Firing Low Viscosity Liquid Fuels in Heavy Duty Gas Turbines

Abstract

Sustained economic growth has created a strong demand for electrical energy worldwide. Security of fuel supply and cost are therefore very often critical issues for thermal capacity additions. Also the distance from fuel sources and available fuel transport infrastructure is an important factor in the cost of generation. Many plant locations have only limited supplies of conventional gas turbine fuels, namely natural gas and distillate fuels, thus a drive to diversify the fuels involved. For other electricity producers, the optimal use of existing or potential fuel resources is a must for economical reasons. Therefore, the possibility of using alternative gas turbine liquid fuels, such as volatile and/or low viscosity fuels like naphtha, gas condensates, kerosene, methanol, ethanol, or low lubricity distillate fuels; refinery by-products such as BTX fuels (benzene-toluene-xylene mixtures), LCO-light cycle oil, or in the future synthetic fuels (GTL) are particularly interesting for their ability to be fired in heavy duty gas turbines. However, the practical use of these fuels creates specific issues such as low lubricity properties which can affect sensitive key components like fuel pumps and flow dividers. This paper addresses the many practical aspects of using fuel lubricity additives for reduced component wear in gas turbine fuel systems, and for reliability and successful plant operation on these alternative gas turbine liquid fuels. Also an overview of acquired experience is given.

The Fuel Flexibility of Gas Turbines: A Review and Retrospective Outlook

“…Conversely, some light liquids (naphtha, alcohols) are low-viscosity fuels and have poor "lubricity", a property which is evaluated via the "HFRR test" [49,50]. If it is insufficiently "lubricious", dosing a lubricity improving additive may prove necessary.…”