As the full effect of the Federal Clean Air Act (CAA) Amendments passed by Congress in 1990 continue to impact today's industry, many manufacturing operations have become subject to stricter local, state, and federal clean air regulations. Both VOC (volatile organic compound) and HAP (hazardous air pollutant) emissions are strictly regulated since they lead to the formation of ground level ozone (or smog). The CAA singled out 188 air pollutants that are of special concern, many of which are used in everyday production and/or manufacturing atmospheres.
Depending upon the quantity of VOCs and/or HAPs involved, many businesses either have or will be required by local, state, or federal laws to install new or additional air pollution control equipment. With well over 25 years of proven success in a wide variety of industries, both catalytic and thermal oxidation have become very popular methods for controlling these VOC and/or HAP emissions.
Catalytic and thermal oxidation systems destroy the harmful VOCs and HAPs emitted from a manufacturing process by collecting the emissions and destroying them using elevated temperature and/or an industrial grade catalyst. Both catalytic and thermal oxidation assure thorough VOC and/or HAP destruction. Today's modern and efficient systems utilize high efficiency heat exchangers, natural gas fired burners, industrial grade blowers, electric or pneumatic actuators and programmable logic controllers (PLCs) to ensure safe and efficient operation.
Points To Consider When Selecting an Air Pollution Control System
The VOCs and HAPs present in typical process air streams can be destroyed by both catalytic and thermal oxidation systems. The type and quantity of VOCs and HAPs will, however, help to dictate the preferred abatement technology. High VOC/HAP concentrations would completely eliminate some technologies, while low concentrations could clearly favor an alternate technology.
Space requirements and installation locations should also be considered. The technology selection criteria should not be heavily influenced by the equipment floor plan. Most often, air pollution control systems are installed outdoors and can be placed on the ground, on the building roof and/or on an elevated structural steel platform. Depending upon the process airflow requirements, systems will range from 8 ft wide x 20 ft long and 8,000 lb (on the smaller size) to 40 ft wide x 60 ft long and 180,000 lb, and larger. The purchaser should first become comfortable with the technology selection from an operational point of view and then consideration should be given to space requirements.
When selecting and/or sizing an air pollution control system, the facilities growth expectations for the next 2 to 5 years should be considered. It is typically less costly to install a system that is designed to handle additional capacity now rather than to install a second system at some time in the near future. Also, many equipment vendors have the capability of providing/installing their systems under a turnkey contract where the vendor is responsible for all aspects of both installation and start-up.
As the cost of energy in North America continues to rise, purchasers should consider options to utilize the heat/energy being emitted to atmosphere. Depending upon the VOC/HAP abatement technology being used, exhaust stack temperatures will vary between 150°F and 700°F. This heat/energy can be recovered and returned back to the manufacturing facility for uses such as process supply air for web dryers and curing ovens, to heat hot oil or water coils, to make low pressure steam, for building comfort heating or a combination of the above.
Maintenance costs have been drastically reduced over the years as air pollution control systems supplied by reputable vendors have become very reliable. However, long-term repair costs could vary greatly between different technologies if a major failure were to occur; such as the airflow switching valves or the media support structure (in a regenerative oxidizer), the shell-and-tube heat exchanger (in a recuperative oxidizer) or the catalyst (in a catalytic oxidizer). To insure proper long-term operation and to reduce the future risk of major repairs, the purchaser should implement and adhere to a stringent preventative maintenance (PM) program. In-house maintenance personnel could be trained to support PM checks, or the user could purchase an annual PM program from an air pollution control system vendor.
When purchasing an air pollution control system, a user will be installing a piece of equipment that will impact their plant operation for many years. An experienced vendor can help select the appropriate technology, provide estimated operating and maintenance costs, and submit formal proposals with firm pricing details. While in some cases a prepackaged air pollution control system may suffice, in many situations the customer may get an enhanced design/system by seeking a customized solution. Many air pollution control system vendors offer customized solutions at no additional cost.
An Air Pollution Control Technology Selection Table is available in .pdf format. (Click here to view .pdf.)
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