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Cimac Congress | Shanghai 2013 low frequency plane wave range and high frequency non-plane wave range. The low frequency plane wave range acoustic source characteristics of an IC engine can be determined accurately by using for example process simulation software and acoustic multi-load methods. If the diameter of the studied duct is small as in automotive systems, the low frequency plane wave range source characterisation might be enough. When studying noise from a medium-speed power plant or marine IC engine, the duct diameters are large and therefore the acoustic source characteristics in the high frequency nonplane wave range are also important. The goal of this study is to estimate how the acoustic source data of a medium-speed IC engine exhaust system can be determined in the low frequency plane wave range and also in the high frequency non-plane wave range using engineering practices and acoustic power based methods. In this study the source characteristics are determined based on simulations and measurements, then the low- and high-frequency source characteristics are combined in a way that allows them to be used in multiport simulations. The effect of piston structure parameters on the lube oil consumption Jilin Lei, Zhejiang University, China Xiaoli Yu, Zhejiang University, China Jun Wen, Chendu Galaxy Power Co, Ltd, China Lizhong Shen, Kunming University of Science and Technology, China Zhentao Liu, Zhejiang University, China Based on the measurement of temperature filed of piston and cylinder sleeve, the dynamic model of 2D25 diesel piston assembly was established. The effect of piston structural multi-parameters and single parameters on lube oil consumption was analysed by orthogonal experimental design method and conventional method, and the single parameters, including the radial clearance between piston skirt, piston head and cylinder inner wall, and piston pin offset. The results indicate that the radial clearance between piston skirt and cylinder inner wall has the greatest impact on the lub-oil consumption, followed by the piston head radial clearance and the piston pin offset. The convex position of piston skirt profile, stiffness and ovality of piston skirt had little impact on the oil consumption. The lub-oil consumption had little change with the radial clearance between piston skirt and inner wall from 0.06mm ~ 0.09mm, but the lub-oil consumption increased rapidly when the radial clearance between piston skirt and inner wall was at the range of 0.09mm ~ 0.15mm. The lub-oil consumption had a little increment with the piston head radial clearance. The lub-oil consumption was the lowest when the piston pin offset to main bearing surface was 0.5mm, and the lub-oil consumption was increasing with piston pin offset to main bearing surface was increasing, but the range was not obvious. Thursday May 16th / 08:30 – 10:00 Users´ Aspects Marine Application – Service Experience Room B Service experience of MAN B&W two-stroke diesel engines – an update Stig Baungaard Jakobsen, MAN Diesel & Turbo, Denmark After the introduction of the Tier II versions of the MAN B&W M-range of two-stroke diesel engines, around 85% of all new orders are specified as electronically controlled ME/ME-C/ME-B types. This trend is covering all engine sizes; however the trend is most dominating for large-bore engines (80, 90, 98) where nearly 100% of all orders are specified in electronic controlled versions. It is therefore of extreme importance that the ME engines have reached a matured development status and this paper confirms that this is indeed the case. Today, the ME engine concept is widely accepted among major shipowners and the benefits of electronic control is seen more and more as the concept is enhanced with features as auto-tuning, integrated control of exhaust bypass, variable turbine area turbochargers, turbocharger cut-out and in the near future (Tier III era) integrated control of exhaust gas recirculation, water in fuel emulsion and SCR. An update of service-related issues on the electrohydraulic control will be given. The continued change in economics for shipping following the worldwide financial crisis starting in autumn 2008 has called for continued focus on extreme low continuous load operation of several types of vessels. This focus started for large container vessels operated down to 10% load continuously. However, now it also becomes relevant for other ship types like tankers and bulkers. An update on service experience will be given, including service experience with ’high-pscav tuning’ as retrofit. Lower design speed for newly ordered ships has called for new engine types in various types of vessels applying larger diameter and more efficient propellers. For large container vessels, about 8,000 - 14,000 TEUs, the S90ME-C engine in Mark 8 and Mark 9 versions have become new industry standard. An update on service experience with this new application of the well-proven S90 engine, formerly predominantly specified for VLCC propulsion, will be given. The trend of applying lower propeller revolutions on various ship types has also called for the introduction of the ultra-long stroke G-type engine series. Early service experience of these engines will be given. Common for both the ME/ME-C and the MC/MC-C engine series is the well-documented possibility to do condition based overhaul (CBO) with average time between overhauls (TBOs) of 32,000 hours and above. For tankers, this opens up the possibility to do only major overhauls at dockings with five years interval. Many shipowners do now have the experience with CBO. Development of a new piston ring package for small bore engines (50 bore and lower) has made it possible also to enjoy extended time between piston overhauls on these engine types. The so-called POP (Port On Plane) top piston ring will also be introduced. Diesel engines optimisation and fuel savings Magnus Karlsson, Stolt Tankers BV, The Netherlands The aim of this paper is to present how to achieve a reduction of fuel oil consumption and maintenance cost through optimisation of diesel engines. Furthermore, the paper will also handle combustion-related problems of Marpol Annex VI emission Tier I, low NOx settings of diesel engines and diesel engine optimisation in general. All presented cases are real and are backed up with real combustion diagrams, measurements and calculations carried out during performance and energy audits onboard Stolt Tanker’s vessels by the author of this paper. The author has as well attended several factory acceptance tests for diesel engines. A diesel engine combustion analyser instrument is used when carrying out the performance tests of diesel engines onboard vessels. Based on the results from the combustion diagrams achieved from the combustion analyser and other relevant performance data, the diesel engines are optimised for improved performance. The work process in the combustion diagrams will be explained and also how the diagrams should look like to achieve the most efficient combustion. The paper will show examples of diesel alternator engines with Marpol Tier I low NOx emission settings. The paper reveals that newly installed diesel engines on vessels optimised in compliance with low NOx emission limitations 68 SPECIAL Schiff&Hafen | Ship&Offshore | May 2013
Monday, May 13th Tuesday, May 14th Wednesday, May 15th Thursday, May 16th can be poorly optimised and therefore in a state of combustion unbalance. The paper shows that it is possible to optimise these poor factory-adjusted diesel alternator engines to achieve a more efficient combustion and thereby a reduced fuel oil consumption and maintenance cost and still comply with the low NOx emission limitations. One special case of wrongly designed diesel alternator engines in compliance with low NOx emission limitation installed on the new vessels in the fleet is presented. In connection to this special case an older diesel alternator engine was optimised to make it possible to compare the design of the fuel injection in the two engines. Furthermore, there will be examples of optimisation of older diesel engines that do not need to be in compliance with Marpol Tier I low NOx regulation, both a twostroke main engine and a four-stroke diesel alternator engine. The author believes that the paper can be enlightening for both shipowners and engine makers. Design and field experience of Hyundai-Wärtsilä twostroke RT82 family engine Jang Ho Kim, Hyundai Heavy Industries Co, Ltd, South Korea Byoung Gi Kim, Hyundi Heavy Industries Co, Ltd, South Korea Sang Lip Kang, Hyundai Heavy Industries Co, Ltd, South Korea Bal Young Kim, Hyundai Heavy Industries Co, Ltd, South Korea Ju Tae Kim, Hyundai Heavy Industries Co, Ltd, South Korea Bo Soo Kim, Hyundai Heavy Industries Co, Ltd, South Korea Since an official shop test of proto camshaft-controlled Hyundai-Wärtsilä RTA82C engine was carried out in April 2008 at Hyundai Heavy Industries Co, Ltd (HHI-EMD), more than 90 sets of the RT82 family engine (RTA82C, RTA82T, RT-flex82C and RT-flex82T) are in service with very good service feedback to date. Accumulated service hours of the 8RTA82C engine, which entered into service firstly in the RT82 family engine, is exceeding approximately 25,000 hours. Design improvement on fuel injection and hydraulic pump system, common rail supply system etc. was performed, through sufficient validation tests, in order to provide economical, reliable and prolonged times between overhauls for shipowners. Through enhanced product care activities, aforementioned design modifications have been introduced accordingly on newbuildings. Measurement of optimised engine performance, stresses and temperatures measurement of all major components for IMO Tier II emission regulations on RTA82C as well as RTA82T engines was carried out successfully, and it was confirmed that all of design philosophy met the market demands. Verification test of increased waste heat recovery system (WHRS) bypass ratio and fuel actuated sacless technology (FAST) injector was successfully performed on the 7RT-flex82T engine at the test bed of HHIEMD in very close cooperation with Wärtsilä Switzerland Ltd. According to the test result, shipowners can be offered more competitive and economical engine operating conditions. This paper presents the latest market trend, design improvement and field experience of the RT82 family engine. Also, proactive activities of HHIEMD satisfying market demand will be described. Condition-based maintenance of the two-stroke propulsion engine Oyvind Toft, BW Fleet Management AS, Norway Henrik Rolsted, MAN Diesel & Turbo, Denmark Per Samuelsson, Federal Mogul Gothenburg AB, Sweeden Tormod Opsahl Linnerud, Det Norske Veritas, Norway Tormod Opsahl Linnerud, Det Norske Veritas, Norway The typical time between overhaul of two-stroke main engine cylinder units has been in the range of 10,000 to 15,000 hours. This has been regarded as best practice in the shipping industry for the last three decades - a practice that has ascertained safe and reliable operation. The development of design and material technology in this period has lead to significantly higher outputs, improved reliability, lower emissions and higher cost efficiency. Examples are improved designs of the turbocharger, combustion chamber, bearings, fuel system, lubrication system and piston rings. There may still be challenges in certain areas, but all in all the gains have been considerable. At the same time ship operators have increasingly been challenged by their business partners as well as the public at large to operate within ever larger safety margins. Amongst others, this has implied that even planned overhauls requiring disabling of the main engine when the ship is in service, becomes increasingly difficult - especially for any kind of tanker vessel. For a long time, there have been restrictions in place hindering overhauls when alongside at terminals. This restraint has recently also been imposed by authorities of some of the most strategic anchorages. Disabling main engines commonly requires standby tugs in these areas thereby increasing costs for overhauls to a large degree, and many operators see this as shrinking opportunities to carry out planned maintenance in a cost-effective way. To mitigate this situation attempts have been made to operate main engines from ’dock-to-dock’, i.e. at five-year intervals, which requires about 30,000 hours between overhauls. This would entail several advantages. Clearly, planning, lead time for acquiring spare parts, availability of assistance etc. would improve the quality of work and perhaps also reduce spare part costs to some degree. Furthermore, the time loss would become reduced. The results from the aforementioned tests have been encouraging to the degree that one could think of main overhaul intervals of even up to ten years, which would require safe operation for up to 60,000 hours. Largely prolonged service periods as well as the trend towards higher engine outputs would call for changes to the specifications for some highly loaded key components whose service life is not always predictable. A section of this paper explains the specific challenges for piston rings. Various types of coating on the running face and on the side face are now state of the art for the high efficient two stroke engines. The design of the ring groove plays also an important role if one wants to achieve running hours of approximately 60,000 hours. The hard chromium plating used today might not always be the right choice. New coatings in the piston grooves besides on the piston rings may be a necessity. Further, as the engine designers have come up with more and more powerful engine versions, demand on the piston rings has increased. Additionally, a more prolonged TBO together with the new SECA regulation will have an important influence on the ring design for the future. The exhaust valve spindle is another example where heavy duty material may be required to withstand the stress and fatigue imposed by such long service time. Since costs for overhauls when the ship is docked tend to increase somewhat due to yard assistance and increased costs for heavy duty components, the proposition to carry out overhauls at alternate dockings becomes much more interesting as cost efficiency would increase sharply and more than outweigh operating costs associated with current practices. The paper reports on results obtained with two MAN B&W 6 S 60 MC-C engines and discuss requirements to components and operational procedures. Furthermore, an outline of a maintenance programme based on condition monitoring to achieve ten-year intervals between main overhauls for two-stroke main engines is proposed. May 2013 | Schiff&Hafen | Ship&Offshore SPECIAL 69
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