Feature 2
Cat has IMO II in its sights
First IMO II-compliant MaK M 43 C Low Emission Engine is already in
operation.
W
hat is said to be the first known ratio was raised to 14-15 and for IMO II
vessel afloat with an IMO II- ratios of 17 will be needed. A cornerstone
compliant engine running on of the MaK LEE concept is the Miller
Heavy Fuel Oil (HFO) is in full operation. Cycle, ie modification of the engine’s valve
The MaK 7 M 43 C medium-speed engine timing to achieve cooler combustion. For
onboard the chemical tanker Fure West IMO I, only a small Miller effect of 5% was
has been upgraded to a Low Emission utilised. However, IMO II requires a Miller
Engine (LEE) to meet expected future effect of 20%. This is a big challenge for
IMO emission regulations. the turbocharger, says Caterpillar, which
Furetank Rederi AB of Donsö, Sweden, has to provide boost ratios of 5 in order to
operates five modern product and maintain today’s Mean Effective Pressure
chemical tankers on European shipping Fure West - retrofitting MaK 7 M 43 C (BMEP) values.
routes. Fure West was delivered by Edward marine engine to LEE standard 1. By combining increased compression
Shipbuilding Co, of Shanghai, in 2006. ratio and the Miller effect, NOx emissions
With 144m length, 21m beam, and 9m can be reduced by around 30% without
draught, these 16,000dwt tankers reach a connecting rod, thus reducing combustion sacrificing engine efficiency (BSFC).
top speed of 15.4knots. volume and increasing compression ratio. However, such a simple LEE engine would
Until October 2007, the vessel relied As a result, the anti-wear ring needed suffer from poor load pick-up at idle
on IMO-compliant MaK 7 M 43 C main replacing with a shorter version. and visible soot emissions at part load.
engines rated 6180kW at 500rev/min. In a second step, the camshaft segments Because of this, the MaK LEE concept
However, Furetank owner Lars Höglund were replaced with modified FCT versions, uses a ‘flexible camshaft’ to enable both
said: ‘We have committed ourselves enabling load-dependent variation of low NOx emissions, excellent load pick
to being in the lead when it comes to the fuel and air system. Lower valve up, and invisible soot at all loads.
the preservation and protection of the trains, injection pumps, and injection Flexible Camshaft Technology (FCT)
environment.’ nozzles were exchanged accordingly. In enables variation of the fuel system and
The existing MaK7 M 43 C on Fure West addition, specialists from ABB rebuilt the air system at part load operation. By
was converted to LEE standard during a the turbocharger for increased loading advancing the start of the fuel injection
scheduled vessel stopover in the port of pressure, replacing the diffusor and nozzle and increasing injection pressure,
Rostock, Germany, in October 2007, with ring. combustion is improved and soot
connecting rods, camshaft segments, and The key issue for low NOx emissions is emissions are reduced by 50%. Shifted
lower valve trains reworked to cope with to increase the compression ratio of the inlet valve timing switches off the Miller
LEE requirements. First, a conrod spacer base engine. Ten years ago, a compression Cycle and contributes another 25%
was mounted to lengthen the split-shaft ratio of 11-12 was standard. For IMO I, the reduction in soot. Overall, MaK FCT
reduces soot emissions at part load by
75% while improving engine performance
at transient operation.
Onboard Fure West, Caterpillar
says emissions have been significantly
reduced compared with current standard
IMO I-compliant marine engines. NOx
emissions are down to 8.3g/kWh, or 36%
below current IMO regulations, and soot
emissions reduced to less than 0.5FSN
(Filter Smoke Number) over the whole
load range. NA
Chemical Tanker Fure West powered by
MaK 7 M 43 C Low Emission Engine.
The Naval Architect March 2008 49
NA Mar 08 -
p49.indd 49 10/03/2008 12:02:30
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