PureNOx

EGR water treatment with a difference

Alfa Laval PureNOx has long been the choice for water treatment in Exhaust Gas Recirculation (EGR), a leading technology for Tier III NOx compliance. Today it’s available in an even more streamlined solution – PureNOx LS (Low Sulphur) – that supports both Tier III NOx compliance and Tier II fuel savings. PureNOx LS is optimized for EGR engines that operate on low-sulphur fuel. Upon request, solutions for use with high-sulphur fuel can also be tailored using PureNOx technology.

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Optimization makes the difference

  • Developed in close cooperation with MAN Energy Solutions
  • Technology proven in thousands of hours of PureNOx operation
  • Streamlined design, optimized for EGR engines using low-sulphur fuel
  • 50% smaller centrifugal separator module
  • More cost-efficient EGR

PureNOx LS reflects the global sulphur cap, which will lead to far more vessels sailing with low-sulphur fuel. Based on the latest engine maker guidelines, the system is optimized specifically to clean EGR bleed-off water in a setup similar to that of a bilge water system. The result is a smaller EGR water treatment system than ever before, but with the same reliable PureNOx technology. In turn, that means a more cost-efficient EGR solution. In addition, PureNOx LS has a unique strength compared to other systems on the market. It supports Tier II fuel savings with Eco EGR – and is the only water treatment solution that can.

How it works

PureNOx LS is designed for use with EGR engines that operate on low-sulphur fuel. In the EGR process, water is used to remove soot particles from the exhaust gas that is recirculated into the engine. This creates a certain amount of condensate, called EGR bleed-off water, that must be cleaned before discharge in accordance with EGR guidelines from the MEPC307(73).

PureNOx LS cleans the EGR bleed-off water by means of centrifugal separation, a method that has proven successful in years of real-life EGR water treatment at sea. Based on experience from years of real-life operation, MAN Energy Solutions has determined that EGR process water cleaning is not necessary when low-sulphur fuel is used. This allows for a PureNOx LS setup that resembles a bilge water system, where the centrifugal separator cleans the water down to a level of 15 ppm oil in water and uses an oil monitor and a three-way valve to verify its cleanliness before discharge overboard.

Unique support for Eco EGR

As well as supporting Tier III NOx compliance, PureNOx LS supports Eco EGR. Eco EGR is a fuel-saving engine mode in which EGR is performed using a smaller amount of exhaust gas (10–15%) during Tier II operation. For EGR engines with Eco EGR capability, the savings are considerable when running on low-sulphur fuels.

Eco EGR allows the engine to be trimmed for maximum fuel efficiency, optimizing specific fuel oil consumption to produce fuel savings of up to 6 g/kWh. However, Eco EGR requires continuous water treatment. PureNOx LS is proven in continuous use, whereas other systems on the market can only operate intermittently. This makes PureNOx LS the only solution on the market that is compatible with Eco EGR.

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