|Modern Coal Related
Clean Coal Related Technologies
Clean coal technology seeks to reduce harsh environmental effects by using multiple technologies to clean coal and contain its emissions.
The MidAmerican Energy Company's Council Bluffs Energy Unit 4 will be the country's first power plant company to have mercury limits specifically noted in its air emissions permit; this signifies a resurgence to coal-fueled technology. See how clean coal works in this video from Hitachi True Stories.
Carbon Capture and Storage (CCS)
An approach to mitigating global warming by capturing carbon dioxide (CO2) from large point sources such as power plants and subsequently storing it instead of releasing it into the atmosphere.
Coal washing involves grinding the coal into smaller pieces and passing it through a process called gravity separation. One technique involves feeding the coal into barrels containing a fluid that has a density which causes the coal to float, while unwanted material sinks and is removed from the fuel mix. The coal is then pulverized and prepared for burning.
Burning coal produces a range of pollutants that harm the environment: Sulphur dioxide (acid rain); nitrogen oxides (ground-level ozone) and particulates (affects people's respiratory systems).
There are a number of options to reduce these emissions:
Sulphur dioxide (SO2)
A venturi scrubber is designed to effectively use the energy from the inlet gas stream to atomize the liquid being used to scrub the gas stream. This type of technology is a part of the group of air pollution controls collectively referred to as wet scrubbers.
A venturi scrubber consists of three sections: a converging section, a throat section, and a diverging section. The inlet gas stream enters the converging section and, as the area decreases, gas velocity increases (in accordance with the Bernoulli equation). Liquid is introduced either at the throat or at the entrance to the converging section. The inlet gas, forced to move at extremely high velocities in the small throat section, shears the liquid from its walls, producing an enormous number of very tiny droplets. Particle and gas removal occur in the throat section as the inlet gas stream mixes with the fog of tiny liquid droplets. The inlet stream then exits through the diverging section, where it is forced to slow down. Venturis can be used to collect both particulate and gaseous pollutants, but they are more effective in removing particles than gaseous pollutants.
Nitrogen oxides (NOx)
Fabric Filter Systems