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Wet Scrubber System: History, Types of Technology, Installation and Maintenance

Historical Development of Wet Cleaning Technologies

The history of wet scrubbers begins in the 19th century (Early Origins). The concept of using liquids to clean gases dates back to the 1800s, during the rise of heavy industry. Early versions were very simple: sprays or water curtains that washed dust and fumes out of smokestacks. The first documented use of an absorption tower dates back to 1858 in Great Britain, where water sprays were employed to reduce dust in mining operations.

Industrial Revolution Era
As industries such as steelmaking, chemical production, and power generation expanded, so did the need to control smoke, dust, and acidic vapors. By the late 19th century, wet scrubbers were commonly installed in coal-fired boilers and smelters to capture ash and sulfur compounds.

Early 20th Century
Wet scrubber designs became more sophisticated, incorporating:

Spray towers (vertical chambers with liquid sprayed downward against rising streams).
Packed beds (where air passed through wetted packing materials for greater contact).
They were primarily used to reduce particulate emissions and to neutralize acidic compounds such as sulfur dioxide (SO₂).

Mid-20th Century (1940s–1970s)
With rising environmental concerns, especially after WWII, wet scrubber cleaning became increasingly important in industries releasing corrosive or toxic compounds. Newer designs emerged:

Venturi units use high-velocity gas streams that come into contact with a fluid to capture fine particulates.
Cyclonic configurations employ centrifugal forces and absorbent solution sprays to remove particulates from the stream.

In the 1960s and 1970s, with the enactment of environmental laws such as the U.S. Clean Air Act of 1970, this equipment became a crucial tool for regulatory compliance.

Late 20th Century – Present
By the late 20th century, the wet collector or scrubber was widely applied in:

Power plants (especially for flue gas desulfurization, FGD).
Chemical and fertilizer plants.
Metal smelting and refining.

They evolved to handle a wide range of pollutants, including acids, particulates, odors, and volatile organic compounds (VOCs). Advanced systems were developed to improve efficiency, reduce water use, and minimize waste sludge.

Modern Developments (21st Century)
Integration with wastewater treatment is necessary to handle wet scrubber air filter effluent. Alternative absorbents (e.g., lime, sodium hydroxide, ammonia) replace plain water for treating specific pollutants.

Over the past decades, wet scrubber manufacturers have continuously improved designs to handle increasingly strict emission standards.

TORNADO Fluidized Bed Scrubber

Description and Main Components

This wet scrubber description outlines how the system cleans emissions by bringing them into contact with a liquid, highlighting its key parts and functions.

The operation of a wet scrubber filter is based on the deposition of dust particles on the surface of droplets or a liquid film. In such cases, water is used for dust removal, or a chemical solution is applied to remove harmful gaseous components along with dust. An important factor is the wettability of the particles by the liquid.

The following table summarizes the main function of wet scrubber and its purpose in industrial air cleaning:

Main Components of a Wet Scrubber

Leading wet scrubber suppliers continually update their designs to handle a wide range of industrial pollutants effectively.

Inlet Section – Polluted flow enters and is evenly distributed, often using guide vanes or diffusers.
Scrubbing Chamber – The core of the wet scrubber section is where gas contacts liquid via nozzles, packing materials, film surfaces, or a narrow throat (Venturi) to maximize interaction.
Liquid Injection System – Sprays or film distributors produce fine droplets to increase gas- fluid contact.
Mist Eliminator – Captures droplets, preventing carryover and returning fluid to the system.
Outlet Section – Cleaned air exits to the atmosphere or further treatment.
Liquid Collection & Recirculation System with Pumps & Piping – Collects and circulates liquid, allowing reuse or treatment.

Wet Scrubber Diagram

Optional Components

The reagent system can use chemicals such as lime slurry for SO₂ removal, sodium hydroxide for acid neutralization, sodium carbonate for CO₂ absorption, or ammonium hydroxide for ammonia scrubbing, depending on the specific pollutant being treated.
Instrumentation & controls – sensors for pressure, flow, pH, and fluid level.
Slurry handling setup – for removal of solids or sludge.
Packing, plates, or grids inside the tower—like Raschig rings, saddle rings, bubble trays, valve plates, wire mesh, or perforated sheets—promote efficient contact between the phases.

CASE STUDY: Effective Neutralization of Acidic Vapors at a Landfill

At a municipal landfill in Florida, Torch-Air supplied a wet scrubber to neutralize acidic vapors from waste storage tanks. The system achieved up to 99% removal efficiency, fully complying with OSHA and EPA standards. Using our equipment helped reduce air pollution and minimize environmental risks. The solution features low operating costs and easy maintenance. Read more

Types of Technology

Wet scrubber units employ several technologies to remove particulate matter and gaseous pollutants from industrial emissions, each optimized for different applications and operating conditions.

Packed Bed Towers feature columns filled with packing material, which can be either structured (regular) or random (irregular). While structured packing like corrugated sheets or rings promotes even gas flow and high mass transfer efficiency, random packing creates turbulent flow to improve phase contact. They are widely used to remove acidic compounds such as SO₂ and HCl, as well as to control submicron dust, providing high efficiency with a relatively low pressure drop when structured packing is employed.

TORNADO FB Fluidized Packed Bed Scrubber

Performance:
100 — 175 000 cfm

TORNADO RP Vertical Wet Scrubber

Performance:
600 — 24 000 cfm

TORNADO SP Packed Bed Scrubber

Performance:
600 — 30 000 cfm

Another common technology is the Tray Tower or Plate Column, often referred to as a barbotage system. In these devices, the wet scrubber process involves gas bubbling through layers of liquid distributed across trays, with each tray acting as a separate stage for mass transfer. It is especially effective for treating high dust loads or effluents with soluble pollutants, as often found in chemical and metallurgical industries. Thanks to its simplicity and low maintenance requirements, it is a practical choice for a wide range of wet scrubber applications.

TYPHOON Tray Tower Scrubber

Performance:
100 — 175 000 cfm

Venturi installations operate on a different principle: gas is accelerated through a converging-diverging throat at high velocity while treatment fluid is injected. The resulting turbulence and shear forces atomize the liquid, creating fine droplets that efficiently capture particles, including submicron aerosols. They are highly effective for industries producing fine dust, such as cement, metal grinding, or coal-fired boilers, although they have higher energy consumption due to significant pressure drops.

Wet Venturi Scrubber

Performance:
100 — 175 000 cfm

TORNADO FB Venturi Packed Bed Scrubber

Performance:
600 — 30 000 cfm

Spray Towers are often employed for moderate particulate removal or absorption of various substances. Polluted air passes through a chamber where an absorbent solution is sprayed through nozzles, forming droplets that remove pollutants by impaction, interception, and diffusion. This technology is simple to construct, requires minimal maintenance, and can handle large gas volumes, though very fine particles require optimization of droplet size for maximum efficiency.

TORNADO ST Spray Tower Wet Scrubber

Performance:
600 — 30 000 cfm

BOREAS-P1 Horizontal Wet Scrubber

Performance:
100 — 175 000 cfm

Specialized devices, such as flow-through hydrophilic filters with spark-arrestor functionality, combine particle removal with safety. The airstream passes through a wetted filter medium that traps particulates and aerosols, with a design that prevents ignition in combustible environments. These units are especially useful in chemical plants, biomass processing, and grain handling facilities, where both filtration and spark protection are necessary.

Overall, the choice of wet scrubber technology depends on the type of contaminants, air flow characteristics, and operational requirements. Structured or random packing, tray configurations, Venturi throats, spray nozzles, or hydrophilic filters can be selected individually or in combination to achieve the desired removal efficiency while balancing energy consumption and maintenance needs. Our team ensures every wet scrubber install meets strict environmental standards and operates at maximum efficiency.

Installation Process

The installation of a wet scrubber system involves several key stages to ensure proper operation, safety, and compliance with all design specifications. The process begins with site preparation, including the verification of foundation strength, floor leveling, and clearance for maintenance access. A reinforced concrete or steel foundation is typically required to support the wet air scrubber, liquid tank, and associated piping.

Next, the mechanical assembly of the equipment components is carried out. This includes erecting the main unit body, installing packing, trays, or grids, and assembling internal sections such as spray nozzles, mist eliminators, and fluid distribution mechanisms. Structural supports and platforms are added as needed to allow safe access for maintenance and inspection.

The piping and pump installation follows, connecting the tower to the process gas ducting, liquid supply, and recirculation network. This step ensures proper alignment, leak-proof joints, and integration of valves, flow meters, and instrumentation for monitoring pressure, flow, and fluid levels.

After mechanical and piping work, electrical and instrumentation connections are completed. Pumps, sensors, control panels, and automation equipment are wired and calibrated to ensure accurate operation of liquid flow, gas velocity, and chemical dosing setups.

Finally, the equipment undergoes pre-commissioning checks. These tasks involve checking structural integrity, conducting leak tests, cleaning the circulation lines, testing pumps and nozzles, and confirming the correct operation of the mist eliminator and instrumentation. Once these checks are successfully completed, equipment is ready for start-up and commissioning, during which the unit is gradually brought online, process parameters are adjusted, and its performance is verified against the design criteria.

Maintenance Procedure

A wet scrubber factory typically provides a maintenance checklist with standard operating procedures.

A Clear and Simple Guide to Annual Wet Scrubber Inspections

Here are the main tasks:
Daily Inspection

Check inlet and outlet ducts for blockages or excessive dust buildup.
Monitor fluid levels in the collection tank and ensure proper circulation.
Observe pumps, valves, and nozzles for leaks or abnormal vibrations.
Check pressure drop across the chamber; abnormal values may indicate clogging or uneven flow.

Weekly Checks

Inspect spray nozzles for clogging or wear; clean or replace if necessary.
Verify mist eliminator condition, ensuring it is free from accumulated liquid or debris.
Examine packing or trays for fouling, corrosion, or scaling.
Check chemical feed devices (if applicable) for correct operation and sufficient reagent supply.

Monthly Maintenance

Perform a thorough cleaning of liquid tanks and piping to prevent sludge buildup.
Inspect structural components such as supports, ladders, and platforms for corrosion or damage.
Test instrumentation and sensors for accuracy (pH, flow, pressure, level).
Check the pump performance, including bearings and seals, and lubricate as needed.

Quarterly or Semiannual Maintenance

Remove and clean packing materials or trays if fouled or scaled.
Inspect venturi throat or high-velocity sections for erosion or wear.
Perform a full system calibration of control valves, flow meters, and reagent feed units.
Check electrical connections and motor insulation on pumps and fans.

Annual Maintenance

Conduct a complete inspection of all components, including body, ducts, piping, and mist eliminator.
Replace worn-out parts, including nozzles, packing, gaskets, and seals.
Conduct a wet scrubber performance test to ensure that the system’s removal efficiency meets the design specifications.
Update maintenance logs and plan for any required upgrades or retrofits.

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We always perform precise calculations and offer expert assistance in selecting the optimal dust collection or gas cleaning systems, typically completing this process within 1 to 2 days

Head of Engineering,
Vladimir Nikulin

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