Air Pollution Control

About Air Pollution Control Equipment and Air Pollution Control Including: Air Scrubbers, Electrostatic Precipitators, Incinerators, Mist Collectors, Odor Control Systems & Oxidizers.

Air pollution control equipment removes and eliminates a wide variety of pollutants, known as volatile organic compounds (VOCs)-including fumes, gases, odors and vapors-from the atmosphere. Hazardous Air Pollutants (HAPs) can cause even more serious environmental and biological damage than other VOCs, but they can also be destroyed by air pollution control equipment. Oxidation, a process in which contaminated air pollutants are broken up and reformed into new, safe compounds, is at the heart of most of these systems. Automotive, agricultural, oil and gas, mining, woodworking, chemical and pharmaceutical industries utilize air pollution control. A facility is considered to have significant air pollution emissions if it releases about one or more tons per calendar year. To remain in compliance with regulatory requirements, facilities can use data-providing Continuous Emissions Monitoring Systems (CEMS) to aid in the control, monitoring and reporting of pollutant emissions.
 
A variety of air pollution control equipment exists. Knowing the amount of airflow and the amount and type of VOCs being emitted basically determines which technology would be most appropriate. The %LEL is based on the type and concentration of the contaminants. It is also helpful to know what to look for in VOC destruction efficiency, attrition rate and heat exchanger efficiency. What are the requirements for the inlet/outlet temperature? What are the gas pressure requirements? Having the answers to these questions is also advantageous when choosing what type of air pollution control equipment is needed in a given facility. Air pollution control services can work with each application's specific needs in order to find the best solution.
 
Oxidizers come in two broad types: thermal and catalytic. Thermal and catalytic oxidizers are typically either regenerative or recuperative. Regenerative thermal oxidizers oxidize organics in a retention chamber and have two or more ceramic heat transfer beds that act as smaller heat exchangers. Recuperative thermal oxidizers use a plate, shell, tube or other conventional type of heat exchanger to heat incoming air with air from the oxidation process. A regenerative catalytic oxidizer preheats VOC-contaminated process gas in an energy recovery chamber. A catalyst oxidizes the VOCs, which then release enough energy to allow self-sustained operation. A catalytic recuperative oxidizer preheats VOC-laden air through the tube side of the heat exchanger. The air is raised to the operating temperature and passed through the catalyst, causing a heat releasing reaction to take place. The contaminant-free air is then released back into the atmosphere.
 
Air pollution control equipment is available in a variety of other types. Particulate controls include electrostatic precipitators, which use electrical fields to remove particulate from boiler flue gas, and fabric filters, which use tightly woven fabric to sieve flue gas and collect particulate. Wet scrubbers, which include venturi scrubbers, are effective as acid gas and SO2 controls but have low efficiencies for smaller particles. Multiple cyclones have a large number of small cyclones in parallel to control particulate, but collection efficiencies drop off rapidly with particle size. NOx 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 to use. Thermal and catalytic oxidation and biofiltration are common VOC controls utilized when the VOC stream has no recovery value.

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.

Air Pollution Control Equipment Types

• Air scrubbers consist of a fan containing several filters that separate contaminants from clean air and recirculate the air into the atmosphere.
  
• Catalytic oxidizers utilize a metal catalyst, such as platinum, within the unit to speed the break down of hazardous compounds. The use of a catalyst allows the substance breakdown to occur at a lower temperature than that of a thermal oxidizer.
  
• Dust collectors use an online process to either retrieve usable granular solid or powder from process streams or to eliminate granular solid pollutants from exhaust gases before they are vented into the atmosphere.
  
• Electrostatic precipitators utilize grounded electrodes called collection plates to ionize and capture dust and particulate matter in contaminated air. These systems are often used prior to other pollution control equipment.
  
• Gas scrubbers use a high-energy liquid spray to remove gaseous pollutants, such as sulfur, from an air stream, either by absorption or chemical reaction.
  
• Incinerators are apparatuses, such as a furnace, designed to burn waste.
  
• Ionizing wet scrubbers remove acid gases and fine particulate that can include a variety of heavy metals such as antimony, lead and zinc from the air stream.
  
• Mist collectors, which consist of a filter containing mesh and steel wire, capture mists of water and oil created during industrial applications.
  
• Odor control systems neutralize unpleasant smelling gases.
  
• Oxidizers are chemicals that readily yield oxygen and can be used to start or to feed fires.
  
• Particulate control systems utilize systems, such as electrostatic precipitators (ESPs), baghouses, wet particulate scrubbers, mechanical/inertial collectors (cyclones/mutilcyclones) and high temperature/high pressure (HTHP) particulate control systems, to control ash that is emitted into the atmosphere through combustion, industrial processes, fugitive emissions and natural sources.
  
• Rotary concentrators compress air and gas streams containing small amounts of VOCs into concentrating streams containing greater volumes of VOCs, which makes it easier for oxidizers to break down.
  
• Thermal oxidizers heat contaminated air in order to break down hazardous compounds into carbon dioxide and water vapor, a process called oxidation. In order to conserve energy, many thermal oxidizers contain a heat exchanger (http://www.heatexchangers.org) that recovers and reuses the heat from incoming polluted air.
  
• Venturi scrubbers are wet scrubbers that collect extremely tiny (less than a micron) dust particles from the gas stream in a slurry system using an orifice to spray water into the vortex in the cyclone section.
  
• VOC abatement is a process in which VOCs are rendered inert by removing them from the point of generation, subjecting them to high temperature and long residence time and then discharging the resulting treated gas into atmosphere.
  
• VOC destruction is the oxidation process in which VOCs are heated by incineration or subjected to microorganisms (biodegradation) to produce carbon dioxide and water.
  
• Wet scrubbers are devices in which exhaust air is forced into a spray chamber wherein the water particles cause the dust to drop from the air stream.