Engine designer demands drive evolution in EGR

Recent specifications from MAN Diesel & Turbo provide greater clarity on what level of treatment is required depending on the sulphur content of fuel. The result is that centrifugal separator modules on two new systems to be launched later this year will be 50% smaller than that of the current PureNOx Prime technology.

“By taking advantage of the new EGR specifications, we will provide optimised and more compact water treatment systems that lead to more cost-efficient EGR,” said Ayla Körlof, global business manager, Alfa Laval PureNOx.

Under the new specification, only the bleed-off water must be treated when recirculating exhaust from burning low-sulphur fuel, with overboard discharge to be governed by forthcoming IMO guidelines. This enables the new PureNOx LS to boast a configuration similar to a bilge water system, where the centrifugal separator is combined with an oil monitor and a three-way valve.

For engines burning high-sulphur fuel in combination with EGR treatment and exhaust gas cleaning, PureNOx HS will also treat process water. An initial filter stage will remove process water contaminants while heavier particles will be separated from bleed-off water prior to discharge through the scrubber system.

Both modules will support ‘Eco EGR’ engine mode, whereby the system is used for Tier II rather than full Tier III compliance, offering substantial fuel savings as well as NOx reduction. To enable Eco EGR the water treatment system must be able to operate continuously.