Various physical and chemical processes interact during a manufacturing or synthesis process in a stirred tank reactor, including:
- Heat Transfer
- Thermodynamics; Equilibrium
- Mass transfer between phases
- Mixing to disperse multiple phases
- Physical property changes
For effective scale-up, an understanding of how the numerous physical and chemical processes interact is essential. Critical time constants in a synthesis process that control process performance include:
- Kinetic rate
- Gas-liquid mass transfer
- Reactor circulation
- Residence time
- Heat transfer, liquid-liquid mass transfer, etc.
The magnitude of these rate constants dictate scale-up strategy, problem diagnosis, optimization, etc. It is essential to scale-up on one of these key variables.
Scale-up requires balancing different process rates as they change with process size. Unfortunately, the process rates do not change uniformly with volume and equipment size. It is best to scale-up with one mixing variable as the basis for your scale-up. If the mixing scale-up fails the required yield, quality, or physical properties of the product, manufacturing costs may significantly increase. Failure to provide the necessary mixing may result in severe manufacturing problems on scale-up, ranging from costly corrections in the plant to complete failure of a process.
To learn more about the importance of mixing in scale-up, view the free on-demand webinar: The Importance of Mixing: How to Compare Lab Scale Mixing with Full Scale Process Vessel Performance. During this free online seminar, Ray Machado compares lab scale and large scale mixing and features excerpts from two short courses “Fundamentals of Scale-up” and “iControl Mixing Guidelines”.