Wet exhaust gas treatment, gas scrubbers

wet scrubber is a simple method to clean exhaust air or exhaust gas and remove toxic or smelling compounds. In the flue gas scrubber, the gas gets in close contact with fine water drops in a co-current or counter current flow. This method is more effective when the water drop size gets smaller and the total surface between water or washing fluid and the gas gets larger. The water or washing fluid is recirculated normally in order to save water and reduce the amount of waste water.

Wet scrubber

A gas scrubber can remove the following components from exhaust gas:

  • Water-soluble substances are dissolved.
  • Dust particles are suppressed (precipitated).
  • Hydrolyzable substances are decomposed.
  • Water vapor is condensed.

The result of wet cleaning is detoxification, dedusting, dehumidification/condensation and removal of smelling in benifit of our environment.
In particular, water-soluble contaminants are very effectively removed from the gas by dissolution. By absorbing substances from the gas, the washing liquid may become contaminated. Often the absorbed substances are acidic or basic chemicals, such as hydrogen chloride HCl, nitrogen oxides or ammonia NH3. With an integrated neutralization unit in the scrubber, the wastewater can be kept at a neutral pH and thus detoxified. Furthermore, a slightly acidic washing liquid is more effective for basic gas components, and a slightly basic washing liquid is more effective for removing acidic gas components.

Dusts are suppressed and may form sludge in larger quantities, which must be filtered out of the wastewater. The filter sludge can, under certain circumstances, be hazardous waste.

Hydrolyzable substances decompose in contact with water. The chemical reaction may produce water-soluble products that are immediately dissolved out of the gas or solid components that collect as sludge in the collection tray and must be filtered and disposed of. Thus, in the semiconductor industry wet scrubbers are used to remove TEOS (tetraethoxysilane) or TiCl4 (titanium tetrachloride).

A wet scrubber can be combined with other exhaust gas cleaning methods. For example, gases can first be washed, then thermally treated and washed again after thermal treatment. This is done in our SBW and SWB exhaust gas cleaners.

Overview of wet scrubber types

Gas scrubbers for semiconductor process equipment

SemiAn offers gas scrubbers developed for cleaning exhaust from process equipment commonly used in the semiconductor industry and in the production of liquid crystal displays, as well as in associated laboratories. Our exhaust cleaners are designed for gas flows of approx. 100 - 1,200 slm (6 - 72 m3/h). We are also happy to supply scrubbers of this size for other applications, reliably and cost-effectively.

SSW-200-K

The SSW-200-K is designed for a gas flow of 200 slm and provides efficient wet cleaning of water-soluble gases that do not require chemical decomposition.

Specification
Technical features Product data
Maximum gas flow 200 SLM
Gas inlet 65A flange, 1 connection
Gas outlet 65A flange, 1 connection / −25 to −75 mm H2O
Electrical power consumption Max. 300 W
Voltage / Phase 208–220 V / 1-phase, 60 Hz
Water Max. 4 SLM; 2–3 kgf/cm²; 1/4" Lok fitting
N2 (optional) Max. 25 SLM; 4–6 kgf/cm²; 1/4" Lok fitting
Wastewater drain VP40 union
Dimensions 600 (W) × 500 (D) × 1500 (H) mm
Weight 200 kg
Certification CE
SSW-200-K

Wet scrubber SSW-200-E with neutralization

The SSW-200-E is also designed for a gas flow of 200 slm and provides efficient wet cleaning of water-soluble gases that do not require chemical decomposition. In addition, this model features an integrated water neutralization unit for the resulting wastewater.

Specification
Technical features Product data
Maximum gas flow 200 SLM
Gas inlet 100A flange, 1 connection
Gas outlet 65A flange, 1 connection / −25 to −75 mm H2O
Electrical power consumption Max. 300 W
Voltage / Phase 208–220 V / 1-phase, 60 Hz
Water Max. 25 SLM; 4–6 kgf/cm²; 1/4" Lok fitting
Air Max. 2 SLM; 4–6 kgf/cm²; 1/4" Lok fitting
Wastewater drain VP40 union
Dimensions 400 (W) × 500 (D) × 1500 (H) mm
Weight 200 kg
Certification CE
Scrubber SSW-200-E

Wet scrubber SSW-500

The SSW-500 is designed for a gas flow of 500 slm and provides efficient wet cleaning of water-soluble gases that do not require chemical decomposition.

Depending on requirements, the model is available with or without integrated wastewater neutralization.

Specification
Technical features Product data
Maximum gas flow 500 SLM
Gas inlet VP20 PVC pipe, 3 connections
Gas outlet VP100 PVC pipe, 1 connection / −25 to −75 mm H2O
Housing ventilation VP63 PVC pipe (silencer), 1 connection / −25 to −75 mm H2O
Electrical power consumption Max. 2 kW
Voltage / Phase 208–220 V AC / 1-phase, 60 Hz
Water Max. 8 SLM; 2–3 kgf/cm²; 1/2" Lok fitting
Air Max. 2 SLM; 4–6 kgf/cm²; 1/4" Lok fitting
Wastewater drain VP25 union
Dimensions 990 (W) × 750 (D) × 1850 (H) mm
Weight 450 kg
Certification CE
Scrubber SSW-500

Additional wet scrubbers

Exhaust extraction from etch baths

A special application is the exhaust extraction of acid and alkaline baths or etch baths. Baths containing water-soluble solvents such as alcohols or acetone can also be extracted. In this case the exhaust contains only relatively small amounts of acids, alkalis or solvents and the gas volume to be cleaned is relatively high. SemiAn can also offer adapted gas scrubbers for this application, such as the SSW-500 model.

Central scrubbers

For cleaning large volumes of exhaust gas from industrial emissions and combined exhausts from several process tools, large scrubbers are often used which are installed next to or on top of the building. We can also supply such systems on request.

Exhaust scrubber product overview

In addition to scrubber systems we also offer other scrubber types for different processes, which you can find on our scrubber product overview page.