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Author: Michael Klepik, Chief Executive Officer
An air pollution scrubber is a device used to clean airstreams of pollutants such as dust, gases, vapors, and aerosols larger than 0.3–1.0 microns, as well as dust from hot and explosive streams. They are widely employed in industry to reduce the emission of harmful substances into the atmosphere.
Main Cleaning Mechanisms
According to the scrubber air pollution definition, these units are integral to compliance with environmental regulations and are typically classified as wet or dry based on the method of pollutant capture.
Absorption
This involves the absorption of gaseous pollutants by a liquid, usually water or an alkaline/acidic solution. In physical absorption, the contaminant dissolves in the liquid without a chemical reaction, whereas in chemical absorption, a reaction occurs between the gaseous components and the absorbent. The most commonly used absorbents include water, sodium hydroxide (NaOH) solution, sulfuric acid (H₂SO₄), and limewater (Ca(OH)₂).
A wet scrubber air pollution control device is effective at removing chemical impurities and vapors, odors, aerosols, and fine particulate matter, as well as complex mixtures. They are commonly employed, for example, to remove SO₂, HCl, and NH₃.
How is a scrubber used for pollution?
In the column of the pollution scrubber, nozzles spray the absorbent solution, ensuring contact with the airstream. The droplets capture larger pollutant particles, and the cleaned air exits the top of the device. The collected fluid is then subject to regeneration or disposal. To improve efficiency, especially when dealing with very fine particles, additional elements like packing materials or bubble-cap trays are employed to enhance mass transfer.
A wet scrubber air pollution control device is effective at removing chemical impurities and vapors, odors, aerosols, and fine particulate matter, as well as complex mixtures. They are commonly employed, for example, to remove SO₂, HCl, and NH₃.
How is a scrubber used for pollution?
In the column of the pollution scrubber, nozzles spray the absorbent solution, ensuring contact with the airstream. The droplets capture larger pollutant particles, and the cleaned air exits the top of the device. The collected fluid is then subject to regeneration or disposal. To improve efficiency, especially when dealing with very fine particles, additional elements like packing materials or bubble-cap trays are employed to enhance mass transfer.
Scheme
Typical Scrubber Configurations
Among various scrubber air pollution technologies, the spray tower stands out for its simplicity and ease of maintenance. It has no internal packing and relies on liquid sprayed through nozzles to remove contaminants from the airstream.
The specific water consumption in spray towers is about 3–6 L/m³, and the gas flow velocity ranges from 0.7 to 1.5 m/s. They are relatively ineffective for fine particulate matter but offer low cost and easy maintenance.
Among various scrubber air pollution technologies, the spray tower stands out for its simplicity and ease of maintenance. It has no internal packing and relies on liquid sprayed through nozzles to remove contaminants from the airstream.
The specific water consumption in spray towers is about 3–6 L/m³, and the gas flow velocity ranges from 0.7 to 1.5 m/s. They are relatively ineffective for fine particulate matter but offer low cost and easy maintenance.
A Venturi scrubber air pollution control device is highly effective at capturing PM₁₀ and PM₂.₅, achieving efficiencies of 70–99%, and often exceeding 99% when optimal pressure drop (Δp) and L/G ratios are employed. Venturi scrubber pollution solutions are widely applied in high-temperature, high-concentration processes in metallurgy, cement, chemical, energy industries, and waste-to-energy plants.
The unit is designed as a tube with a smooth converging section (converging nozzle), a narrow throat (the Venturi throat), and a diverging section (diffuser). Liquid is introduced via nozzles upstream of the throat. The particle-laden flow accelerates through the throat, where it intimately contacts the atomized solution.
The unit is designed as a tube with a smooth converging section (converging nozzle), a narrow throat (the Venturi throat), and a diverging section (diffuser). Liquid is introduced via nozzles upstream of the throat. The particle-laden flow accelerates through the throat, where it intimately contacts the atomized solution.
Tray Tower (Plate Column) – These units feature specially designed trays with holes, slits, or nozzles.
How does a scrubber remove air pollutants? The gas stream enters from the bottom and rises through the column, meeting liquid introduced from the top or side. As the air velocity reaches 2–2.5 m/s, the liquid begins to foam, forming a stable structure where particles and contaminants closely interact with foam bubbles. The foam eventually collapses (either naturally or in a designated section), and the cleaned stream exits from the top. A plate column scrubber for air pollution control reaches a dust removal efficiency of 95–96% with water consumption of 0.4–0.5 L/m³. They have lower energy consumption compared to Venturi units and require less maintenance due to the absence of complex moving parts.
How does a scrubber remove air pollutants? The gas stream enters from the bottom and rises through the column, meeting liquid introduced from the top or side. As the air velocity reaches 2–2.5 m/s, the liquid begins to foam, forming a stable structure where particles and contaminants closely interact with foam bubbles. The foam eventually collapses (either naturally or in a designated section), and the cleaned stream exits from the top. A plate column scrubber for air pollution control reaches a dust removal efficiency of 95–96% with water consumption of 0.4–0.5 L/m³. They have lower energy consumption compared to Venturi units and require less maintenance due to the absence of complex moving parts.
Packed Bed Towers – In these, contaminated airflows through a bed of packing material that is continuously wetted by working fluid. The packing offers an extended interface between phases, enhancing mass transfer and the removal of harmful substances.
Their highly developed surface enhances gas-liquid interaction. They are suitable for handling aggressive and hot gas streams and provide stable operation. However, there's a risk of clogging under high dust loads, and their hydraulic resistance is higher than that of spray towers. This type is most effective in the chemical and metallurgical industries for capturing acidic and alkaline gases, such as ammonia vapor, sulfur dioxide, and hydrogen fluoride. A packed air pollution control equipment scrubber is also frequently used as an absorption column in integrated air treatment installations.
Their highly developed surface enhances gas-liquid interaction. They are suitable for handling aggressive and hot gas streams and provide stable operation. However, there's a risk of clogging under high dust loads, and their hydraulic resistance is higher than that of spray towers. This type is most effective in the chemical and metallurgical industries for capturing acidic and alkaline gases, such as ammonia vapor, sulfur dioxide, and hydrogen fluoride. A packed air pollution control equipment scrubber is also frequently used as an absorption column in integrated air treatment installations.
A centrifugal scrubber in air pollution control is a piece of equipment that removes particles using a combination of inertial (centrifugal) forces and interaction with a washing solution.
It performs especially well in extracting large dust particles, aerosols, droplets, and partially soluble compounds. These units feature low hydraulic resistance but require a stable rotational flow and are sensitive to turbulence. They are typically employed for purifying emissions of dust and aerosols and for trapping acid mists, soot, and oil particles. Suitable for foundries, chemical, and food processing industries.
It performs especially well in extracting large dust particles, aerosols, droplets, and partially soluble compounds. These units feature low hydraulic resistance but require a stable rotational flow and are sensitive to turbulence. They are typically employed for purifying emissions of dust and aerosols and for trapping acid mists, soot, and oil particles. Suitable for foundries, chemical, and food processing industries.
Adsorption Method
It is the process of capturing contaminants on the surface of a solid material—called an adsorbent (e.g., activated carbon, zeolite, or lime)—through physical or chemical interactions. This method is commonly applied for the elimination of VOCs (volatile organic compounds), heavy metal vapors, and odors.
Air Extraction and Dry Filtration Systems for Electroplating Tanks and Other Industrial Uses
How does a scrubber remove pollutants using adsorption?
Contaminated flow is directed through adsorption cartridges, where it is purified before being released from the chamber. This technique is often utilized to extract CO₂ from storage tanks. The filter can purify both incoming and outgoing air, which is why it is referred to as a breather filter.
Contaminated flow is directed through adsorption cartridges, where it is purified before being released from the chamber. This technique is often utilized to extract CO₂ from storage tanks. The filter can purify both incoming and outgoing air, which is why it is referred to as a breather filter.
Dry scrubbers like these do not produce liquid waste and are easier to operate. However, it is generally less effective than a wet scrubber for air pollution control when it comes to removing fine particles. Additionally, the adsorbent material must be replaced or regenerated regularly.
We also manufacture models adapted for indoor use, including mobile versions for added flexibility.
We also manufacture models adapted for indoor use, including mobile versions for added flexibility.
Energy Consumption and Maintenance Requirements
Type | Energy Consumption (Pressure Drop) | Maintenance Requirements |
Spray | 🔋 Low to Medium (50–600 Pa) | Simple; requires occasional nozzle cleaning |
Foam / Fluidized Bed | 🔋 Medium (300–700 Pa) | Maintain proper foaming level |
Centrifugal | 🔋 Low to Medium (300–800 Pa) | Stable, but rotation and sealing must be monitored |
Venturi | 🔋 High (1000–3000 Pa or more) | Frequent cleaning, throat wear, requires powerful fan |
Packed Bed | 🔋 Medium (500–1500 Pa) | Risk of packing clogging; requires regular washing |
If high efficiency in the elimination of fine particulate matter and gaseous pollutants is a priority, choose Venturi or packed bed towers — but be prepared for higher energy consumption and more intensive maintenance.
For pre-treatment, removal of coarse dust, and resource savings, centrifugal, spray, or hollow scrubber pollution control devices are suitable options.
When compactness and resistance to chemically aggressive environments are important, consider a foam, spray, or packed bed scrubber to reduce air pollution.
Operational Practices and Maintenance
Operating a wet scrubber air pollution control unit can pose certain challenges, particularly due to droplet carryover of water or absorbent solution from the tower, as well as deposit buildup on internal surfaces caused by phase interactions.
To reduce moisture entrainment, the equipment should function under stable operating conditions and include demisters or mist eliminators. To deal with internal buildup, the chamber surfaces are regularly washed and mechanically cleaned to remove adhered materials.
In recent years, synthetic coatings have been increasingly applied to protect equipment from deposits. For example, in U.S. practice, fan and blower blades are often coated with Teflon, which is durable and can be applied to blades of various shapes.
Since some gas components (such as SO₂) can dissolve in the absorbing liquid and form acids, a wet scrubber air pollution control system must also include corrosion protection measures for the equipment and ductwork. Additionally, proper neutralization of the wastewater (sludge water) is necessary to ensure safe discharge and environmental compliance.
To reduce moisture entrainment, the equipment should function under stable operating conditions and include demisters or mist eliminators. To deal with internal buildup, the chamber surfaces are regularly washed and mechanically cleaned to remove adhered materials.
In recent years, synthetic coatings have been increasingly applied to protect equipment from deposits. For example, in U.S. practice, fan and blower blades are often coated with Teflon, which is durable and can be applied to blades of various shapes.
Since some gas components (such as SO₂) can dissolve in the absorbing liquid and form acids, a wet scrubber air pollution control system must also include corrosion protection measures for the equipment and ductwork. Additionally, proper neutralization of the wastewater (sludge water) is necessary to ensure safe discharge and environmental compliance.
Annual Inspection Protocol
Sludge Formation and Mitigation
The washing solution applied in absorption towers becomes saturated with contaminants such as SO₂, HCl, NH₃, and solid particles, and may contain toxic compounds as a result.
Sludge, formed through the precipitation of solid contaminants and chemical reactions in the treatment fluid, may include:
To reduce environmental impact, the following measures are commonly implemented:
Monitoring the composition of the sludge is essential for hazard classification and selecting the appropriate disposal method.
Sludge, formed through the precipitation of solid contaminants and chemical reactions in the treatment fluid, may include:
- Sulfates, chlorides, and heavy metal salts
- Organic residues and ammonium compounds
- Corrosive and toxic reaction products
To reduce environmental impact, the following measures are commonly implemented:
- Filtration and sedimentation of solids, allowing the treated fluid to be recycled back into the process.
- Chemical regeneration of absorbents—e.g., neutralizing alkaline solutions with acids and vice versa.
- Use of closed-loop (recirculating) systems, where the washing solution circulates continuously, with periodic adjustments to its chemical composition.
- Biological treatment of wastewater—particularly effective for ammonia-containing solutions.
Monitoring the composition of the sludge is essential for hazard classification and selecting the appropriate disposal method.
Control Panel
Automated Monitoring and Management
Modern emission management setups increasingly incorporate automated monitoring and control solutions, enhancing the reliability, predictability, and cost-efficiency of equipment operation.
Key Functions of Automation:
• Continuous Process Monitoring
Includes measurement of:
o pH and liquid temperature
o Pressure and pressure drop (Δp)
o Composition of inlet and outlet streams
o Flow rates of gas and fluid
• Equipment Condition Tracking
Monitoring the operation of pumps, fans, spray nozzles, mixers, and liquid levels in tanks; automatic shutdown in case of malfunctions.
• Reagent Dosage Regulation
Automatic dosing of alkali, acid, or water depending on current pH, temperature, or contamination levels.
• Alarm and Emergency Shutdown
Built-in alarm system activates when parameters exceed acceptable limits. Integration with industrial SCADA setups can be implemented.
• Remote Access and Operation
Many setups are equipped with modems and web interfaces for remote configuration and diagnostics.
Advantages of Automated Systems:
📉 Reduced Operating Costs — automation optimizes reagent and energy consumption.
🛡️ Accident Prevention — early detection of abnormalities allows for timely intervention.
🔁 Improved Process Stability — real-time parameter adjustment maintains high efficiency in contaminant removal.
🧰 Reduced Staffing Needs — less manual supervision and intervention are required.
Example:
The Tornado FB is a scrubber to control air pollution that utilizes automatic pH regulation with feedback: when the pH drops below a set level, the unit doses NaOH to restore neutral conditions. This prevents equipment corrosion and ensures consistent NOₓ treatment performance.
The development of advanced technologies in air pollution scrubber factories contributes significantly to cleaner air and sustainable industry.
Key Functions of Automation:
• Continuous Process Monitoring
Includes measurement of:
o pH and liquid temperature
o Pressure and pressure drop (Δp)
o Composition of inlet and outlet streams
o Flow rates of gas and fluid
• Equipment Condition Tracking
Monitoring the operation of pumps, fans, spray nozzles, mixers, and liquid levels in tanks; automatic shutdown in case of malfunctions.
• Reagent Dosage Regulation
Automatic dosing of alkali, acid, or water depending on current pH, temperature, or contamination levels.
• Alarm and Emergency Shutdown
Built-in alarm system activates when parameters exceed acceptable limits. Integration with industrial SCADA setups can be implemented.
• Remote Access and Operation
Many setups are equipped with modems and web interfaces for remote configuration and diagnostics.
Advantages of Automated Systems:
📉 Reduced Operating Costs — automation optimizes reagent and energy consumption.
🛡️ Accident Prevention — early detection of abnormalities allows for timely intervention.
🔁 Improved Process Stability — real-time parameter adjustment maintains high efficiency in contaminant removal.
🧰 Reduced Staffing Needs — less manual supervision and intervention are required.
Example:
The Tornado FB is a scrubber to control air pollution that utilizes automatic pH regulation with feedback: when the pH drops below a set level, the unit doses NaOH to restore neutral conditions. This prevents equipment corrosion and ensures consistent NOₓ treatment performance.
The development of advanced technologies in air pollution scrubber factories contributes significantly to cleaner air and sustainable industry.
Key Automation Features
Selection Algorithm
Choosing the appropriate solution requires a systematic assessment of multiple operational and environmental factors. The following criteria outline the key parameters to consider when selecting a suitable configuration, ensuring both technical compatibility and long-term performance.
1. Gas Flow Rate (m³/h)
This is the fundamental parameter that determines the size and cross-sectional area of the column. For low gas flow rates, up to 1,000 m³/h, compact units are typically suitable. In contrast, medium to high flow rates, ranging from 5,000 to 50,000 m³/h or more, require modular or multi-stage systems to ensure effective treatment and operational flexibility.
2. Type and Nature of Pollutants
Contaminants may be physical—such as dust, aerosols, and vapors—or chemical, including harmful compounds like SO₂, HCl, HF, NH₃, NOₓ, and VOCs. The nature of the contaminant determines the appropriate choice of absorbent (e.g., water, NaOH, or H₂SO₄) and whether adsorption-based treatment is applicable.
3. Inlet Gas Temperature
Elevated gas temperatures require the use of heat-resistant construction materials such as fiberglass-reinforced plastic, titanium, or PVDF.
4. Emission Load (g/m³)
The emission load affects the required absorption capacity and the volume of recirculating liquid. In cases of high pollutant concentrations, a pre-treatment stage for coarse cleaning is often necessary.
1. Gas Flow Rate (m³/h)
This is the fundamental parameter that determines the size and cross-sectional area of the column. For low gas flow rates, up to 1,000 m³/h, compact units are typically suitable. In contrast, medium to high flow rates, ranging from 5,000 to 50,000 m³/h or more, require modular or multi-stage systems to ensure effective treatment and operational flexibility.
2. Type and Nature of Pollutants
Contaminants may be physical—such as dust, aerosols, and vapors—or chemical, including harmful compounds like SO₂, HCl, HF, NH₃, NOₓ, and VOCs. The nature of the contaminant determines the appropriate choice of absorbent (e.g., water, NaOH, or H₂SO₄) and whether adsorption-based treatment is applicable.
3. Inlet Gas Temperature
Elevated gas temperatures require the use of heat-resistant construction materials such as fiberglass-reinforced plastic, titanium, or PVDF.
4. Emission Load (g/m³)
The emission load affects the required absorption capacity and the volume of recirculating liquid. In cases of high pollutant concentrations, a pre-treatment stage for coarse cleaning is often necessary.
TORNADO Fluidized Bed
5. Space Constraints and Installation Limitations
Horizontal configurations are preferable in low-ceiling environments, while vertical units are more suitable when floor space is limited.
6. Required Cleaning Efficiency (%)
For preliminary treatment, simple spray-based systems may be sufficient. However, to achieve a removal efficiency greater than 95–99%, Venturi towers, packed beds, or fluidized bed units should be considered.
7. Presence of Aggressive Media and Corrosion Resistance
In environments with corrosive media, it is essential to select corrosion-resistant materials for both the housing and packing. Suitable options include stainless steel, various plastic linings, and protective coatings capable of withstanding acids, alkalis, chlorine, and other aggressive substances.
8. Presence of Solid Particles (Dust Load)
High dust loads require designs with self-cleaning capability and abrasion resistance. In such cases, combined system configurations or the addition of pre-filtration stages are recommended.
This structured approach ensures the selection of an industrial air pollution scrubber tailored to technical, environmental, and operational requirements.
Horizontal configurations are preferable in low-ceiling environments, while vertical units are more suitable when floor space is limited.
6. Required Cleaning Efficiency (%)
For preliminary treatment, simple spray-based systems may be sufficient. However, to achieve a removal efficiency greater than 95–99%, Venturi towers, packed beds, or fluidized bed units should be considered.
7. Presence of Aggressive Media and Corrosion Resistance
In environments with corrosive media, it is essential to select corrosion-resistant materials for both the housing and packing. Suitable options include stainless steel, various plastic linings, and protective coatings capable of withstanding acids, alkalis, chlorine, and other aggressive substances.
8. Presence of Solid Particles (Dust Load)
High dust loads require designs with self-cleaning capability and abrasion resistance. In such cases, combined system configurations or the addition of pre-filtration stages are recommended.
This structured approach ensures the selection of an industrial air pollution scrubber tailored to technical, environmental, and operational requirements.
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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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