31 - Gas turbines

Abstract

Gas turbines have dominated warship propulsion for many years but their potential remains to be fully realized in the commercial shipping sector. The main contenders for gas turbine propulsion in commercial shipping are cruise ships, large fast passenger ferries or freight ferries, LNG carriers, and fast containerships. Optimizing the combination of low power maneuvering and high power operation is accomplished in many naval applications by using a combined diesel or gas turbine propulsion system (CODOG). The advent of lightweight gas turbine-generator sets (weighing approximately 100 tons) has allowed naval architects to locate them in the base of a cruise ship's funnel. Such an arrangement replaces the gas turbine inlet and exhaust ducts normally running to the engine rooms with a smaller service trunk housing power lines, fuel and water supplies to the gas turbine package. A lower operating temperature and more controlled combustion process also enable gas turbines to deliver exhaust emissions with significantly lower concentrations of nitrogen oxides (NOx) and sulphur oxides (SOx) than diesel engines.