Scrubbers Air Washers

Overview

Engineering reference data for Scrubbers Air Washers in material science and properties.

Key Formulas

Stress

$\sigma = \frac{F}{A}$

Force per unit area.

Strain

$\varepsilon = \frac{\Delta L}{L_0}$

Change in length per original length.

Hooke's Law

$\sigma = E \varepsilon$

Stress proportional to strain in elastic region.

Thermal Expansion

$\Delta L = \alpha L_0 \Delta T$

Length change due to temperature.

Variables

Scrubber Configurations

Air scrubbers are available in several basic configurations, each suited to different process requirements:

• Orifice scrubbers - air or gas velocity is increased through an orifice, increasing turbulence to atomize water droplets.
• Venturi scrubbers - air or gas velocity is increased through a venturi shape, using increased turbulence to atomize water droplets.
• Fiber-bed scrubbers - air passes through wet-laden fiber mats where mists are collected. Not suited for solid particles as the mats may plug.
• Mechanical scrubbers - a mechanically driven rotor produces fine water droplets in the air.
• Impingement-plate scrubber - a vertical scrubber with horizontal plates; air flows from bottom to top, water from top to bottom.
• Spray nozzle scrubbers - water is sprayed with high pressure through nozzles to produce droplets in the air.

Typical Scrubber Data

The following table provides typical operational ranges for spray nozzle scrubbers.

Scrubber Efficiency

The performance of a scrubber depends on its configuration and number of banks:

• 60-70% efficiency with one bank of nozzles downstream.
• 65-75% efficiency with one bank of nozzles upstream.
• 85-100% efficiency with two banks of nozzles.

Humidifying Efficiency

The humidifying efficiency of a scrubber is a key parameter, especially in processes requiring precise humidity control (e.g., for bio beds treating odor-polluted air). It is calculated by:

$\mu_h = \frac{t_1 - t_2}{t_1 - t_w} \times 100\%$

Where:

• $\mu_h$ is the scrubber humidifying efficiency (%)
• $t_1$ is the initial dry bulb temperature (°C)
• $t_2$ is the final dry bulb temperature (°C)
• $t_w$ is the initial wet bulb temperature (°C)

Important Notes

• Water Management: Evaporated water is replaced by fresh water and chemicals. Dust and pollution products are removed periodically through the drain.
• Legionella Risk: Low-temperature scrubbers can be a potential source for Legionella disease. Special cleaning and disinfection precautions must be taken if the operating temperature is within the "Legionella range."

References

• Original Source