Turbocharger retrofit carried out on Maersk VLCC

03 Oct 2013
MHI has retrofitted its variable turbine inlet system to the turbochargers of a Maersk tanker, with good results

MHI has retrofitted its variable turbine inlet system to the turbochargers of a Maersk tanker, with good results

Mitsubishi Heavy Industries Marine Machinery & Engine Co (MHI-MME) says that it recently retrofitted its variable turbine inlet (VTI) system to the turbochargers of a Maersk Tankers VLCC.

The work was carried out on the 318,000dwt Maersk Ingrid, during the ship’s first dry docking in May 2013. VTI was developed for MHI’s MET turbocharger series, and operates by closing a valve in the gas inlet passage during slow steaming.

The on-off valve is designed to change turbine capacity in two stages by admitting the exhaust gas into two separated concentric segments of the nozzle ring. When the vessel is operating under slow steaming mode, scavenging air pressure of main engine is increased by closing the valve, lowering fuel consumption rate and CO2 emission. Although several systems have been delivered for newbuilding projects, this was the first VTI installation retrofitted to turbochargers on a shipin service.

Maersk Ingrid has a Wärtsilä 7RTA82T main engine with two Mitsubishi MET71MA turbochargers, manufactured under licence by Hyundai Heavy Industries. The retrofit work was carried out over a four-day period, and when NOx emissions were measured in sea trials the installation was confirmed as IMO Tier II compliant. The trials additionally confirmed that the expected reduction in fuel consumption at low load was achieved without sacrificing the performance at high-load range.

Maersk’s project leader, Vaibhav Chavate, confirmed a reduction in fuel consumption reduction of1.6% to 3.2% in the 10% to 50% MCR range, meaning that the pay-back period for the modification should prove attractively short. As a result, the A.P. Moller group is said to be considering application of VTI to further MET turbocharger-equipped vessels.

MHI-MME says that the simple structure of the VTI system results in high reliability with low cost and simple maintenance. It can be retrofitted to conventional MET turbochargers by just adding a nozzle and the on-off value to the exhaust gas inlet.

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Mitsubishi Heavy Industries Marine Machinery & Engine Co

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