An Innovative variable layout steam plant for waste heat recovery from marine dual-fuel engines

The paper describes an original Waste Heat Recovery (WHR) variable layout plant to produce steam from the exhaustgases of marine dual-fuel engines. A large part of the steam feeds an electric turbogenerator to improve the ship's energy efficiency.The layout of the proposed steam plant is conceived in a double configuration to satisfy both the stack temperature constraints of theengine exhaust gas, due to the use of diesel oil (no less than 160°C as outlet gas temperature) or natural gas (there are no particularstack temperature limits). The comparison with a traditional WHR single pressure steam plant shows the potential benefits of thevariable configuration. Indeed, the proposed solution allows a better exploitation of the potential thermal energy of the natural gas,without precluding a proper performance even in diesel mode, with a moderate weight increase compared to a single pressure WHR system.