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Selective non-catalytic reduction (SNCR) is a method to lessen nitrogen oxide emissions in conventional power plants that burn biomass, waste and coal.The process involves injecting either ammonia or urea into the firebox of the boiler at a location where the flue gas is between 1,400 and 2,000 °F (760 and 1,090 °C) to react with the nitrogen oxides formed in the combustion process.
This is sometimes called the reverse water–gas shift reaction. [20] Water gas is defined as a fuel gas consisting mainly of carbon monoxide (CO) and hydrogen (H 2). The term 'shift' in water–gas shift means changing the water gas composition (CO:H 2) ratio. The ratio can be increased by adding CO 2 or reduced by adding steam to the reactor.
2), and water (H 2 O). A reductant, typically anhydrous ammonia (NH 3), aqueous ammonia (NH 4 OH), or a urea (CO(NH 2) 2) solution, is added to a stream of flue or exhaust gas and is reacted onto a catalyst. As the reaction drives toward completion, nitrogen (N 2), and carbon dioxide (CO 2), in the case of urea use, are produced. Selective ...
Selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR) reduce post combustion NO x by reacting the exhaust with urea or ammonia to produce nitrogen and water. SCR is now being used in ships, [38] diesel trucks and in some diesel cars.
Hydrocarbonate is an archaic term for water gas composed of carbon monoxide and hydrogen generated by passing steam through glowing coke.Hydrocarbonate was classified as a factitious air and explored for therapeutic properties by some eighteenth-century physicians, including Thomas Beddoes and James Watt. [5]
In addition to changing the fuel, US engineers have also come up with two other principles and distinct systems to all on-market products that meet the U.S. 2010 emissions criteria, [citation needed] [needs update] selective non-catalytic reduction (SNCR), and exhaust gas recirculation (EGR). Both are in the exhaust system of diesel engines ...
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An illustrative example is the effect of catalysts to speed the decomposition of hydrogen peroxide into water and oxygen: . 2 H 2 O 2 → 2 H 2 O + O 2. This reaction proceeds because the reaction products are more stable than the starting compound, but this decomposition is so slow that hydrogen peroxide solutions are commercially available.