CIMAC Congress - Schiff & Hafen

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<strong>CIMAC</strong> CONGRESS | BERGEN 2010 Japan because of the higher butane content in Japanese manufactured gas, which can reach to as high as 3%. The autoignition mechanism in these large-sized gas engines should be clarified in order to inhibit knocking development and to achieve higher thermal efficiency. Unfortunately, knocking observation is awfully difficult especially in large engines since the high and impactive in-cylinder pressure limits the size of glass windows and thus restricts the viewing field into the end-gas region. In this study, a RCEM (Rapid compression and expansion machine) was introduced to realize both the in-cylinder conditions compatible with actual gas engines and the full transversal access into the combustion chamber by utilizing a reservoir tank of compressed and preheated air. This RCEM was firstly motored with its intake valve closed. After it reached to its rating speed, the intake valve was activated only once synchronously with its piston motion to simulate the intake stroke of a real engine. The pre-compression and preheating of the intake air allowed lower geometric compression ratio, which enabled its clearance volume to be a square block of an opposed pair of transparent windows. The dimensions of the windows are 200mm in width and 50mm in height, whereas the compression pressure and maximum combustion pressure exceeded 10 MPa and 20 MPa respectively. Visualization results revealed the autoignition phenomena in large-sized gas engine for the first time. Tiny cores of autoignition were clearly captured to scatter around the whole combustion chamber over a certain range of intake temperatures. The boundaries dividing heavy knocking, mild autoignition like HCCI combustion, and premixed flame propagation initiated by pilot diesel flame were examined in detail through changing the experimental conditions precisely. KIVA 3V code coupled with CHEMKIN II package was also applied to examine the effect of Butane content in manufactured gas since Butane has the smallest octane index in the manufactured gas components and it is one of the smallest hydrocarbons that show the negative temperature gradient, which effect on ignition delay is difficult to simulate the effect on ignition delay. The simulations were carried out for both the RCFM and Mitsui 6MD20G engine. The results showed that 3D CFD with detailed chemical kinetics successfully reproduce the onset of knocking in the actual gas engine and it could be useful to predict the effect of some engine parameters like EGR rate to avoid knocking or abnormal combustion. 10:30 June 15th Room Klokkeklang (9–2) Turbochargers & Turbomachinery – Advanced Turbocharging Systems IMO III emission regulation: Impact on the turbocharging system E. Codan, S. Bernasconi, H. Born, ABB Turbo Systems Ltd., Switzerland In combination with advanced turbocharging, a number of internal engine measures have been considered for fulfilling the IMO Tier II, the second stage of the IMO’s regulations on exhaust emissions from marine engines. Coming into force at the beginning of 2011, IMO Tier II requires a reduction in emissions of oxides of nitrogen (NOx) of 20% compared to IMO Tier I. In order to fulfil the requirement of the IMO Tier III stage coming into force in 2016, a major decrease in specific NOx emissions (about -80% compared to the IMO Tier I values) needs to be achieved in designated Emission Control Areas (ECAs). Emissions of oxides of sulphur (SOx) and particulate matter (PM) are to be controlled by limiting the sulphur content of the fuel used. An alternative measure is the use of SOx abatement equipment such as sea water scrubbers, fresh water scrubbers or a dry exhaust gas cleaning system. For IMO Tier III either external measures (aftertreatment technologies) or a combination of internal engine technologies are required. This paper provides an overview of IMO Tier III solutions with regard to NOx reduction measures and their impact on the engine turbocharger system, taking into account both, single stage and 2-stage turbocharging. From a range of possible solutions, two NOx reduction technologies with high potential, SCR and EGR, have been selected for study in greater detail. Selective Catalytic Reduction (SCR) is a proven technology that basically allows any engine to fulfil IMO Tier III. Nevertheless some configurations require SCR to be installed before the turbine (two-stroke engines, two-stage turbocharging), which affects transient operation. The impact on the system and an evaluation of several countermeasures are detailed based on transient simulations. Exhaust Gas Recirculation (EGR) is an established NOx-reduction technology in the automotive sector but is not yet state-of-the art for large engines. An evaluation of several strategies with regard to NOx reduction, fuel consumption, and other relevant parameters demonstrate the potential and the advantages of recirculating exhaust gases. A further challenge for the turbocharging system is the necessity to provide the variability needed to allows an engine to fulfil the low emission limits within the ECA’s while running with the highest fuel economy elsewhere. Utilisation of cylinder air injection as a low load and load acceptance improver on a medium-speed diesel engine C. Wik, S. Hostman, Wärtsilä Finland Oy, Finland Development of engine concepts for lower NOx emissions e.g. by means of Miller valve timing (early inlet valve closure) makes loading capability worse, especially at low loads. Continuous increase of cylinder output makes the situation even worse; larger absolute load steps, as kW or bar BMEP, and larger turbochargers mean longer rotor acceleration and slower pressure increase. Furthermore, Miller timings demand higher charge air pressure, i.e. the pressure ratio capacity of the turbocharger must be greater. This causes the optimum efficiency of turbocharger to move towards higher pressure and decreased efficiency at low load which results in poor load response at low load. Future engine concepts will probably also include a shorter valve overlap (scavenge period), which also deteriorates low load performance. Poor load response is directly linked to high smoke and particle emissions. All this sums up in the fact that low load operation of state-of-art medium speed diesel engines is known to result in fairly high smoke emissions and thermal loads. This is a problem in transient operation and especially for auxiliary engines that need to be fast reacting generating sets. There are different means available to compensate for the transient problems, of which, air injection in different ways before the combustion starts is one. Air could be injected directly on the turbocharger compressor; so called air jet assist or into the air receiver. Both these methods, however, always give a certain time delay in load response situation, and the air receiver injection may also force the turbocharger to stall. There is one additional method that has potential in bringing large benefits compared to the available methods mentioned above and this is injection of pressurized air directly into the cylinders. In this paper, focus will be put on air injection into the air receiver or into the cylinders. Preliminary transient and stationary tests aimed for proving the potential on a medium speed diesel engine have been performed utilising the existing starting air valves. These tests resulted in considerable reduction of smoke opacity during engine start-up as well as ability to run 2-step load application fulfilling classification criteria. Final outcome of the tests will be presented in the paper. Design of a production system for an auxiliary engine, with its challenges, will be presented together with rig test results for system optimisation, verification, and validation. Ultimate engine test results, proving the concept, will finally be reported upon availability. 48 Ship & Offshore | 2010 | No. 3
Monday, 14 June Wednesday, 16 June Thursday, 17 June Tuesday, 15 June This project has been a part of the Tekes, National Technology Agency of Finland, financed LOSPAC project and performed in cooperation with VTT Technical Research Centre of Finland, Yrkeshoegskolan Novia, and CITEC Engineering. Design and first application of a two-stage turbocharging system for a medium-speed diesel engine T. Raikio, B. Hallbäck, A. Hjort, Wärtsilä Finland Oy, Finland It is obvious that strong reductions in nitrogen oxides (NOx) and carbon dioxide (CO 2 ) are required for combustion engines in the near future. One efficient means to achieve both targets is to apply Miller valve timing. However advanced Miller timing requires strongly increased charge air pressure. The best concept for achieving this is two-stage turbocharging, which gives more or less unlimited boost pressure with a high efficiency level. Earlier two-stage turbocharging feasibility tests on Wärtsilä 20 engine, reported in <strong>CIMAC</strong> 2007, confirmed the performance expectations put on advanced Miller timing and 2-stage turbocharging. Used hardware was however suitable for test purposes only, not for serial production. Parts of the turbocharging unit were located ”off-the- engine”, which cannot be regarded as the optimum production solution, merely a mediocre compromise. After the test on Wärtsilä 20 attention was directed to create a production standard design for a larger size Wärtsilä engine. Design targets: • All turbocharging modules/components preferably located on the engine • Maintain excellent engine dynamic properties • Maintain compact engine dimensions simultaneously maintaining a good serviceability • Include necessary controls (air/exhaust gas/cooling water) in the above mentioned dimensions • Necessary valve timing controls included in the design Achieving the design targets is challenging especially considering the fact that two-stage turbocharging in practise doubles the amount of turbocharging system components. Design work was supported with extensive optimisation using detailed FE-calculations, taking into consideration especially the strongly increased internal pressure. Flow channels were optimised by means of latest CFD tools. To ensure proper and easy manufacturing the design, especially castings, was reviewed and finalised in co-operation with suppliers. This paper presents the design project aiming at the optimum 2-stage turbocharging system for a medium-speed diesel engine. Additionally operation and performance experiences are summarised. Testing experiences are covering assembly and operational feedback of the 2-stage turbocharging system specific components. Two-stage turbocharging – flexibility for engine optimisation E. Codan, C. Mathey, A. Rettig, ABB Turbo Systems Ltd., Switzerland With demand for greater economy, lower emissions and higher output continuing to influence engine development, a wider range of flexibility is required in modern engine designs. Two-stage turbocharging can make a significant contribution towards satisfying these requirements. Parallel with its participation in different research and development projects, such as HERCULES and HERCULES-B, ABB Turbo Systems Ltd in recent years has developed turbochargers specifically for two-stage turbocharging. Several studies have been carried out in connection with these activities which show the potential of two-stage turbocharging on diesel and gas engines, not only in terms of actual performance, but also in respect of the improved flexibility it offers modern engine design. This paper shows and discusses some of the possibilities offered by two-stage turbocharging regarding engine output increase, emissions reduction and, last but not least, fuel consumption improvements. A large number of engine cycle simulations, some of them verified by engine tests, have been performed for diesel engines in different applications as well as for gas engines of either spark-ignition or dual-fuel design. Different control modes, e.g. variable valve timing or the use of an exhaust waste gate, and emission reduction methods such as exhaust gas recirculation or selective catalytic reduction, have also been taken into account. The results of these investigations served equally well as boundary conditions for the development of the specific two-stage turbochargers and their major components. Also presented is the design of a newly developed two-stage turbocharging system that is currently undergoing an extensive validation and qualification program in ABB’s turbocharger test centre. ABB has invested considerably in new turbocharger test rigs for two-stage turbocharging in recent years, and as a result turbocharger performance tests can be performed under realistic conditions. The design of these turbochargers with overall pressure ratios of 8 and above differs considerably from that of conventional turbochargers, especially with respect to the highpressure stage. First prototypes have already been tested on several engines. The first engines with these two-stage turbocharging systems are scheduled for field operation in 2010. 13:30 June 15th Room Peer Gynt Salen (1–5) Product Development – Diesel Engines – Low Speed Engines Cutting edge technologies of UE engine for higher efficiency and environment H. Sakabe, N. Hosokawa, Mitsubishi Heavy Industries, Ltd., Japan This paper describes the latest technologies of the UE engine. The UE engine program is continuously updated to meet customer demands. For this purpose, the number of types of the latest engine series, the LSE, has increased. In this paper, new LSE engines have been reported, and especially the UEC40LSE/35LSE, which have just begun development, are focused on. Also their design features with several new technologies are described. In addition, “environment” is the key word in the marine industry these days. The UE engine is an environmentally friendly engine, and some technical progress in this field is introduced, such as technologies for reduction of fuel oil consumption and NOx. The design concepts of the latest UE engine series, the LSE, are excellent reliability, economy, easy maintenance and environmentally friendly, with higher engine power for faster and larger ships. The first LSE engine, the UEC52LSE, was released in 1998. Since then, five engine types of bore sizes from 45 to 68 cm have been added to the LSE program. Now, the UEC40LSE/35LSE engines have been introduced into the portfolio. The UEC40LSE/35LSE have been jointly developed in cooperation with Wärtsilä Switzerland to accommodate various small- and medium-sized ships such as handy bulk carriers, product tankers, and reefer vessels, which are less than 30,000 dwt. At the same time, replacement from middle-speed four-stroke engines is also targeted. Low load operation systems and waste heat recovery systems are being developed due to high crude oil prices, owner’s requirements of operation cost reduction, CO 2 reduction. In order to continuously operate an engine at low load, a special fuel valve atomizer, increase of the auxiliary blower capacity and modification of the turbocharger specification are applied. In addition, the one- No. 3 | 2010 | Ship & Offshore 49
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