Waste Heat Recovery

The waste heat recovery system generates electrical energy from a ship's exhaust gases. This reduces the ship's fuel consumption and CO2 emissions by up to twelve percent. Energy costs consequently fall by some 10 percent, so the ship runs more economically.

With the aid of the waste heat recovery system, the exhaust gas from the main diesel engine is used to generate steam in a waste heat boiler which, in turn, drives turbo-generators. The electrical power thus generated can be used to supply the ship's power system and/or the booster drive – an electric motor integrated into the propulsion shaft. If the output from the main engine is not fully utilized, the motor can act as a shaft generator and supply electrical energy to the ship’s power supply system, thus enabling the diesel engines of the on-board power supply system to be temporarily switched off. This shaft generator can also be used as a booster electric motor to increase the ship's propulsive power. The shaft generator can also be used in motor mode as the sole source of propulsion for maneuvering in harbor or cruising at slow speed with the main engine switched off. Utilizing the waste heat improves the overall efficiency of the propulsion system, and reduces not only the operating hours but also operating and maintenance costs of the existing auxiliary generators. Used in combination with Siemens booster/shaft generator systems it reduces fuel consumption. All the functions of the WHR system are controlled by an energy management system. A WHR system can be easily incorporated into the design of a new ship or retrofitted in a completed ship. The main engine can also be designed with a lower rated power, and the engine room can be used more flexibly because the shaft generator is installed in the propulsion shaft tunnel, thus requiring no extra space.

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