L21/31 Adopting Tough Tug Operation into Engine Developement

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1 L21/31 Adopting Tough Tug Operation into Engine Developement

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3 Contents Synopsis...5 Introduction of MAN Diesel A/S, Denmark...5 L21/31 propulsion engine tailored to purpose...5 Design parameters...5 L21/31 main data...6 Fuel injection system...6 Simple exhaust gas system...6 a part of the engine...6 TCR Turbochargers the new unique generation for L21/ Operating tests and engine characteristics...7 Engagement torque related to main engine...7 Part load optimised turbocharger design & characteristics...8 Dynamic capability, acceleration and deceleration...9 Maximum bollard pull Control and monitoring Alphatronic 2000 LMCS Local Monitoring Control and Safety system Alphatronic 2000 LMCS new monitoring standards Operator orientation Flexible monitoring and safety functions Alphatronic 2000 PCS Propulsion Control System for MAN CP Propellers...11 Manoeuvrability and overall economy Pitch and engine speed slew rates Charge air limit curves (control of the fuel/air ratio) A green approach to propulsion power Summary MAN B&W Diesel L21/31 Adopting Tough Tug Operation into Engine Developement 3

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5 L21/31 Adopting Tough Tug Operation into Engine Developement Synopsis The combination of competences in research & development of diesel engines, turbochargers and decades of experience in all propulsion aspects, forms the basis for the MAN Diesel L21/31 propulsion engines for tugs. This paper describes the integration and optimisation of turbocharger technology, governor characteristics, fuel equipment and an electronic control system operating all functions securing the dynamic behaviour of the L21/31 engine. Introduction of MAN Diesel A/S, Denmark MAN Diesel A/S, Frederikshavn, Denmark is part of the worldwide MAN Diesel Group. MAN Diesel is a subsidiary of the MAN Aktiengesellschaft, Germany with employees. The Frederikshavn based propulsion centre, produces two and four stroke propulsion engines for the output range to BHP (750 to kw), reduction gears, CP Propellers, propulsion management and control systems. France, China and the Czech Republic the group achieves an annual turnover of approx 1.8 billion Euro. L21/31 propulsion engine tailored to purpose Design parameters Both in engine design, as well as in tug design the challenge is to find the optimum compromise between a vast number of demands and wishes as listed below in random order: Cold start ability Superior acceleration and load acceptance Good idling performance Immediate response to manoeuvres Low fuel oil consumption Low lube oil consumption Low emission levels Low noise levels Power reserve to account for peak loads and hull fouling Low maintenance costs through long TBO s and long life time Simple and proven technology No nonsense diagnostic system Ease of installation Further to this, engines are to match the demands from various propulsion applications, such as: Conventional systems with CPP or FPP Azimuthing thrusters Azimuthing Pods Voith Schneider propulsors Z Pellers Schottel rudder propellers As a ship propulsion specialist, MAN Diesel master all the complex design disciplines in house and together with the MAN Diesel and Turbocharger Divisions optimised turbocharger technology, governor characteristics, fuel equipment and electronic control system are integrated into the new generation of state of the art medium speed engines for the marine market. MAN Diesel offers today a very wide programme of propulsion packages and engines. The below diagram shows including the L21/31 the four stroke range most suitable for tugs. (Fig. 1) The MAN Diesel Group is leading supplier of large bore diesel engines for marine propulsion and power stations with a unit output of up to 97 Megawatt ( BHP) per engine. The two and four stroke engines produced by MAN Diesel and their licensees are, with a market share of approx 50 percent, leaders on the world market with regard to propulsion of large ocean going vessels. Moreover, the company is one of the leading suppliers of diesel power stations and turbochargers. With approx employees and manufacturing plants in Germany, Denmark, England, MAN B&W Diesel S p eed [rev/m in ] P o w er R ange [kw ] L 21/ L 27/ L 32/ L 32/44C R Fig. 1: L21/31 - and MAN Diesel s medium speed engine range for tugs L21/31 Adopting Tough Tug Operation into Engine Developement 5

6 L21/31 main data The L21/31 engine is optimised for propulsion applications, but is also available for marine GenSets as well as for stationary Power Plant applications in a completely different execution. L21/31 is the latest engine in the new generation and is designed in line with the proven family design concept of the L27/38 propulsion engines and an array of adapted components, which meet the specific requirements of propulsion service in that output range. The L21/31 governor unit consists of a hydraulic governor and an optional electronic speed setting control module. Bore mm 210 Stroke mm 310 Stroke/bore ratio 1.5:1 Swept volume/cylinder litres 10.7 Cylinder numbers in line Power/cylinder kw Power range kw Speed rev/min 1000 SFOC (MCR) g/kwh SLOC g/kwh Bmep bar Mean piston speed m/s 10.3 Pmax bar 200 Fig. 2: The 6 cylinder version of the L21/31 propulsion engine The ideal technology for every application is secured by the L21/31 s opti- Optimised camshaft profile for injec- Optimised injection intensity mised injection system featuring: tion High injection pressure Simple exhaust gas system Optimised injection duration a part of the engine NO x optimised injection timing The L21/31 propulsion engine is designed with a simple constant Emission optimised injection nozzles pressure Fuel injection system The fuel injection system is an essential prerequisite for every ecologically acceptable diesel engine. The integrated high pressure injection system in combination with optimised air swirl from cylinder heads makes it possible to combine the demand for low pollutant emissions with the requirement for low fuel consumption and a long service life. Fig. 3: Cut away view of a TCR Turbocharger 6 L21/31 Adopting Tough Tug Operation into Engine Developement

7 turbocharger and exhaust gas system integrated with a narrow exhaust gas receiver in an optimised size for quick take up of the engine load response. Advantages for constant pressure turbocharger: Engine operating line C blow by open C blow by closed Simplicity Easy maintenance Suitability for any number of cylinders Standardisation of many identical parts One turbine gas inlet TCR Turbochargers the new unique generation for L21/31 Based on MAN Diesel s successful and trend setting design philosophy, the integrated TCR constant pressure turbochargers feature a simple, integrated, reliable and high efficiency air supply (excellent fuel/air ratio) to the main engine for all load steps. The compressor map is customised to the L21/31 engine operating line with good margins to the surge line for engine stability over the entire power range. (Fig. 4) The TCR turbochargers are designed to comply with the special demands made for HFO and MDO engines. An optimised turbocharger matching and case by case a tailor made matching secure the complete range of possible applications, as for instance propulsion of tugs and off shore vessels, which are subject to the most strict requirements with regard to turbocharger performance. With the new TCR Turbocharger series integrated and optimised for the L21/31 main propulsion engines the following have been obtained: Fig. 4: Example of compressor map for L21/31 High specific volume flow High turbocharger efficiency Extended compressor map Compressor map is customised to engine operating line Increased part load charging pressure for propeller law operation Low moment of inertia inside turbocharger for best dynamic behaviour Round outlet flange for direct connection to exhaust gas piping Advanced design ensures long life time and easy maintenance The high turbocharger performance and efficiency over the entire engine load range eliminates the use of old fashioned, complicated two (three) step turbochargers and even pulse pressure turbochargers have become secondary for heavy duty propulsion engines. D1a = 142.,mm A4K = 36.,4 cm 2 A4K/A1K = 0.,406 The TCR is an integrated part of the L21/31 propulsion engine with smart design for convenient installation such as: Un cooled casings, lubrication by engine lube oil system, integrated oil inlet and oil drain for pipeless design. No sealing air is required. Operating tests and engine character istics A number of tests and simulations have been carried out in order to fine tune the L21/31 engine to it s tough working conditions with various loads and demands from the vessels operating profiles and different propulsor solutions. Engagement torque related to main engine To evaluate the safety margin of the dynamic engine behaviours at low load MAN B&W Diesel L21/31 Adopting Tough Tug Operation into Engine Developement 7

8 an engagement torque analysis has been simulated. A case study has been performed based on M/V Sarawak, a Multi Mission Special Function Vessel. The vessel is powered by 2 x 8L21/31 main engines, 31VO16EV reduction gearboxes and CP propellers: To evaluate the torque variation for the main engine during clutching in of a CPP system an engagement analysis has been carried out. Clutch-in torque Engagement torque [k/m] 3,00 2,50 2,00 1,50 1,00 0,50 Sarawak Slipways nb. SS2174 Enganement torque related to main engine 8L21/31 with 31VO16EV clutching in at 600rpm The engagement torque is evaluated on the gearbox input shaft and consists of the following contributions: 0,00 0,00 0,50 10,00 1,50 2,00 2,50 3,00 3,50 4,00 Time [sec] 1. A breakaway torque corresponding to stick slip friction in the stern tube bearings. The torque is evaluated to 0.29 knm and considered to vanish after approx 0.5 revolution. Fig. 5: Clutch-in torque Power reserves Engine power reserve at low load - L21/31 2. Inertia torque of the gearbox and propeller parts to be accelerated from 0 rpm to the main engine idling speed of 600 rpm in 3 seconds. The acceleration is assumed to be constant and the constant torque is knm. 3. The hydrodynamic torque from the propeller operating in zero pitch condition. The power consumption of the propeller in zero pitch condition and idle speed is predicted to 93 kw corresponding to a torque of 1.48 knm. After acceleration to idling speed this is the only torque present. The complete engagement torque is shown (Fig. 5) as a curve for the first 3.5 seconds of engagement. Engagement torque [k/m] 8,00 7,00 6,00 5,00 4,00 3,00 2,00 1,00 0,00 Fig. 6: Power reserves at low load Engine [rpm] Power reserve - Thermal overload line Theoretic propeller curve Fixed pitch propeller curve Part load optimised turbocharger de sign & characteristics The TCR turbocharger design of bearing casing and rotor shaft sealing prevents lube oil leakage if the turbocharger is operated for a long time at low load or it is used in stand by mode, idling for hours/days. The mixture formation of fuel/air, and the soot values under steady state operating conditions as well as for transient 8 L21/31 Adopting Tough Tug Operation into Engine Developement

9 operation were even improved under part load operation by the high efficiency TCR turbocharger. 69 Expected turbocharger efficiency of TCR series D2 Comp >318 mm A pressure difference is necessary to allow the charge air to flow from the air receiver through the top dead centre cylinder space into the exhaust duct. This pressure difference is determined by the turbocharging system and the turbocharger efficiency. When the turbocharger efficiency is low, the exhaust gas pressure is only slightly lower than the charging air pressure and the cross over point is relatively high. The new L21/31 with integrated TCR turbocharger, however, sets new standards for radial flow turbochargers with high efficiency and good performance at low load, which consequently leads to a higher pressure difference between charge air pressure and exhaust gas pressure. At the L21/31 engines with TCR turbocharger the cross over point is as low as at 20% propeller load. (Fig. 7) Eta TL tot-stat [%] Figure 7. TCR Turbocharger eficiency Customer required running up load for different application ranges Time Clutch in Time [10 35] [sec] 1st load step % [35 60] [sec] Dynamic capability, acceleration and deceleration The variety of dynamic demands from different ship types is wide with regard to manoeuvring, shaft generator load steps, clutching in procedures, dynamic positioning and various propeller 2nd load step % [60 90] [sec] 3rd load step % [90 100] [sec] Application Offshore vessels Trawlers Cargo vessels Ferries Tugs & Salvage Dredger 3 Full load application TCR 18 Part load application Compressor pressure ratio Pi tot Comp [-] 4th load step % [sec] types. Consequently, the choice between several engine layouts must be provided in order to ensure the optimal propulsion solution. The L21/31 has a good basic dynamic capability, which for more demanding applications can be supplemented with various optional steps of turbocharger matching, jet assist on the turbocharger, engine timing, exhaust gas systems and waste gate applications. It is well appreciated that Dynamic Positioning (DP) or any close contact manoeuvring, for that matter requires precise management of the propulsion system. The response from the engine and propeller to helm commands must be immediate, reliable and exact. (Table 1, Fig. 8 and 9) Table 1. Load increase and running up MAN B&W Diesel L21/31 Adopting Tough Tug Operation into Engine Developement 9

10 Engine load [%] Output [%] 100,0 Load increase for L21/31 Demanding service ,0 80,0 70,0 60,0 50,0 40,0 30,0 20,0 10,0 0, Time [second] Fig. 8.: Typical load increase Clutch-in time Minimun 3 seconds recommended Engine load Normal service Engine load Demanding service Engine speed Normal service Engine speed Demanding service L21/31 Engine power ranges Pme [bar] 31,2 28,8 26, ,0 100 Turbocharger surge line 21,6 L21/31-PROP MCR %output = 215 kw/cyl 19,2 100% speed = 1000 rpm Theoretical propellercurve 80 Idling = 600 rpm (60%) Max. bollard pull 16,8 70 TC = NR20/S 14, ,0 50 Power reserve at low load high torque limit 9,6 40 Fixed pitch propeller curve 7,2 30 Free sailing vessel 20 1,8 10 Peak load area allowed for max.15 sec. during engaging/break away torque Engine Speed [%] Fig. 9: L21/31 engine power ranges Engine speed [RPM] Maximum bollard pull When the L21/31 engine operates continuously in the so called MCR pinch point at maximum bollard pull load, superior performance is ensured due to the safety margins inherent in the basic design. The L21/31 technology and engine features provide kw low NO x power Low environmental impact Low fuel consumption Low lube oil consumption Good long term engine performance High reliability and long TBO s Overall optimised operating economy Control and monitoring In the process of projecting and estimating propulsion systems, the associated control system is a soft item frequently handled with less attention. The propulsion control system is often regarded as a necessary auxiliary element that just follows the primary propulsion elements. But the long term performance, fuel efficiency and overall propulsion efficiency of the hard engine and propeller elements are, however, undermined without the correct matching and correct performing control and safety system! Alphatronic 2000 LMCS Local Monitoring Control and Safety system This state of the art propulsion management system for L21/31 consists of two modularised systems: the Local Monitoring, Control and Safety system (LMCS) and the Propulsion Control System (PCS). 10 L21/31 Adopting Tough Tug Operation into Engine Developement

11 Fig 10. Engine operator panel Alphatronic 2000 LMCS new ne moni toring standards The L21/31 engine exploits a fully electronic and redundant local instrumentation concept for both engine and gearbox/propeller thus proving extensive monitoring and an unsurpassed overview for the operator. The operator panel for the engine is placed next to the governor. This is done to give the operator the best possible condition for controlling and for monitoring the complete engine from one position only. Operator orientation In order to further facilitate a good overview and a well organised platform for the total package, the operator panel for the gearbox and propeller will be found next to the operator panel for the engine. (Fig. 10) Flexible monitoring and safety functions The number and type of parameters to be monitored are specified in accordance with but not limited to the requirements of the classification societies. The engine has as standard shut down functions for: Low lube oil pressure Overspeed HT cooling water pressure HT cooling water temperature Emergency stop Alphatronic 2000 PCS Propulsion Control System for MAN CP Propellers Manoeuvrability and overall economy The Alphatronic Propulsion Control System plays a key role in the optimising function of the entire propulsion plant. The control system not only optimises the function of the propeller but also the engine functioning as well as securing the vessel s manoeuvrability and best overall economy with respect to engine dynamics, fuel oil consumption and propeller efficiency. MAN B&W Diesel L21/31 Adopting Tough Tug Operation into Engine Developement 11

12 Pitch and engine speed slew rates The acceleration and deceleration slew rates can be specified independently for ahead and astern direction and with a third separate curve for crash stop. The slew rates are adjustable with six independent pitch rates on each curve and five break points, which is common for the three curves. Charge air limit curves (control of the fuel/air ratio) The low part load charging air pressure leads to a low air/fuel ratio for the combustion and a high thermal loading of the parts in the combustion chamber. The charge air limitation will protect the engine against thermally overload by limiting the propeller pitch and thereby reducing the fuel index/shaft torque, as a function of the main engine charge air pressure. (Fig. 11) Pitch and engine speed slew rates time [sec.] Normal pitch rate ahead Pitch rate at crash stop Normal engine speed rate Engine speed rate at crash stop Normal pitch rate astern Fig. 11: Pitch and engine speed slew rates Propeller pitch [%] The main engine charge air limitation curve is characterised by a number of adjustable break points for maximum fuel index/shaft torque with corresponding charge air pressure. (Fig. 12 and 13) Engine load limit [%] Fuel pump index [%] Running up time [min] Charge air pressure [Bar] Run up, normal Charge air limit, load restrictions cancelled Run up, load restrictions cancelled Charge air limit curve, normal Fig. 12: Running Up Load program Fig. 13: Charge air limit curves 12 L21/31 Adopting Tough Tug Operation into Engine Developement

13 A green approach to propulsion power Optimised key components and the use of additionally implemented engine functionalities are exploited for all propulsion conditions in order to fulfil today s and tomorrow s environmental demands. The design of the L21/31 has been performed with careful attention to its impact on the surroundings. Some key points are: Exhaust gas: A minimum of visible smoke during acceleration and at any load point. Exhaust gas emissions below the IMO NO x limits Noise emission: Special noise dampening engine covers are applied Vibration: Well balanced engine with low vibration levels transmitted to foundation, accommodation even when rigidly seated Waste: No disposal or chemical waste problems with used lube oil filter cartridges thanks to self cleaning automatic full flow lube oil filter. Easy handling and no disposal costs. Fuel oil: Minimal fuel oil consumption within legal emission limits for reduced operating costs Lube oil: Low and stable lube oil consumption is another important cost factor Heat emission: High engine and turbocharger efficiency, low heat emissions with good possibility to exploit surplus heat in auxiliary systems Man and machine: Operator safety and handling friendliness due to extensive use of ergonomically correct solutions related to lifting Invisible smoke and low emissions Smoke values Bosch number [x6] Specific NO emission ISO weighted [g/kwh] x 1,8 1,6 1,4 1,2 1 0,8 0,6 0,4 1,2 18,00 16,00 14,00 12,00 10,00 8,00 6,00 L21/31-PROP smoke values Bosch number x6 E3 Cycle 0 Idling Engine propeller load [%] Smoke values Bosch number x6 Invisible smoke NO x emission L21/ kw/cyl. at 1000 rpm Test cycles E2 and E3 in accordance with ISO Rated engine speed [rpm] IMO limit curve for NOx emission L21/ kw/cyl at 1000 rpm [E3] L21/ kw/cyl at 1000 rpm [E2] 6L21/ kw at 1000 rpm Fuel: MGO Date: Nov High swirl, ε = 15.5 Inj. Cam: V04 Inj. Nozzels: 9 x x 156 Fig. 14: Smoke values Bosch number x6. Smoke value 1 (x6) = Smoke value 0.2 (x1) Fig. 15: NO x emission for L21/31 gear, hydraulic tools, flanges and couplings 10.4 g/kwh acc E3 9.8 g/kwh acc. E2 MAN B&W Diesel L21/31 Adopting Tough Tug Operation into Engine Developement 13

14 SRP Summary The combination of propulsion competences in research & development of diesel engines, turbochargers and decades of experience in all propulsion aspects, forms the basis for the MAN Diesel L21/31 propulsion engines as the perfect tug engine ready for installation in a large number of different tug and salvage applications. The integration and optimisation of turbocharger technology, governor characteristics, fuel equipment and electronic control system operating all functions securing the dynamic behaviour over a wide operating speed range for the L21/31 engines. The combination of Alphatronic 2000 load control, jet assist, charge air pressure control and the governor speed control secures superior acceleration and load acceptance for a complete propulsion package integrated with a L21/31 propulsion engine. Fig. 16: L21/31 a perfect engine for tough tug operation High turbocharger efficiency secures high power reserve (more than 20%) to account for peak loads such as clutch in, breakaway torque, gearbox, shaft line, shaft generator ac- L.B. L.C. celeration and hull fouling. The engine acceleration is integrated in the Pp.AD Pp.AV Alphatronic 2000 and controlled by a ram function over an adjustable time. Fig. 17: General arrangement, Fratelli Neri tugboat with 2 x 9L21/31driving SRP s At the low load operation immediate The main propulsion systems with response to manoeuvres from low load up to MCR load have been obtained. Furthermore, good idling performance down to 25% of MCR load can be demonstrated. the modular design concept can be optimised for a wide variety of power demands and ship types, fulfilling the requirements of shipyards and owners with a high degree of flexibility. 14 L21/31 Adopting Tough Tug Operation into Engine Developement

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17 All data provided in this document is non-binding. This data serves informational purposes only and is especially not guaranteed in any way. Depending on the subsequent specific individual projects, the relevant data may be subject to changes and will be assessed and determined individually for each project. This will depend on the particular characteristics of each individual project, especially specific site and operational conditions Copyright MAN Diesel & Turbo Subject to modification in the interest of technical progress ppr Aug 2011 Printed in Denmark MAN Diesel & Turbo Niels Juels Vej 15 DK-9900 Frederikhavn, Denmark Phone Fax