Dry Scrubber for Air Pollution Control

1. Introduction about Dry Scrubbers for Air Pollution Control

Dry scrubbers are a crucial component of industrial air pollution control technologies and systems used for the removal of acidic gases and volatile contaminants from industrial emissions. Unlike wet scrubbers, dry systems use solid or powdered reagents, making them ideal for facilities where water usage or wastewater treatment is undesirable.


2. What is a Dry Scrubber?

A dry scrubber is a type of gas-cleaning system that uses sorbent materials to chemically or physically bind pollutants from a gas stream. They are widely used in fume extraction systems and emissions control where dry operation is preferred, such as in waste incineration and chemical processing.


3. Working Principle

Dry scrubbers typically function through the following steps:

  • Contaminated flue gas is introduced into the dry scrubber chamber.

  • A dry sorbent (e.g., sodium bicarbonate, hydrated lime) is injected or passed through.

  • The sorbent reacts with acidic gases (e.g., SO₂, HCl) to form solid salts.

  • The treated air is then sent to a filter (e.g., baghouse) for final particulate removal.

This makes dry scrubbers extremely valuable in industrial air pollution control technologies and systems requiring dry waste output.


4. Types of Dry Scrubbers

Type Description
Dry Injection Systems Sorbent is injected into the flue gas directly and then filtered out.
Spray Dryer Absorbers Atomized lime slurry is sprayed and dried rapidly, creating a dry residue.
Circulating Dry Scrubbers Recirculates sorbent for higher utilization efficiency.

Each type serves unique purposes in fume extraction system and emissions control setups.


5. Key Components

  • Sorbent Injection Unit

  • Reaction Chamber

  • Ductwork and Gas Distribution

  • Bag Filter / Dust Collector

  • Waste Collection Bin


6. Design Parameters

Parameter Typical Value
Sorbent Usage Rate 1.0 – 2.0 stoichiometric ratio
Efficiency (SO₂) 70 – 90% (higher with optimized design)
Airflow Capacity 1,000 – 150,000 m³/hr
Pressure Drop 80 – 200 mm W.C.

7. Industrial Applications

Dry scrubbers are commonly applied in:

  • Waste-to-Energy Plants: Removal of SO₂, HCl, HF

  • Glass & Ceramics: Acidic emissions from firing processes

  • Power Plants: Especially those using coal or pet coke

  • Steel & Metal Processing: Pickling, galvanizing emissions

  • Chemical Manufacturing: Gaseous acid removal without water


8. Advantages

  • No liquid effluent treatment required

  • Suitable for high-temperature gases

  • Smaller footprint compared to wet scrubbers

  • Fast response time and easier maintenance

  • Complements bag filters in industrial air pollution control technologies and systems


9. Limitations

  • Sorbent cost can be high for long-term operation

  • Lower removal efficiency compared to wet scrubbers for some gases

  • Generates dry waste that requires safe disposal


10. Maintenance Aspects

  • Regular inspection of sorbent feeders

  • Dust collector bag replacement

  • Monitoring of reaction chamber pressure drop

  • Sorbent reactivity testing and feed control


11. Regulatory Compliance

Dry scrubbers help comply with:

  • US EPA MATS and NSPS Standards

  • EU IED & BAT Directives

  • India CPCB Standards for Acid Gases

  • Saudi Arabia PME & UAE MOCCAE for industrial emissions

Bag House Dust Collectors

Pulse Jet Dust Collector System

Cyclone Separators Control Particulate Emissions

Electrostatic Precipitators for Clean Air

Activated Carbon Filters for VOC Odor Removal

Multi Stage Scrubbing Systems

NOx and SOx Emissions

Air Pollution Control in Cement Industry

Air Pollution Control Foundries Metal Processing Units

Wet Scrubber for Chemical Industry

Wet Scrubbers for Industrial Emissions Control


12. Conclusion

Dry scrubbers remain a cornerstone of fume extraction systems and emissions control especially in sectors where water conservation and dry waste handling are critical. As sorbent technologies improve, their role in industrial air pollution control technologies and systems is set to expand further with hybrid and modular solutions.

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