Editorial
May 2014
A potentially game-changing
pressurized EGR boiler from Alfa Laval
is now ready for testing
Exhaust Gas Recirculation (EGR) has firmly shown its ability to comply with Tier III NOx
limits, which will enter into force in January 2016. Developed by MAN Diesel & Turbo,
the EGR process already relies on Alfa Laval’s PureNOx, which provides the vital
cleaning of the scrubber water. Now Alfa Laval is cooperating with MAN Diesel & Turbo
to implement an EGR boiler, which could potentially add major energy benefits to the
secure emission compliance.
Over 1000 hours of EGR operation have now been achieved aboard the Maersk Cardiff, a
container newbuild from A.P. Moller-Maersk with a two-stroke MAN B&W 6S80ME-C9 engine.
Having demonstrated reliable compliance with Tier III NOx legislation, as well as the potential
for fuel savings in Tier II operation, the vessel’s EGR installation will soon be expanded with
another remarkable technology: a pressurized EGR boiler from Alfa Laval.
“We have shown that EGR works smoothly and that it complies fully with the NOx limits
appearing in 2016,” says Michael Witt, Head of Retrofit Development R&D at MAN Diesel &
Turbo. “Together with Alfa Laval and A.P. Moller-Maersk, we are now looking beyond
compliance to optimize the system and to utilize opportunities for energy savings.”
According to Anders Busk Nielsen, Project Manager at Alfa Laval’s Product Centre Boilers,
one such opportunity is waste heat recovery. “EGR is a fantastic technology that is already
well served by Alfa Laval’s separation know-how,” Nielsen says. “Now we are adding our
expertise in waste heat recovery, by placing a pressurized exhaust gas boiler in the EGR
circuit. If successful, it could add substantial energy savings to NOx emission compliance.”
Reclaiming the diverted waste heat
The reasons for developing an EGR boiler are straightforward. In the EGR process, around
Aalborg and PureNOx are trademarks owned by Alfa Laval Corporate AB. Alfa Laval is a trademark registered and
owned by Alfa Laval Corporate AB. Alfa Laval reserves the right to change specifications without prior notification.
page 2/6
30% of the exhaust gas is directed back into the engine, which reduces the combustion
temperature and thereby the production of NOx. This also reduces waste heat recovery by
30%, since only 70% of the gas reaches the traditional exhaust gas boiler after the
turbocharger. The remaining heat energy is dissipated in the EGR scrubbing process.
“The idea is to place an in-line boiler ahead of the EGR wet scrubber, before the scrubber jets
cool the exhaust gas,” says Nielsen. “In this location, the boiler would have access to much
higher temperatures and pressures than traditional exhaust gas boilers. That would allow a
lighter and more compact boiler, which would be self-cleaning due to the high speed of flow.”
The heat would be recovered from the EGR circuit, and the availability of service steam would
be unchanged from today. Moreover, as part of an integrated waste heat recovery system, the
EGR boiler would enable a major increase in efficiency.
Standing up to extreme post-engine conditions
If the theory is simple, the challenges of constructing an EGR boiler are anything but. Today’s
waste heat recovery involves temperatures of around 270°C, whereas temperatures before the
EGR scrubber are twice that. In addition, the potential gas pressure in the EGR circuit is 2-4
bar(g), which necessitates a pressurized boiler casing.
“Managing the extreme conditions has been a real challenge for the Alfa Laval development
team,” says Nielsen. “These are conditions no ordinary boiler would be able to survive. But
what we’ve developed is no ordinary boiler.”
The boiler Nielsen refers to is the new Aalborg XW-HPX pressurized EGR boiler, which is
indeed lighter and more compact than any boiler with an equivalent output. Tentatively
planned for launch in 2015, the boiler has moved off the drawing board and is now scheduled
for test installation aboard the Maersk Cardiff late this summer.
“As a front-runner in the pursuit of green technologies, we are interested in testing the new
EGR boiler aboard the Maersk Cardiff in order to hopefully demonstrate its promising potential
for energy optimization in connection with the existing EGR installation,” says Ole Christensen,
Senior Machinery Specialist at A.P. Moller-Maersk.
Aalborg and PureNOx are trademarks owned by Alfa Laval Corporate AB. Alfa Laval is a trademark registered and
owned by Alfa Laval Corporate AB. Alfa Laval reserves the right to change specifications without prior notification.
page 3/6
Up to 10% more steam power production
What exactly could the Aalborg XW-HPX achieve if successful? As a producer of service
steam, it would provide the same saturated steam as a traditional exhaust gas boiler, though it
would be more cost-efficient and easier to install.
Yet a great potential lies in integrating the Aalborg XW-HPX with existing waste heat recovery
after the turbocharger, so that it shares a steam drum with the traditional exhaust gas boiler.
With the output of the traditional boiler feeding into this drum, the Aalborg XW-HPX would
produce extremely high-quality steam with a temperature of 400°C, bringing the waste heat
recovery system to a much higher level of efficiency.
“Producing steam of this quality would greatly increase the performance of the steam turbine,”
says Nielsen. “To give an indication, we’ve made calculations together with a leading steam
turbine supplier. Those calculations put the power generation increase at 7.5-10%, depending
on installation factors.”
On the Maersk Cardiff, for example, the additional generated power could be used to cool
containers, thereby limiting the fuel consumed by the genset. But if fed into a shaft generator,
it could instead increase the efficiency of the propulsion system, saving considerable fuel as a
result.
Fuel savings through even slower steaming
Given the higher output, the increased efficiency in waste heat recovery would be interesting
for any vessel like the Maersk Cardiff. Yet the Aalborg XW-HPX could prove its worth in still
other ways. Most importantly, using it in an integrated boiler system would allow waste heat
recovery to occur at lower main engine loads than today – creating the possibility for even
slower steaming.
“The Maersk Cardiff has around 20 sister vessels, all with traditional waste heat recovery
systems to compare with,” says Nielsen. “With the Aalborg XW-HPX, we should be able to
both increase the efficiency and extend the operating hours of waste heat recovery, which
would enable slower steaming and a massive fuel savings. That would be reflected not only in
a lower fuel bill, but also in a CO2 reduction on top of the NOx abatement.”
Aalborg and PureNOx are trademarks owned by Alfa Laval Corporate AB. Alfa Laval is a trademark registered and
owned by Alfa Laval Corporate AB. Alfa Laval reserves the right to change specifications without prior notification.
page 4/6
“This is perhaps the most exciting prospect of Alfa Laval’s EGR boiler,” says Witt. “If the
Aalborg XW-HPX can shift the operating balance for waste heat recovery by even a small
percentage, the potential savings for ship owners and operators is enormous.”
Figure 1: Combining Alfa Laval’s Aalborg XW-HPX pressurized EGR boiler with a traditional
installation could extend the operating range for waste heat recovery, enabling fuel savings
through even slower steaming.
Potential savings within the EGR circuit
Finally, employing the Aalborg XW-HPX within the EGR circuit could create synergies within
the EGR system itself. By removing some of the exhaust gas heat prior to the wet scrubber, it
might allow the already compact PureNOx water cleaning unit to be downsized.
“When you take exhaust gas at 450°C and spray water through it to cool it to 50°C, you need a
lot of water and a high-capacity water cleaning unit,” explains Nielsen. “If the EGR boiler can
first make use of most of that heat, there will be less heat left to enter the scrubber. Potentially,
that could mean less water needed and an even smaller PureNOx.”
Aalborg and PureNOx are trademarks owned by Alfa Laval Corporate AB. Alfa Laval is a trademark registered and
owned by Alfa Laval Corporate AB. Alfa Laval reserves the right to change specifications without prior notification.
page 5/6
Ready for testing at sea
The theory behind the EGR boiler is solid, and land-based concept tests have already shown
that a smaller installation can withstand the operating extremes. What remains to determine,
however, is the boiler’s effect on the NOx abatement process. This is the reason for adding an
Aalborg XW-HPX to the existing EGR installation on the Maersk Cardiff.
“Up to now, we have wanted to run the EGR system aboard the Maersk Cardiff without the
influence of additional equipment,” says Witt. “Based on the good results seen there, however,
we are confident of EGR’s ability to meet the NOx limits appearing in 2016. This means we
can take the next step, installing the Aalborg XW-HPX as a part of energy-optimizing the NOx
abatement technology.”
Supported by the Danish Energy-Technological Development and Demonstration Programme
(EUDP), the project continues the close partnership between MAN Diesel & Turbo, Alfa Laval,
A.P. Moller-Maersk and Aalborg University. “We are happy to extend the good cooperation
that already exists aboard the Maersk Cardiff, and we look forward to being part of the EGR
boiler test,” says Christensen. “The test will provide further knowledge and experience, and
hence enable us to make informed decisions regarding the selection of NOx abatement
technologies for coming Tier III projects.”
Testing of the Aalborg XW-HPX aboard the Maersk Cardiff will begin in the second half of
2014, and Nielsen foresees no interference with the EGR system. On the contrary, he
anticipates that the EGR boiler will add to the overall attractiveness of EGR as a NOx
abatement strategy.
“With an EGR boiler as part of the complete EGR system, it should be possible not only to
reduce NOx by 80%, but also to reduce the emission of CO2, since there is the potential of
substantially lower fuel consumption,” Nielsen says. “Nothing is proven yet, but this is
absolutely what we expect.”
To learn more about exhaust gas boilers and Alfa Laval’s approach to waste heat recovery, as
well as the PureNOx water cleaning unit, visit www.alfalaval.com/marine
Aalborg and PureNOx are trademarks owned by Alfa Laval Corporate AB. Alfa Laval is a trademark registered and
owned by Alfa Laval Corporate AB. Alfa Laval reserves the right to change specifications without prior notification.
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Editor’s notes
About Alfa Laval
Alfa Laval is a leading global provider of specialized products and engineering solutions based
on its key technologies of heat transfer, separation and fluid handling.
The company’s equipment, systems and services are dedicated to assisting customers in
optimizing the performance of their processes. The solutions help them to heat, cool, separate
and transport products in industries that produce food and beverages, chemicals and
petrochemicals, pharmaceuticals, starch, sugar and ethanol.
Alfa Laval’s products are also used in power plants, aboard ships, in the mechanical
engineering industry, in the mining industry and for wastewater treatment, as well as for
comfort climate and refrigeration applications.
Alfa Laval’s worldwide organization works closely with customers in nearly 100 countries to
help them stay ahead in the global arena.
Alfa Laval is listed on Nasdaq OMX, and, in 2013, posted annual sales of about SEK 29.9
billion (approx. EUR 3.45 billion). The company has today about 16,300 employees.
www.alfalaval.com
For further information, please contact:
Anne Henningsen
Central Communication Manager
Marine & Diesel Division
Alfa Laval Aalborg, Denmark
Phone: +45 9930 4016
E-mail: Anne.Henningsen@alfalaval.com
André Szczerba
Central Communication Manager
Marine & Diesel Division
Alfa Laval Tumba AB, Sweden
Phone: +46-8 530 653 07
E-mail: andre.szczerba@alfalaval.com
www.alfalaval.com/marine
Aalborg and PureNOx are trademarks owned by Alfa Laval Corporate AB. Alfa Laval is a trademark registered and
owned by Alfa Laval Corporate AB. Alfa Laval reserves the right to change specifications without prior notification.