An emissions control device is used to control the amount of air pollution emissions from being released in the atmosphere. We encounter different sources of air pollution emissions in our daily lives. Some of the major sources are stationary sources, which may include steel mills, power plants, cement plants, smelters, refineries and other various industrial processes. These stationary sources of air pollution emissions release pollution and contaminants in the air such as aerosols, particulates gases and vapors.
With a good emissions control device, the emissions are controlled to a high level of efficiency. In many situations, such as factories, the pollution can be significantly reduced by means of different combustion controls and process modifications. However, most of the time some sort of add-on emissions control device needs to be attached to the ductwork and lead to the smoke stack to meet the minimum emissions limits allowable.
Some of the most common methods of reducing or eliminating gaseous forms of pollution are destroying pollutants by catalytic combustion such as a catalytic combustion reactor or flare stack; converting pollutants to a less harmful from by chemical reduction or using an air pollution system to collect pollutants. The most common emissions control devices used are electrostatic filters, catalytic reactors, carbon absorbers, thermal oxidizers, biofilters, wet scrubbers, fabric filters, or cyclones. In severe cases of pollution, more than one type of emissions control device may be used at one time.
Another source of air pollution emissions that we see every day is the automobile. The automobile creates forms of carbon monoxide, hydrocarbons and oxides of nitrogen during the combustion process, emits it out of the tail pipe and into the atmosphere. The crankcase of the automobile emits hydrocarbons as well as the vaporization of gasoline. In 1977, the Clean Air Act set limits as to how many of these pollutants the automobile could emit. As a result of the Clean Air Act, automobile makers created the self-adjusting engine and pollution or emissions control devices.
These new engines has a component called an oxygen sensor, which would measure the amount of fuel in the exhaust system, send a signal to the microprocessor where it would be analyzed and adjusted to the proper ratio of air/fuel. Automobiles are made with a variety of emissions control devices including catalytic converter, EGR valve, PCV valve, air pump and charcoal canister. Each of these devices plays a different role in controlling pollution from escaping in the atmosphere. Although the automobile can be driven without some of these devices, the law states that each vehicle driven on the highway must have the proper emissions control device.