APES Unit 7.6 Reduction of Air Pollutants

Conservation

Using less fuel and increasing efficiency techniques 

•   → Reduces the total amount of pollutants emitted at the source 

Alternative Fuels

Switching to cleaner fuels like oil instead of coal or anthracite instead of bituminous coal

• → Lowers the concentration of sulfur and other impurities

Vapor Recovery Nozzle

A device on gasoline pumps that prevents fumes from escaping while fueling

• → Prevents VOCs from entering the atmosphere

Cap-and-Trade

A system of buying and selling sulfur dioxide allowances on the open market

• → Uses free-market incentives to reduce overall SO2 emissions

Vehicle Restrictions

Limiting driving days or expanding public transit

• → Reduces photochemical smog and improves visibility in urban areas 

The Catalytic Converter

• Location: Added before the muffler in cars and trucks 

• The Process: Uses a metal catalyst to increase the rate of a chemical reaction without being consumed 

• Input Pollutants: Nitrogen oxides, carbon monoxide and hydrocarbons 

• Output (Less Harmful): Nitrogen gas, carbon dioxide, oxygen, and water

Wet Scrubber

 Uses a combination of air and liquid to cause particulates to coalesce and be removed as sludge. 

•  Particulates and sulfur dioxide 

Electrostatic Precipitator

Uses an electrical charge to make particles coalesce so they stick to collection electrodes 

• Particulate matter 

Fabric / Baghouse Filter  

A filtration device that allows gases to pass through while trapping almost 100% of particulates

• PM

Fluidized Bed Combustion  

Burns granulated coal in close proximity to calcium carbonate to absorb sulfur 

• SO2

NRG Trade-Off

Control devices require the use of more fuel to operate and create resistance to airflow 

• "Lesser of Two Evils”: stops the pollutants from entering the process in the first place, rather than cleaning them up afterward. 

Nitrogen Oxides in Control Devices

To reduce NOx: burn temps must be lowered and oxygen controlled.

• → BUT: this leads to less complete combustion, which reduces efficiency and increases CO2

Catalyst

A substance that increases the rate of a chemical reaction without undergoing a permanent change 

VOCs

carbon-based chemicals that easily evaporate into the air 

Gypsum

A byproduct of "scrubbing" that can be recycled into wallboard/sheetrock for houses