COGAS plant as possible future alternative to the diesel engine for the propulsion of large ships

Strong restrictions on emissions of engines for marine propulsion (particularly SOx, NOx) will probably be adopted in the near future. In this paper, by using specifically developed simulation techniques, a COGAS plant solution is proposed in substitution of the originally adopted prime mover (a two stroke low speed diesel engine), for the propulsion of a large container ship, whose characteristics and performance are known. Starting from the performance and cycle characteristics of an existing gas turbine, the COGAS steam cycle characteristics and related components are defined through an original design procedure. The combined cycle is compared with a Diesel engine, not only with regard to the plant performance and efficiency at design and high load off-design conditions, in both steady state and dynamic situations, but also for what concerns: engines dimensions and weights, engine room layout, overall propulsion plant weight, ship hull loading capacity, economic considerations.