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Marine Propulsion & Auxiliary Machinery

Marine Propulsion & Auxiliary Machinery

High efficiencies promised from high-pressure fuel injector

Mon 14 Aug 2017 by Paul Gunton

High efficiencies promised from high-pressure fuel injector
the RKI as a self-pressurising diesel fuel injector that receives its initial pressure from the piston compression in the combustion chamber

A novel fuel injector concept could replace common rail fuel delivery to give improved efficiency and lower emissions

RK Labs’ managing director Gavin Houghton told Marine Propulsion that the new injector will be offered as a direct replacement for current common rail diesel fuel injection systems. He said the RKI nozzle can generally fit into the existing cavity of the common rail injectors but it is larger than common-rail injectors so smaller engines may need the cylinder head entry point to be enlarged. The engine management software would also need updating, he said.

It will be aimed at a number of industries, including marine, for which it is setting up a dedicated division. This will work closely with RKLabs’ main powertrain consultancy, Powertrain Technology of the UK, and its development partners, Mazda and the Technical Research Centre of Finland (VTT), whose board reports to that country’s Ministry of Economic Affairs and Employment.

The company’s development team will be moving from locations in Switzerland and the UK to be near VTT in Helsinki and Mr Houghton provided a briefing paper that had been presented to the Finnish government about the technology.

That paper describes the RKI as a self-pressurising diesel fuel injector that receives its initial pressure from the piston compression in the combustion chamber. This is multiplied within the injector and uses it to force the fuel into the combustion chamber through up to 180 tiny holes 0.025mm in diameter. This combination of ultra-high pressures and a large number of small injection holes “has the natural effect within the combustion chamber of creating optimal combustion conditions,” the paper reports.

A conventional injector has between four and eight holes, the paper notes, and the large number in the RKI version creates a unique spray pattern that improves the air-fuel mix in the combustion chamber. This improves the combustion process and lowers the temperature and compression within the combustion chamber, the paper says. It is these conditions that lead to its main benefits, it says.

In operation, it says, there is a natural feedback within the RKI as it takes its initial signal from the compression pressure and will only provide the amount of fuel that the combustion chamber will effectively burn, so no fuel will be wasted. However, the injector can also be controlled electronically through solenoid valves in the same way as existing injectors, the paper says.

RKLabs’ paper sets out both benefits and challenges of its concept, both of them related to one of its claimed benefits: its ability to use a wide spectrum of fuels, from HFO to bio-diesel. The company told the Finnish government that it will allow modern large bore two or four stroke engines to exceed emission and fuel regulations using one fuel for both propulsion and electricity generation with no need for post combustion clean-up equipment.

However, the challenge is to make this practical. To make an injector able to cope with the wide range of fuel specifications and qualities “will require a series of technical modifications from the current optimal fuel specifications used in marine,” the paper says. In particular, current HFO specifications present “a unique challenge to the RKI injector and will require expertise in metallurgy, fuel heating, filtering and treatment in order for the fuels to be able to be injected successfully,” it says.

RKLabs is now “on the sixth generation of physical prototype,” Mr Houghton said in mid August, with two classes of test injectors being built for testing in Japan and by VTT in Finland. The company is now looking to establish long term partnerships with shipowners and engine manufacturers. “To be fully operational in a marine engine we need to co-operatively work with a partner or a project with several key stakeholders to design, build and test our injectors on a range of marine engines,” he said.


Ferries fit LNG fuel systems

A double-ended ropax ferry will be delivered in November with a dual-fuel propulsion arrangement, the first vessel of its kind in the Mediterranean to be fitted with LNG propulsion. Gas will be handled by an LNG fuel-gas supply system (FGSS) from MAN Cryo – MAN Diesel & Turbo’s marine LNG fuel-gas-system manufacturer.

Its fuel system consists of a 150m3 vacuum-insulated storage tank, complemented by auxiliary equipment including an LNG vaporiser, a pressure build-up unit, a bunker station and a heat exchanger.

The 133m double-ended ferry is being built by Sefine Shipyard in Turkey for Italian shipowner, Caronte & Tourist. It will and will primarily operate on the strait of Messina between Villa San Giovanni – the main access point to Sicily from the Italian mainland – and the city of Messina.

MAN Cryo is also due to supply FGSSs to the Vard Shipyard Group in Norway for two ferries for shipowner and ferry operator, Torghatten Nord. The equipment is due for delivery in Q1 2018 and will consist of a 175m3 vacuum-insulated storage tank along with similar auxiliary equipment to that for the Italian ferry.

When MAN Cryo announced its supply contract in April, its managing director Mikael Adler spoke of “a clear trend in the market with an increasing number of inquiries for fuel-gas systems.” He saw this as pointing “towards LNG’s positive growth as a choice of fuel.”

Each ferry will be equipped with a gas-electric, hybrid-propulsion system that features optional fast-charging from shore. Their concept was developed by the Norwegian designer Multi-Maritime, which MAN Cryo said has extensive experience of advanced vessels. Their aim has been to produce vessels with energy-efficient propulsion and a hull shape that offer the best environmental performance, comfort and reliability.

Purchasing manager at Vard Group, Thor Inge Skov, cited these the ships’ expected performance as “a very important reason to why we have chosen MAN Cryo as fuel-gas supplier.” The 134m double-ended ropax ferries will operate between Halhjem and Sandvikvåg, south of Bergen.


L’Orange finds a cause and a cure for sticking fuel pumps

Sticking fuel pump plungers are a common complaint among marine engineers and engine manufacturers recommend regular checks and cleaning to keep them working effectively. For example, one engine project guide readily available online recommends lubricating and checking every fuel injection pump for signs of sticking on a weekly basis when running on HFO.

That guide is for Rolls-Royce’s Bergen C25:33 engine and now, L’Orange – a Rolls-Royce company – has developed anti-stick pump elements that it believes will increase their time before overhaul and reduced engine downtime, giving up to 10 times more running hours. The anti-stick pump elements can be retrofitted to existing pumps.

It has identified the problem as being caused by deposits in the piston barrel, which it believes are most often the result of an incompatibility between the fuel and lubricating oil, which could be caused by low total base number values, or incompatibility between different fuels.

When it brought the new version of the pump to market in May, it explained that it had succeeded in reducing the formation of these deposits and therefore reducing the risk of sticking. “What makes this possible is the combination of an innovative coating together with targeted design optimisations,” it said. It assured customers that the new version has the same the hydraulic properties of previous models.

Its literature does not identify the coating material, but says that it reduces deposits on the plunger. The design changes have introduced a microgroove with a scraper ring that separates the lubricating oil from the fuel to reduce the deposits building up in the barrel. As well as the technical benefits, the new pump’s longer service intervals will reduce servicing costs, L’Orange predicted.


Get ready for MRV, warns Royston

Many ships must have fuel monitoring plans in place by 31 August to meet the EU’s monitoring, reporting and verification (MRV) regulation, Damian McCann, product manager at the UK diesel power specialist Royston reminded Marine Propulsion readers.

In a paper prepared in July, he said that thousands of vessels may need to retrofit monitoring equipment to ensure compliance while shipbuilders have to consider their options for installing suitable technology as part of their ship system infrastructure specifications. For system manufacturers – such as Royston – “moves in this direction will be seen as a boost,” he admitted.

Plans must be submitted for verification before formal reporting starts in January 2018. CO2 emissions and transport work data for 2018 must then be consolidated in an annual report, which must be verified by an independent accredited verifier by 30 April 2019, he said. Once that has been done, the report must be submitted to the European Commission and the Flag State, and the vessel should carry the document of compliance from June 2019.

The requirement applies to vessels equal to or larger than 5,000gt that call at EU ports. The move is designed to generate a 2 per cent reduction in CO2 levels.

IMO’s similar requirement under Marpol Annex VI for ships to have a Ship Energy Efficiency Management Plan (SEEMP) also requires data to be collected on fuel use. It also applies to ships of 5,000gt and above and sets a deadline of 31 December 2018 for them to include a description in their SEEMP of the methodology that will be used to collect the data and the processes that will be used to report the data to the ship’s flag state.

Royston has published a case study about a project in which it supported a European tanker operator to log accurate fuel consumption data, both to contribute to its SEEMP and to optimise its operations.

A tailored on-board enginei software package was developed through which the captain logs ports, times, bunker cost, ship condition, voyage notes and weather using a touch-screen on the bridge. All this information is then tied into the fuel consumption data, giving the operator very detailed fuel reports and trends, the company reported.

After six months recording the data, the operator discovered its recommended steaming speed was 0.5kt too high on certain classes of vessel. As a result, it has been able to save 4 per cent of its fuel.

• Royston’s ‘AutoMode’ capability for its enginei fuel consumption monitoring and management system, won the 2017 Environmental Award from Marine Propulsion’s sister publication Offshore Support Journal. The award was presented during that magazine’s annual conference in February. AutoMode was described in Marine Propulsion, August/September 2016. The award’s judges had been impressed by its ability to optimise OSV fuel consumption across different vessel operating phases.





































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