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Author: Anna Frank, Equipment Selection Expert
What is a Gas Scrubber?
Gas scrubber system — a device used to purify solid or gaseous media from contaminants in various chemical and technological processes.
A large number of modern chemical and technological operations involve crushing, grinding, and transporting bulk materials. In the process, part of the material inevitably becomes aerosolized, forming dust that is released into the atmosphere along with ventilation or exhaust flows.
Their popularity stems from their effectiveness in capturing fine particles and managing high-temperature, potentially explosive exhaust flows.
A clear gas scrubber definition helps distinguish it from other filtration or adsorption technologies.
From an engineering perspective, the gas scrubber meaning includes both the functional principle of mass transfer and the mechanical design adapted to specific stream compositions.
A large number of modern chemical and technological operations involve crushing, grinding, and transporting bulk materials. In the process, part of the material inevitably becomes aerosolized, forming dust that is released into the atmosphere along with ventilation or exhaust flows.
Their popularity stems from their effectiveness in capturing fine particles and managing high-temperature, potentially explosive exhaust flows.
A clear gas scrubber definition helps distinguish it from other filtration or adsorption technologies.
From an engineering perspective, the gas scrubber meaning includes both the functional principle of mass transfer and the mechanical design adapted to specific stream compositions.
TORNADO Fluidized Bed Scrubber
Main Pollutants and Gas Scrubber Applicability
Substance Type | Example Substances | Notes |
Acidic vapors | SO₂, HCl, HF, HBr | Alkaline solution often used (NaOH, Ca(OH)₂) |
Alkaline emissions | NH₃, amine compounds | Treated with mildly acidic solutions (H₂SO₄, HCl) |
Airborne oxidants | NO, NO₂ | Require oxidation to HNO₃ or special treatment technologies |
Volatile Organic Compounds (VOCs) | Benzene, toluene, aldehydes | Poorly soluble, often treated with adsorption or oxidation technologies |
Dust and aerosols | Fine dust, soot | Venturi technology excels at removing fine dust and aerosol contaminants during production |
Chlorine and its compounds | Cl₂, HCl | Effectively captured with water or alkaline solutions |
Hydrogen sulfide | H₂S | Requires oxidizing agents or alkaline medium |
Cyanides | HCN | Requires caution and appropriate reagent selection |
Fluorinated compounds | HF, SiF₄ | Common in aluminum and glass industries |
Organometallics and metal vapors | Mercury (Hg), Arsine (AsH₃) | Require specialized systems, possibly with filtration |
Function of Gas Scrubber
- Removal of pollutants — captures harmful substances such as sulfur dioxide, hydrogen chloride, and ammonia from industrial exhaust streams.
- Absorption of toxic compounds — facilitates chemical neutralization through interaction with reagents, improving workplace and environmental safety.
- Emission reduction — decreases contaminant concentrations to meet environmental regulations and clean air standards.
- Cooling of hot incoming streams — reduces temperature as needed before further treatment or release.
- Capture of aerosols and acid mist — effectively traps fine droplets and vapor-phase particles.
- Enhanced operational safety — mitigates the release of aggressive or potentially explosive compounds in manufacturing environments.
- Odor control — minimizes or eliminates unpleasant smells, especially in chemical, pharmaceutical, and food-processing applications.
Working Principle
How does a gas scrubber work? In wet dust collectors, particulate matter is removed from the air stream by wetting the particles and carrying them away with water. During the dust removal process, the stream comes into contact with a liquid that forms a barrier and flows down the walls of the apparatus as a thin film, carrying the contaminants with it.
Air purification from suspended particles in modern systems is typically divided into four main stages:
Air purification from suspended particles in modern systems is typically divided into four main stages:
- Flow conditioning by spraying at the inlet of the unit;
- Capture (wetting) of particles by the liquid;
- Separation of the sludge from the air stream;
- Sludge removal from the unit.
Gas Scrubber Diagram
In general, gas scrubber operation is based on the intensive contact between the polluted airstream and the cleaning solution. This contact may occur in various forms depending on the type of gas scrubber: through spray nozzles, packed beds, rotating trays, or Venturi throats. The efficiency of the equipment is influenced by factors such as droplet size, airstream velocity, exposure time, and the interaction between the liquid and target contaminants.
The gas scrubber working principle can be adapted for both solid particles and hazardous compounds in vapor form. For example, alkaline solutions are used to neutralize acidic compounds like SO₂ and HCl, while oxidizing agents can remove hazardous compounds such as H₂S or NOx. Some advanced devices even combine absorption, chemical reaction, and mechanical separation to achieve high removal efficiency across a wide range of contaminants.
Thanks to their versatility and reliability, they are widely used in chemical industry, metallurgy, waste incineration, pharmaceuticals, and other industries where clean air and environmental compliance are critical.
The gas scrubber working principle can be adapted for both solid particles and hazardous compounds in vapor form. For example, alkaline solutions are used to neutralize acidic compounds like SO₂ and HCl, while oxidizing agents can remove hazardous compounds such as H₂S or NOx. Some advanced devices even combine absorption, chemical reaction, and mechanical separation to achieve high removal efficiency across a wide range of contaminants.
Thanks to their versatility and reliability, they are widely used in chemical industry, metallurgy, waste incineration, pharmaceuticals, and other industries where clean air and environmental compliance are critical.
Design Parameters and Configuration
Depending on the type of unit, the gas scrubber design may vary, but the main components are:
Based on these parameters, the suitable configuration is chosen: a spray tower for basic applications, a packed bed for high-efficiency chemical absorption, a tray tower for enhanced phase interaction, or Venturi-based equipment for fine particulate capture.
Horizontal gas scrubbers feature a compact layout and are convenient for indoor operation. All components are easily accessible from the ground or a small platform, making maintenance straightforward. Vertical gas scrubbers offer a higher mass transfer coefficient due to natural counterflow, but require ladders and platforms for maintenance.
Our company specializes in custom-built gas scrubbers for sale, designed to meet strict environmental standards.
- Tower — a column with a circular or rectangular cross-section, usually made of stainless steel, plastic (PP, PVC), or FRP. The height ranges from 2 to 10 meters depending on capacity. The diameter of the column is determined by the air volume. It can be installed vertically or horizontally.
- Inlet gas scrubber zone — located at the bottom of the column. Contaminated flow enters the column from the bottom up (counterflow). It is often equipped with a distributor to ensure uniform flow.
- Packing zone or foam layer. In packed towers, packing material (plastic, ceramic, or metal) is placed on a support grid to increase the contact area between phases. Examples of packing media: Raschig rings, Intalox saddles, and mesh-type blocks.
- The foam layer in tray-type equipment is created by nearly flat circular trays that rotate inside the housing. Trays with fine perforations are irrigated and form a foam layer as they interact with the incoming flow.
- Nozzles — the spray system located in the upper part of the unit. It distributes the cleaning fluid evenly across the column cross-section.
- Mist eliminator — a mesh or fibrous structure above the packing that captures liquid droplets.
- Liquid collection section — located at the bottom of the column and equipped with a pump for recirculation or discharge of the scrubbing solution.
- Additional components — reagent dosing nozzles (NaOH, H₂O₂, etc.), pH sensors, temperature sensors, level indicators, pressure sensors. The fan is commonly located after the purification equipment to maintain flow.
Based on these parameters, the suitable configuration is chosen: a spray tower for basic applications, a packed bed for high-efficiency chemical absorption, a tray tower for enhanced phase interaction, or Venturi-based equipment for fine particulate capture.
- The column diameter and height are calculated to ensure sufficient interaction time between phases.
- L/G ratio is determined based on the solubility and reactivity of pollutants.
- The system’s pressure drop is estimated to size the fan.
- Material selection is based on resistance to corrosive media and thermal conditions.
- Auxiliary components such as droplet separators, pH sensors, and dosing setups are integrated as needed.
Horizontal gas scrubbers feature a compact layout and are convenient for indoor operation. All components are easily accessible from the ground or a small platform, making maintenance straightforward. Vertical gas scrubbers offer a higher mass transfer coefficient due to natural counterflow, but require ladders and platforms for maintenance.
Our company specializes in custom-built gas scrubbers for sale, designed to meet strict environmental standards.
Tornado ST
Types Overview
The choice of equipment depends on pollutant properties, air volume, and process conditions.
Spray Tower — a hollow column equipped only with spray nozzles to irrigate the contaminated airstream.
Featuring the lowest aerodynamic resistance, the unit ensures minimal energy use.
Effective for filtering particles >5 µm, odor-bearing vapors, unpleasant fumes, and harmful components such as SO₂, HCl, HF, NH₃, Cl₂, HBr, and H₂S.
Not suitable for contaminants with a low mass transfer coefficient — for example, VOCs, as they are often hydrophobic and require sorption or oxidation. To improve efficiency, proper gas scrubber sizing is essential.
Spray Tower — a hollow column equipped only with spray nozzles to irrigate the contaminated airstream.
Featuring the lowest aerodynamic resistance, the unit ensures minimal energy use.
Effective for filtering particles >5 µm, odor-bearing vapors, unpleasant fumes, and harmful components such as SO₂, HCl, HF, NH₃, Cl₂, HBr, and H₂S.
Not suitable for contaminants with a low mass transfer coefficient — for example, VOCs, as they are often hydrophobic and require sorption or oxidation. To improve efficiency, proper gas scrubber sizing is essential.
Packed Bed — a column equipped with packing materials to improve phase contact.
Effectively handles all contaminants managed by a Spray Tower and is also suitable for:
Effectively handles all contaminants managed by a Spray Tower and is also suitable for:
- mercaptans,
- sulfur compounds,
- toxic substances such as HCN, PH₃, AsH₃,
- SO₂ present in emissions from power plants,
- HCl removal from emissions during chlorine-plastic recycling,
- ammonia capture in fertilizer plants.
Tray Tower (plate column) — equipped with special circular trays.
Air flows through vertically arranged trays or pans filled with scrubbing solution, providing multiple surfaces for interaction.
Ensures effective interaction through the formation of a bubbling (foam) layer on the tray surface.
Effectively captures dust and various industrial contaminants.
The disadvantage of this configuration is higher aerodynamic resistance compared to other units and the complexity of calculating efficiency due to the specific flow distribution during phase interaction.
Air flows through vertically arranged trays or pans filled with scrubbing solution, providing multiple surfaces for interaction.
Ensures effective interaction through the formation of a bubbling (foam) layer on the tray surface.
Effectively captures dust and various industrial contaminants.
The disadvantage of this configuration is higher aerodynamic resistance compared to other units and the complexity of calculating efficiency due to the specific flow distribution during phase interaction.
Venturi — features a venturi-shaped tube with a diffuser, throat, and converging section, as well as liquid inlets with nozzles. Velocity in the throat reaches 30–200 m/s.
The Venturi technology effectively captures fine dust and acid mists in metallurgical and chemical industries.
It is used for scrubbing emissions from electroplating baths and in waste incineration processes where aerosols are generated.
Efficient filtration requires a high-power fan.
The Venturi technology effectively captures fine dust and acid mists in metallurgical and chemical industries.
It is used for scrubbing emissions from electroplating baths and in waste incineration processes where aerosols are generated.
Efficient filtration requires a high-power fan.
These configurations are used both as standalone units and in combination with one another.
Case Studies
Cost Factors Explained
Gas scrubber prices in the U.S. vary widely depending on type, capacity, design, and application. Below are general pricing categories:
🧪 Laboratory Cleaners
Tailored for purification of limited exhaust flows in lab setups.
• 3-liter unit: approx. $5,225
• 20-liter unit: approx. $10,129
🏭 Industrial Structures
Applied across various industrial operations to control high exhaust output:
• Small to mid-size unit cost: from $5,000 to $100,000
• Large-scale devices: from $100,000 to several million dollars, based on complexity and performance
Cost-Influencing Factors:
• Technology used: Venturi, Packed Bed, Spray Tower, and more.
• Materials: stainless steel, FRP, PVC, etc.
• Capacity: air flow rate in m³/h
• Removal efficiency: required contaminant elimination level
• Additional features: automation devices, mist eliminators, pumps, and more
Factors such as flow rate, chemical resistance, and automation features significantly influence gas scrubber cost.
🧪 Laboratory Cleaners
Tailored for purification of limited exhaust flows in lab setups.
• 3-liter unit: approx. $5,225
• 20-liter unit: approx. $10,129
🏭 Industrial Structures
Applied across various industrial operations to control high exhaust output:
• Small to mid-size unit cost: from $5,000 to $100,000
• Large-scale devices: from $100,000 to several million dollars, based on complexity and performance
Cost-Influencing Factors:
• Technology used: Venturi, Packed Bed, Spray Tower, and more.
• Materials: stainless steel, FRP, PVC, etc.
• Capacity: air flow rate in m³/h
• Removal efficiency: required contaminant elimination level
• Additional features: automation devices, mist eliminators, pumps, and more
Factors such as flow rate, chemical resistance, and automation features significantly influence gas scrubber cost.
General Specifications
We provide detailed gas scrubber specifications for each model to help you choose the right system.
Below are general parameters:
Below are general parameters:
Parameter | Description |
Construction material | Depends on media aggressiveness — stainless steel (SS304, SS316L), FRP, PVC, polypropylene, or rubber-lined carbon steel. |
Capacity | From 500 to 100,000 m³/h and beyond — determined by emission volume calculations. |
Inlet air temperature | Typically up to 80 °C (cooling required above this); materials selected accordingly. |
Operating pressure | Operates at atmospheric or slightly reduced pressure; acceptable pressure drop ranges from 50 to 500 mm H₂O, with exact values defined by the system's configuration. |
Pollutants removed | Gaseous compounds (SO₂, HCl, NH₃, H₂S, Cl₂, etc.) as well as dust and aerosols down to 0.5–5 μm. |
Removal efficiency | Up to 95–99.9% depending on configuration, neutralizing substances, and operating conditions. |
Scrubbing solution | Water, NaOH, H₂SO₄, NaOCl, hydrogen peroxide, or other agents. Recycled water with periodic regeneration may also be used. |
Liquid consumption | Pollutant concentration removal requirements span 2–20 L/m³, contingent on equipment and substance. |
Mist eliminator | Necessary to eliminate liquid carryover, using devices like mesh pads or vane mist eliminators. |
Automation device | May include controls for pH, fluid level, temperature, and pressure; system operation can be manual or PLC-controlled. |
Overview TORNADO-RP
Efficiency Optimization
There are several ways to improve gas scrubber efficiency:
– Increasing the contact surface area between interacting phases;
– Enhancing the degree of interaction between these phases.
A direct method to increase the contact area is by enlarging the packing layer, as used in packed bed devices. However, this often leads to clogging due to adhesive particles, as greater surface area typically results in reduced porosity.
An indirect method involves generating a fine mist instead of a continuous film, thereby increasing the interaction surface between the phases. Enhancing the phase interaction through controlled turbulent flow not only increases the surface area (by creating fine droplets), but also intensifies the exchange between phases (by continuously renewing the interface).
Absorption towers that utilize this indirect intensification method include inertial-type units: Venturi, rotary, and dynamic units. When handling resinous contaminants, uninterrupted operation requires internal geometry that maintains proper hydrodynamic conditions. This entails creating a fine-dispersed environment for pollutant capture and avoiding dry zones and stationary internal components inside the unit.
– Increasing the contact surface area between interacting phases;
– Enhancing the degree of interaction between these phases.
A direct method to increase the contact area is by enlarging the packing layer, as used in packed bed devices. However, this often leads to clogging due to adhesive particles, as greater surface area typically results in reduced porosity.
An indirect method involves generating a fine mist instead of a continuous film, thereby increasing the interaction surface between the phases. Enhancing the phase interaction through controlled turbulent flow not only increases the surface area (by creating fine droplets), but also intensifies the exchange between phases (by continuously renewing the interface).
Absorption towers that utilize this indirect intensification method include inertial-type units: Venturi, rotary, and dynamic units. When handling resinous contaminants, uninterrupted operation requires internal geometry that maintains proper hydrodynamic conditions. This entails creating a fine-dispersed environment for pollutant capture and avoiding dry zones and stationary internal components inside the unit.
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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
Vladimir Nikulin
CALCULATION AND SELECTION
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