This article takes an in depth look at Air Scrubbers.
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An air scrubber is an air purification system designed to remove particulate matter from the air by using moisture, cooling, or filtration methods as air passes through the unit. There are two main types of air scrubbers: wet and dry, which differ in their particle removal techniques. The primary role of an air scrubber is to make the air breathable again after it has been contaminated by toxic fumes, chemicals, gases, or pollutants.
Air scrubbers are crucial in industrial settings where pollutants or toxic gases are generated. They ensure that the air exiting a facility is free from contaminants, hazardous emissions, and pollutants. In addition to their primary role in air purification, air scrubbers also help eliminate unpleasant odors and provide fresh, clean air.
Concern about air quality has significantly increased over the past fifty years. What was once deemed an acceptable byproduct of industry is now recognized as a threat to public health and quality of life. In response to the growing demand for environmental protection, companies and government agencies are working diligently to establish standards and regulations to ensure that the air we breathe is clean and free of pollutants.
One significant advancement in the fight against pollution is the widespread adoption of air scrubbers. These devices are engineered to remove contaminants and harmful substances from the air. Air scrubbers come in various sizes to accommodate both large industrial operations and residential needs, making them a crucial tool in addressing air pollution.
The air scrubber process is conducted in multiple stages, with each stage performing a specific function. It begins with a series of filters designed to capture larger particles that could interfere with the scrubber’s operation.
In any air filtration system, there will be large particles that may hamper the process and clog parts of the mechanism. Though these particles are regarded as large, they are not visible to the naked eye and can be as small as 2.5 micrometers (µm) and up to 5 µm in diameter with some as large as 90 µm to 100 µm. These are the types of particles that irritate your eye without being seen.
Prior to air entering an air scrubber, the minute particles must be removed and filtered out of the air stream; this is completed by a pre-filtration system using a high efficiency particulate air (HEPA) filter capable of removing 99.95% of contaminants. Pre-filters protect larger filters from clogging and enhance filter lifespan. Another benefit of a pre-filter is its ability to maintain a regular and even airflow rate.
While the pre-filter effectively captures many small particles, some particles smaller than one micron may still pass through. To ensure the complete removal of all particulate matter, regardless of size, a primary filter is used in the second stage of the air scrubber process.
The primary filter, also a HEPA filter, is designed to capture particles as small as 0.3 microns. This additional filtration step further purifies the air, ensuring the air scrubber operates efficiently. As illustrated in the image below, the primary filter is thicker and heavier compared to the pre-filter.
A carbon filter is not typically a standard component of an air scrubber but is often added for specific applications and conditions. The primary function of an air scrubber is to remove toxic materials, pollutants, chemicals, and other hazardous substances from the air, which is its main purpose and design.
Certain industries, such as portable toilet services, juice production, and solid waste management, generate strong and unpleasant odors. These odors can be bothersome for workers and lead to numerous complaints from nearby residents.
Adding a carbon filter to an air scrubber helps address these issues by removing gaseous molecules responsible for unpleasant smells. Carbon filters work by attracting and absorbing odors. For example, just one gram of activated carbon can absorb odors over an area of 2,000 square meters (2,391 square yards).
Carbon bed filters are designed to remove organic contaminants from inorganic fluid streams. The filter consists of activated carbon placed in a frame that captures organic particles as the fluid flows through it. The purified fluid is then expelled through an outlet nozzle. The carbon used in these filters is granular activated carbon derived from coal, which has been activated through high-temperature steam treatment.
The activation process enhances the carbon’s ability to absorb impurities of various molecular weights, giving it a longer service life and fewer operational issues. Activated carbon can absorb up to 20% of its weight in impurities.
Carbon bed filters are employed in sensitive environments such as military applications, food processing, and pharmaceutical laboratories. They are particularly useful in situations where oil or other contaminants might be present in the air.
Each air scrubber design is unique and tailored to the specifications of its manufacturer. Additional features and components, such as carbon filters, may be incorporated to enhance the efficiency and effectiveness of the system. For example, some air scrubber models include ultraviolet (UV) lights as part of their design.
In such systems, UV lights help inactivate airborne pathogens and microorganisms, including mold, bacteria, and viruses, as they pass through the air stream. By disrupting the DNA of these contaminants, UV light renders them ineffective. While traditional filters can trap and contain pollutants, UV air purification actively kills and neutralizes them, providing an added layer of protection.
For an air scrubber to operate at maximum efficiency, it must include a mechanism to draw the air stream into the filtration and purification system. This component is commonly referred to as a blower, though it may also be called a fan depending on the design and manufacturer.
Despite the variations in design and configuration, the blower or fan is essential for pulling air through the system, allowing it to be filtered and cleaned of odors and particulates. Some blowers are equipped with variable speeds to adjust to different airflow rates and pressures, optimizing the air scrubber's performance.
A spray tower scrubber directs the gas stream into a spray chamber where it is treated with chemicals via spray nozzles that apply scrubbing liquids. The droplet size is carefully controlled to enhance contact with particles and improve separation from the gas stream. The flow configuration of the spray chamber can be set for cross flow, countercurrent flow, or concurrent flow, and often includes baffles to maximize the interaction between gas and liquid.
In this process, the spray tower scrubber forces contaminated fumes through a mist of liquid, which captures and removes the gas particles. Spray tower scrubbers are effective at trapping particles as small as 10 microns and can also remove gases such as sulfur dioxide, chromic acid, hydrogen sulfide, ammonia, chlorides, and fluorides.
Dry air scrubbers utilize high-speed sprayed reagents that are introduced into the exhaust stream to target specific pollutants. The chemical reaction between the reagent and the pollutants causes the contaminants to be removed from the air stream. The captured pollutants, along with the reagent, are either burned off by the heat of the exhaust stream or collected in a filter, making dry air scrubbers an environmentally friendly option.
Dry air scrubbers are also more cost-effective to operate because they do not require the management or disposal of wastewater. They are primarily used for capturing solvents and acidic gases.
Air scrubbers are available in various types to accommodate different conditions, types of particulate waste, and environmental needs. As industrial processes have evolved, so has air scrubber technology, adapting to address a broader range of pollutants. The focus has expanded from controlling smoke and carbon monoxide emissions to managing a diverse array of chemicals associated with modern production.
Manufacturers have refined air scrubbers to specialize in targeting specific pollutants, chemicals, and toxic substances. Research into industrial waste has revealed that different industries produce unique types of contaminants. This insight has driven the development of air scrubbers designed to handle either a single type of pollutant or multiple contaminants effectively.
Electrostatic precipitators use electrical energy to remove dust and contaminants from gasses. The design of an electrostatic precipitator has to match the polarity and charge of the material to be removed such that it binds to them and captures them. Each configuration of electrostatic precipitator can be adjusted, so it targets the specific needs of an application.
A plate precipitator is one of the simplest air cleaning devices. It features rows of wires connected to large, flat plates that are evenly spaced. As the air stream flows over these plates, a negative voltage is applied between the wires and the plates. This voltage ionizes the particles in the air, causing them to adhere to the grounded plates, where they are then removed from the air stream and collected.
In a dry electrostatic precipitator, high-voltage electrodes impart an electrical charge to particles in the gas stream. These charged particles are then attracted to a grounded collecting surface. To remove the collected particles, vibrations are applied, causing them to dislodge and fall into a hopper for disposal.
Dry electrostatic precipitators operate at temperatures above the dew point of the gas stream and are designed to collect wood and coal ashes from boilers and incinerators. The major benefit of dry electrostatic precipitators is their ability to collect and move collected toxic materials in a dry condition; this eliminates the use of water and pollution concerns.
A wet electrostatic precipitator (WESP) employs a highly charged electrical field to attract and collect particles from an air or gas stream onto a grounded surface. Negatively charged particles adhere to metal plates or wires, where they are subsequently washed off using water spray, irrigation, or condensation, and then collected in a container. WESPs are particularly effective at removing airborne liquid droplets, such as sulfuric acid mist.
WESP air scrubbers come in various designs, including tubular, circular plate, concentric plate, or flat plate configurations, and often feature an external cooling system to maintain clean walls. These designs contribute to a smaller footprint and reduced cost. They are ideal for gas exhaust streams that contain sticky, condensable hydrocarbons and potentially hazardous or explosive materials.
Additionally, WESP air scrubbers are equipped with a pre-quench water spray system that cools and saturates gases before they enter the electrical field. They offer a high efficiency rating of 99% for particle removal down to 0.01 microns, with a pressure drop of 1.0 inches of water column (WC).
A tubular electrostatic precipitator features high-voltage tubes arranged in parallel, forming a circular, square, or hexagonal honeycomb structure. The gas stream can flow either upward from the bottom or downward from the top of the unit.
One of the key advantages of the tubular design is its effectiveness in removing large dust particles. It achieves a high removal rate, capturing nearly 90% of the pollutant material from the air stream. Tubular electrostatic precipitators are particularly suited for environments where viscous or dense particles are present.
Portable air scrubbers are utilized during renovations or other extensive indoor projects where contaminants might be released into the air, and installing a permanent air scrubbing system is not feasible. These units are equipped with exhaust tubes that channel air from the interior space to the outside environment.
These portable units feature a series of HEPA filters to purify the air before it is expelled. Additionally, they are often equipped with photocatalytic purifiers that, similar to UV light, convert pollutants into harmless substances.
A negative air scrubber operates by creating negative air pressure within a confined area to capture and collect contaminants. This principle leverages the natural tendency of air to flow from high-pressure areas to low-pressure ones. By maintaining negative pressure, the scrubber ensures that air, along with contaminants, is drawn into the work area rather than escaping through leaks or openings.
Negative air scrubbers are particularly essential during the renovation of older buildings, where hazardous materials like asbestos—once commonly used but now banned—might be present. These scrubbers effectively prevent asbestos and other contaminants from escaping into the environment, thus avoiding serious legal and environmental issues.
These units can handle airflows of up to 2000 cubic feet per minute (56 cubic meters per minute) and are equipped with a triple-stage HEPA filtration system designed to capture mold, asbestos, bacteria, dust, and other airborne pollutants. The continuous, efficient operation of a negative air scrubber helps maintain a clean, safe, and healthy environment.
Packed bed or packed tower scrubbers are specially designed wet scrubbers for chemical scrubbing of gaseous contaminants. A packed bed is a hollow tube, pipe, or container that is filled with material that can contain a catalyst such as zeolite pellets and granular activated carbon, a packing media to facilitate intimate contact between a scrubbing reagent liquid and the gas to be scrubbed.
In a vertical packed bed air scrubber, contaminated gas ascends through the tower while scrubbing liquids descend. The packing section facilitates the absorption of gases, enabling purified air to exit through the top of the tower. Conversely, in a horizontal packed bed air scrubber, the contaminated gas flows horizontally through the scrubber.
A cyclone spray chamber integrates both a cyclone tower and a spray tower. As the air stream enters the chamber at high velocity, it generates a cyclonic effect. This action propels heavier droplets, which contain contaminants and particulate matter, against the chamber walls, while the cleaner, lighter air escapes. Although cyclone spray chambers are highly effective, they demand significant energy to maintain their high-pressure operation.
A venturi air scrubber features a venturi-shaped chamber with a narrow throat at its center. This device utilizes a wet water jet method to clean the air stream. As dust-laden air accelerates through the converging section of the venturi, it is atomized in the throat where dust particles interact with water droplets. The heavier droplets, now containing contaminants, are then directed into the cyclonic section of the scrubber. Here, they are forced against the chamber walls and then flow down into a collector at the bottom.
Different manufacturing processes generate distinct chemicals and pollutants, including ammonia, chlorine, various dust types, and acids. To effectively remove these specific contaminants, air scrubbers must be tailored to address each type of pollutant. Typically, these are wet scrubbers that incorporate chemical agents, as water alone is often insufficient for effective cleaning.
Chemical and gas air scrubbers achieve optimal efficiency when there is adequate contact between the contaminants and the scrubbing agents. Typically, these scrubbers are packed bed designs that incorporate recycle pumps and mist eliminators to enhance performance and ensure thorough removal of pollutants.
Particulate scrubbers are designed to manage gas streams that contain moisture or operate at elevated temperatures. These compact units are capable of removing both particulate matter and gaseous contaminants effectively.
An ammonia scrubber is a specialized wet scrubber designed to treat ammonia-laden gas streams. It operates by directing the ammonia through a packed bed tower, where it is sprayed with a chemical solution specifically formulated to react with ammonia. Often, this chemical solution includes a substantial amount of sulfuric acid, which is a cost-effective method for ammonia removal.
A chlorine air scrubber is a type of packed bed scrubber that employs a neutralizing agent, such as soda ash. When chlorine gas enters the system, it is exposed to the cleaning agent, which reacts with and neutralizes the chlorine. The treated gas then passes through a packing medium for further processing.
A dust air scrubber is a type of wet air scrubber designed to remove particulate matter from the air. It operates by directing the air stream at high velocity into a wetted throat, where it strikes the walls and causes the particulates to break into droplets. These droplets then fall into a sump, forming a sludge for removal. To ensure thorough removal, the air from the sump is further processed through a mist eliminator.
Chemical producers that emit sulfur-based materials are legally required to remove any toxic byproducts from their processes. The most common air scrubber used for sulfuric acid is a wet packed bed scrubber, which employs a recirculated liquid caustic solution, such as sodium hydroxide, to neutralize the acid. This solution removes vapors, and the process is completed with a mist eliminator. The sulfuric acid removal process typically involves multiple stages, starting with the packed bed scrubber.
Commercial kitchens generate a range of pollutants that may not comply with existing exhaust standards. To address this gap, Underwriter Laboratories (UL) and air scrubber manufacturers developed UL 8782, an Outline of Investigation for Pollution Control Units (PCUs). UL 8782 specifies the requirements for PCU assemblies used in commercial cooking operations, including the types of ducts for exhausting heat, smoke, and grease-laden vapors.
UL 8782 is aligned with NFPA 96, the Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations, as well as the International Mechanical Code and the Uniform Mechanical Code. The standard incorporates testing and safety concepts from UL's guidelines for commercial kitchen exhaust systems.
The primary benefit of air scrubbers is their ability to remove toxic materials and pollutants from the air. This key function makes air scrubbers essential for preventing environmental contamination and air pollution.
The Environmental Protection Agency (EPA) closely monitors air quality due to the potential health effects of polluted air, ranging from minor to severe. The EPA's vigilance, along with the concerns of manufacturers and producers, has driven the widespread adoption of air scrubbers.
Air scrubbers are utilized in a variety of settings, including homes, factories, offices, and commercial locations. Essentially, wherever clean air is a priority, an air scrubber is likely to be employed.
Enclosed spaces often have air quality that is two to five times more polluted than outdoor air. According to the EPA, indoor air in buildings, homes, and manufacturing plants can be up to five times more hazardous than outdoor air.
Air scrubbers provide an ideal solution to this problem, capable of removing up to 99.99% of pollutants, contaminants, and toxins. Nearly every commercial operation utilizes air scrubbers to safeguard the health of its workers and customers, highlighting their exceptional effectiveness and importance in maintaining a safe environment.
Each year, the list of chemicals requiring control has expanded in accordance with the Clean Air Act Amendments of 1990. This list includes 189 hazardous air pollutants (HAPs), ranging from acetaldehyde to xylenes, which must be managed to prevent accidental release. Among these, 100 chemicals are classified as extremely hazardous air pollutants (EHAPs), necessitating government approval for their prevention and control measures.
The increasing environmental concerns have driven the development and adoption of methods to prevent and control the emission of HAPs and EHAPs. While various methods are being explored, air scrubbers have emerged as a highly reliable and effective solution to address these environmental challenges.
Many facilities rely on air conditioning systems to manage airflow and reduce the spread of pollutants. However, while these systems are effective at controlling air flow, they lack the robust capabilities of an air scrubber.
Manufacturer data indicates that air scrubbers are 50 times more effective than HVAC systems in eliminating and controlling airborne contaminants and pathogens. An air scrubber's filtration system can remove up to 90% of pollutants and contaminants within the first half-hour of operation.
Air fresheners are marketed as solutions for eliminating odors and adding a pleasant scent to the air. However, they can actually contribute to air pollution by introducing additional chemicals into already contaminated air. Unlike air scrubbers, which work to remove harmful substances, air fresheners often add more pollutants to the environment.
In contrast, air scrubbers use charged ions to kill and remove bacteria, odors, contaminants, pollutants, and chemicals, including those from air fresheners. They effectively eliminate odors from spoiled food, rotting substances, and manufacturing processes, replacing them with fresh, clean air.
HVAC systems work hard to regulate air temperature and filter out pollutants, which can lead to increased wear and a shorter lifespan. By installing an air scrubber, the workload on the HVAC system is significantly reduced, thereby extending its longevity and efficiency.
With an air scrubber in place, the air is cleansed of fine particles like pollen and dust, allowing the HVAC system to focus on cooling rather than dealing with airborne contaminants. This not only improves the system's performance but also enhances overall air quality.
Approximately 36 million people suffer from some form of allergy, with pollen being the most common allergen. Pollen, a fine powder produced by trees, flowers, grasses, and weeds, is essential for plant reproduction but can trigger uncomfortable allergic reactions in sensitive individuals.
Most air conditioning or HVAC systems struggle to filter out pollen due to its tiny size. In contrast, air scrubbers are designed to capture and remove even the smallest pollen particles and other pollutants. By employing deionization and advanced filtration systems, air scrubbers effectively control pollen and alleviate allergy symptoms. They purify the air, making it clean, clear, and free of pollen.
Indoor air is often polluted by particulate matter, volatile organic compounds (VOCs), and microscopic organisms. Particulate matter includes dirt, pollen, various chemicals, as well as skin and hair residues. VOCs encompass a wide range of odors, smells, vapors, and smoke.
Microscopic life forms such as bacteria, viruses, mold, and mildew also contribute to indoor air pollution. While most of these microbes are harmless, they can cause unpleasant odors and act as pollutants.
Over the years, air scrubbers have demonstrated their effectiveness in combating air pollution, removing up to 99% of microbes, particulate matter, and VOCs.
The initial cost of installing an air scrubber can seem high, ranging from $1,000 to $4,000. While the upfront expense may be significant, the long-term benefits make it a worthwhile investment. Air scrubbers offer substantial savings by reducing maintenance costs, lowering energy consumption, and minimizing medical expenses related to airborne diseases.
By removing airborne particles that strain air conditioning systems and eliminating disease-causing pathogens, air scrubbers help reduce cleaning costs, energy bills, and medical expenses.
The quality of indoor air has become a significant topic of discussion, with numerous reports, studies, and research projects highlighting its impact on public health. Various devices are designed to clean and purify indoor air, including air purifiers, HVAC systems, and moisture control systems.
Among these devices, air purifiers and humidifiers are the most well-known and widely used. They are commonly found in homes, factories, offices, and businesses as effective solutions for improving air quality and removing particulate matter. Recently, air scrubbers have emerged as an even more efficient and productive option for eliminating odors and purifying the air.
Mold is a prevalent issue in structures of all types, regardless of the environment or weather conditions. As a fast-growing fungus, it can rapidly infest indoor spaces, leading to significant deterioration of air quality, damage to surfaces, and serious health concerns.
Air scrubbers offer an effective solution for mold problems, as they are designed to tackle severe pollution across large areas.
In most cases, a portable air scrubber can effectively remove mold from the air and may only be needed until the mold issue is resolved.
Many people believe they are allergic to dust, but they are often allergic to dust mites—tiny creatures that live in dust. An air scrubber effectively addresses this issue by killing and removing dust mites from the air. Every type of air scrubber is capable of completely eliminating 100% of dust mite contamination.
As an air scrubber cleans the air, it releases oxidizers that spread through the atmosphere and assist in eliminating pathogens on surfaces and in the air. Though not necessarily a listed aspect of an air scrubber, it is a benefit that enhances and cleans the environment as well as prevents the collection of dust.
The particulate matter released from an air scrubber becomes supercharged, enabling it to effectively attack, destroy, and eliminate fungi, mold, and bacteria. These charged particles actively seek out and neutralize offensive matter, regardless of its location.
An air scrubber is a natural and eco-friendly method for cleaning the air. Unlike air fresheners, which can further pollute the air, air scrubbers work to transform and recondition the air by removing toxins in a natural and safe manner.
In essence, the primary function of an air scrubber is air cleaning. They are engineered to significantly reduce and eliminate VOCs, contaminants, mold, odors, gases, and other pollutants. Air scrubbers are utilized in a variety of settings, from factories producing acids and gases to homes seeking cleaner, healthier living environments.
Extensive research by manufacturers and users has demonstrated the effectiveness of air scrubbers in filtration. Data shows that air scrubbers are 99.99% effective in purifying and removing toxic substances from the air stream.
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