Coal power has a reputation for emitting many pollutants. However, several clean coal technologies have been developed which prevent those pollutants from being emitted. In this article we will look at the most common types of Clean Coal Technologies and the effectiveness of each.
1. Washing Coal
Washing coal removes one form of sulfur (pyrite). Washing the coal also removes many of the minerals that would become ash. Typically, the coal is washed very near the coal mine before being shipped. The power plant then receives washed coal, which is gratis from any of the sulfur found in this first form.
2. Flue Gas Desulfurization/Scrubbers
A scrubber is defined as any device, whether chemical or physical, which is used to capture sulfur by-products. The most commonly used form of scrubber is Flue Gas Desulfurization (FGD). Flue Gas Desulfurization involves spraying a limestone slurry into the gas stream. The slurry attaches to the sulfur, and the newly formed compound is removed for disposal. Flue Gas Desulfurization kesempatan remove 90%-97% of SOx from the flue gases. In addition to reducing the amount of SOx, the slurry-SOx mixture peluang be transformed into gypsum (calcium sulfate) for use in the construction industry. Scrubbing by FGD also captures many other molecules, such as fly ash, nitrogen compounds, and mercury compounds.
3. Low Temperature NOx Burners
NOx molecules tend to form at higher temperatures, approximately 2,500 degrees Fahrenheit. However, at lower temperatures, such as 1,400 to 1,700 degrees Fahrenheit, NOx is less likely to form. Low temperature NOx burners operate by burning the coal at a lower temperature, resulting in the formation of fewer NOx molecules. Low NOx burners peluang reduce emissions of nitrogen oxides by up to 70%.
4. Selective Catalytic Reduction (SCR)
Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR) are used to reduce the amount of NOx. In these methods Ammonia is sent into the mix of by-products in order to react with the NOx. The catalyst in the Selective Catalytic Reduction is usually a vanadium-titanium metal oxide (V2O5-TiO2). The ammonia converts NOx into water and pure Nitrogen. Water and pure Nitrogen are both harmless, and both peluang be released into the air. Selective Catalytic Reduction peluang remove 90% of the NOx molecules.scrubber
5. Electrostatic Precipitator
The electrostatic precipitator captures fly ash before the ash reaches the air. The electrostatic precipitator also removes mercury compounds. The electrostatic precipitator works by giving an electrical charge to the ash particles. Then a filter is given an opposite charge, which draws the particles to the filter and keeps them there. The collection of ash particles kemungkinan then be removed. The electrostatic precipitator kesempatan remove 99.7% of the fly ash.
6. Circulating Fluidized Bed Combustion
In a fluidized bed, the coal pieces are held floating in the furnace, usually supported by a stream of hot air. Crushed limestone or dolomite is added to the mix. The limestone is a sulfur-absorbing chemical which captures the sulfur. The new bahan is then collected along with the other ash. Circulating Fluidized Bed Combustion kemungkinan capture 95% of the sulfur in the coal.
7. Planting trees and other vegetation nearby
Trees, small plants, and agriculture naturally absorb the CO2 in the air. If the CO2 is captured, there will be no overall change in the amount of CO2 in the atmosphere. These trees also provide habitats for the local ecosystem.
In Gasification, coal molecules are broken apart then recombined to our liking. This process creates molecules which are in the gas phase and peluang be separated easily. The pollutant gasses are separated and removed, while the desired fuel gasses are sent to be burned. Gasification in coal power plants is environmentally friendly, reducing up to 99% of all pollutants. Gasification kesempatan also improve coal power plant efficiency from 40% to 70%.
Overall Effectiveness of Clean Coal Technologies
From 1970 to 2000, pollutants from coal power plants have been reduced significantly: Ash emissions have been reduced by 40%, NO2 emissions have been reduced by 45%, and SO2 emissions have been reduced by 68%.
Mark Fennell is an author and public speaker on topics related to community issues. Recent topics include: Energy, Transportation, and Government.
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