised. 

If, on the other hand, a quantitative statement regarding the process results and product quality is required, experiments with the original formulation are indispensable. These include cosmetic or pharmaceutical products as well as paints, adhesives, and polymer mixtures, which must have a reproducible mixing quality. Even a drying curve as a basis for the design of stirred convection dryers must be determined experimentally with the original product in the EKATO pilot plants. 

The conversion of a chemical reaction and the amount of by-products can only be determined under the actual operating conditions. 

Finally, the test results must lead to the design of an operating system. EKATO has sophisticated tools and a team of experienced specialists who perform this scale up.

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