Pivotal debate

The latest Motor Ship Propulsion Conference in Amsterdam was attended by over 200 people and touched on some controversial subjects.

Germanischer Lloyd?s Hans Jacob Gatjens chaired the conference and introduced speakers giving papers ranging from engine problems to podded propulsion systems, as well as impending emissions legislation.

Opening the conference was keynote speaker Dr Martin Stopford, md of Clarkson Research, with an overview of shipbuilding trends, predictions of future demand and thoughts on future newbuilding prices. Questions started with one about the effect of the Erika incident, to which Dr Stopford said there had been an immediate dip in earnings of older tonnage, especially tankers, but this had now recovered. Recently some good charterers have taken on vessels over 25 years old at rates of up to $22,000/day and Clarkson had revised downwards its predictions on scrapping.

Terence Byrne of Danfoss asked if the EU?s actions would affect Korea?s pricing policy, but the answer was probably not. However, Dr Stopford did add that Korea does not appear to have followed through on its stated intention of moving into high-tech vessels and has stayed with the more steel intensive ships.

A paper from MaK?s Gerd Pommerening opened the Engine Markets and Technology session. This concentrated on the growth of four-stroke engines as main propulsion, and the improvements in the medium-speed units. This was followed by Peter Sunn Pedersen from MAN B&W who gave a progress report on computer controlled two-stroke engines. The latter paper prompted a question about what other engine functions would be computer controlled. Mr Sunn Pedersen answered that in addition to the functions mentioned, the starting air system was also controlled by a computer. Consultant Keith Wilson asked about the effects of placing a 7 micron filter in system oil which acts as a hydraulic fluid to operate the fuel injectors and the exhaust valve. “Not much” was the reply in that with one back flushing per hour the maximum pressure differential was 0.6 bar. Over time the system “significantly cleaned” the system oil and there were no clogging incidents during a two-year trial. But if the filter did block an automatic bypass would ensure the engine continued running.

Dr Stopford asked Mr Sunn Pedersen if shipowners were considering running a low-speed engine on boil-off for LNG propulsion, and what were the issues of concern. These were engine maintenance, and interruptions to the LNG fuel supply: twin engines overcome the first problem and the second does not arise as the engine can run on MDO, used as a pilot fuel, if required. A delegate from DNV enquired about the effect of using low sulphur fuel on cylinder liners. No actual figures exist, said Mr Sunn Pedersen, but while acidic corrosion would not occur, there is historic evidence of scuffing problems. Mr Byrne asked about the varied approach of class societies towards approvals of temperature and pressure sensors. Mr Sunn Pedersen said this was a concern, and that CIMAC has started discussions with class societies to try and arrive at a uniform approach.

The chairman asked if gas turbines posed a threat to medium-speed engines in cruise ships, but Mr Pommerening said only 15 per cent of cruise ships were using turbines.

Pierpaolo Barbone and Alberto Guglia?s paper on the first Wartsila 64 opened the session on Service Experience with the New Generation Engines. The duo from Wartsila NSD Italia (the new name for GMT) described the findings of inspections after the engine?s first 2,500 running hours. This paper was followed by a joint presentation between MAN B&W?s Ole Grone and Hapag Lloyd?s Klaus Marek on service experience with the 7K98MC. The session?s final contribution came from P&O Nedlloyd?s Henk JJ van Heel and Kaspar Aeberli of Wartsila NSD and concentrated on problems experienced with the first RTA96C engines and solutions devised by the designers.

Questions to Mr van Heel centred on the lack of a 100MW (135,960 bhp) propulsion system for the 12,000 TEU container ship he wishes to build. A 16-cylinder 98 bore engine had been proposed but Mr van Heel said that an in-line engine would be too long. Mr Grone highlighted the possibility of a vee version but said that owners were undecided. Mr Marek considered the way forward was for higher rated engines, or even larger bores. Mr van Heel was asked if he had considered gas turbines. He said he had, but the initial cost and fuel costs ruled them out.

Castrol Marine?s Robert Allen opened the Lubrication session by looking at engine trends, the increasing stress on lubricants, and the choices this posed for the operator. The paper from K C Lim of BP Marine examined cylinder lubrication for low-speed engines and questioned operators? perception of BN as a guide to oil quality. Laboratory test methods for marine lubricants was the subject of the paper given by Jean-Philippe Roman from Elf Antar. This included some graphic illustrations of what the tests can reveal. The effect of lubricant on the reliability of medium-speed engines was the topic of the paper from Ing. Andre Verhelst of FAMM (Fuel and Marine Marketing).

Stamatis Bourboulis from Ceres Hellenic Shipping enquired about potential cylinder lubrication problems when using low sulphur fuel. Mr Lim said work was underway with MAN B&W to examine extended running on 1.5% sulphur fuel and it is clear that excess alkalinity can cause build-up on the piston crown. Mr Wilson asked why there was not more dialogue with the users rather than concentrating on the engine builders. Mr Lim countered that as chairman of the CIMAC lubricants group he is in very close contact with shipowners. The chairman asked if MAN B&W?s new cylinder lubrication system would effect the cylinder lubricant. Mr Allen said it would, and that if owners wanted to use less oil it had to be of a better quality. Mr Lim added that in analysing the TBN of cylinder drain oil it was clear that a lot is wasted, and that it may be possible to use analysis to match the feed rate and BN to the engine?s requirements.

Opening the Problems and Solutions session was MAN B&W?s Uffe Mikkelsen who examined the problems and countermeasures on large bore engines. Markus Geist from Wartsila NSD explained to delegates the problems that have occurred with Sulzer engines over recent years and the modifications made to overcome these.

System reliability was under examination in a paper from Piet Kloppenburg of Techno Fysica. The company undertakes 350-400 investigations per year ? many of which are caused by lack of system engineering, poor communications or lack of knowledge about operating conditions.

The session ended with a discussion about the findings of the CIMAC users group ? details of which were given by group chairman, Jorn Dragsted, senior superintendent engineer with AP Moller. Mr Dragsted outlined the contents of the CIMAC User Group?s database, which contains details of 825 main and auxiliary engines. Of these, around 350 are two-stroke, 200 or so from MAN B&W, and about 50 from Wartsila NSD. Problems had been reported on about two thirds of the engines and the largest area of concern was hot components.

Questions from the floor started with one to Mr Mikkelsen about how many of the bearing failures were due to poor bonding ? he replied that it was about 10-15%. The chairman added that engine problems were often very complex, and that other factors like vibration played a big part. Mr Wilson asked if it was reasonable for engine builders to make offset bearings to counter alignment problems, and if class should look at the situation again. Mr Mikkelsen replied that MAN B&W did not like the concept of offset bearings, but this can be done when machining the bedplate and if it cured the problem, then why not.

From the floor Mr van Heel said some operators are not running their engines at 90% MCR in the tropics and asked if it was possible to retrofit a new design of water catcher used on the 98-bore engines to his fleet?s K90MC units. Mr Mikkelsen replied that this was under investigation. From the floor Mr Sunn Pedersen said the first installations were retrofits and that part of the reason for offset bearings was to counteract the stiffer structure of the aft end of the engine.

Another questioner asked if MAN B&W?s controlled pressure release (CRP) top ring rotated in operation, and at what speed. Mr Sunn Pedersen said say the ring did rotate but nobody had looked at the speed. One questioner asked what obligation there was to repeat engine test bed performance at sea. Replies centred on the differences of the test (run on the theoretical propeller curve) against sea trials and added that all subsequent work uses sea trials results. Mr Dragsted agreed with the questioner who asked why fuel consumption is verified in shop tests rather than at sea trials, and added that discrepancies were above acceptable limits. The reply from the manufacturers was that testing fuel consumption during sea trials was not easy. However, Mr Dragsted said he has seen many such discrepancies and that while he would not accuse the engine companies of cheating, he felt it was very close.

BP?s Mr Lim asked if the problems mentioned with hot components in low-speed engines were effected by the lub oil feed ? but the speaker said this information was not recorded. Mr Gatjens added that the cost of replacing hot components was far lower than that for main bearings. Castrol?s Graham Carroll asked if the marine industry should have some form of compulsory incident reporting. Mr Dragsted replied that that was not the intention of the Users Group but it wanted to see solutions and not bureaucracy. The chairman added that class societies had to treat all information as confidential.

The second day opened with a session on Applications and Machinery Selection, and started with Javier Romero of Astilleros Espanoles describing the use of boil off as a fuel for low-speed main propulsion engine in LNG carriers. This was followed by Wartsila NSD?s Torbjorn Henriksson who described its “smokeless” engine and also looked to refute some of the potential savings available when using gas turbine propulsion on cruise ships. Heikki Sipila from Kvaerner Masa-yards also looked at machinery selection for cruise ships and showed some futuristic designs. Ending the session was a paper from ABB Marine?s Rami Jokela which examined the machinery selection on a chemical tanker.

Questions started with one on the costs of adding SCRs to a diesel electric cruise ship. Mr Henriksson said if a SCR is run throughout the year the urea cost would be $800,000, but lowering the NOx production with water injection could halve this. Tom Wismann from dk-Teknik asked if cruise ships with low smoke engines were fitted with analysers to measure the opacity of the exhaust. Mr Sipila said this had not been thought of by the yard – but it was possible – to which the questioner commented that it would be a good idea. A delegate from Napier Turbochargers asked is inside cabins were becoming more acceptable with quieter machinery, to which Mr Sipila replied the trend was for bigger cabins with better views. Ship operator Odfjell questioned the high minimum capacity generating sets (three 2,620kW) on the chemical tanker. A second delegate replied that when pumping, the electricity demand was quite high, justifying the rating.

Andy Wright from ABS Europe asked about the correlation between Wartsila NSD?s smoke measurements with visible smoke and particulate emissions ? especially the transient performance. Mr Henriksson said there may be some smoke during take-up but the company was looking to improved system integration to overcome this.

Napier?s Ken Winn opened the Turbocharging section with an outline of the challenges facing turbocharger manufacturers. This looked at titanium compressor wheels, high-speed generators, air and magnetic bearings, and even fuel cells. The next paper was given by Volkmar Haueisen from ABB Turbo Systems explored the development of the TPL..-B turbocharger. High temperature corrosion in turbochargers on medium-speed engines was the theme of a paper delivered by Bert Buchholz of Motoren-und Energietechnik. Ian Webster from Exxon Mobil asked why turbochargers were lubricated with system oil, as this will introduce contaminants. Mr Haueisen said that the bearing was designed to tolerate typical particles found in system oil and that users were free to install a separate lubrication system provided it met the relevant specification. In answer to a second question he replied that bearing life should be 35,000 hrs when using system oil.

Dennis Siu Hung Chan from DNV asked if the TPL..-B could be used on four-stroke engines. He was told that problems could arise on medium-speed engines as the unit has a restricted gas inlet temperature and can only be used for constant pressure systems. The same delegate then asked how precise the predictions were for pulsed systems and the effect this has on the engine. Mr Winn said computer modelling is now very good but engine testing was still needed as verification.

Moving on to The Emissions Issue session, Capt Cornelius de Keyzer from the Port of Rotterdam took a look at how shipping caused pollution, the need for emissions reductions, and some of the current strategies. The paper from ABS Europe?s Andy Wright took a closer look at how the IMO?s NOx code will affect ship operators. Emissions reduction on medium-speed engines was the theme of Georg Wachtmeister, head of engine technology at MAN B&W in Augsburg. NOx reductions using the Humid Air Motor (HAM) aboard Viking Line?s Mariella was explained by the company?s technical manager Kaj Jansson. The final paper in the session from Wartsila NSD?s Arne Lundkvist examined direct water injection as used on the company?s medium-speed engines.

David Batie from DMI enquired about the supply of marked, NOx related spare parts for certified engines. Mr Wright said that there could be a monopoly in the supply of marked parts, and that it was up to the shipowner to look closely at the technical file that accompanies the engine to see what is included. If there is not enough information for parts to be sourced from other suppliers, then shipowners must ensure this is added so they are not tied to one supplier. Mr Verhelst asked about the potential of combining HAM with water injection, and was told the effects were positive and being investigated. Another question regarded turbocharger matching with HAM. Mr Jansson said a wastegate had been added to prevent overspeeding the turbocharger at full load. Mr Lundkvist said that the HAM unit was fitted to a 10-year old engine, and with the water injection system on new engines the turbocharger matching was such that the water could be turned on and off without causing problems.

John Liddy from BP Marine asked about the cost of retrofitting the HAM system and water injection. Mr Jansson replied that the HAM unit was a prototype made of very high grade material but some parts could be replaced with plastic, and the market would dictate the price. He suspected it would be around the price of an SCR but without the additional expense of urea. The price of adding direct water injection was lower than an SCR, said Mr Lundkvist, and is dependent on the engine size. Jeroen Waalewyn from Wolfard?s Werktuigbouw asked why steam from a waste heat boiler is not used in place of the HAM evaporating system. There are other uses for the steam generated in the boilers and requires high quality water whereas the HAM system is simple and uses seawater, replied Mr Jansson. Another delegate asked if grey water could be used in the HAM system but was told that potential problems exists with soaps (causing foaming) and other chemicals.

Opening the final section on Podded Drives was Jukka Kuuskoski, sales manager of ABB Marine. His paper explored the advantages of using a pod behind a conventional driveline to give a contra-rotating propeller effect, while removing the need for a rudder. Legal technicalities forced Siemens to withdraw its paper on SSP propulsion for ropax ferries, although delegates should receive a copy of the paper once the difficulties are resolved. The last paper, from Capt H C van Mameren of Ha-Ce Marine, also featured the SSP but this time on a heavy lift vessel for COSCO.

Capt de Keyzer asked about the ballast capacity for the heavy lift vessel and was told it was 36,000t, enabling 9m of water above the main deck. He then asked about complying with potential ballast water regulations. Capt van Mameren replied that there is no need to flood the fuel tanks, and that problems with ballast water were more or less unavoidable with heavy lift vessels. Kieob Yoon from Hyundai Heavy Industries enquired about how using an Azipod system reduced NOx. Mr Kuuskoski said this was down to lower fuel consumption due to better propulsion efficiency, as well as running the diesel engines at constant speed.

Thanking both speakers and delegates, Dr Gatjens closed the conference.