Air Pollution Control Industry Information

Air pollution control equipment removes and eliminates a wide variety of pollutants, known as volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) including sulfuric fumes, gases, odors and vapors from the atmosphere. VOCs and HAPs cause serious environmental and biological damage resulting in smog, acid rain, carbon emissions and global warming, but they are reduced or eliminated by air pollution control equipment. To remain in compliance with federal emissions regulations, facilities must install emission control systems to keep air pollution output below levels specific to facility size and pollutant type. Oxidizers perform a process in which air pollutants such as hydrogen sulfide are broken up and reformed by incinerators into safe, non-toxic carbon; this process, called oxidation, is performed by burning air pollutants and is at the heart of most of these systems. Depending on the type of air pollution being controlled, facilities may also use wet scrubbers or dry air scrubbers, mist collectors, electrostatic precipitators, odor control systems or simply air filtration systems. Automotive, agricultural, petrochemical processing, mining, pharmaceutical and most industrial manufacturing facilities require air pollution control systems to regulate air purity inside the facility and without. To recuperate the some of the cost of running this equipment, many manufacturers use heat recovery systems as well.

Oxidizers may be thermal or catalytic, using either high heat or elemental additives to catalyze oxidation, or burning of VOCs. Catalytic oxidizers typically wash polluted air in platinum or palladium, causing oxygen to separate from VOCs and create non-toxic bi-products such as nitrogen and oxygen, as opposed to nitric oxide. Both catalytic and thermal oxidizers may be regenerative or recuperative. Recuperative oxidizers use ceramic heat transfer beds to recover as much energy as possible from the oxidization process -- often as much as 90% to 95%. These heat transfer beds act as heat exchangers, coupled to a retention chamber where the organics are oxidized. Regenerative thermal oxidizers recover up to 90-95% of the heat energy released from oxidation processes with ceramic heat transfer beds. Recuperative oxidizers use a plate, shell, tube or other conventional type of heat exchanger to preheat VOC-contaminated process gas in an energy recovery chamber. A catalyst - either heat or elemental additives - oxidizes the VOCs, which then release enough energy to allow self-sustained operation.

Non-oxidizing air pollution control equipment uses a variety of filtering methods to separate volatile organic and inorganic compounds from processed air. Air scrubbers may be dry scrubbers or wet scrubbers; dry scrubbers remove acid gases such as sulfuric oxide and hydrogen chloride using dry sorbent alkaline materials, while wet scrubbers clean flue gas of larger pollutants and dust using water or other liquid reagents. Electrostatic precipitators clean pollutants and dust particles from polluted air using electrical ionizing fields and tightly woven fabric filters to remove particulate from boiler flue gas and other process air. Electrostatic precipitators often filter process smoke, mist or other large liquid or solid particle contaminants in a process called mist collection. Mist collectors and oxidizers are often used as odor control systems for high methane producing facilities such as pulp and paper or livestock processing. Nitrogen oxide controls include the processes of selective catalytic reduction, which controls emissions of nitrogen oxides from stationary sources, and selective non-catalytic reduction, which changes oxides of nitrogen (NOx) into molecular nitrogen (N2). If VOCs have recovery value, carbon adsorption, scrubbing and condensation are typical techniques may recuperate materials. Thermal and catalytic oxidation and biofiltration are common VOC controls utilized when the VOC stream has no recovery value.
 
The Environmental Protection Agency has stipulated federal regulations regarding industrial facility air pollution emissions which limit the type and quantity of Volatile Organic Compounds and Hazardous Air Pollutants industrial manufacturing facilities may emit during processing. VOCs and HAPs pose threats not only to the safety of the environment and local ecosystems, but to human health as well. 188 HAPs have been regulated which are suspected or proven to cause cancer, birth defects and other serious health effects. Based on the federal regulations laid down in the Clean Air Act, the National Ambient Air Quality Standards (NAAQS) is a set of emissions standards based on scientific studies spanning several years designed to protect the health and safety of the environment and public. Most of these standards are recent, having been implemented only within the last ten to twenty years. Facilities may use data-providing Continuous Emissions Monitoring Systems (CEMS) to aid in the control, monitoring and reporting of pollutant emissions. VOC and HAP emissions have significantly decreased as a result of these strict regulations, but the emission of carbon, a non-volatile organic compound, is becoming of greater concern to environmentalists, lobbyists, state and federal legislators in recent years due to global climate change. Recent and proposed state and federal emissions regulations are beginning to concentrate on lowering carbon emissions further, a regulation which may require manufacturers to seek alternatives to oxidizers and incinerators.

Air Pollution Control Equipment and Air Pollution Control Images Provided by Anguil Environmental Systems, Inc.	Air Pollution Control Equipment and Air Pollution Control Images Provided by APC Technologies, Inc.