Micro Gas Turbines on Mega Yachts - A Feasibility Study

Abstract

This thesis has been realized in collaboration with Blohm+Voss Shipyards GmbH, in the Mechanical Engineering Design Department located in Kiel. The changing of the limits of the exhaust gas in accordance with the IMO Tier III regulations, which enters into force in January 2016 for new ship constructions, makes necessary to adapt the future power units such that they are able to achieve the strictly threshold of oxides of nitrogen (NOx). In order to fulfil such requirements, conventional diesel engines need an additional exhaust gas treatment unit, increasing the investment, operational and maintenance costs, as well as weights and space required inside the ship. Another solution is to replace the diesel engines by micro gas turbines, which do not require post-treatment in the exhaust system. Besides, the technology of the micro gas turbines is conceived such it only has one rotating component, and all the lubrication needed is carried out with air bearings. Thus, there is no need of LO (lube-oil) system. As a consequence, the maintenance required is broadly reduced, as well as vibrations and noise levels, since the turbines are already installed in a sound enclosure, therefore there is also no need of silencer. The mega yacht BV80 from Blohm+Voss will be used as the case study to replace its current generator sets by micro gas turbines. The project is currently in an advance stage (the first ship from the BV80 series started to be built on October 2015). For this reason, one of the aim of the study is to replace this system trying to modify the less things as possible in the general arrangement of the ship. Different solutions are analyzed, starting from a direct comparison of both systems, and followed by different alternatives that could increase the performance of the micro gas turbines. Every solution contains an economical evaluation in order to compare the systems in terms of lifetime costs, technical feasibility, advantages and drawbacks. Based on the case study of the BV80, the results can be extended to similar projects in the maritime sector, for which micro gas turbines technology offer an outstanding comfort.