Coagulation Tank Design Calculation

Velocity Gradient Equation:

\[ G = \sqrt{\frac{P}{\mu \times V}} \]

Velocity Gradient (G):

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1. What is the Velocity Gradient Equation?

The velocity gradient equation calculates the velocity gradient (G) for coagulation mixing in water treatment processes. It relates power input, fluid viscosity, and tank volume to determine the mixing intensity required for effective coagulation.

2. How Does the Calculator Work?

The calculator uses the velocity gradient equation:

\[ G = \sqrt{\frac{P}{\mu \times V}} \]

Where:

\( G \) — Velocity gradient (s⁻¹)
\( P \) — Power input (W)
\( \mu \) — Dynamic viscosity (Pa·s)
\( V \) — Volume (m³)

Explanation: The equation calculates the root mean square velocity gradient, which represents the intensity of mixing in the coagulation tank. Higher G values indicate more intense mixing.

3. Importance of Velocity Gradient Calculation

Details: Proper velocity gradient calculation is essential for effective coagulation in water treatment. It ensures optimal mixing intensity for particle collision and floc formation while avoiding excessive mixing that can break up formed flocs.

4. Using the Calculator

Tips: Enter power input in watts, dynamic viscosity in Pa·s, and volume in cubic meters. All values must be positive and greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical range for velocity gradient in coagulation?
A: Typical G values range from 20-100 s⁻¹ for rapid mixing and 10-75 s⁻¹ for flocculation, depending on the specific treatment objectives.

Q2: How does temperature affect the calculation?
A: Temperature affects dynamic viscosity (μ). Water viscosity decreases as temperature increases, which increases the velocity gradient for the same power input.

Q3: What are the units for velocity gradient?
A: Velocity gradient is measured in reciprocal seconds (s⁻¹), representing the rate of velocity change per unit distance.

Q4: How is power input typically determined in practice?
A: Power input can be calculated from motor power, impeller design, and mixing efficiency, or measured directly using torque measurements.

Q5: What factors influence the optimal velocity gradient?
A: Optimal G values depend on water quality, coagulant type, temperature, and the specific treatment objectives for particle removal.