MAN Diesel & Turbo Technology Boosts Efficiency

MAN Diesel & Turbo used the world premiere of its MAN B&W ME-GI gas engine in Copenhagen to present efficiency technologies for its two-stroke engines, namely its WHR (Waste Heat Recovery) systems, that include its TCS-PTG turbines, and which are offered as an integrated solution.

WHR exploits, among other things, exhaust-gas energy and can be used in the production of electricity to cover a ship’s electrical needs. All ME- and MC- types in MAN Diesel & Turbo’s engine portfolio are suitable for WHR where, generally speaking, the greater the engine output, the greater the potential WHR offers and the quicker the economical return. As a result, WHR technology has traditionally been applied to container-ship and power-station applications.

MAN Diesel & Turbo offers total WHR system packages with exhaust boiler, steam and power turbine generator unit, PTO/PTI and power management.

High-load optimisation is a major part of the WHRS principle where a power turbine is placed in parallel with the main-engine turbochargers and/or steam turbine, thus utilising the heat from the exhaust gas after the turbochargers. Up to approx. 10% MCR power can be obtained with a full WHR system, that is, featuring both power and steam turbines.

MAN Diesel & Turbo offers a number of WHR options for exhaust-gas utilisation:

• power turbine stand-alone: PTG – Power Turbine Generator
• steam turbine stand-alone: STG – Steam Turbine Generator
• combined turbines: Steam turbine – Power turbine

WHR aboard container ships
The installation of a WHR system aboard a container ship requires a larger exhaust piping system to ensure an even exhaust-gas distribution within the exhaust boiler. The exhaust boiler itself requires a collector to control the exhaust-flow velocity, velocity distribution and to collect the exhaust-boiler washing water. For its exhaust-boiler systems, MAN Diesel & Turbo recommends the installation of an exhaust by-pass and by-pass exhaust valves.

For WHR exhaust systems, MAN Diesel & Turbo recommends that shipyards use computational fluid dynamics to calculate and ensure an even exhaust-gas velocity distribution into the exhaust boiler using guide vanes. This is important in securing a high WHR system efficiency. Back-pressure calculations for the exhaust system are also necessary to ensure the correct functionality of the WHR system – the correct exhaust velocity up through the exhaust boilers ensures optimal functionality and minimises the risk of soot collection on the internal surfaces of the exhaust boiler. Engine data can be provided for exhaust systems with higher back pressures in cases where WHR systems and scrubber systems are combined, a situation that especially will arise in the case of new ships serving routes in SECA areas.

Complete service
MAN Diesel & Turbo is a complete WHR system supplier and designer of main engines, turbochargers, steam turbines and power turbines. The company optimises and guarantees the performance of the complete WHR cycle for shipyards and ship owners.

TCS-PTG
TCS-PTG is the first unit of the new generation of power turbines based on MAN Diesel & Turbo’s TCR/TCA turbines; the company first patented its TCS-PTG system in 1957. In Copenhagen, MAN Diesel & Turbo displayed the first of two TCS-PTG18 units that were assembled and extensively tested in Germany and which are bound for a power project in London.

London power turbine order
H. Cegielski – Poznan S.A. ordered two TCS-PTG18 power turbine systems in 2010 to boost the efficiency of two environmentally friendly, diesel power plants currently nearing construction by Land & Marine for renewable energy company Blue-NG in London. Each plant is powered by an MAN B&W 7K60MC-S engine producing 13.9 MW. Blue-NG is committed to being best in class at building the most efficient power plants in the world, and is sparing no effort to optimally use the energy created by the two Combined Heat and intelligent Power (CHiP) sites.

MAN Diesel & Turbo’s latest, market-leading, high-efficiency TCA turbochargers make it possible to divert more exhaust gas to power turbine-based, energy-recovery systems. In such applications, the power turbine is inserted into the exhaust-gas system parallel to the turbocharger. Here, it drives an electrical generator via a reduction gearbox and receives up to 12% of the exhaust-gas flow, diverted from the main-engine power.

A TCS-PTG18 will be employed at each of the coming plants, based on the newly developed, high-efficiency turbine of a TCR18 turbocharger. A high-efficiency, high-speed gearbox will reduce turbine speed to generator speed, with the generator and gearbox connected to each other by a highly flexible coupling. The TCS-PTG18 will supply up to 570 kW to the grid and increase the power plant’s overall efficiency by some 3%. At lower engine loads, the TCS-PTG will be shut down. Control valves and fast-acting emergency valves for emergency shutdown are installed in the exhaust system to ensure reliable, safe operation.

MAN Diesel & Turbo has more than 30 years’ expertise in the development, production and servicing of power-turbine applications, and can boast of some 50 reference plants, mostly installed aboard ships. The London order sets another milestone as it is the first order for the newly developed generation of power turbines based on the new TCR turbocharger series.

MAN Diesel & Turbo sees much potential for further TCS-PTG waste-heat recovery applications in diesel power plants and marine applications as the recent increase in fuel prices has revived interests in systems that maximise overall system efficiency. The company predicts that the ongoing CO2-debate and companies’ growing interest in environmental issues for newbuilding projects will make the power-turbine system an interesting option.

Low-temperature WHR
MAN Diesel & Turbo recently signed a cooperation agreement with Swedish energy and environmental technology company, Opcon, to exploit the possibilities arising from the merging of Opcon’s ‘Powerbox’ WHR technology with MAN Diesel & Turbo’s diesel engines for cutting fuel consumption and reducing emissions. The companies will examine how best to exploit the possibilities offered by re-using waste-heat energy from low-temperature heat sources utilising the Opcon Powerbox technology.

The first, groundbreaking reference – a marine installation that utilises waste heat for electricity production – is currently underway with the Opcon Powerbox integrated with a two-stroke MAN B&W 8S60ME-C8 engine aboard a newbuilding owned by Wallenius, the Swedish shipping group.

The Opcon Powerbox can be integrated with smaller engines in contrast with existing WHR units that are targeted at higher-temperature applications and larger engines. It directly influences the performance of ships by reducing the amount of fossil fuels they consume during operation by 5-10%. It also significantly reduces consumption and directly cuts carbon, NOx and sulphur emissions

Total WHR systems
The following illustrations give an indication of investment costs, payback times and possible WHR system generator outputs depending on the main-engine size selected for a ship project. MAN Diesel & Turbo is happy to discuss data and advise on WHR possibilities for particular projects. WHR systems help combat both high fuel prices and emissions and will deliver better EEDI figures for ships in the future.

MAN Diesel & Turbo, Press Release