CIMAC Congress - Schiff & Hafen

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<strong>CIMAC</strong> CONGRESS | BERGEN 2010 measurements, used as reference, findings regarding the flow scheme in cylinder oil supply lines will be discussed. This comprises two types of common electronically controlled injector systems. Measurements did reveal a surprisingly high flow dynamic in the low pressure feed lines which require further corrective actions to ensure precise results. The paper includes measurement results as well as a discussion of the options to further reduce cylinder oil consumption. The latter are based on the availability of real time consumption measurement results which can be used for the calibration of electronically controlled injector systems. Combustion quality of marine residual fuel – trend, control, effect on engine A. Takeda, N. Iijima, S. Umemoto, H. Miyano, Nippon Yuka Kogyo, Japan, H. Nakatani, K. Adachi, H. Nomura, K. Adachi, NYK Line, Japan, H. Tajima, Kyushu University, Japan The effectuation of the IMO/MARPOL 73/78 Annex VI and the requirement for reducing the sulfur content in accordance with future regulations have strongly influenced the qualities of marine residual fuels. For example, since light cycle oil (LCO) and clarified light cycle oil (CLO), which are obtained in the fluid catalytic cracking (FCC) process, contain a low level of sulfur and low viscosity, they are suitable for use as raw material for low sulfur fuels such as cutter stocks. However, a major portion of these types of oil generally contain aromatic compounds, and in the case they are blended in large quantities to marine residual fuel, its ignition and combustion quality deteriorate. As a result, lowered combustibility causes problems such as poor combustion in large two-stroke diesel engines (main propulsion engines), which can potentially result in major failures such as damage to the piston rings and the cylinder liner. However, there is no limit value or criterion regarding ignition and/or combustion quality of marine residual fuel at the current moment. Therefore, fuel oil suppliers do not need to pay attention about ignition and/or combustion in the petroleum refinery process with which marine residual fuel MFO is made. Energy Institute (EI) had standardized the test method (IP541) of ignition and combustion characteristics for residual fuel by using constant volume combustion chamber such as Fuel Combustion Analyzer (FCA) in 2006. However, a practical evaluation method and the criterions for the ignition and combustion quality are currently under consideration in <strong>CIMAC</strong> and ISO, and are therefore not yet established. And, there are few reports on the ignition and combustion quality of a large number of marine residual fuels by IP541. Since combustion problems are increasing in recent years, the consumer takes the necessary measures to minimize engine problems caused by poor combustion quality. In this paper, we will report the results of investigation and research for ignition and combustion quality, and the experiences obtained from operations of engine. The users views of having to use lowsulphur fuels combined with slowsteaming K. Wilson, Keith Wilson and Associates, England The present world wide economic situation has meant that almost all ship operators have to employ slow steaming with their ships. Long hours, or days, with engine operation at loads of 30 per cent, or even less, bring problems with those engines and these are not easy to solve, including ensuring that the exhaust gas meets with local requirements, where necessary. At the same time, the increasing number of sea areas (SECA’s) which demand the use of low sulphur content fuels or, very low sulphur exhaust gas emissions, from all ships, present more problems for the engine operator – the User. The paper sets out to show the depth of these problems and in particular the effects on engine operation, and how the Users are dealing with them. Since the use of low sulphur content fuel oils is now mandatory in different areas, the USER has to invest in extra equipment to deal with such fuel oils at the same time as extra investment in sometimes complex adaptations of the engines, have to be made. In addition, there now seems to be a problem of how much low sulphur content fuel can be supplied in some ports, particularly where large ships are concerned. Furthermore, new regulations have been brought forward rapidly, where exhaust gas emissions are concerned, in waters off the state of California, USA. These go well beyond the present requirements laid down by the IMO to which all Users have taken considerable steps, in conjunction with the engine designers, to meet the present IMO tier requirements and the next IMO tier. The latest requirements as laid down for Californian waters, mean that each User has to invest in further equipment on board when it will only be used for a relatively short time in each voyage. The need for unilateral exhaust gas emissions across the world is paramount to the Users but there are now several authorities who demand their own exhaust gas emission levels. Apart from the larger main engines on board many of the Users’ ships, the change over from heavy marine fuel to a much lighter grade of fuel oil can cause problems with auxiliary engines designed to use only one fuel oil type. For those Users operating machinery in tankers, the problem is further aggravated by having to deal with the exhaust gas emissions from the boilers where much use is made of heavy fuel oil for considerable periods since fresh water generation onboard is essential. Dealing with sulphur in the exhaust gas, on board has yet to be fully exploited. Environment-friendly operation using LPG on the MAN B&W dual fuel ME-GI engine R. S. Laursen, MAN Diesel & Turbo SE, Denmark, V. W. Rudh, Hamworthy Gas Systems AS, Norway With the new gas code, the use of LPG, i.e. propane and butane, as fuel for propulsion of ships has now come one-step closer, and MAN Diesel is ready with an engine design for this specific use. LPG has been used as a fuel in the car industry for many years, and now, with the dual fuel ME-GI engine, it is also possible to use LPG on ships in general. The discussion and interest in lowering CO 2 , NOx, SOx and particulate emissions have increased operators’ and ship owners’ interest in investigating future fuel alternatives. Using LPG as fuel on the two-stroke ME-GI offers the same emission benefit as with LNG, where emissions can be reduced significantly compared with MDO. Therefore, there are very good environmental reasons for using this fuel in coastal areas and on inland waterways. The GI system can also be applied on the small bore ME-B engines, which suit into smaller tankers, bulk carriers, container vessels and RoRo ships. Because of the general need to reduce CO 2 emissions, it is already seen in some regions, especially in the Mediterranean, that a lot of traffic is being moved from the highways to the seaways. This trend is expected to continue because sea transportation has proved to be less CO 2 polluting than both trucks and trains. This CO 2 benefit can be further improved by using gas as the fuel. Many ship owners have realised that in the next five to six years there will most likely be an overcapacity in the LNG carrier fleet and in the LNG production. Obviously, this generates an interest in using LNG and LPG as a fuel on ships in general, since the gas fuel for a period is expected to be cheaper than other types of fuels, and the difference will be even bigger when comparing with other types of low-sulphur fuels. LNG is considered the fuel of the future, and very few doubt 76 Ship & Offshore | 2010 | No. 3
Monday, 14 June Tuesday, 15 June Thursday, 17 June Wednesday, 16 June this prediction. But establishing the LNG bunkering facilities, comprising small-size LNG terminals and a network of LNG supply ships, is costly and time consuming and, furthermore, it is also a subject to safety concerns and public debate in some countries. Only a few countries have an LNG network in place for general use of gas as a marine fuel, one example being Norway, but unless an unrealistic high price for the LNG can be obtained, the use of LNG is not just around the corner for ship operation. However, in due time it will be. To establish a supply network for use of LPG as a fuel is far easier because LPG terminals are less costly and not such a big safety concern, simply because LPG has been around for a long time. Older LPG carriers can be brought into use where they could function as bunkering stations. All the old LPG carriers have an onboard reliquefaction plant installed, which is less expensive to run, when compared to reliquefaction systems for LNG. Furthermore, ship to ship loading of LPG is not considered complicated, and would be a possible scenario when LPG is bunkered from an LPG carrier. Some MAN Diesel gensets are already running on LPG as the fuel on LPG carriers. Taking it now one step further, this paper describes the technology behind the ME-GI dual fuel MAN B&W two-stroke engines, using LPG as fuel, and its associated fuel supply systems. The engine requires a gas supply pressure of 550 bar and a temperature of 35°C. At this temperature and pressure, the LPG is liquid and different fuel supply solutions are available for generating this pressure for the liquid. Hence, the ME-GI for LPG will use liquid gas for injection, contrary to the ME-GI for LNG, where the methane is injected in gaseous form. All the way from tank to engine the LPG remain in liquid phase and non-cryogenic pumps can be used to generate the pressure. These pumps are standard equipment in the LPG industry, where quite a big number of suppliers are available. Safety is a concern when LPG is being used, since in gaseous form, contrary to methane, both propane and butane are heavier than air and will drop in case of leakage. This safety needs to be analysed and our safety considerations and precautions will be described in detail. Evaluation of using natural gas as a fuel for LNG carriers “Application of marine gas turbines“ A. Radwan, M. Morsy, University of Alexandria, Egypt, M. Fahmy, Arab Academy for Science and Technology, Egypt Liquid natural gas (LNG) shipping industry has increased dramatically since 1959. The cargo capacity has jumped from 150,000m 3 to 250,000m 3 meanwhile; the transport distance reached 7000 Nmile. Numerous LNG carriers demonstrate a good experience with using their boil off gas (BOG) as a fuel for propulsion machinery, mainly steam turbines. Lately, about 40% of the new orders shifted to slow speed diesel engines with reliquefaction plant (SSDRL) and dual fuel diesel electric propulsion (DFDE). So far, marine gas turbines are not applied yet in LNG carriers. This paper discusses the applicability of using natural gas as a fuel with marine gas turbine electric propulsion (DFGE), utilizing natural boil off gas (NBOG) and forced boil off gas (FBOG) as well as investigating its economical and environmental beneficial over other propulsion options. The benchmark ship chosen for this study has a capacity of 150,000m 3 powered by conventional steam propulsion. For this purpose a spreadsheet model were developed to determine the LNG carrier operating cost for different propulsion options. This is in addition to a sensitivity analysis to study the effect of varying range, (HFO) and natural gas (NG) prices on ship operating cost. It was found that, using (NG) as a fuel with the proposed marine gas turbine cycle at current HFO and NG prices provides the highest cost saving for a distance less than 4000 Nmile. With the expected changes in fuel prices, the proposed cycle achieves cost saving of 3% per round trip and this saving is directly proportional with increasing of fuel prices compared to other options. 13:30 June 16th Room Scene GH (2–3) Fundamental Engineering – Piston Engines – Combustion Two Strokes In-situ optical combustion diagnostics on a large two-stroke marine diesel engine H. H. Poulsen, J. Hult, S. Mayer, MAN Diesel & Turbo SE, Denmark Large two-stroke Diesel engines offer several challenges to successful implementation of the type of optical and laser based measurement techniques which have been applied with so much success in smaller automotive engines during the last decade. In this paper we will present the first steps taken towards implementing optical diagnostics in a full sized and fully operational two-stroke diesel engine for marine application. Optical ports, fitted with sapphire windows, have been developed, which allow normal uninterrupted engine operation over several hours. Considerations connected with the design of those ports, which have window diameter up to 40 mm, are introduced. Results from several measurement campaigns undertaken on this optical test engine will also be presented. The evolution and movement of burning fuel clouds are visualized at high framing rates (18 kHz) using a high-speed CMOS camera. Two types of high-speed soot luminescence imaging have been performed. By simply recording all visible light, the structure and dynamics of the luminous regions can be studied. From such image sequences individual flame ignition and propagation events can be followed in a cycle-resolved fashion. In a second set of experiments two-colour pyrometry is implemented, by splitting the emitted black body radiation into two separate optical channels. These are both captured on the same highspeed camera, whereby the temperature of the soot in the flame envelope can be estimated from the ratio of the two signals. The latter approach thus provides complementary information on the temperature distribution of the luminous regions during the engine cycle. Study of exhaust gas separation (EGS) system on 2-stroke engine M. Takahashi, I. Tanaka, M. Ohtsu, Mitsui Engineering and Shipbuilding Co., Ltd., Japan 2-stroke diesel engines have been improved to the state-of-the-art heat engine, so thermal efficiencies of those have already been achieved to the level of more than 50% since some 15 years ago, and there seems to be no room for further substantial thermal efficiency improvement by engine itself. On the other hand, turbocharger mounted on engine is being significantly improved to be more than 70% at total efficiency, so that more and more excessive energy in exhaust gas receiver is available for other use. Accordingly, attention toward 2-stroke engine as earth friendly heat engine is focused on how to utilize the excessive energy in exhaust gas receiver, and many kinds of heat recovery equipments are under investigation and/or development. In some cases of those applications, heat recovery equipments have been already materialized. On 2-stroke engine, scavenge process in combustion chamber is performed by nearly stratified fresh air through scavenge ports of cylinder liner, so exhaust gas from exhaust valve has similar profile of gas content and temperature along time after opening of exhaust valve. If a gas No. 3 | 2010 | Ship & Offshore 77
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CIMAC Congress - Schiff & Hafen

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