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Graceful Scale-Up of Mixing Systems – Make it Happen for You

When acquiring a process that involves one or several mixing steps, foresight for scale-up or expansion remains to be a subtle but important factor for long-term success. As production requirements grow, your ability to shift gears smoothly, quickly and efficiently is critical because it can spell the difference between an economical transition and a financial disaster.

Many process engineers have answered the call for greater capacity while avoiding scale-up entirely by simply adding more mixers identical to the ones they already had. This strategy certainly increases production but misses to capture many economies of scale. With every square foot of floor space occupied by numerous small mixers, these associated costs go up when they really don't need to if only a larger mixer version is used instead.

The textbook concept on scalability is defined in terms of process, material and machine variables, grouped into ratios and equations establishing geometric, kinematic and dynamic similarities. But virtually all of these classic formulas applyonly to simple, low-viscosity liquid-liquid mixing systems involving a single agitator. Real mixing applications of today are much more complex than that. Mixing involving multiple stages that correspond to varying levels of viscosity, density, vacuum/pressure requirements, shear-sensitivity and heat requirements cannot be neatly quantified using standard scale-up equations. Hence, for many mixing systems, traditional academic analysis provides only a starting point. From there, we rely on collective experience and our ability to identify and control the most important variables at work in a specific application. For instance, we may narrow our focus on such variables as shear input, power density, blade or ribbon agitator tip speeds, drive requirements, batch turnover rates or flow rates.

Below are some considerations that could help your business grow while reaping the benefits of reliable scale-up and other creative ways of increasing production.

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