CIMAC Congress - Schiff & Hafen

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<strong>CIMAC</strong> CONGRESS | BERGEN 2010 15:30 June 15th Room Scene GH (3–6) Environment, Fuel & Combustion – Diesel Engines – Emission Reduction Sailing towards IMO Tier III – Exhaust after treatment versus engine-internal technologies for medium speed diesel engines G. Tinschmann, D. Thum, S. Schlueter, P. Pelemis, G. Stiesch, MAN Diesel & Turbo SE, Germany Large engines capable of burning heavy fuel oil (HFO) offer unrivalled efficiency in operation, long maintenance intervals and thus hold a dominant market share of over 95% as propulsion engines in merchant shipping. Taking into account of the tonnages transported ships are the most economical and lowest emissions means of transport. However, the proportion of shipping related emissions of oxides of nitrogen (NOx) und oxides of sulphur (SOx) is increasing constantly, especially on shipping routes with a high traffic concentration and in ports. Issued by the International Maritime Organization (IMO), with MARPOL 73/78 Annex VI the first internationally valid piece of legislation for the limitation of gaseous harmful emissions from marine diesel engines came into force in 2005, retroactively to 1st January 2000 and is by now titled IMO Tier I in relation to its NOx limits. Scheduled for 2011, IMO Tier II targets for a 15 - 22% reduction in the NOx limits to be complemented in 2016 by IMO Tier III which calls for the application of a reduction in NOx emissions of 80% compared with today’s standard in certain waters yet to be defined – so called Emission Control Areas or “ECA’s”. For the reduction of sulphur oxide (SOx) emissions from marine engines IMO has nominated SOx- Emissions Control Areas (SECAs). In these zones, only fuels with a maximum sulphur content of today 1.5% may be used or the ship operators are required to employ an equally effective exhaust aftertreatment. Since the sulphur content of the fuel has an enormous influence on the particulate emissions of an engine, with the introduction of Annex VI the maximum sulphur content of marine fuels will be further limited not just for the ECA’s but worldwide. To fulfil the limits set by the IMO MAN Diesel is focussing on technologies which are best to meet the requirements. On the one hand engines have to fulfil IMO Tier II limits on the free ocean and it is allowed to burn heavy fuel oils with up to 3.5% sulphur until 2020. On the other hand NOx emissions must be 80% below IMO Tier I inside the ECA’s and low sulphur fuel has to be used or equivalent techniques for reducing the SOx-Emissions have to be applied. This paper describes investigations carried out at MAN Diesel SE and deals with the following questions and tasks: • What is the preferred technology for IMO Tier III having the lowest capital and operational expenditures in mind? • Is exhaust gas aftertreatment with an SCR catalyst the preferred solution to reach the NOx-limits or are there alternatives like Miller-Cycle, exhaust gas recirculation and wet methods? Are these options technically feasible and competitive? • Is a flexible engine necessary, switching from Tier II to Tier III operation when entering ECA’s? • What’s the benefit of an exhaust gas scrubber and which are the major challenges if we use HFO also in ECA’s? • What is the preferred solution for a small genset engine and which is the favourite for large propulsion engines? After giving a short overview of technical solutions including test results, the paper summarizes the challenges and concludes with the evaluation of several Tier III technologies.. Exhaust emission control of Mitsubishi UE diesel engine A. Miyanagi, K. Watanabe, J. Yanagi, Mitsubishi Heavy Industries, Ltd., Japan This paper shows our approach and perspective to exhaust emission control of Mitsubishi UE low speed two-stroke diesel engine for marine propulsion. Regulations for the emission from marine diesel engines are tightened still further. IMO Tier II regulation requires nitrogen oxides to be reduced approx. 15% by 2011 and Tier III requires them to be reduced 80% by 2016. Sulfur oxides are required the phased reduction of sulfur content in fuel. Carbon dioxide is also the matter being discussed for the future regulation. UE engine adapts to IMO Tier II with engine parameter optimization such as Miller cycle, fuel injection rate, optimization of fuel spray and swirl flow in combustion chamber in order to prevent large increase of carbon oxide. For IMO Tier III regulation, aftertreatment of emission is under consideration. Combination of exhaust gas re-circulation and water injection could be possible to reduce nitrogen oxides. However, this combination possibly brings some carbon dioxide increase and reliability degradation caused by sulfuric acid. For sulfur oxides, reduction of sulfur content in fuel might be well received and suitable for after treatment and EGR system because of low sulfuric oxides. In future, demand for carbon dioxide reduction will probably be strengthened. Several measures are under investigation such as waste heat recovery system, hybrid turbocharger and so on. It is assumed that this approach would be significant in conjunction with shipping mode optimization. Two-stroke engine emission reduction technology: state-of-the-art M. F. Pedersen, A. Andreasen, S. Mayer, MAN Diesel & Turbo SE , Denmark Future emission regulation requires drastic reductions of harmful regulated pollutants from large diesel engines. For marine diesel engines, especially the recently adopted amendments to MARPOL Annex VI, contains significantly tightened regulations in terms of emission control for both existing and new engines. Engine-out emissions can be controlled either by primary or secondary methods. Primary methods focus on the process on emission formation and involve e.g. adjustment of the engine injection equipment, injection and exhaust valve timing, as well as technologies such e.g. Water-In- Fuel emulsion (WIF) and exhaust gas recirculation (EGR). Secondary methods focus on exhaust gas after-treatment and involve for instance NOx reduction using selective catalytic reduction (SCR) and scrubber technology for washing out sulfur species as well as particulate matter. This paper will focus on primary methods. The regulation, as well as an increasing demand from various owners, operators, ports and other concerned task holders, has led to MAN Diesel using part of its R&D resources in developing retrofit measures for existing engines. The retrofits are aimed at reducing NOx, but will also be beneficial for other emission and operation aspects. Recent results on this work will be presented in the paper. Water in fuel emulsion (WIF) is an existing wellproven technology for large two-stroke engines, especially for land based stationary diesel power plants. Recently WIF has been further investigated on the 4T50ME-X test engine in Copenhagen. Both the NOx reduction potential as well as the effect on other emissions is investigated. In this paper water contents up to 90 % vol. added water have been achieved and a NOx reduction approaching 60% has been obtained. While the emission of unburned hydrocarbons (HC) increase somewhat it is shown that WIF is very effective in reducing the emission of CO. Results from investigations on exhaust gas recirculation (EGR) will 58 Ship & Offshore | 2010 | No. 3
Monday, 14 June Tuesday, 15 June Wednesday, 16 June Thursday, 17 June be presented. The results will include an overview of the potential for NOx reduction and the influence on other emissions such as CO and HC. High EGR ratios exceeding 40% have been achieved and it has been shown that EGR has the potential to fulfil the IMO Tier III legislation. While the emissions of HC decrease slightly the CO emissions increase. As a result from the extensive testing of the EGR technology on the 4T50ME-X test engine, it has been decided to test the technology onboard a ship. EGR and WIF technologies can be combined for even further NOx reduction. Results from combinatorial tests are presented in the paper. Extremely low emission of NOx down to 0.2 g/kWh has been demonstrated while achieving low emission levels of both HC and CO. Theoretical and experimental study on measures to minimize the NOx -SFC tradeoff K. Sugiura, K. Shimada, Mitsui Engineering and Shipbuilding Co., Ltd., Japan, K. Takasaki, K. Okazaki, Kyushu University, Japan (100% fuel + 30% water) without any increase of SFC has been confirmed from running tests using a medium-speed engine. Improvement of spray combustion applying FWE that compensates the bad effect of water has been clearly visualized by the visual test engine. Further MES has achieved a long-time record of FWE application to a Mitsui MAN B&W two-stroke engine for electric power generation in Guam Island. Regarding DWI, a clear drop in flame temperature has been found in the visual data. A 75% NOx reduction with less than 3% increase of SFC has been achieved at low load (25% load) as best record using a two-stroke test engine (400 mm bore). 2. Miller cycle technique, a method to lower the maximum combustion temperature by lowering the temperature at the beginning of combustion (at the compression end). As a fundamental research work, the Miller cycle effect has been examined using the CVCC (constant volume combustion chamber). MES (Mitsui Engineering and Shipbuilding Co., Ltd.) and Kyushu University have been theoretically and experimentally investigating effects of some measures to clear the IMO NOx regulations for marine diesel engines, MARPOL Tier II starting from 2011 and Tier III from 2016. Formation of NOx, a product from thermal dissociation of combustion air, is strongly influenced by the maximum combustion temperature (flame temperature). For example, lowering the flame temperature of 200K (for example, from 2400K to 2200K) realizes a NOx reduction to one tenth. On the other hand the higher the flame temperature, the better combustion results and the higher the maximum temperature in the thermodynamic cycle, the higher the thermal efficiency. For that reason, NOx and specific fuel consumption (SFC, directly linked to CO 2 emission) are in a ’trade-off’ relation. The authors introduce some unique ’trade-off minimum’ measures, with which NOx can be reduced keeping the sacrifice of SFC to a minimum. Effects of the following measures have been verified with visualization of spray combustion using a specially designed visual test engine and a constant volume combustion chamber (CVCC) simulating the combustion chamber of a marine diesel engine: 1. Water utilization, the measures to cool the combustion flame and restrain NOx formation using water 1-1. FWE, fuel water emulsion 1-2. DWI, direct water injection (DWI is defined as the method of water injection into the cylinder from other injection holes than the fuel injection holes.) Applying the water technologies, following results have been derived: For FWE, 30% NOx reduction by adding 30% water Headquarter FTI GmbH Ausserfeld 4 CH-6362 Stansstad Switzerland Tel: +41 41 612 32 30 Fax: +41 41 612 32 31 doctor@fuchstechnology.ch www.fuchstechnology.ch Service Center FDCP AG Seewadelstrasse 22 CH-8444 Henggart Switzerland Tel: +41 52 316 28 86 Fax: +41 52 316 28 87 A new era of portable engine monitoring systems THE DOCTOR DM 8-32 Portable multi-cylinder real-time engine performance analysis system EASY · FAST · ACCURAT · ONLINE Like never before - balance engines accurately - optimize performance - save fuel - minimize operation cost - reduce emissions - reduce service and spare part costs <strong>CIMAC</strong> 14. – 17. June 2010 Bergen, Stand 6 SMM 2010 7. – 10. September 2010 Hamburg, Stand B7.452 No. 3 | 2010 | Ship & Offshore 59
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