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Selective catalytic reduction (SCR) means converting nitrogen oxides, also referred to as NO x with the aid of a catalyst into diatomic nitrogen (N 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 ...
Within the SCR catalyst, the NO x are reduced by the ammonia into water and nitrogen, which are both nonpolluting. The water and nitrogen are then released into the atmosphere through the exhaust. [7] SCR was applied to automobiles by Nissan Diesel Corporation, and the first practical product "Nissan Diesel Quon" was introduced in 2004. With ...
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.
EGR valve the top of box on top of the inlet manifold of a Saab H engine in a 1987 Saab 90. In internal combustion engines, exhaust gas recirculation (EGR) is a nitrogen oxide (NO x) emissions reduction technique used in petrol/gasoline, diesel engines and some hydrogen engines. [1]
A NO x adsorber is designed to reduce oxides of nitrogen emitted in the exhaust gas of a lean burn internal combustion engine.Lean burn engines, particularly diesels, present a special challenge to emission control system designers because of the relatively high levels of O 2 (atmospheric oxygen) in the exhaust gas.
Plasma cleaning is the removal of impurities and contaminants from surfaces through the use of an energetic plasma or dielectric barrier discharge (DBD) plasma created from gaseous species. Gases such as argon and oxygen, as well as mixtures such as air and hydrogen/nitrogen are used. The plasma is created by using high frequency voltages ...
These techniques prevent the compounds from reacting with components of air, usually water and oxygen; less commonly carbon dioxide and nitrogen. A common theme among these techniques is the use of a fine (10 0 –10 −3 Torr) or high (10 −3 –10 −6 Torr) vacuum to remove air, and the use of an inert gas: preferably argon, but often nitrogen.
The AOP procedure is particularly useful for cleaning biologically toxic or non-degradable materials such as aromatics, pesticides, petroleum constituents, and volatile organic compounds in wastewater. [5] Additionally, AOPs can be used to treat effluent of secondary treated wastewater which is then called tertiary treatment. [6]