How To Calculate Reactor Agitator Power Requirement

Power Equation for Agitated Reactor:

\[ P = N_p \times \rho \times N^3 \times D^5 \]

Power Number (N_p):

dimensionless

Density (ρ):

kg/m³

Impeller Speed (N):

rps

Impeller Diameter (D):

Power Requirement (P):

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1. What is the Reactor Agitator Power Equation?

The agitator power equation calculates the power required to operate an impeller in a reactor vessel. This is essential for proper mixer selection and ensuring efficient mixing operations in chemical processes.

2. How Does the Calculator Work?

The calculator uses the agitator power equation:

\[ P = N_p \times \rho \times N^3 \times D^5 \]

Where:

\( P \) — Power requirement (W)
\( N_p \) — Power number (dimensionless)
\( \rho \) — Fluid density (kg/m³)
\( N \) — Impeller rotational speed (rps)
\( D \) — Impeller diameter (m)

Explanation: The power number depends on impeller type and flow regime, with typical values ranging from 0.2 to 6.0 for different impeller designs.

3. Importance of Power Calculation

Details: Accurate power calculation ensures proper motor sizing, prevents equipment failure, optimizes energy consumption, and maintains process efficiency in mixing operations.

4. Using the Calculator

Tips: Enter power number based on impeller type, fluid density in kg/m³, impeller speed in revolutions per second, and impeller diameter in meters. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What are typical power number values?
A: Power numbers vary by impeller type: Rushton turbine (4-6), pitched blade turbine (1-2), marine propeller (0.3-0.6), anchor (0.2-1.0).

Q2: How does viscosity affect power requirement?
A: Higher viscosity fluids require more power for the same mixing intensity. Power number may change with Reynolds number in transitional flow.

Q3: What units should be used for impeller speed?
A: The equation requires speed in revolutions per second (rps). If you have RPM, divide by 60 to convert to rps.

Q4: Can this equation be used for non-Newtonian fluids?
A: For non-Newtonian fluids, apparent viscosity must be calculated and power number correlations may differ significantly.

Q5: How important is impeller diameter in the calculation?
A: Extremely important - power scales with the fifth power of diameter, making it the most sensitive parameter in the equation.