AdBlue and SCR technology

SCR (Selective Catalytic Reduction) technology uses an additive called Adblue that is injected into the exhaust gases before they pass through an SCR catalytic converter. In the catalytic converter, the nitrogen oxide is turned into harmless nitrogen gas and water vapour - substances that are already found naturally in our environment. 

The active substance in Adblue - Urea is made from natural gas. Urea is a white crystal powder that is also found naturally in the environment. It is stable and non toxic substance that has no restrictions concerning either storage or transport. 

VOLVO is working with leading oil and chemical companies to create intelligent solutions for a distribution infrastructure for handling AdBlue. There are many suppliers and they offer complete tank systems and equipment that are already available for delivery. 

The VOLVO SCR System consists in principle of an AdBlue tank, positioned alongside the standard diesel tank, an AdBlue pump, an injector and an SCR catalytic converter. 

1.  The AdBlue tank is positioned alongside the regular diesel tank.
2. AdBlue is injected in finally atomised form into the exhaust gases. Exact metering ensures the optimum mixture for every operating condition. 
3. In the SCR catalyst, the toxic oxides of nitrogen are converted into nitrogen gas and water. The catalytic converter is fully integrated into the silencer. 

Pic Courtesy : www.adblue-contamination.co.uk

Easily fitted on the Truck : 

In comparision with diesel fuel, AdBlue does not take up a lot of space. With a 4% blend, 1000 litres of diesel fuel will require just 40 litres of AdBlue. The consumption of AdBlue always remains in fixed proportion to the consumption of diesel fuel. Tanks for AdBlue are available in various volumes from 30 to 120 litres. The tanks are made of aluminium or plastic. 

AdBlue and the catalytic process : 

AdBlue consists of an ammonia reagent - Urea and Water. The heat in the exhaust system converts the urea into ammonia (NH3) and carbon dioxide (CO2). It is the ammonia that is the active substance and the main ingredient in the ongoing process in the SCR catalytic converter. In the chemical - catalytic process that follows, the nitrogen oxides (NOx) are converted into nitrogen gas (N2) and water vapour (H2O). Nitrogen gas is a natural ingredient in the air we breathe. Any possible residues of ammonia are removed in the integrated clean - up catalytic converter. 

Acknowledgements : VOLVO Trucks, VOLVO Trucks UK and Ireland