Question

In scaling up agitators from a lab model to industrial scale, which one of the following is preferred as a scale-up criterion?

• A. Mixing time
• B. Reynolds No.
• C. Power number
• D. Power / volume of fermenter

Hint:

Use the Power number as the scale-up criterion to ensure consistent mixing behavior in larger fermenters.

Answer 1

The Correct Option is C

Step 1: Understanding Scale-up Criteria 
When scaling up a process, the criteria used must ensure that similar flow conditions and mixing behaviors are achieved between the lab and industrial scales. 
Step 2: Evaluating Options 
- Mixing time: Dependent on several factors, not a primary scale-up criterion. 
- Reynolds No.: Helps compare flow types, but doesn't always predict mixing efficiency. 
- Power number: Relates to the power required for mixing in different scales and is preferred for scale-up since it ensures similar flow and mixing characteristics. 
- Power/volume of fermenter: Useful for scaling but doesn’t directly address flow similarity. 
Step 3: Conclusion 
The power number is the most effective criterion for scale-up, as it directly impacts the mixing efficiency across different scales.