Reactor Scale Up Calculations

Reactor Scale Up Equations:

\[ \text{Scale Factor} = \left( \frac{V_{\text{large}}}{V_{\text{small}}} \right)^{1/3} \] \[ P \propto N^3 D^5 \]

Large Reactor Volume (V_large):

m³

Small Reactor Volume (V_small):

m³

Small Reactor Speed (N_small):

rpm

Small Reactor Impeller Diameter (D_small):

Small Reactor Power (P_small):

Scale Factor:

Large Reactor Impeller Diameter (D_large):

Large Reactor Speed (N_large):

Large Reactor Power (P_large):

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1. What is Reactor Scale Up?

Reactor scale up involves translating laboratory or pilot-scale reactor conditions to industrial-scale operations while maintaining similar mixing, heat transfer, and reaction characteristics. It is a critical step in chemical process development.

2. How Does the Calculator Work?

The calculator uses geometric similarity and power relationships:

\[ \text{Scale Factor} = \left( \frac{V_{\text{large}}}{V_{\text{small}}} \right)^{1/3} \] \[ P \propto N^3 D^5 \]

Where:

\( V \) — Reactor volume (m³)
\( N \) — Impeller speed (rpm)
\( D \) — Impeller diameter (m)
\( P \) — Power consumption (W)

Explanation: The scale factor is derived from geometric similarity, while power relationships maintain similar mixing intensity and fluid dynamics.

3. Importance of Scale Up Calculations

Details: Proper scale up ensures consistent product quality, efficient mixing, adequate heat transfer, and predictable reaction rates when moving from laboratory to industrial scale reactors.

4. Using the Calculator

Tips: Enter all reactor parameters in consistent units. Ensure small reactor data is accurate as it serves as the baseline for scale up calculations.

5. Frequently Asked Questions (FAQ)

Q1: What is geometric similarity in scale up?
A: Geometric similarity means all linear dimensions scale by the same factor, maintaining the same shape and proportions between small and large reactors.

Q2: Why is power proportional to N³D⁵?
A: This relationship comes from dimensional analysis and applies to turbulent flow conditions in agitated vessels, where power number is constant.

Q3: What are the limitations of geometric scale up?
A: Geometric scale up may not maintain identical flow patterns, heat transfer rates, or mixing times due to changes in Reynolds numbers and other dimensionless groups.

Q4: When should I use constant power per volume scale up?
A: Constant power per volume is often used for similar mixing intensity, but may require different impeller types or configurations at large scale.

Q5: How do I account for non-Newtonian fluids?
A: For non-Newtonian fluids, additional considerations for apparent viscosity and shear rate distribution are needed, often requiring computational fluid dynamics.