Reactor Agitator Design Calculation

Power Equation for Reactor Agitator:

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

Power Number (N_p):

Density (ρ):

kg/m³

Rotational Speed (N):

rps

Impeller Diameter (D):

Power (P):

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1. What is the Reactor Agitator Power Equation?

The reactor agitator power equation calculates the power required to drive an agitator in a mixing vessel. It is essential for proper agitator design and motor selection in chemical and process engineering applications.

2. How Does the Calculator Work?

The calculator uses the agitator power equation:

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

Where:

\( P \) — Power (W)
\( N_p \) — Power number (dimensionless)
\( \rho \) — Density of fluid (kg/m³)
\( N \) — Rotational speed (rps)
\( D \) — Impeller diameter (m)

Explanation: The power number depends on the impeller type and flow regime (laminar or turbulent). Common values range from 0.3 to 6.0 for different impeller designs.

3. Importance of Agitator Power Calculation

Details: Accurate power calculation is crucial for selecting appropriate motors, ensuring efficient mixing, preventing equipment failure, and optimizing energy consumption in industrial processes.

4. Using the Calculator

Tips: Enter power number (dimensionless), fluid density in kg/m³, rotational speed in revolutions per second (rps), and impeller diameter in meters. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is the power number (N_p)?
A: The power number is a dimensionless parameter that characterizes the resistance of an impeller to rotation in a fluid. It depends on impeller geometry and Reynolds number.

Q2: How do I determine the power number for my impeller?
A: Power numbers are typically obtained from manufacturer specifications, experimental data, or published correlations for specific impeller types.

Q3: What are typical power number values?
A: For standard impellers: Rushton turbine ~5.0, pitched blade turbine ~1.3-1.5, marine propeller ~0.3-0.6, anchor ~0.3-1.0.

Q4: Does this equation work for all flow regimes?
A: The equation is valid for turbulent flow. For transitional and laminar flow, the power number becomes a function of Reynolds number.

Q5: What factors affect agitator power requirements?
A: Fluid viscosity, density, impeller type and size, rotational speed, baffle configuration, and vessel geometry all influence power requirements.