Within the marine market the trend is towards faster ships and shorter turnaround times, combined with continued high-load capability and an emphasis on enhanced overall economy. Due to the low weight-to-power ratio of gas turbines, they are moving into the growing high-speed propulsion market being a viable alternative to high-speed diesel engines. The ABB light industrial marine gas turbine has a low life cycle cost, easy service, low emissions and minimal structural vibration. The GT35 starting motor, which acts as power supply for auxiliaries during operation, can be rated to supply ship electrical power. Electricity for general use in the ship can be supplied efficiently, both during full-load operation and while idling in port. This means that the traditional generating sets can be peak-load rated or in some cases reduced in number. During overhauls, the gas generator of the gas turbine is removed from the vessel for workshop overhaul. A spare gas generator can replace the original gas generator in order to minimise downtime. The durable design of the gas turbine permits long time between overhaul, normally 4-6 years.
The GT35 gas turbine can be equipped with a dry, low emission combustion system for liquid fuels. Low emission levels are achieved without incurring additional costs in terms of performance, maintenance or handling. The NOx reduction is also achieved without it being necessary to install external NOx reduction processes like selective catalytic reduction (SCR). With the ABB dry, low-emission technology, the ABB Stal gas turbines will achieve NOx emission figures that are a tenth of those of similar-sized diesel engines. The level in 1998 is 60 ppmv (2 g/kWh). The emission target for the turn of the century is 25 ppmv (0.8 g/kWh).
A key factor in fuel economy is the price of the fuel being used. The GT35 marine gas turbine can operate on a wide range of liquid fuels, including marine diesel oil and selected heavy fuel oils. In marine applications, an IF30 type fuel can be used. (IF30 is a mixture of IF180 and marine diesel oil). For a commercial ship operating for up to 6,000 hours annually, each US$ 10/t difference in fuel price gives US$ 500,000 annually in fuel cost savings. This is of particular importance to operators of fast ferries. More information: ABB STAL AB Anna Eidem