MAN 45/60 – the game changer3 February 2018
The latest generation of four stroke reciprocating engine from MAN offers unrivalled efficiency, high power density and the operational flexibility to meet the needs of today’s demanding power market. With a focus on remote or island applications, it represents a game changing approach to engine design for owners and operators. By David Appleyard
To welcome a new family member is always an occasion worthy of celebration. The arrival of the 45/60 is no exception. The newest member of the MAN Diesel and Turbo portfolio of reciprocating engines, this 450 mm bore and 600 mm stroke design builds on the company’s 250-year history of innovative engineering. It is the world’s most powerful four stroke engine.
The decision to expand MAN D&Ts already comprehensive portfolio was prompted by market demand. As well as the perennial requirements for energy efficiency, reliability and low emissions, owners and operators are now calling for new capabilities from their power plant engines. With the use of decentralised and renewable energy generation expanding right around the globe, so too has the requirement for operational flexibility with repeated start-ups for load following and peak shaving. There is also an underlying trend for larger engine-based power plants to be supplying baseload power in key markets.
Recognising the need for new capabilities in the high output class – which is currently met by its 48 and 51 families of engines – MAN aimed for a new design with a game-changing level of power density and efficiency. The 45/60 expands the current capacity range by more than 4 MW, while offering a best-in- class efficiency of more than 50%, even with the pumps and auxiliaries attached. This is a 3.5 percentage point improvement in total efficiency relative to the 48/60 B, for example. Furthermore, the new machine offers a power density of 1300 kW per cylinder.
With an output of up to 21.6 MW, the 48/60 TS is the current top end in the MAN four- stroke power portfolio. Now up to 26 MW is available, providing about 17% more power than the TS. And, while the new engine shares many features with the proven 48/60 family of engines – for example the common rail fuel injection system – it also represents a significant departure. For instance, increasing the operational speed from the 500 rpm of the predecessor up to 600 rpm for the 45/60 increases the power density. It also allows the number of poles on the generator to be reduced, cutting alternator costs by 10-15% when compared with the previous flagship.
Multiple markets, multiple options
At the heart of the 45/60 is a modular philosophy allowing multiple tailored configurations across a wide range of applications. The 45/60 is built around three central modules: the power unit, which includes the cylinder head, pistons and liners; the base engine including the crank shaft and block or base frame; and the turbo charger module which includes low pressure and high pressure turbos and their associated ducting.
Combining these three major modules enables a whole variety of different application variants to be developed without producing every single variant as a single unique unit. In turn this enables lower costs and easier retrofit. For example, if an owner decides to switch from liquid fuels to gas as that becomes available this is a relatively easy process requiring modification of the power unit only.
This medium speed four stroke engine is designed for both marine and power generation versions with in-line (L) and V cylinder arrangements. For power applications, outputs range from 15.6 MW to 26 MW, with 12 and 20 cylinders.
An L-configuration for power applications will be considered at a later stage. Focus for the market entry was clearly on the V engine which offers low costs in terms of $ per kW installed.
Though gas and dual fuel versions are also in the development pipeline, initially the 45/60 is being launched as a liquid-fuelled V unit for power generation in locations where gas supplies are not necessarily available. There is significant demand for such a machine across markets in remote locations and islands. Additionally many developing countries face increasing power demand but limited fuel supply infrastructure. As a result, with their growing need for for mid- and small-size power generation capacities, Africa, the Middle East, Asia and the Americas are anticipated to feature heavily in the order book.
Designed as a solution for captive power applications in these demanding locations, the 45/60 is capable of withstanding extreme site conditions such as high ambient temperatures and high altitudes with no de-rating. Even at 2500 metres above sea level and in ambient temperatures over 50°C the engine shows no drop in output. This compares favourably with predecessor engines like the 48/60 B which sees its performance drop above 35°C.
Meanwhile, under hot start standby conditions with the oil temperature at 40°C and water jacket at 60°C the 45/60 reaches full load in less than 30 seconds.
Starting with a requirement for low life-cycle costs, the best efficiency, lowest specific fuel consumption and highest power density, it was clear the new machine had to be designed from scratch. While demanding, this requirement also represented an opportunity to reduce both capex and opex for owners.
For instance, higher power densities reduce power plant volume, with fewer cylinders needed to meet the desired total output. In a scenario where a customer wants to build, say, a 200 MW plant using the previous 48/60 TS workhorse, its output of 1200 kW per cylinder would require 10 engines for a total of 180 cylinders and a 216 MW peak output. Using the 45/60 in the V20 configuration, the same application would require just eight engines and 160 cylinders while the output at 208 MW is closer to the actual target. At around 25% less required space and 20 less cylinders, there are fewer moving parts and less equipment. Better fuel consumption also reduces operating costs immensely.
Demands for higher reliability and lower maintenance costs, together with high power density and low specific fuel consumption potentially represent conflicting requirements and therefore require careful consideration at the design stage. MAN used both technology and simulation tools to design the major component parts of the engine. For example, multiple optimisation stages were used to design the crank shaft, which is of course the beating heart of the engine, narrowing the initial 12 000 possible designs to the final one.
Another example of design rigour emerges from the combustion analysis, one of the key elements of engine development. Starting with simulations to derive the turbocharger arrangement, compression ratio and valve lift curves, thermodynamic engine process calculations and a computational fluid dynamics (CFD) simulation followed to detail the injector nozzles and the piston bowl shape. Having completed the various simulation processes a single cylinder test bed unit was constructed to validate the efficiency and emissions calculations.
A testament to the significant improvement in power density, the result is a compact unit. As a V20 the base engine length (without alternator) is 12.6 m, width 4.6 m and height 5.5 m. The turbo charging module is 6.5 m long, 5.7 m wide and 7.4 m high.
In addition to the compact design, the new unit also extends the philosophy of simplicity of installation, servicing and maintenance with less skid- mounted modules around the engine and rather more items already integrated and more easily interfaced. For example, the associated pipework for media interfaces such as the water jacket, injector nozzle cooling and lubrication oil feeds are clustered. For the 20V engine, all pipe connections are at ground level on one side for direct and short connection to auxiliary modules. Similarly, the double- skinned ducting for the exhaust includes integrated insulation, rather than employing separate insulated covers. The lubrication pump is integrated into the crankcase, while the nozzle cooling module and lubrication oil cooler and filter are available as modules on the engine. A riser on site enables ‘plug and work’ functionality.
Two-stage turbo charging with intercoolers enables more energy to be extracted from the exhaust and allows compression ratios to be optimised, particularly at higher pressures. Air inlet pressures are between 6 and 7 bar for the 45/60. This leads to efficiency gains of 1-1.5%. Despite the series arrangement of turbos on the 45/60, load pick-up behaviour is the same as for the single-stage turbo 48/60 engine.
Coupled with Miller Cycle valve timing – in which the intake valve is closed earlier in order to decrease the combustion chamber temperature – the engine is more powerful with better economy. Fully electronic variable valve timing enables the use of the Miller Cycle.
The high pressure (1600 bar) common rail injection system delivers constant fuel pressure to all cylinders. In use for a decade and more it has now been adapted to suit higher engine speeds. It relies on a single camshaft for the pump drive as well as valve timing. With the common rail injection system, engine load points can be individually optimised in terms of specific fuel consumption, particulates or NOx.
Environmental friendliness is of course one of the key features to be successful in today’s power market. The 45/60 ensures compliance with the World Bank 2 (2007/2008) emission standard for heavy fuel oil (HFO), which defines maximum emission levels for NOx.
State-of-the art development in this regard is a selective catalytic reduction (SCR) system which will reduce NOx emissions by up to 80%. This exhaust gas after treatment goes hand in hand with the high allowable back pressures of up to 50 mbar without any performance impact.
Injection pressure and valve timing is electronically controlled. Indeed, the key to this engine’s impressive performance figures is the engine management system with, for instance, its advanced kinematics to manage the variable valve timing. The latest generation digital Safety and Control System (SaCoS 5000) also follows a decentralised design concept with a smaller cable harness and a single access point for data, making it online-ready but also equipped for the digital future of power generation.
Flexibility, high power density and efficiency
As a modular and flexible power unit for all applications, the 45/60 offers operators unrivalled operational flexibility with a high power density and efficiency. Commercial test bed units are due to begin operation in March 2018 with delivery to large customers anticipated around the beginning of 2019 and serial production expected to commence in early 2020.
MAN says this next generation of high power four stroke engine offers total fuel flexibility, the lowest fuel consumption in its class, “no derating anywhere” and full emissions compliance. This engine really will change the game.