Objective
Due to the increased efficiency of modern turbo chargers for large main diesel engines for propulsion purposes of vessels, approx.3 percent of the main engine power can be converted from exhaust gas energy into electrical energy instead of being wasted and can supply the board net. The advantage of the proposed system is that remaining electrical energy not consumed by the board net will be consumed in the shaft-driven generator/motor and will increase propulsion thrust.
The pay-back period of the additional investment for the exhaust gas turbo generator is at present approx.3.9 years, but as vessels's life time is about 20 years, the total savings will influence the ship owners to install such systems. Furthermore, the exchange rate of the US as well as the price for fuel oil influence the pay-back period of the investment significantly.
During the past the number of ships with shaft-driven generators increased. Shipowners have great interest in such systems. Commercial success can be expected therefore. The system can be installed on newbuildings as well as on existing vessels.
The EGA/EGSA exhaust gas-turbo- and shaft-driven alternator system which had been developed for cost-efficient and environment-friendly generation of electric power on board ships with high-powered two stroke main diesel engines was subjected to trials under practice-related conditions.
Depending on the extent of the mains load, the system is in a position to supply the ship's mains either alone or in parallel with one or several diesel generating sets. The combination with a shaft alternator system with intermediate circuit inverter offers the additional possibility of providing the propulsion shaft with surplus power so that full use of the entire exhaust gas surplus energy can be made at any time?
The introduction of the system reduces the cost for fuel and maintenance for the auxiliary diesel sets.
In addition, the continuously adjustable control flaps do not only improve the operating performance of the diesel engine under partial load, but also permit matching of the delivered output to the ship's mains requirements.
The aim of the project is to design and construct an energy cost saving mains'supply system containing a set with a specific type of synchronous generator driven by an exhaust gas turbine via a gearbox and the related control and monitoring system. The combination between shaft-driven generator and exhaust gas-turbo generator system enables to reduce the size of the shaft generator up to 25%. For parallel operation of the turbo generator system with a shaft generator a two-pole type synchronous generator is required whereas for direct supply to the ship's mains a four-pole-type synchronous generator is necessary. There are four advantages in comparison with the mechanical exhaust gas-turbo system named eta-booster :
With this turbo generator system there are no problems with continuous measuring of the converted energy, this system is more flexible because the recovery of exhaust gas energy can be taken either for the boardnet or for the propulsion. An uncomplicated installation of an exhaust gas-turbo generator on existing vessels with shaft generator is possible with a minimum of costs, because the electrical supply is made via electric cables and overspeed of the exhaust gas turbine is impossible due to the electrical shaft principle.
Comparison is only possible with the mechanical solution of transmitting a part of exhaust gas energy via the exhaust turbine and a gear to the propeller shaft (eta-booster). the solution with direct mechanical/electrical conversion is about 40% cheaper than the eta-booster-system, needs less maintenance and has no torque oszillation problems.
Periodical cleaning of the exhaust gas turbine will be made automatically. The cleaning material is normal water. Other components of the system are electrical components and the maintenance costs are negligible.
As mentioned this generator is suitable for direct supply to the ship's mains in single operation or in parallel operation with a diesel generator.
Programme(s)
Topic(s)
Call for proposal
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DEM - Demonstration contractsCoordinator
22763 Hamburg
Germany