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Removing CO2 using ammonia
The main process of removing CO2 using ammonia is similar to the process of using amines, but has the advantage that the regeneration process requires less energy.
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The process of removing CO2 using ammonia
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Simplified schematic of the CO2 removal process using ammonia. (Source: Alstom/ZERO) |
The challenge is that ammonia is highly volatile and vaporizes easily. In CO2 separation this can be solved by using energy to cool the flue gas before separation. This will slow down the reaction speed and increase the size of the required absorber.
Ammonia in aqueous solution is in commercial use as an absorbent for SO2 from power plant flue gas. Marsulex and Alstom are two companies that provide this solution. The technology has been tested in laboratories, among other places at Stanford University. Several pilot plants are being built, the first one was finished in the autumn of 2007 at a coal power plant in the USA.
E.ON Sweden is building the first pilot plant in Europe using ammonia technology. The 5 MW plant is being built in cooperation with Alstom Power at one of the boilers at E.ON’s oil powered reserve plant in Karlshamn.
American Electric Power (AEP) is building a demonstration plant for CO2 capture using chilled ammonia at the Mountaineer Plant power plant in New Haven, West Virginia, intended for start-up in 2008. This facility is projected to remove 100,000 tons of CO2 a year, the gas being stored in a nearby deep aquifer. AEP and Alstom are also planning a large commercial plant for removing approximately 1.5 million tons of CO2 a year from the North-eastern Station power plant in Oologah, Oklahoma. Planned start-up for this plant is 2011.
The ammonia technology is best suited for flue gas with high levels of CO2 such as from coal and oil power plants, but it is also being tested on gas power plants.
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