QUANTUM Two-stroke LNG By DNV and MAN Diesel & Turbo

Transcription

1 QUANTUM 9000 Two-stroke LNG By DNV and MAN Diesel & Turbo

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3 Contents Introduction...5 Concept Overview...6 Trade Route and Operational Profile...8 The Engine...11 Exhaust Gas Recirculation (EGR)...16 Test Experience...19 Gas Supply System...20 LNG Tanks...23 Class Requirements...24 Bunkering...25 Hull Optimisation...26 General Arrangement...27 LNG Tank Arrangement...28 Main Engine Room Safety...28 Recommendations for the Utilisation of Available Energy from LNG...29 Reduction of Power Need for Reefer Containers...29 Cool Down Air Supply to Turbocharger...30 Other Cooling Needs...30 Ballast Water...31 Propeller Optimisation...32 Cost-benefit Calculations...32 Conclusion...34 References...34 Quantum

4 4 Quantum 9000

5 Quantum 9000 Introduction The need for seaborne transportation will increase significantly in the years to come. At the same time, the fuel oil price is increasing, stricter emission requirements are coming into force, and the public is becoming more concerned about the environmental footprint of shipping. As a result, the industry is investigating alternative fuels for shipping. Liquefied natural gas (LNG) is an attractive option since it reduces the emissions, and is expected to be cheaper than fuel oil in the future because of the large world reserves of natural gas. Background The use of liquefied natural gas (LNG) as ship fuel is not a new idea. LNG has been used for many years on gas carriers with boilers (in the case of steam turbine propulsion), four-stroke diesel mechanical propulsion or diesel electric propulsion installed. All these solutions are based on consumption of the readily available LNG as the fuel, and/ or boil-off gas from the LNG tanks. In recent years, the LNG infrastructure, particularly in Norway, has developed to the extent that other ship types, like Ro-Ro and smaller ferryboats, use LNG as the fuel, and it is now established as a clean and reliable fuel for propulsion and auxiliary power generation. In April 2010, DNV presented the LNGfuelled container ship concept Quantum. The Quantum concept introduces a number of innovative solutions to increase efficiency and reduce the environmental impact of container ship operation. Based on input from the industry, flexibility was found to be the answer to the many uncertainties facing the industry in the years to come. The machinery arrangement is based on electric propulsion and dual fuel gensets. This was selected with the need for flexibility in mind, and is based on an assessment of the alternative solutions available at the time. With the recent technology development, MAN Diesel & Turbo can now offer both dual fuel medium speed engines, and low speed MAN B&W LNG-burning ME-GI type engines offering propulsion power with reduced emissions. The development of the ME-GI engine has made it possible to install a simple, yet unique propulsion power solution, with a total system efficiency similar to conventional vessels, but with reduced emissions. Hence, the further development of the DNV Quantum project with a single propulsion line, using an ME-GI main engine as the power source, is a natural and obvious progression for future container ship designs to obtain a reliable, energy efficient, and emissionfriendly LNG solution. As a result of recent market trends, it was decided to increase the ship size from the 6,000-teu range to the 9,000- teu range. With the new Panama Canal, this ship size is very relevant for the Asia- US trade through the Panama Canal. The hull form and arrangement has, consequently, been modified and optimised for the new machinery arrangement, ship size and trade. Emission regulations The ME-GI engine will fulfil IMO Tier III NO x levels when combined with the exhaust gas recirculation (EGR) technology. A technology developed by MAN Diesel & Turbo for the complete low speed B&W engine programme for compliance with IMO Tier III NO x emission regulations. Fig. 1: Quantum 9000 Quantum

6 Methane slip, a problem commonly associated with dual fuel engines, is not an issue with the ME-GI engine, due to operation according to the Diesel cycle principle. In this respect, the ME-GI is not vulnerable to the valve overlap, or localised gas fuel pocket formation on the cylinder wall, resulting in methane slip, and which may occur as a consequence of operation according to the Otto cycle principle. Concept Overview Quantum 9000 has been designed to be more efficient and environmentally friendly compared with existing ships, without introducing major complications in the building and operation of the ship. The new solution for LNG machinery, the ME-GI engine, demonstrates that improvements can be achieved on both the machinery and hull side, by using existing and well-proven technology. container ships. Highlights of the new concept are outlined below: Main features Gas-fuelled main engine two-stroke ME-GI Dual fuel auxiliary engines Full fuel flexibility (HFO/DFO/LNG) Full ECA compliance (Tier III) Optimised according to the operational profile Improved EEDI Cost-efficient solutions. Machinery Efficiency improvements and reduced emissions are obtained with the MAN B&W two-stroke ME-GI gas engine. The benefits are: Simple modifications Conventional engine room Proven performance High fuel efficiency High fuel flexibility High reliability. Hull design and arrangement The hull design and arrangement has been optimised for maximum space utilisation, minimum hull fuel consumption, minimum need for ballast water, and increased safety. The main benefits are: Better space utilisation with twin island Greatly improved sightline from the bridge Sufficient LNG capacity without loss of cargo space Pressurised type-c LNG storage tanks for maximum reliability Reduced need for ballast water Increased ship beam, reduced block coefficient 4-blade propeller optimisation. The first Quantum concept study introduced a diesel-electric arrangement with pod propulsion. This is a proven system in the cruise industry, but new to the container ship market, where a single-screw low speed two-stroke solution has been the predominant choice of propulsion. The Quantum 9000 introduces LNG to the preferred container ship propulsion system, making it more available to container ship owners. Fig. 2: The ship hull performance Twin island designs are common for bigger ships in the 12-14,000 teu range. Single island has been the common solution for 9,000 teu size. Benefits such as increased container loading and improved vision from the bridge justifies a twin island solution also for the smaller size ship. Collisions and groundings are among the most common incidents for Fig. 3: The hull arrangement 6 Quantum 9000

7 FORECASTLE DECK MAIN DECK POOP DECK CONTAINER VESSEL QUANTUM 9000 CONCEPT Class: DNV CONTAINER CARRIER NAUTICUS(Newbuilding) E0 DG-P TMON BIS LCS-SI Optional notations: RC-1(1072/131) NAUT-AW CLEAN BWM-T COMF-V3 VIBR F-M B.L. D.B. MAIN PARTICULARS: Length betw. perpendiculars, Lbp m Length overall, Loa m Breadth moulded, B 48.0 m Depth moulded, D 26.4 m Draught moulded, T 15.0 m Design draught, Td 13.5 m Min. design draught at AP 13.5 m Min. design draught at FP 13.5 m Block coefficient, Cb (@Td) 0.58 Waterplane area coefficient, Cwp Deadweight, design Deadweight, scantling Lightship (esimated/preliminary) 81,155 t 98,618 t 34,432 t Design speed 22.0 kn (at design draught, 85% MCR / 15% sea margin) Crew Suez TANK CAPACITIES: Heavy Fuel Oil (HFO) 4,000 m 3 Liquid Natural Gas (LNG) 6,500 m 3 Marine Diesel/Gas Oil (MDO/MGO) 1,600 m 3 Lubricating Oil 16 m 3 Fresh Water 360 m 3 Ballast Water 24,728 m 3 All oil tanks according to MARPOL Oil Tank Protection Cruising range ENGINE PLANT: Main engine: Propeller: AUX engine/gen Sets : approx. 16,000 nm MAN 9S80ME-C9.2-GI MCR: 40, rpm Fixed pitch, 4 blades, dia. 10 m 4 x 2,500 kw Emergency generator : 1 x 250 1,800 rpm Bow Thrusters: 2 x 2000 kw WHR plant MCR ISO): 2,709 kw CONTAINER STOWAGE: Container capacity (total) 8,708 TEU On deck: 5,570 TEU Below deck (cargo hold): 3,138 TEU Reefer capacity (total) 1,203 FEU On deck: 1,072 FEU Below deck (cargo hold): 131 FEU Rows (max) on deck / in cargo hold 19/17 Tiers (max) on deck / in cargo hold 9/9 Pontoon hatch covers (composite/light weight): Hatch 01C (1x): x m Hatch 02F PS & SB (2x): x m Hatch 02F C 09A C (14x): x m Hatch 02A PS 09A PS (13x): x m Hatch 02A SB 09A SB (13x): x m Stability: 14t/TEU, 8 6 high, 50% HcG 6,539 TEU Fig. 4: Quantum 9000 concept ship design data Quantum

8 Trade Route and Operational Profile Newark Based on recent market trends, the 9,000-teu range was selected as the Yokohama Oakland Los Angeles Charleston Savannah target case for the concept develop- Shanghai ment, together with the Asia US east Hong Kong Kaohsiung coast trade route through the new Panama Canal, see Fig 5. Panama For several years, since the building of Fig. 5: Trade route the first Post-panamax container vessel in 1988, the existing Panama Canal has been too small for the larger container vessels. In order to accommodate a larger proportion of the current and future fleet, and thereby the cargo carriage through the Panama Canal, the Panama Canal Authority has decided to extend the existing two lanes with a Fig. 6: Panamax and Post-panamax vessel particulars bigger third lane with a set of increased size of lock chambers. The lock chambers will be 427 m long, 55 m wide and 18.3 m deep, allowing passage of ships with a maximum breadth of 49 m, maximum passage draught of 15 m and an overall maximum ship length of 366 m. The new canal is scheduled to open in 2014 at the 100th anniversary of the existing canal, and to be fully in operation in When serving the east coast of USA, there is another limitation that needs to be observed. Ships entering the Newark container terminal in Port of New York must pass under the Bayonne bridge. The air draft limitation is currently 151 feet, which imposes a restriction on the bigger ships. There has been news in the press that the bridge may be raised, giving a new air draft of 215 feet, but this is yet to be confirmed. Operational profile In order to achieve a high efficiency in the operational phase, it is necessary to understand the operational demands Time [%] of leg time 100,0% Time in operating state as percentage of total leg time 90,0% Saling 10 [kn] Saling 12 [kn] 80,0% Saling 21,5 [kn] Port man. 70,0% Load/unloading 60,0% Refuelling Waiting 50,0% 40,0% 30,0% 20,0% 10,0% 0,0% Leg 2 Leg 3 Leg 4 Leg 5 Leg 6 Leg 7 Leg 8 Leg 9 Leg 10 Leg 11 Leg 12 Leg 13 Voyage leg Fig. 7: Operational profile when the ship is designed. An operational profile must be made before optimisation of the hull and machinery can be started. If the ship is to operate on a specified trade, the operational profile can be determined on the basis of on an optimisation of the actual trade route. Optimising the hull and machinery for a wide range of speeds and draughts is difficult. Therefore, the ideal situation is to define the route so that the ship can operate close to the design point for as much of the time as possible. Fig. 7 shows the operational profile defined 8 Quantum 9000

9 for this concept, including all sailing legs and all operational modes. The required propulsion power and electric power demand has been calculated for each leg and operational mode. Time [weighed kw] 30% 25% 20% 15% 10% 5% 0% SPEED [knots] Fig. 8: Operational profile Trade is often unknown at the design stage, or it is expected that the trade may change during the ship s life. In that case, it may be better to establish the operational profile using statistics from operation. The example below is showing time spent at various speeds, and time at various drafts and trims for one specific speed. It should be noted that operational patterns from the past are reflecting market conditions and fuel prices, and are not necessarily representative of the future. Distance 7 Trim [m] 0.5 Trim [m] 1 8 Drafta [m] 9 Trim [m] 1.5 Trim [m] 2 10 Trim [m] 2.5 Trim [m] 3 Fig. 9: Operational profile Based on the operational profile selected, the hull and machinery should be optimised to give the highest possible efficiency when the entire route is considered, rather than only the design speed and draught. For the hull, this applies especially when it comes to the main dimensions, block coefficient, centre of flotation and bulb design. For the machinery, it is the selection of main engine and auxiliary engines so that the propulsion power and electric power needed can be produced as efficiently as possible in all the different sailing legs and different operational modes. Design according to the operational profile Container ship designers have optimised the ship at the point of maximum fuel consumption, which is normally at maximum speed and maximum dwt/ draught. Any savings made at this point will probably yield the maximum gain. A design point or interval has to be selected for optimisation, as it is difficult to optimise over a large range of conditions. Savings can be made in one point at the expense of a loss in other points. So it is important to understand how the vessel is going to be operated, both with regard to speed and loading. There was an oversupply of ships in the market during the financial crisis in 2009, and profitability suffered. Fuel could be saved by reducing speed, but the need for a regular service remained. More ships had to be added to the service loop when average speed dropped. The additional ships would also burn fuel, but the net cost reduction still remained substantial. The extra ships employed also reduced the number of idle ships during the crisis. The slow steaming experience led to a focused interest on optimal speed of container ships. The optimal main dimensions and hull lines will vary depending the speed and draught. Could savings in fuel and emissions be increased if the speed and DWT profile was taken into consideration when optimising? We will illustrate how this can be done in the example below. POWER [kw] 45,000 P13 = 7,897V 2,6745 T=13 40,000 T=11 T=10 35,000 30,000 25,000 20,000 15,000 10,000 5, SPEED [knots] Fig. 10: Speed-power curves Fig. 10 shows the relationship between speed and power for three different draughts. The graph illustrates that the maximum power is consumed at max. draught and max. speed. Detailed power data are given in Table 1. Speed distribution and dwt/draught distribution may be obtained from the expected operational profile coupled with actual recordings and past experience. Quantum

10 As the future operations are uncertain, a probability distribution of speed and loading may be a better term. A typical example is shown in Table 2 where the percentage of operating time spent at a given draught and speed is given. The weighted power consumption is given in Table 3. The percentage time at a given speed interval is presented in Table 4. The power consumed at different draughts and speeds can now be weighted and combined in a power curve for various draughts and speed intervals. This is shown in Table 5 and Fig. 11. From the graph it can be seen that the greatest weighted power consumption is in the interval knots. This information can then be used for choice of optimising interval, which will give the highest probable saving for future operations. POWER profile [kw] at V and T 7,000 6,000 Biggest effect of optimisation 5,000 4,000 3,000 2,000 1, SPEED [knots] Fig. 11 Weighted Power Consumption Speed [knots] Draft T10 13,799 16,192 18,867 21,751 24,927 28,540 32,313 36,459 Draft T11 15,155 17,716 20,562 23,638 27,011 30,799 34,785 39,138 Draft T13 17,976 20,772 23,824 27,145 30,741 34,622 38,800 43,277 Table 1: Power [kw] at different drafts Speed [knots] Draft T10 37% 33% 17% 12% 13% 13% 5% 4% Draft T11 48% 45% 65% 68% 69% 69% 65% 35% Draft T13 15% 22% 18% 20% 18% 18% 30% 61% Table 2: Time [%] at different drafts Speed [knots] Draft T10 5,106 5,343 3,207 2,610 3,240 3,710 1,616 1,458 Draft T11 7,274 7,972 13,365 16,074 18,638 21,252 22,610 13,698 Draft T13 2,696 4,570 4,288 5,429 5,533 6,232 11,640 26,399 Table 3: Weighted power [kw] at different drafts Speed [knots] Speed time [%] at speed V 2% 15% 25% 24% 15% 10% 6% 3% Table 4: Time [%] at different speeds Speed [knots] Power [kw] at T and V 302 2,683 5,215 5,787 4,112 3,119 2,152 1,247 Table 5: Power [kw] at different speeds and drafts Data given in Tables 1 to 5 and Figs. 10 to 11 are for illustration purpose only, and does not reflect in detail the Quantum 9000 data 10 Quantum 9000

11 The Engine The ME-GI engine is not a new engine in technological terms, rather a natural development of the MAN B&W low speed electronically controlled ME family of engines. In 1987, the first testing of the GI principles was carried out on one cylinder of a 6L35MC two-stroke engine in Japan and Denmark. The MC/ME/ME-B engine types are well-proven products in the stationary power plant industry, Ref. [1]. The GI solution was developed in parallel with standard engine types, and completed for testing in the early 1990s. In 1994, the first two-stroke GI engine, a 12K80MC-GI-S, was put into service on a power plant at Chiba, Tokyo, Japan. So far, the Chiba engine has operated as a peak load plant for almost 20,000 hours on high-pressure gas. At the same time, in 1994, all major classification societies approved the GI concept for stationary and marine applications. Technically, there is only a small difference between fuel and gasburning engines. The gas supply line is designed with ventilated double-wall piping and HC sensors for safety shutdown. The GI control and safety systems are add-on systems to the normal engine systems. Apart from these systems on the engine, the engine and auxiliaries will comprise some new units. The most important aspects, apart from the gas supply system, are listed in the following: Ventilation system for venting the space between the inner and outer pipe of the double-wall piping Sealing oil system, delivering sealing oil to the gas valves separating control oil and gas Control oil supply for actuation of gas injection valves Inert gas system, which enables purging of the gas system on the engine with inert gas. The GI system also includes: Control and safety system, comprising a hydrocarbon analyser for checking the hydrocarbon content of the air in the double-wall gas pipes. Fig. 13: ME-GI engine add-ons compared to the standard ME engine Fig. 12: ME-GI engine The control and safety system is designed to fail to safe conditions. All failures detected during gas fuel running, including failures of the control system itself, will result in a gas fuel stop/shutdown and a changeover to HFO operation. Blow-out and gas-freeing purging of the high-pressure gas pipes and of the complete gas supply system will follow. The changeover to fuel oil mode is always done without any power loss on the engine. The operation modes for gas are illustrated in Fig. 14. Quantum

12 The ME-GI engine gives good flexibility in selecting the best fuel. Based on an environmental and economic perspective, the owner can choose a vessel designed to accommodate fuel stores for both HFO and LNG. The pilot oil can be low-sulphur marine gas oil for ignition and back-up fuel, particularly useful when sailing in emission controlled areas (ECA). This means that the ECA sulphur emission requirements can be met even when the twostroke main engine has to switch off gas operation at very low loads. Fuel-oil-only mode: Operation profile as conventional engine Gas mode Minimum fuel 100% 90% 80% Gas-fuel-operation modes: Gas mode minimum fuel Full operation profile Full load acceptance Full power range Load variation by gas injection Full pilot fuel oil flexibility Minimum pilot fuel used Increased pilot fuel at low loads Dynamic mix of gas and fuel oil 0 5 Automatic Fuel/Pilot oil Engine load (%SMCR) 70 Gas % 60% 50% 40% 30% 20% 10% 0% 100 Fuel index % Mixed mode Specified gas Mixed mode Specified gas 100% 90% 80% Full operation profile Gas fuel is specified on Gas MOP Load variation by fuel oil injection Gas 70% 60% 50% 40% 30% Fuel index % 20% Fuel/Pilot oil Engine load (%SMCR) % 0% 100 Fig. 14: ME-GI engine operation modes 12 Quantum 9000

13 Engine selection The ship speed, hull lines and propeller size selected for this container ship design require a two-stroke low speed 9S80ME-C9.2-GI engine to fulfil the requirements, with 15% sea margin and 10% engine operation margin. Fig. 15 shows a 3D model of the engine. This engine has the following main data: Power:... 40,590 kw Speed: rpm Bore: mm Stroke:... 3,450 mm Length:... 14,102 mm Width:... 5,280 mm Height:... 13,500 mm Weight:... 1,130 ton The SFOC figures shown in Table 6 are based on an engine tuned for waste heat recovery. This means that the exhaust temperatures are slightly higher to support waste heat recovery utilisation. Fig.15: 3D model of the selected two-stroke 9S80ME-C9.2-GI engine Expected Pilot and Gas Fuel Consumptions and Heat Rates Engine shaft power Specific pilot fuel oil (re lcv 42,700 kj/kg) Pilot fuel oil consumption (re lcv 42,700 kj/kg) Specific gas fuel consumption (re lcv 50,000 kj/kg) Gas fuel consumption per day (re lcv 50,000 kj/kg) Total heat rate of fuel (re lcv) Heat rate of pilot fuel oil (re lcv) Heat rate of gas fuel (re lcv) % SMCR g/kwh t/24h g/kwh t/24h kj/kwh kj/kwh kj/kwh , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,665.9 * , , ,581.2 * , , ,592.9 * , , ,599.4 * , , ,595.3 * , , ,571.3 * The exhaust gas bypass valve is closed at engine loads below 50.0 %. The main engine is operating in fuel oil mode below 25.0% SMCR power. Table 6: Two-stroke low speed 9S80ME-C9.2-GI engine and fuel SFOC figures Quantum

14 Waste Heat Recovery (WHR) The most efficient way to increase the total efficiency of a ship with a twostroke engine is to utilise the waste heat of the engine. Waste heat is collected primarily from the heat energy of the engine exhaust gas. Technology with power turbines, i.e. steam turbines in combination with high-efficiency turbochargers and boilers, has already shown total system efficiencies of 55%. This corresponds to a 10% increase in efficiency over a standard engine installation without WHR and, thereby, 10% lower fuel consumption and CO 2 emissions. The highest theoretical efficiency is close to 60%. Shaft power output 49.3% Fuel 100% (171 g/kwh) 12K98ME/MC Standard engine version SMCR: 68,640 kw at 94.0 r/min ISO ambient reference conditions Lubricating oil cooler 2.9% Jacket water cooler 5.2% Exhaust gas 25.5% Air cooler 16.5% Heat radiation 0.6% Dual pressure exhaust gas boiler Turbochargers Exhaust Gas Receiver Fig. 16: Waste heat recovery possibilities PTI LP steam HP steam Main Engine Steam Turbine WHR boosting cycle efficiency from 49.3% to approx. 55.0% (+11.5% recovery rate) Main engine Steam turbine Power turbine Total power generation Generator Power Turbine MWmech MWel MWel MWel Auxiliary Diesel Engines Central Control Panel If waste heat recovery is combined with NO x reduction methods and EGR (exhaust gas recirculation), the total efficiency can be raised to approximately 58%. For overview, see Fig. 16. A limited number of ships have been built with such systems over the past 25 years. Shipowners interest in WHR systems has so far been heavily dependent on the cost of HFO, the expectations to the development in the cost of HFO and, furthermore, the willingness of the shipyards to deliver ships designed and built for the WHR concept. From 2009, there has been an increasing interest in waste heat recovery systems, especially during times of rising fuel prices. They will be of particular interest because of the Energy Efficient Design Index (EEDI) that is expected for future ship designs. The most used waste heat recovery steam system is a dual pressure system, as illustrated in Fig. 17. Exh. gas boiler sections: LP-Evaporator HP-Preheater LP-Superheater HP-Evaporator HP-Superheater Exhaust gas TC Exhaust gas receiver Scavenge air cooler TC Main engine LP-steam drum HP Feedwater pump LP LP-circ. p. HP HP-circ. p. Surplus valve Power turbine HP-steam drum Jacket water Turbine unit HP Condenser Condensater pump LP Steam turbine Hot well Fig. 17: Dual steam pressure and feed water diagram as normally used onboard container ships of today HP-steam for heating services 14 Quantum 9000

15 This type of steam and feed water system secures a high utilisation of the waste energy in the main engine exhaust. Fig. 18 shows where the heat transmission takes place Temperature Superheated Hp steam Exhaust Superheater LP Exhaust gas boiler sections: A: HP-superheater B: PH-evaporator C: HP-preheater D: Possible LP-superheater E: LP-superheater The steam generated is used to drive a steam turbine as offered by MAN Diesel & Turbo, an example of this unit can be seen in Fig. 19. Saturated Hp steam Steam/water 10 bar abs/180 Min. 20 Min bar abs/144 Exhaust Feedwater proheated be alternative WHR sources A B C D E 5 0 Ambient % Heat transmission Fig.18: Temperature and heat transmission diagram for a dual steam pressure waste heat recovery exhaust boiler Fig. 19: Steam & power turbine unit The two-stroke 9S80ME-C9.2-GI engine with a waste heat recovery system will be able to produce the following electric output (Table 7) depending on the main engine load and temperature conditions Engine ISO Tropical load condition condition % WHR output WHR output kwe kwe 100 3,836 (9.5%) 4,460 (11.0%) 85 2,709 (6.7%) 3,218 (7.9%) 75 2,166 (5.3%) 2,613 (6.5%) Installation of waste heat recovery systems on board container ships must be coordinated in detail by the shipyard, as these systems take space in the engine room and casing, see Fig. 20 showing all main components relative to each other on a container vessels. The arrangement of a waste heat recovery system must be planned in detail to support the functionality of all components involved. Nevertheless, if correctly managed and integrated, the shipowner will have an advantage with respect to both total fuel consumption and meeting future emission demands. Fig. 20: Typical engine room and casing arrangement including advanced high power waste heat recovery system for a large container vessel 50 1,290 (3.2%) 1,584 (3.9%) Table 7: Electric output from the WHRS based on the selected ME-GI engine for this container ship study MAN B&W Diesel Quantum

16 Exhaust outlet Mix Cooler WMC Shut down valve Change over valve Prescrubber Scrubber Blower FW WMC Cooler Polishing Discharge control valve Sea NaOH tank On/off valve Buffer tank Water cleaning Scrubber pump Sludge tank Stop valve NaOH pump Fig 21: EGR process diagram Exhaust Gas Recirculation (EGR) EGR is one of many methods to cut NO x emissions from marine diesel engines. The method of EGR has been used on four-stroke engines, but it has not yet been commercially available for large two-stroke marine engines. By recirculating part of the exhaust gas, a minor part of the oxygen in the scavenge air is replaced by the combustion products CO 2 and H 2 O. Besides reducing the O 2 percentage in the combustion chamber, the heat capacity of the combustion air will be slightly increased and the temperature peaks of the combustion will be reduced. Accordingly, the amount of NO x generated in the combustion chamber is reduced. The NO x reduction ratio is dependent on the ratio of recirculation, but is also followed by a minor fuel penalty. The principle of an EGR system is shown in Fig. 21. Part of the exhaust gas is diverted from the exhaust gas receiver through a scrubber, which cleans the gas and reduces the temperature of the exhaust gas. The gas flows through a cooler, a water mist catcher and the EGR blower, which raises the pressure to the right scavenge air pressure. The ratio of recirculation is controlled by the blower, which in turn is controlled by the oxygen content ratio of scavenge air and exhaust. A water handling system is installed in connection with the scrubber. This system controls the function of the scrubber using a closed loop freshwater system with the addition of an active substance. The EGR system on this ship will be integrated with the main engine, an example of which is shown in Fig. 22 below for a 5S60ME-C8.2 type engine. The 9S80ME-C9.2-GI selected in this project requires two turbochargers, so the EGR system is therefore placed on the fore end of the engine. Fig. 22: EGR fore end arrangement on a two-stroke B&W 5S60ME-C8.2 engine 16 Quantum 9000

17 Specification of the EGR system for a B&W 9S80ME-C9.2-GI Gas system EGR scrubber 1 (or 2) Integrated on engine EGR pre-scrubber 1 (or 2) Integrated on engine EGR cooler 1 (or 2) 17,600 kw Integrated on engine EGR water mist catcher 1 (or 2) Integrated on engine EGR blower - frequency controlled 1 (or 2) 760 kw Integrated on engine Shutdown valve 1 (or 2) Integrated on engine Change-over valve 1 (or 2) Integrated on engine Compensators 2 (or 4) Integrated on engine Water treatment system WMC drainers - placed below WMC 3 (or 6) Integrated on engine Scrubber drainers - placed below WMC 2 (or 4) Integrated on engine Dirty buffer tank - placed below drainers 2 m 3 stainless Water treatment unit Clean buffer tank 2 m 3 stainless Water treatment unit Sludge tank 15 m 3 stainless Ship system Water cleaning unit (WCU) 120 m 3 /h 120 kw Water treatment unit Clean water outlet valve 1 Ship system Feed pump frequency controlled 120 m 3 /h 3 bar 16 kw Water treatment unit Scrubber pump frequency controlled 100 m 3 /h 10 bar 48 kw Water treatment unit NaOH storage tank - 50% NaOH solution 50 m 3 stainless Ship system NaOH day tank - 50% NaOH solution 1 m 3 stainless Water treatment unit NaOH dosing pump 250 l/h 2 bar 0.2 kw Water treatment unit Cooling water Cooling water for EGR Cooler 850 m 3 /h 2 bar Ship system Electrical system Frequency converter feed pump 1 (or 2) In WTS cabinet Frequency converter scrubber pump 1 (or 2) In WTS cabinet Frequency converter blower 1 (or 2) Brake resistance for blower 1 (or 2) Electrical cabinet WTS 1 Water treatment unit Control system EGR CU MPC control system 1 Engine control room EGR control display 1 Engine control room Water handling CU PLC control system 1 Engine control room Water handling display 1 Engine control room Table: 8 MAN B&W Diesel Quantum

18 Emission data The application benefits of the EGR system are described in the emission data diagrams shown in Fig. 23 and Fig. 24. Assumptions: Liq: HFO, 3% S, 86.7%C, LCV 42,700 Gas: LNG, 74.97% C, LCV 50,000 EGR system included for Tier III Pilot fuel 5% at 100% load NO x & SO x (g/kwh) CO2(g/kWh) % 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% NOx - Tier II NOx - Tier III SOx CO2 Engine Load (% SMCR) Fig. 23: Emissions Main engine running on LNG with pilot oil NOx & SOx (g/kwh) CO 2 (g/kwh) % 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% NOx - Tier II NOx - Tier III SOx CO2 Engine Load (% SMCR) Fig. 24: Emissions Main engine running on 100% HFO 18 Quantum 9000

19 Test Experience EGR in Service on Alexander Maersk From August 2008 until March 2010, MAN Diesel & Turbo has developed, designed, and manufactured the very first Exhaust Gas Recirculation (EGR) system for a two-stroke marine diesel engine for operation on a container vessel in service. In partnership with A. P. Moller - Maersk, the EGR prototype system has been installed, and commissioned, on the vessel Alexander Maersk. The 1,092-teu container vessel was built in 1998, and it is currently sailing between Southern Europe and Northern Africa. The main engine is a Hitachi B&W 7S50MC Mk 6, with a specified maximum continuous rating of 10,126 kw at 127 rpm, originally equipped with two turbochargers. Service test objective The main objective of the service test is to investigate the impact of running with EGR on the main engine, i.e. cylinder condition, exhaust system condition, and EGR system condition. Besides performance, settings and controlling, the software needs to be tested in situ in order to tune the control system for best possible performance. The EGR system developed for Alexander Maersk is designed for minimum 20% recirculation of the exhaust gas, which corresponds to minimum 50% reduction of the NO x emitted, compared with the basis emission level. Design of a retrofit EGR system The first retrofit EGR system is specifically designed for installation on Alexander Maersk, using expertise obtained during years of testing on the 4T50ME-X MAN B&W Diesel research engine in Copenhagen. The main EGR components are the scrubber, cooler, water mist catcher, blower, shutdown and changeover valves, water treatment plant (WTP), water cleaning unit (WCU), control, and safety systems. The exhaust gas is drawn through the scrubber, cooler, and water mist catcher, by suction created from the blower. The exhaust gas is pressurised by the blower, and then mixed with the charge air in a unique charge air pipe before entering the main engine coolers. Within the scrubber, the exhaust gas is mixed with water, which then becomes acidic due to the sulphur in the exhaust gas dissolving in the water. NaOH dosing is therefore required to neutralise the acidic scrubber water. A significant amount of particulate matter (PM) will also become suspended in the scrubber water, which will also need to be handled in the water treatment unit (WTU). It is therefore necessary to have a water cleaning unit (WCU) that can remove the PM from the scrubber water, and discharge it as concentrated sludge into the sludge tank on the vessel. The WCU is designed for cleaning the scrubber water to enable discharge of the cleaned water into open sea in compliance with the IMO scrubber water discharge criteria. In order to make the EGR system easy to operate for the ship crew and to ensure correct and fast reactions to engine load variations, a fully automated EGR control system was developed. A standard MAN Diesel & Turbo MPC controller is used as the main controller, and as a secondary system, a PLC is used for controlling the WTU. Installation of EGR In July 2009, Alexander Maersk docked at Lisnave shipyard for 30 days, during which all the large EGR components were installed and the majority of the installation work was completed. The EGR unit (consisting of the scrubber, cooler, water mist catcher, and blower) was installed on the middle platform, adjacent to the exhaust receiver on the main engine. The two original turbochargers were removed, and a single high-efficiency turbocharger with variable turbine area was installed in their place, with the new charge air pipe that distributes the mixture of charge air and recirculated gas between the two existing main engine coolers. The main engine cooler elements were replaced with special nano-coated cooler elements to prevent such corrosion that might otherwise occur due to the condensation of sulphuric acid caused by possible carry-over of SO x. The remaining equipment and pipework for the WTU was installed in the starboard corner of the engine room, on the main floor. EGR in service Commissioning of the EGR system on Alexander Maersk commenced in March All gas and water pipe work has been pressure-tested, the system functionality has been established, and an initial service test after 500 hrs. has been scheduled to evaluate the performance of the EGR system. An additional 3,000 hrs. in service is then planned for further evaluation of the EGR. An important part of the service test is to assess the effect of EGR on a main engine over a period with the engine running on heavy fuel oil (HFO). Quantum

20 The preliminary results from the commissioning phase have met our expectations to the EGR system performance. After some minor modifications, the system is now fully functional. ME-GI The first gas-fuelled two-stroke engine went into operation in July 1994, at the Chiba power station in Japan. This 12K80MC-GI-S engine went on to operate on gas fuel for 20,000 hrs. from 1994 to 2001, successfully proving the technology behind the MAN Diesel & Turbo two-stroke gas-fuelled engine concept. The engine concept has been class approved, and all the experience gained from Chiba has been incorporated into the ME-GI engine design. In order to promote the ME-GI concept further, MAN Diesel & Turbo has decided to make a full-scale demonstration and performance verification test of the gas injection principle for all kinds of marine applications on its R&D research engine, which was rebuilt to a 4T50ME- GI engine ready to operate on natural gas at the beginning of signed an agreement with Korea s Daewoo Shipbuilding & Marine Engineering Co., Ltd. (DSME) to jointly develop and exploit the adaptation of DSME s highpressure cryogenic gas-supply system for installation with the ME-GI engine. ME-GI two-stroke engines features economical and operational benefits compared with other low speed engine plants, irrespective of ship size. Based on the successful electronically controlled ME heavy-fuel-burning diesel engines, the ME-GI design accommodates natural gas and liquid fuels. MAN B&W ME-C and ME-GI engines are broadly similar, and essentially share the same efficiency, output and dimensions. In comparison, the key components of the ME-GI engine are its modified exhaust receiver, modified cylinder cover with gas injection valves and gas control block, an enlarged top gallery platform, high-pressure fuel supply pipes, and gas control units. Gas Supply System Dual fuel operation with ME-GI requires the injection of both pilot fuel and gas fuel into the combustion chamber. Different types of fuel valves are used for this purpose, with two additional valves fitted for gas injection together with the two original HFO fuel valves, which are used for pilot fuel injection. As known from LNG carriers, the arrangement of LNG systems on board ships must fulfil class rules more about this in the section titled Class requirements. The fuel gas supply (FGS) system for the ME-GI engine requires a delivery pressure of 300 bar and a temperature of 45ºC ±10ºC. Today, several supply companies can deliver high-pressure cryogenic pumps or compressor systems to fulfil these requirements, see Fig. 25. MAN Diesel & Turbo sees significant opportunities arising for gas-fuelled tonnage, as fuel prices rise and exhaust emission limits tighten. Indeed, previous research indicates that the ME-GI engine, when combined with exhaust gas recirculation (EGR) and waste heat recovery (WHR) technologies, delivers significant reductions in CO 2, NO X and SO x emissions and, thereby, fulfilling Tier II and Tier III regulations. The test plan continues the momentum built up at a ceremony in Copenhagen in 2010, where MAN Diesel & Turbo Fig. 25: LNG FGS unit suppliers 20 Quantum 9000

21 6312 AIR SUCTION V9 NC 6320 V6 NC V2 NO V7 NC V1 NC 6001 K3???? SILENCER These suppliers have experience with FGS systems, and are able to supply LNG tanks for ME-GI projects in some cases. In this project, the most relevant FGS system consists of a high-pressure cryogenic pump with capacity for BOG burn off in a gas combustion unit. In fact, for all vessel types other than LNG tankers it would probably not (depending on tank size/route) be necessary to have a reliquefaction system installed on board, and a high-pressure cryogenic pump would be the most energy efficient method of gas fuel delivery to the ME-GI engine. The energy required by the FGS system is very low, and corresponds to an approx. 0.5% reduction of the efficiency of the ME-GI engine compared with an ME-C engine. GCU * * Optional No boil off gas pressurized tank LNG Drum Fuel tanks HP pump M Cool down and mini flow line Supply system PC LNG vaporizer LNG damper PC ME-GI engine Two-stroke engine Fig. 26: LNG Fuel Gas Supply (FGS) system with high-pressure cryogenic pump (courtesy of Cryostar) INSIDE ENGINE ROOM OUTSIDE ENGINE ROOM FS VENTING AIR INTAKE FS SILENCER XT XT <0,1bar The gas injection valve design is shown in Fig. 28. This valve complies with traditional design principles of the compact design. Gas is admitted to the gas injection valve through bores in the cylinder cover. To prevent a gas leakage between the cylinder cover/gas injection valve and the valve housing/ spindle guide, sealing rings made of temperature and gas resistant material have been installed. Any gas leakage through the gas sealing rings will be led through bores in the gas injection valve to the space between the inner and the outer shield pipe of the double-wall gas piping system. Such a leakage will be detected by HC sensors. Sealing ring Nozzle O-ring ELGI CYLINDER COVER PILOT OIL FUEL FUEL VALVE SEALING OIL VALVE GAS GAS VALVE VALVE CONTROL OIL V4 625 V3 V5 ELWI GAS BLOCK ACCU FUEL OIL INLET HYDRAULIC OIL DRAIN FUEL OIL DRAIN SEALING OIL SYSTEM XC 6103 PT 6104 SEALING OIL UNIT PT 6110 PT 6405 FUEL OIL PRESSURE BOOSTER Gas venting pipe VENTILATING SYSTEM FOR THE ENGINE XC XT GAS SUPPLY SYSTEM XC 6019 ZS ZS XC 6014 PT ZS ZS P9 PT 6024 ZS 6010 XC 6018 ZS PT P2 XC?? Gas control system FUEL GAS SUPPLY SYSTEM Spring Head Gas valve Housing Fig. 28: Gas injection valve Spindle Holder Spindle guide 620 ELFI XT 6333 HYDRAULIC OIL HYDRAULIC OIL, PILOT OIL, SEALING OIL SYSTEM ZS ZS INERT GAS DELIVERING UNIT DRAIN ZS PT AIR SUPPLY 7BAR ZS 9BAR XC INERT GAS DELIVERING UNIT INERT GAS SYSTEM Fig. 27: Diagram of ME-GI auxiliary systems MAN B&W Diesel Quantum

22 The gas acts continuously on the valve spindle at a max. pressure of about 300 bar. To prevent gas from entering the control oil actuation system via the clearance around the spindle, the spindle is sealed by sealing oil at a pressure higher than the gas pressure (25-50 bar higher). The pilot oil valve is a standard ME fuel oil valve without any changes, except for the nozzle. The fuel oil pressure is constantly monitored by the GI safety system in order to detect any malfunctioning of the valve. The fuel oil valve design allows operation solely on fuel oil up to SMCR, with capacity for 10% above SMCR once every consecutive 12-hour period. In the gas engine mode, the ME-GI can be run on fuel oil at 100% load at any time, without stopping the engine. However, for prolonged operation on fuel oil, it is recommended to change the nozzles and gain an increase in efficiency of around 1% when running at full engine load. As can be seen in Fig. 29, the ME-GI injection system consists of two fuel oil valves, FIVA (fuel injection valve actuator) to control the injected fuel oil profile, and two fuel gas valves, ELGI (electronic gas injection) for opening and closing of the fuel gas valves. Furthermore, it consists of the conventional fuel oil pressure booster, which supplies pilot oil in the dual fuel operation mode. The fuel oil pressure booster is equipped with a pressure sensor to measure the pilot oil on the high-pressure side. As mentioned earlier, this sensor monitors the functioning of the fuel oil valve. If any deviation from a normal injection is found, the GI safety system will not allow opening for the control oil via the ELGI valve. In this event, no gas injection will take place. Under normal operation where no malfunctioning of the fuel oil valve is found, the fuel gas valve is opened at the cor- rect crank angle position, and gas is injected. The gas is supplied directly into an ongoing combustion. Consequently, the risk of having unburnt gas, eventually slipping past the piston rings and into the scavenge air receiver, is considered very low. Monitoring the scavenge air receiver pressure and combustion condition safeguards against such a situation. In the event of too high a combustion pressure, the gas mode is stopped, and the engine returns to burning fuel oil only. The gas flow to each cylinder during one cycle is be detected by measuring the pressure drop in the accumulator. By this system, any abnormal gas flow, whether due to seized gas injection valves or blocked gas valves, is detected immediately. In this event, the gas supply is discontinued and the gas lines are purged with inert gas, and the engine continues running on fuel oil only without any loss of power. Low pressure fuel supply Fuel return Measuring and limiting device. Pressure booster ( bar) Injection Gas supply Position sensor 800 Bar abs 300 bar hydraulic oil. Common with exhaust valve actuator FIVA valve 600 Pilot oil pressure The system provides: Pressure, timing, rate shaping, main, pre- & post-injection ELGI valve Control oil pressure Deg. CA Fig. 29: ME-GI fuel/gas injection system. 22 Quantum 9000

23 LNG Tanks For merchant ships, several possibilities of equipping the ship with an LNG tank are available. For smaller ship sizes, prefabricated vacuum-isolated cryogenic tanks can be found in a wide range of sizes with an allowable working pressure of up to 20 bar. Some of these tanks have been installed and are already in operation on ferries and supply vessels. For bigger ships, several other possibilities exist, some of which are listed below: Membrane tank design Dominating for LNG carriers, but vulnerable to sloshing. BOR range %/day. Spherical tanks, i.e. Moss type Self-supporting and invulnerable to sloshing, but space problems and very few manufacturers. BOR %/day. IHI type B tanks Self-supporting and invulnerable to sloshing. Low-pressure tanks and built on a licence in some yards. BOR %/day. TGE type C tanks Single or bilobe design, 4 barg pressure vessel tank design (up to 50 travelling days), self-supporting and invulnerable to sloshing. BOR %/day. have advantages and disadvantages. For instance, in the IHI design it is possible to adapt the tank form to follow the shape of the ship. Practically any tank size can be chosen. In the TGE design, the hull form can only be followed to some extent if the bilobe design. The max. tank size in the bilobe design is in the range of 20,000 cum. The space required for the LNG tanks is almost 2.5 times the size of an HFO tank system, due to lower density and the heavy insulation required to keep the LNG cold an area where shipyards need to develop new arrangement ideas. Tank pressure [bar g] 4,5 4,0 3,5 3,0 2,5 2,0 1,5 1,0 LNG composition: N2: 2% CO2: 0% C1: 89% C2: 5.5% C3: 2.5% C4: 1% Pressure increase estimation for type C tanks An advantage of the TGE tank design is the ability to accumulate the BOG in the tank during operation, thanks to its allowable working pressure of up to 4 barg. If a non-pressurised tank design is used, an alternative method to handle BOG has to be incorporated in the fuel gas supply system. Therefore, the C-type tank has been chosen for this project, eliminating the need for any reliquefaction system. The pressure rise in the LNG storage tanks for this vessel is illustrated in Fig. 30. With this in mind, it can be concluded that the technology for a gas driven two-stroke ME-GI engine is available. 304L: 2.5 bar g max. level: 92.6% 4 bar g design max. level: 90.3% 0,5 Tank volume: 2x2,500m 3 Insulation: 300mm PS/PU Initial pressure: 140 mbar g 0, Sailing time [days] Fig 30: Pressure rise in LNG storage tanks for Quantum vessel courtesy of TGE Marine Gas Engineering The IHI B-type tank design and the C- type design from TGE seem to be the most promising for larger conventional ships. Common for both tank designs is that it is possible to operate the ship with a partially filled tank, which is a basic requirement when using the tank for fuel storage. The above tank designs MAN B&W Diesel Quantum

24 Class Requirements The gas engine, LNG tanks and gas fuel systems are designed according to the requirements set out in the DNV class rules for gas-fuelled engine installations [2] and IMO's Interim Guidelines on safety for natural gas-fuelled engine installations in ships [3], as summarised in the following. Redundancy The propulsion and fuel supply system must be so designed that the remaining power for propulsion and power generation after any gas leakage with following safety actions is in accordance with the requirements for remaining power and main functions after a single failure. The ME-GI main engine has full fuel flexibility, meaning that the fuel oil is also a back-up fuel for the LNG. Engine room and piping The engine room is designed as an inherently gas safe machinery space. This implies that the engine room is considered gas safe under all conditions, normal as well as abnormal conditions. All gas supply piping within the machinery space boundaries must be enclosed in a gas tight enclosure, i.e. double wall piping or ducting. Gas fuel piping must not be led through accommodation spaces, service spaces or control stations. Gas pipes passing through enclosed spaces in the ship must be enclosed in a duct. This duct must be mechanically underpressure ventilated. Gas piping must not be located less than 760 mm from the ship s side. An arrangement for purging gas bunkering lines and supply lines with nitrogen must be installed. The double piping between the forward tank room and the engine room is fitted in the double bottom, with the required distance from side and bottom. Gas supply lines passing through enclosed spaces must be completely enclosed by a double pipe or duct. The arrangement and installation of the high-pressure gas piping must provide the necessary flexibility for the gas supply piping to accommodate the oscillating movements of the engine, without running the risk of fatigue problems. The length and configuration of the branch lines are important factors in this regard. Storage tanks and tank room The tank room boundaries must be gas tight. The tank room must not be located adjacent to machinery spaces of category A. If the separation is by means of a cofferdam, then additional insulation to class A-60 standard must be fitted. Access to the tank room is as far as practicable to be independent and direct from open deck. The storage tank used for liquefied gas must be an independent tank designed in accordance with the Rules for Classification of Ships, Pt.5 Ch.5 Sec.5, which is in accordance with the IMO International Gas Carrier Code (IGC Code). The tank is to be either an IMO type A, B or C tank. Here, a type C tank is used. Pressure relief valves must be fitted. The outlet from the pressure relief valves must be located at least B/3 or 6 m, whichever is greater, above the weather deck and 6 m above the working area and gangways. It must be possible to empty, inert and purge bunker tanks and associated gas piping systems. Gas in a liquid state with a maximum acceptable working pressure of 10 bar can be stored in enclosed spaces. The gas storage tank(s) must be located as close as possible to the centreline and: minimum, the lesser of B/5 and 11.5 m from the ship side minimum, the lesser of B/15 and 2 m from the bottom plating not less than 760 mm from the shell plating. In the current concept, the distance to side and bottom satisfies the above requirements. For vessels other than passenger vessels, a tank location closer than B/5 from the ship side may be accepted and approved by the Society, on a case by case basis. The storage tank and associated valves and piping must be located in a space designed to act as a secondary barrier in case of a liquid gas leakage. Alternatively, pressure relief venting to a safe location (mast) can be provided. The space must be capable of containing leakage and be isolated thermally, so that the surrounding hull is not exposed to unacceptable cooling in the event of a liquid gas leakage. This secondary barrier space is called tank room in other parts of this chapter. When the tank is double-walled and the outer tank shell is made of cold resistant material, a tank room could be arranged as a box fully welded to the outer shell of the tank, covering all tank connections and valves, but not necessarily all of the outer tank shell. 24 Quantum 9000

25 Bunkering station The bunkering station must be located so that sufficient natural ventilation is provided. Stainless steel drip trays must be fitted below liquid gas bunkering connections and where leakages may occur. The drip trays should be drained over the ship s side by a pipe that preferably leads down near the sea. The surrounding hull or deck structures must not be exposed to unacceptable cooling in case of leakage of liquid gas. The bunkering system must be so arranged that no gas is discharged to the air during filling of the storage tanks. A manually operated stop valve and a remote operated shutdown valve in series, or a combined manually operated and remote valve must be fitted in every bunkering line close to the shore connecting point. It must be possible to release the remotely operated valve in the control location for bunkering operations and/or another safe location. Means must be provided for draining the liquid from the bunkering pipes at bunkering completion. Bunkering lines must be arranged for inerting and gas freeing. The bunkering pipes must be gas-free during operation of the vessel. In addition to the above requirements, the rules contain specific requirements to ventilation, gas detection and fire protection of tank room, engine room and bunkering station. Bunkering The availability of LNG and how to bunker it is often put forward as the main challenge when it comes to running large ocean-going ships on LNG. A number of LNG terminals exists MAN B&W Diesel around the world, and more are under construction, but so far only Northern Europe has infrastructure for LNG bunkering ready. The most realistic bunkering option in the short term is taking LNG directly from the international trading network for LNG. Here, there are three different sources of bunker; import terminals, export terminals and LNG carriers. Bunkering directly from an LNG import or export facility would represent no major technical barriers. However, the container ship has to sail to the terminal location, which could represent a substantial cost. A better option is to take LNG from import/export terminals via dedicated LNG carriers or bunkering barges to a suitable bunkering location. The container ship would dock alongside the carrier/barge, or the LNG carrier/barge could dock alongside vessel while it is loading/unloading. This solution is flexible with the possibility of low investment cost in the case of the existing LNG carrier option. Bunkering from a LNG barge to a ship is not a technical challenge, since LNG transfer between LNG carriers is already being done today. However, when it comes to LNG fuel bunkering, there is a regulatory gap that needs to be filled to cover this type of operation. In order to limit the need for bunker capacity on the ship, it is proposed to refuel LNG once in Asia and once in US. There are currently terminals in both places that could be suitable for bunkering. Fig. 32 shows a map of existing, proposed, approved and under construction liquefaction and regasification facility stations in Japan. It is assumed that refuelling would take place at a station close to Yokohama. Fig. 31: LNG transfer from LNG carrier to LNG bunker barge In the US, refuelling is assumed to take place on the West Cost, at Port Dolphin outside of Los Angeles. This is an approved LNG terminal not yet built. The refuelling time is currently estimated to 8 hours, but it is expected that the bunkering rate can be increased in the future, so that the refuelling time can be reduced. Ship-to-ship transfer of LNG is done with several thousand cbm/h so, technically, high bunkering rates are achievable. However, as bunker supply infrastructure is not yet in place, there are no supply vessels available with large diameter connections and high capacity pumps. A bunkering rate of about 800 cbm/h is considered realistic to start with. If the ship must go to a dedicated bunkering site, some time will have to be added for this operation. In principle, the bunkering could also take place in the container terminal while loading and unloading cargo, which would eliminate the extra bunkering time for LNG refuelling. However, this would have to be approved by the port authorities in each relevant port. Quantum

26 In preparation for bunkering, the fuel tank pressure should be lowered as far as possible by use of spray pumps, shutdown of pressure build-units and if available switching compressors to direct suction from vapour phase. Further, the bunker piping must be cooled down by circulating LNG. Hull Optimisation The ship hull has to be designed for optimal efficiency according to the operational profile defined. The design speed for Quantum 9000 is 22 knots, which is lower than the normal design speed for modern large container ships. In addition, containerships are in the future likely to operate at a wide range of speeds. Modern engines and propulsion systems are designed with great flexibility and are capable of running at various power settings. However, the ship, as a system, will operate at a high efficiency level only if also the hull is designed to operate at off-design conditions. A flexible hull design with respect to the operating speed and displacements will translate into a reduction of fuel costs and emissions to air, thus making the ship more profitable and greener. Various hull parameters have been studied to arrive at the optimal main dimensions and hull lines. The resulting hull has a wider beam and a lower block coefficient than conventional designs. The new Panama Canal dimensions give designers more freedom when determining the hull length and breadth, while the maximum draught is still restricted by port limitations. Several hull parameters need to be evaluated in order to optimise the hull efficiency: length, breadth, block coefficient, longitudinal centre of floatation and bulb shape, among oth- Fig. 32: Existing, proposed, approved and under construction liquefaction and regasification facility stations in Japan ers. Computational Fluid Dynamic (CFD) A study has been carried out to assess tools are used to optimise the main hull the length/breadth ratio. The breadth dimensions. The wave patterns and the of a container ship can only be varied pressure distribution on the hull can be in steps determined by the container estimated and used to compare different possible design alternatives the breadth was increased to 48 m and width. Starting with a beam of 45.5 m, 50.5 m. The latter is over the maximum Fig. 33 shows the difference in wave breadth of 49 m allowed by the new pattern at design draught and design Panama Canal, but it was included for speed for a hull with two different block comparison purposes. The effect of the coefficients. Here it can be seen that change of breadth on the hull resistance the hull with the higher block coefficient is illustrated in Fig. 34. The figure covers has more pronounced forward shoulder a speed range from 16 to 24 knots. The and aft shoulder waves in addition to a resistance is shown relative to a breadth more prominent stern wave system. of 48 m. It can be seen that the effect of breadth is negligible at the design speed, while at lower speeds the wider hulls have lower resistance. Hence, a wider beam is likely to have a lower resistance in average, and allows for a reduction in ship length at the same displacement. Fig. 33: 1 Wave pattern at design draft, 22 knots: Cb=0.58 (top) vs Cb=0.62 (bottom) 26 Quantum 9000

27 Rt [ratio to Rt 48] 1.10 B = 45.5 m B = 48.0 m B = 50.5 m V [knots] Fig. 34: Hull resistance for different vessel breadths shown as ratio to the 48 m hull Having selected the beam, a study was carried out to determine the optimum block coefficient. A block variation from 0.58 to 0.62 was investigated, as seen in Fig. 35. Typically, the block coefficient for similar container ships is higher. It can be seen that the penalty in resistance of increasing the block coefficient at higher speeds is heavy. However, at speeds lower than 21 knots, a higher Cb would give higher hull efficiency. It should also be remembered that a certain increase in resistance at high speed would result in a heavier fuel penalty than the same reduction in resistance at lower speeds. Rt [ratio to Rt 0.58] 1.15 is found to have clear benefits in this respect. Midship section In the Quantum 6000-teu design, the deck has been made wide with a narrow ship side to maximise the loading capacity in the hold and on deck. However, for the larger Quantum 9000-teu the wide deck solution is not possible due to the New Panama Canal limitation. For the same reason, a narrow ship side does also not give any benefit, as illustrated in Fig. 36. Hence, a conventional midship section is chosen. Twin vs single island The twin and single island options were investigated and compared. It became clear that a twin island solution gives the best loading capacity, in addition to a number of other benefits. This is mainly due to the SOLAS visibility line requirement, shown in Fig. 37, which for a twin-island concept allows higher teu stacks forward in the ship. The twin island solution is also beneficial when space is needed for the LNG tanks. As a result, the teu capacity increased by over 10% compared with a conventional single island design. The main advantages with a twin island solution are: Maximizing carrying capacity Possible to place LNG tanks in the area below fwd wheelhouse Achieve better crew comfort thanks to lower vibration levels Reduce hatch cover deformations fwd Less shaft length since E/R more aft Better load distribution, reduced trim and need for ballast water Increased safety by better visibility Better load distribution, giving lower bending moment and reduced trim Better sight, giving reduced collision risk when maneouvering in port The disadvantage of the twin island is somewhat increased building cost, and some operational challenges due to the large distance between superstructure and engine room. The final general arrangement is shown in Fig Cb = 0.58 Cb = 0.60 Cb = 0.62 Cb = V [knots] Fig. 35 Hull resistance for different block coefficients shown as ratio to the Cb=0.58 hull. General Arrangement The main target for the arrangement is to have maximum loading capacity taking into account the space needed for LNG tanks. A twin island arrangement MAN B&W Diesel Fig.36: Midship section Quantum

28 Fig. 37: Difference in line of sight between single and twin island LNG Tank Arrangement The Quantum 9000-teu has an LNG storage capacity of approximately 6,500 m 3 LNG, divided on two tanks of 2,500 m 3 below the forward deckhouse and an LNG day tank next to the engine room with storage capacity of 1,500 m 3. The tank arrangement is shown in Fig. 38 and 39. The fuel oil is located in cofferdam bulkheads with a capacity of 4,000 tons, giving the ship full flexibility to run on HFO or LNG. As the concept is focusing on available technology, the LNG fuel tanks chosen are of the C type, which is state of the art today. These are standard reliable tanks with long service experience. They are capable of pressure build-up in case of zero consumption, and can accommodate high bunkering rates. Installation is also Fig. 38: LNG tank section frame quick and easy. The main disadvantage is the space requirement, which may lead to development of new, prismatic tank types in the future. Main Engine Room Safety A recently completed investigation, initiated by a group of players in the LNG market, questioned the use of a 250- bar gas supply in the engine room. Especially if located under the ship s Fig. 39: LNG tank illustration accommodation area, where the crew is working and living. Even though the risk of full rupture of both the inner and outer pipe at the same time is considered close to negligible, and in spite of the precautions introduced in the system design, MAN Diesel & Turbo found it necessary to investigate the effect of such an accident, as the question remains in parts of the industry; what if a double-wall pipe fully ruptures and gas is released from a full opening and is ignited? As specialists in the offshore industry, DNV was commissioned to simulate such a worst-case situation, study the consequences and point to the appropriate countermeasures. DNV s work comprised a CFD (computational fluid dynamics) simulation of the hazard of an explosion and subsequent fire, and an investigation of the risk of this event ever occurring and at what scale. As input for the simulation, the volume of the engine room space, the location of major equipment, the air ventilation rate, and the location of the gas pipe and control room were the key input parameters. Realistic gas leakage scenarios were defined, assuming a full breakage of the outer pipe and a large or small hole in the inner fuel pipe. Actions from the closure of the gas shutdown valves, the ventilation system and the ventilation conditions prior to and after detection were included in the analysis. The amount of gas in the fuel pipe limits the duration of the leak. Ignition of a leak causing an explosion or a fire is furthermore factored in, due to possible hot spots or electrical equipment that can give sparks in the engine room. 28 Quantum 9000

29 Calculations of the leak rate as a function of time, and the ventilation flow rates were performed and applied as input to the explosion and fire analyses. Recommendations for the Utilisation of Available Energy from LNG When bunkering LNG, you also bunker available energy (exergy) that can be used for cooling purposes. Today this potential is not utilised; instead most systems use extra energy to pump heating fluids like seawater and glycol/ water to the LNG fuel systems. When this added cooling value for LNG is utilised, it will improve the LNG cost picture, although it is not taken into consideration in the final cost-benefit assessment in this paper. The Quantum 9000 concept operates at a load of 85 % MCR most of the time, using LNG and a small amount of pilot fuel: Gas consumption (from LNG) at 85 % MCR: 134,1 g/kwh Pilot fuel consumption at 85 % MCR: 10 g/kwh The heating capacity needed for regasification of LNG to NG is approximately % of the engine capacity running on natural gas (or LNG percentage); two-stroke low speed engines like the ME-GI engine is located in the lower interval due to temperature rise in the LNG during compression to 300 bar (~10 C rise). Based on the main engine gas consumption at 85 % load and the need for heat exchange for regasification, we have approximately 1,000 kw available for cooling purposes. The upper part of MAN B&W Diesel this heat exchange (to raise the natural gas to 45 C) has to be done against a heat source with a matching temperature interval, like the main engine high temperature cooling circuit. The quest is to minimise the net heat transfer to the surroundings (air & sea). First priority should be to utilise cooling needs close to the engine room (cold box/room) for reasons of feasibility and the costs involved. The air conditioning system, engine related measures and cargo holds near the engine room and cargo holds with reefers are good candidates for this purpose. The available energy (exergy) from LNG regasification varies with engine load (SFOC), for engine loads below 25 % the engine runs on fuel oil only (engine limitation). It is therefore clear that the system design and flexibility is currently restricted, and the easiest way to exploit the cold LNG that needs to be vaporized is to modify the systems that have to cope with normal conditions without LNG available for cooling. The available energy for cooling purposes could be utilised to: 1. Reduce power consumption for reefer containers. Shave off peak air temperatures in the cargo hold 2. Aproximately 7 C is achievable when running in gas mode at 85 % MCR (5-10 % reduction in power need for reefer containers) 3. Cool down the air supply to turbocharger or main engine. Potential to cool down air supply to turbocharger or main engine which results in a gain in main engine efficiency 4. Other cooling needs. ~20-30% additional reduction in power need for seawater cooling pumps when used in combination with frequency converters Peak temperatures in air and seawater tend to increase the power need per degree more than at lower ambient temperatures; overall gain might be best if measures are combined. Reduction of Power need for Reefer Containers The Quantum 9000 concept has 131 reefer containers below deck in cargo holds. Reefer containers are the second largest power consumer after propulsion; they need a lot of power and air changes. To control the peak temperature in the cargo holds with reefer containers would result in a reduction in power consumption. It might also lead to a reduction in power need for cargo hold fans if the available cooling capacity results in the use of a lower air ratio per reefer container, today this might vary from 60 to 100 m 3 /h per reefer container. If we study different datasheets from producers of reefer machines, we see that the power curves are steeper at high ambient temperatures; rise in power need from 40 to 45 C is approximately twice the rise in power need from 30 to 35 C. Quantum

30 For the Quantum 9000 concept the potential to cool down the air supply to the cargo hold is approximately 7 C, based on the main engine LNG use at 85% load: The air supply temperature to the cargo hold is reduced from 35 to 28 C, and the power need for reefer containers is reduced by ~5% (~350,000 kwh saved per year) The air supply temperature to the cargo hold is reduced from 45 to 38 C, and the power need for reefer containers is reduced by ~8% (~490,000 kwh saved per year) The air supply temperature to the cargo hold is reduced from 50 to 43 C, and the power need for reefer containers is reduced by ~10% (~650,000 kwh saved per year) Lowering the supply air temperature to cargo holds with reefer containers gives a moderate direct saving. Spin-off savings like maintenance reductions and fewer problems with temperaturesensitive goods might further improve the potential savings. Conservative design values for air changes and ambient temperatures also put restrictions on the savings potential. The cargo mix and the type of reefer containers affect the potential savings. A state-of-the-art reefer container has advanced automatic controls and software that adjust air changes, temperature and, thereby, power consumption in a way that % savings are achievable. With such state-of-the-art reefers in the cargo hold, the gain of controlled air temperature to the cargo hold could be further improved. Real life data for reefer power consumption at different ambient temperatures is not easily available and also varies with type and quality (baseline vs. state of the art); an old reefer container may need two times as much power as state-of-the-art reefer containers. Future work together with shipowners/operators of container ships, reefer makers and other manufacturers would be the best way to improve the overall energy efficiency and gain experience while maintaining the flexibility to operate under all conditions (with or without the energy available from LNG). Cool Down Air Supply to Turbocharger Utilising the low-temperature LNG to lower the inlet air or charge air temperature increases the power and torque of the main engine; keeping the inlet air or charge air temperature as low as possible, but not below the minimum allowed temperature specified by the engine maker improves the energy efficiency of the engine. Based on the main engine air need and LNG use at 85% load, the available cooling energy from the LNG regasification has the potential to cool down the air supply to the turbocharger with approximately C; a maximum 0.7 % gain in energy efficiency of the main engine could be achieved in this case dependent on the main engine tuning characteristics, however, there are some technical challenges to overcome in order to accomplish this. Another option is to cool down the charge air, using a medium to transfer the cooling effect from LNG vaporisation to the main engine coolers; a maximum of 0.6% gain in energy efficiency could be achieved in this case dependent on the main engine tuning characteristics. Other Cooling Needs Maximum savings are achieved for heat exchange against direct cooling needs like air conditioning where the power input is about one third of the cooling need. If the Quantum 9000 concept needed 1000 kw for air conditioning (cooling), then the potential saving would be approximately 330 kw (~30%). Designing the air conditioning needs for Quantum 9000 was not part of the scope, so these values are given to illustrate potential savings. Another energy efficiency candidate is the seawater cooling system, where it is important for the engine maker that the system delivers the cooling capacity needed at any condition. For a water pump, a 50% volume flow gives an 87.5% reduction in power consumption with speed reduction instead of throttle regulation (affinity laws). n Q 2 2 Q1 n1 3 n 2 2 P1 n 1 P The use of frequency converter for seawater pumps to optimise pump speed according to ambient seawater temperature is deemed to be a low-hanging fruit for energy efficiency improvements and, typically, saves approximately 50%. This figure varies according to the operational profile and sailing pattern. With LNG available for cooling this saving will be improved and amplified (constant cooling at reduced flow gives increased temperature difference); we can control and lower the seawater temperature to the central cooler most 30 Quantum 9000

31 of the time without tampering too much with the system. When LNG is not available, the frequency converter will optimise the power use based on ambient conditions. Additional 20-30% reduction in power need for seawater cooling is expected when used in combination with frequency-converter-controlled seawater pumps. Although the potential savings of utilising the cryogenic LNG energy available are moderate, the costs involved to achieve this savings are small compared with many other possible measures considered today. To utilise the available energy (exergy) in LNG for cooling purposes leads to increased savings instead of increased costs. Ballast Water Sailing with ballast water comes with a cost, both due to the significant amount of energy necessary to transport the seawater across the oceans, and due to the cost of treating it. Eliminating or reducing the amount of ballast water needed in future ship designs offers a large potential gain. With the wider beam, the need for ballast water for stability is eliminated for most loading conditions. However, the trim and longitudinal bending moment may be an issue for some conditions, depending on the weight distribution of the containers. In principle, the trim and bending moment can be controlled by using an intelligent loading system, hence distributing the weight properly in the longitudinal direction. In this case, ballast water is not needed, which means that fuel can be saved and ballast water treatment can be avoided. Due to logistics, it may not always be possible to load the ship in the preferred manner, and ballast water may then be needed. However, also in the design phase there are options for reducing the need for ballast water for trimming and bending moment reduction: 1. The shorter and wider ship has a smaller bending moment compared with the longer ship, for a comparable loading condition. Hence, the need for ballast water to control the bending moment is reduced. 2. By increasing the design draught, the ship will have more buoyancy in the fore and aft part. This also contributes to reducing the bending moment, and reducing the need for ballast water. 3. By using a twin-island arrangement, as shown in Fig. 40, the ship will have a more even loading of containers, which gives a more beneficial trim. In addition, the sightline is better, both of which reduce the need for ballast water for trimming purposes. A traditional single-island container ship comparison resulted in a 20% reduction in ballast water for homogeneous loading conditions. 4. In addition, modifying the hull lines to change the longitudinal centre of flotation, may give a better trim characteristics. However, this may lead to a larger wave resistance. The two effects need to be weighed against each other to determine the optimal hull shape. For Quantum 9000, it was found that there is a penalty in moving the LCB away from the original location for all the conditions where ballast water is not required to achieve the required trim. The added hull resistance varies according to the loading condition and speed, but it can be up to 5%. As a result, moving the LCB aft, to reduce the need for ballast water, would not be beneficial for this project. Fig. 40: Loading condition example MAN B&W Diesel The actual cost of carrying ballast water with respect to added engine power needed has been investigated. The study showed that carrying 5000 tons, in average, of extra ballast water could potentially increase the fuel bill by about USD 250,000 annually. Furthermore, there would be additional costs related to the ballast water treatment system. Quantum