Most powerful common-rail engine successfully tested

The first 12-cylinder Sulzer RT-flex96C low-speed marine engine developed by Wärtsilä Corporation has reportedly successfully completed its official shop test. With a maximum continuous power output of 68,640 kW (93,360 bhp) at 102 rpm, it is the most powerful engine so far to employ common-rail technology.

The engine is one of four ordered in 2003 for the propulsion of four 7700 TEU Post-Panamax container liners contracted by Blue Star Reederei, a subsidiary of P&O Nedlloyd BV, with the Japanese shipbuilding group IHI Marine United Inc.

Built under licence by Diesel United Ltd in Aioi, Japan, it was first started on 17 May 2004 and completed its official shop test on 7 June.

After the initial adjustments and running-in, the engine has been subjected to an extensive series of tests. Optimisation of the Sulzer RT-flex system with this size of engine was completed with an eight-cylinder Sulzer RT-flex96C during March/April at another licensee HSD Engine Co Ltd in Korea. Further tests, however, have been made with the 12-cylinder engine into the performance of the engine with its common-rail systems. Throughout the tests, the engine has run extremely satisfactorily, without any difficulties. Its performance has fully met expectations.

Sulzer RT-flex engines are the most advanced large marine engines available for ship propulsion today. They are the first low-speed diesel engines to have electronically-controlled common-rail systems for fuel injection and valve actuation. This gives unrivalled flexibility in the way the engines operate, to deliver benefits such as smokeless operation at all operating speeds, lower fuel consumption, reduced maintenance costs and lower steady operating speeds for better manoeuvring.

Owing to its number of cylinders, the Sulzer 12RT-flex96C at Diesel United has demonstrated a remarkable ability for stable running at very low speeds. For example, on the test bed it has run steadily at seven revolutions per minute.

The much improved quality of combustion achieved in RT-flex engines which allows such low, stable speeds, together with smokeless operation across the speed range, has proved in service to leave RT-flex engines very clean with consequent benefits for maintenance.

With the successful testing of the Sulzer RT-flex96C engine, common-rail technology has been proven to be an excellent step forward for all sizes of diesel engines from automotive engines up to the largest low-speed two-stroke engines. For Sulzer RT-flex engines, a key virtue of common-rail systems has been that they can be modular with standardised hardware applicable to more than one engine bore size. Standardised software is, of course, employed for all RT-flex engine types.

At the top of the Sulzer RT-flex range, the RT-flex96C engine has been extremely successful in the market. In total, 64 engines have been ordered since the engine type was introduced at the beginning of 2003.

Overall, confirmed orders have been placed for a total of 110 RT-flex engines aggregating 4633 MW (6.30 million bhp). In addition to the 64 Sulzer RT-flex96C engines, the engines in service and on order include seven Sulzer RT-flex84T-D engines for VLCCs, two Sulzer RT-flex68T-B engines for Aframax tankers, 17 Sulzer RT-flex60C engines and 15 Sulzer RT-flex58T-B engines for various ship types, and five Sulzer RT-flex50 engines for bulk carriers.

The first series-built Sulzer RT-flex production engine in operation - the 6-cylinder Sulzer RT-flex58T-B in the bulk carrier "Gypsum Centennial" - entered service in September 2001. It now has more than 15,000 running hours. More recently further Sulzer RT-flex engines have been built at Wärtsilä's Trieste factory in Italy, and by licensees in Korea, Japan and China, and today there are eight RT-flex engines in service at sea.

The Sulzer RT-flex96C is adapted from the well-established Sulzer RTA96C engine, the most powerful Sulzer low-speed marine engine type. This is a popular prime mover for the world's largest types of container liners. There are 226 Sulzer RTA96C and RT-flex96C engines in service or on order with an aggregate power output of 13,130 MW (17.86 million bhp).

Introduced in 1994, the Sulzer RTA96C engine has successfully made its mark in the propulsion of large container ships. All the engines are employed in this application, in ships with container capacities from 3700 to more than 8000 TEU. The first engines entered service in October 1997.

Initially there was an emphasis on engines with ten, 11 and 12 cylinders in-line, giving adequate power in a single engine to suit the newer generation of large Post-Panamax container liners. Some 155 of the engines delivered or on order have ten, 11 or 12 cylinders. In 2001, the power range covered by the Sulzer RTA96C, and now also by the RT-flex96C, was extended to 80,080 kW (108,920 bhp) by the addition of a 14-cylinder model and an increase in cylinder power to 5720 kW (7780 bhp) for all cylinder numbers. More recently, advantage has been taken of the high cylinder output of the Sulzer RTA96C and RT-flex96C to provide compact, high-output engines with down to seven cylinders.