Whether real or virtual, common rail injection technologies can make a dramatic difference to the performance of engines that would otherwise need to be replaced
When the Swedish Maritime Administration needed to improve the fuel efficiency and emissions profile of its 40-year-old icebreaking vessels, it looked to electronic fuel injection systems to prolong the life of its engines. The company enlisted common rail retrofit specialist Heinzmann to manage the project.
The programme began with the retrofit of the icebreaker Ymer, built in 1976. During an on-site survey, Heinzmann reviewed the feasibility and the resulting performance of installing a common rail system to the ship’s five main Pielstick 2.2 engines, each generating 3.5MW. It turned out that the specific customer requirements – in terms of emissions profile, fuel economy and performance – could be met by retrofitting the engines.
After obtaining specification data from original drawings an on-site survey, including on-engine measurements, was performed and a mock-up of the high-pressure fuel piping and rail system was built. As a proof of concept, one of the five main engines was retrofitted with Heinzmann’s common rail injection system to determine the impact on efficiency and emissions.
The system installation and commissioning were done without any major modification to the engine itself. This comprised the complete replacement of the fuel system, the mounting of a local operation panel and the integration of a new control, monitoring and safety system into the ship’s automation system. A second main engine with original hydraulic governor-based configuration was operated under comparable conditions in order to rate the improvements.
Over a two-year-test period it showed that the targeted 5% fuel saving could be met. Emissions met the expected IMO Tier 1 level. Further fuel improvements of 2.5% were achieved with an additional turbocharger upgrade. Visible smoke disappeared completely, and vibration levels fell by 30%. Maintenance costs decreased markedly.
"Over a two-year-test period [a] targeted 5% fuel saving could be achieved [and] emissions met the expected IMO Tier 1 level"
The remaining four main engines were retrofitted at the end of 2016. Further fuel saving potential was planned by reducing the engine speed in part load from 485 rpm fixed speed to 360 rpm at variable speed. A ‘green drive’ enabling this load-dependent speed mode was introduced and resulted in a further fuel saving of more than 4%. As a side effect, lube oil consumption decreased by 50%.
After completion of the commissioning of all five engines, the integration into the ship automation system was verified during sea trials. During measurements in field service, a total fuel saving of 11% was confirmed by SMA. The common rail system has since proven itself through three seasons under harsh operating conditions and the administration is now considering further retrofits for some of Ymer’s sister vessels.
Next generation solutions
In the future, common rail retrofits may not be needed at all. One next-generation solution for improving fuel injection control is the OptixAutorail from Swedish company OptixMarine. The makers claim the ethernet-connected injection control systems can cut fuel consumption by up to 10% on engines with individual fuel pumps.
The OptixAutorail control modules are installed on each individual fuel pump. The exhaust temperature on each cylinder exhaust is measured and the individual fuel pump module is controlled with this as one of its reference parameters. During the installation the original fuel rack is disconnected and the original regulator is replaced by the control processor in the OptixAutorail system. To get a more exact engine speed reading the system has a separate rpm pickup.
The OptixAutorail system improves fuel pump performance on engines with individual fuel pumps
Installation requires docking or off-hire time and is done in two days, after which an engineer joins the vessel for another day to tune the system for the specific engine.
One of the main benefits of OptixAutorail – and one of the reasons it can be called a virtual common rail – is that it offers even cylinder power takeout. On a standard fuel-rack controlled engine power takeout varies between the cylinders, sometimes by as much as 75°C. This leads to a variation in cylinder loading. To reduce the fuel consumption on an engine the easiest way is to reduce engine speed. This often results in increased exhaust temperatures. The turbine temperature is determined by the highest cylinder exhaust temperature, and when a high turbine temperature occurs the load control system de-loads the propeller – causing an interruption to service.
With the OptixAutorail system installed, all cylinders have the same power takeout and therefore the de-load only occurs when all cylinders are genuinely overloaded. After installation the exhaust temperature deviation is within 5-10°C, the makers claim.
The system can also be used to enable better engine and cylinder condition monitoring. OptixAutorail is ethernet connected and uploads condition reports for each part in the system. This information includes daily calibration settings, variations in requested fuel pump settings and so on. Based on this data the system can perform a forecast calculation related to engine wear, maintenance demand and other issues in the engine’s control system.
At Nor-Shipping, OptixMarine launched its fuel valve control system OptixAutosync, which the company claims offers further fuel consumption savings of more than 8% for engines equipped with individual fuel valves, by enabling each individual cylinder’s fuel valve to be controlled to the optimal power, cylinder load and timing. The system constantly measures the top pressure in each cylinder and controls each fuel valve’s injection pressure.
“A normal fuel consumption on a conventional engine is around 210 g/kW and on a common rail engine around 180 g/kW,” says OptixMarine head of marketing and sales Markus Forssén. “With the combination of our two systems, owners are able to achieve reductions of up to 30 g/kW on their main engine, for an investment with a payback of approximately 1.5 years that also offers lower maintenance costs and higher powertrain efficiency.”
Not every vessel may have or need the connectivity that remotely connected pump and valve controls require. But for shipowners that want to look ahead, there are increasing options for controlling engine performance.
Combining engine management with smart analytics
Royston Diesel Power has linked its enginei electronic fuel management system (EFMS) to Opsealog’s maritime smart data analysis platform. The move means that automatically generated fuel consumption and other engine performance data from enginei can be incorporated directly into the Opsealog system to be cross checked with other data by Opsealog’s marine business analysts.
The dedicated marine data integration platform provided by Opsealog is remotely connected to the enginei EFMS, eliminating the need for any additional hardware on the vessels and giving land-based fleet management teams direct access to real-time on-board data. As a result, important fuel monitoring and vessel performance data from the enginei system can now be interpreted directly by Opsealog users for enhanced fleet optimisation, emissions control and other operational improvement decisions.
The enginei EFMS system uses Coriolis flowmeters and sensors alongside advanced algorithms to monitor fuel being consumed by a vessel’s engines. This is tracked against GPS data, environmental conditions and operational mode.
Enginei and Opsealog are already working together on over 20 vessels, mainly in West Africa, helping vessel operators to monitor and manage fuel consumption.