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AdBlue reduces nitrous oxides: Eco-Friendly Conversion

To reduce emissions of nitrous oxides and particles and to satisfy the new laws planned to control emissions, heavy-duty vehicle manufacturers are working on developing new exhaust treatment technologies. With its valves, Buschjost has been involved in these developments from the very beginning. These new technologies are equally suitable for power plants, stationary generators and ship generators.

For heavy-duty diesel truck engines, most European makers have opted for SCR catalytic converters (selective catalytic reduction) as the post-treatment solution to reduce the amount of nitrous oxides in exhaust gases. This technology employed in the exhaust system uses a catalytic converter into which a reagent is injected. This converts the nitrous oxides produced in the engine into harmless nitrogen and water. The reagent used is a 32.5 per cent water/urea solution that goes by the trade name "AdBlue".

The urea solution AdBlue is not mixed in with the diesel fuel; rather, it is kept in a separate tank in the vehicle. Just like fuel, however, it is consumed during operation and must be refilled.

Downstream denitration of exhaust gases also allows certain optimisations of the engine with respect to particle emission, fuel consumption and power. The diesel engine in the heavy-duty vehicle is thereby tuned to lower particle emissions, consumption and power. Overall, SCR technology can reduce nitrous oxides in the exhaust by 85% and soot particles by 40%. These SCR vehicles can consume as much as 5% less than a Euro III vehicle.

Aqueous urea solution is an environmentally sound chemical for cleaning exhaust gas. AdBlue is currently being tested for use in personal cars. This urea solution has already been used for many years to reduce nitrous oxides in stationary engines and for desulfurisation in power plants.

AdBlue can be used under all of Europe's weather conditions. However, if the temperature of AdBlue falls below -11 °C, then the product freezes. To prevent this from happening, AdBlue system components are heated. Heavy-duty SCR vehicles feature heating systems to guarantee reliable operation of the SCR system even at the lowest temperatures.

This is where a Buschjost solution comes in. The company has developed a valve for heating the urea tank. This controls the heating process and always opens when the temperature of the urea drops too low. The valve is extremely robust and flexible. It is available with various types of connectors, e.g. quick-connect fittings. The damped closing action keeps the load on the cooling system very low. The valve can also be customised if desired.

Another Buschjost product for this area is a urea injector. This injector attaches directly onto the exhaust pipe and sprays urea into it. The major advantage of this injector is that it is freeze-resistant. The injector is designed to withstand the hard conditions at the exhaust pipe (pollution, vibration) and can also be customised to individual requirements.

The third solution from Buschjost is a urea/air switching valve. This comes to use above all in ship generators. After the generator is shut off, air must be flushed through the system in order to keep it free of deposits, thus to protect it against blockages. The Buschjost valve is now designed such that water and urea cannot become mixed, which was a typical problem of many solutions from other manufacturers. The valve mounts directly onto the exhaust line. It is quick, compact and does not jam. The Buschjost engineers have also designed the valve to be fail-safe. Should the power ever cut out, the urea line closes so that air and urea cannot mix.

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