On the possible increasing of efficiency of ship power plant with the system combined of marine Diesel engine, gas turbine and steam turbine in case of main engine cooperation with the gas turbine fed in series and the steam turbine

The article presents a concept of a combined large power ship propulsion system consisting of the leading Diesel main engine, associated with a power gas turbine and the steam turbine system which utilise the energy contained in the exhaust gas leaving the Diesel engine. In the examined variant of the combined system the power turbine is fed in series with the exhaust gas. A calculation algorithm is given along with the results of calculations of particular subsystems of: the turbocharging system, the power gas turbine, and the steam turbine cycle. Assumptions and limits adopted in the calculations are presented. Selected system parameters were confronted with the results of experimental investigations available in the literature. The power optimisation of the entire combined ship power plant was only performed taking into account the thermodynamic point of view, leaving aside technical and economic aspects. Numerical calculations were performed for the 52 MW low-speed Diesel engine produced by Wärtsilä.