air pollution control (1)

AIR POLLUTION CONTROLPREPARED BY :ESPIRITU, JOSE FEDERICOCUNANAN, JERIEL B.

What is air pollution control?

It is the Changing or eliminating processes that produces air effluents.

Limiting emissions into the air.

This is how it is controlled

Source Correction Changing or eliminating a process that

produces a polluting air effluent is often easier than trying to trap the effluent. A process or product may be needed or necessary, but could be changed to control emissions. For example, automobile exhaust has caused high lead levels in urban air. Elimination of lead from gasoline, which was needed for proper catalytic converter operation, has also resulted in reducing lead in urban air.

Source Correction

Such measures as process change, raw material substitution, and equipment modification to meet emission standards are known as controls. In contrast, abatement is the term used for all devices and methods for decreasing the quantity of pollutant

Collection of Pollutants

It is the collection of effluent emitted from the sources. This is the most serious problem in air pollution control.

Why? Automobile exhaust is a notorious polluter

mainly because the effluent is so difficult to trap and treat. If automobile exhaust could be channeled to a central treatment facility, treatment could be more efficient in controlling each individual car.

Cooling Process

The exhaust gases to be treated are sometimes too hot for the control equipment, and must first be cooled. Cooling may also drop the temperature below the condensation point of some pollutants, so that they may be collected as liquids.

Cooling Process

Cooling Process

Dilution, Quenching, and Heat Exchange are all acceptable cooling methods.

Quenching has the added

advantage of scrubbing out some gases and particulate matter, but may yield a dirty, hot liquid that itself requires disposal.

Treatment

Selection of the correct treatment device requires matching the characteristics of the

pollutant with features of the control device.

Treatment-Cyclones

CyclonesPopular, economical, and effective means of controlling particulates. Cyclones alone are generally not adequate to meet stringent air pollution control regulations, but serve as pre-cleaners for control devices like fabric filters or electrostatic precipitators.

Treatment-Cyclone

Dirty air enters the cyclone off-center at the bottom; a violent swirl of air is thus created in the cone of the cyclone and particles are accelerated centrifugally outward toward the cyclone wall. Friction at the wall slows the particles and they slide to the bottom, where they can be collected. Clean air exits at the center of the top of the Cone while the pollutants discharge at the bottom

Treatment-Fabric Filters

Fabric Filters

Fabric filters used for controlling particulate matter operate like a vacuum cleaner. Dirty gas is blown or sucked through a fabric filter bag. The fabric bag collects the dust., which is removed periodically by shaking the bag.

Treatment-Fabric Filters

Treatment-Wet CollectorsWet Collectors

The spray tower or scrubber can remove larger particles effectively. More efficient scrubbers promote the contact between air and water by violent action in a narrow throat section into which the water is introduced. Generally, the more violent the encounter, hence the smaller the gas bubbles or water droplets, the more effective the scrubbing

Treatment-Wet Collectors