Operators must balance their options against cost and performance benefits
Operators have a range of possibilities when turbocharging equipment is reaching the end of its service life. For some it is better to replace and gain the benefits of more modern and efficient equipment but this may involve significant cost. For others there may be different factors to consider and overhauling existing equipment may be a more attractive option.
One of the larger upgrade contracts placed in recent years has been MAN PrimeServ contract from Royal Caribbean Cruises Ltd (RCCL) to retrofit turbochargers aboard four of its cruise ships. Covering a total of 30 turbochargers on 22 engines, the scope included retrofit kits and technical support. Grandeur of the Seas and Enchantment of the Seas, both powered by four 12V48/60 MAN engines, were retrofitted with 16 TCA55 turbochargers, while Horizon and Zenith, each powered by two 9L40/54B and five 6L40/54B engines, were retrofitted with four NA40/S and 10 NA34/S turbochargers.
At the time the order was placed, in December 2015, chief sales officer of MAN PrimeServ Diesel Wayne Jones, said that the upgrade would boost engine performance, extend engine their lives and support the entire operation both from a technical and cost perspective. “In the end it’s an investment in sustainability,” he said.
He was equally confident that the work would deliver results that would exceed RCCL’s expectation of the project. The retrofits, which required about 10 days’ work per engine, showed a reduction in exhaust gas temperatures of 60°C, improving both engine efficiencies and costs for the operators.
Another example of a turbocharger upgrade will be carried out on the cruise ship Amadea, operated by Monaco-based V.Ships Leisure and owned by Phoenix Reisen. The work is due to be done in October, although it may start earlier, and will involve retrofitting two MAN TCA66 turbochargers to an MAN 7L58/64 engine to replace the original units. These will be supplied with fully pre-engineered retrofit kits for ease and speed of installation.
A turbocharger efficiency increase of an estimated 6% is expected, delivering fuel savings of the order of 3 g/kWh. In addition, compressor surge margins will be increased and the engine response to load demand will be improved. The new installation will also conform fully to SOLAS requirements.
A number of land-based examples also illustrate the potential benefits from turbocharger overhauls. One example was the decision last year by the owners of Battery Point power station in Scotland to overhaul its 60-year-old ABB VTR turbochargers. This avoided the need for lengthy recertification work.
Battery Point provides a secure source of power for the islands of Lewis and Harris, generating a maximum of 23 MW of electrical power. The VTR turbochargers at the station have been maintained by ABB throughout their life so regular maintenance had extended their operating life. ABB believes that its services have saved millions of pounds over the plant’s lifetime.
Turbocharger upgrades can also increase revenue for power stations, an ABB study in 2016 suggested. It showed that a 64% rate of return on investment resulted from the combination of increased output and reduced fuel consumption of three engines in one power plant. In another example it found that payback time for a power station upgrade was less than a year.
It is not only turbocharger manufacturers that offer upgrades; engine manufacturers also see the business potential in this area. Wärtsilä, for example, offers performance optimisation through turbocharger upgrades for its Wärtsilä 38, 46 and 50 engines. Turbochargers require a major overhaul at 50,000 hours with the replacement of major rotating parts. As an alternative, Wärtsilä offers the option of upgrade packages, which offer the advantage of the latest turbocharger technology to be adopted, giving the potential for fuel consumption reductions of up to 4%.