Dynamic simulation of a COGAS ship propulsion plant

In a previous paper the authors presented a comparison between a COGAS plant specifically designed and the original prime mover (a two stroke diesel engine) used for the propulsion of a large container ship. The comparison showed some advantages of the COGAS solution from both technical and commercial points of view, advantages that could become more evident, in a near future, also from an economic point of view, because of the adoption of increasingly stringent emission regulations in the shipping sector. A feasibility study of the COGAS solution requires the availability of numerical models not only for the propulsion system design and performance evaluation in steady state operation, but also for the dynamic simulation of its behavior in every off-design and transient condition. The last feature is important for the development of the propulsion control system. The paper presents a COGAS plant dynamic simulator, putting into evidence in particular detail the model of the heat recovery steam generator, the most critical component as regards transient situations. For the mentioned container vessel the prime mover dynamic analysis is combined with the overall propulsion system simulation, allowing to obtain some significant results relative to acceleration and deceleration maneuvers of the ship.