How does a selective catalytic reduction work?
In the case of selective catalytic reduction, a catalytic converter converts the nitrogen oxides contained in the exhaust gas into water vapor and nitrogen. For this purpose, a reducing agent is continually injected into the exhaust gas flow using a metering module.
What is catalytic reduction system?
The selective catalytic reduction (SCR) removes nitrogen oxides (NOx) from flue gas emitted by power plant boilers and other combustion sources, and the catalyst is the key component of this system.
What is SCR exhaust?
Selective Catalytic Reduction (SCR) is a proven and advanced active emissions control technology system that injects a liquid-reductant agent through a special catalyst into the exhaust stream of a diesel engine. The reductant source is usually automotive-grade urea, otherwise known as Diesel Exhaust Fluid (DEF).
What is the purpose of DEF?
What is the Purpose of Diesel Exhaust Fluid? In 2010, the EPA required diesel engines to reduce their production of (NOx) nitrogen oxides. That reduction is accomplished with the additive Diesel Exhaust Fluid (DEF). This fluid reduces NOx and air pollution.
How does a doc engine work?
It breaks down pollutants in the exhaust stream from a diesel engine, helping to reduce particulate matter (PM). It’s similar to a catalytic converter in a car. Both carbon monoxide and hydrocarbons are converted in the DOC to carbon dioxide and water vapour.
What is a DOC system?
The DOC is the first device in the after treatment system. It is a flow through filter that contains precious metals to start the oxidation of hydrocarbons, carbon monoxide and unburned fuel and oil.
What is a selective catalyst?
A catalytic reaction which depends upon the pore structure of the catalyst and on the size of the reactant and the product molecules is called shape-selective catalysis. For example, catalysis by zeolites is a shape-selective catalysis.
What is DOC and DPF?
The exhaust aftertreatment devices that are applied to vehicles are Diesel Oxidation Catalysts (DOC), Diesel Particulate Filters (DPF) and Selective Catalytic Reduction (SCR) catalysts.
How much is selective catalytic reduction?
Most surveyed utilities spent between $100 and $200/kW for a selective catalytic reduction system.
What material is in a DPF?
DPF filters are a type of “wall filter,” and they’re typically made of ceramic, silicon carbide, or cordierite.
How DEF is made?
DEF is made from deionized water and a very pure form of urea. Yes, urea is found in urine — quit giggling, please — but this is a refined form of the compound and is mostly used in the agricultural industry as a component of fertilizer.
Can a diesel run without DEF?
If you ignore the DEF warning the truck will cease to work. Some diesel engine manufacturers allow the engine to go into reduced power mode so the truck can “limp home” or limit the number of times you can turn the engine over. At some point though the diesel engine will not start.
On which factors shape selective catalysis depends?
Note: It is important to remember here that, shape selective catalysis depends upon the size of the pores of the catalyst as well as the size of the molecules of the reactant. If the size of the reactant molecule is greater than the pores of the catalyst, it won’t be diffused in the catalyst.
Which is first DPF or SCR?
When the DPF is removed for cleaning it is always a good practice to also remove the DOC and clean it as well if necessary. The last component in the after treatment system is a flow through SCR catalyst which introduces Diesel Emissions Fluid (DEF) to the process.
How does ammonia injection reduce NOx?
Theory of Operation: The SCR process chemically reduces the NOx molecule into molecular nitrogen and water vapor. A nitrogen based reagent such as ammonia or urea is injected into the ductwork, downstream of the combustion unit. The waste gas mixes with the reagent and enters a reactor module containing catalyst.
Who invented DPF?
French Peugeot Company
DPFs have been used in diesel engine vehicles for over 10 years [4,5,6,7,8,9], since the French Peugeot Company invented the DPF system in 2000.