Measurement and abatement of PM emitted by stationary gas turbines: Experience gained with different fuels and combustor types

Whichever the type of combustion installation, liquid fuels burned in gas turbines tend to generate particulate matter (PM) emissions, which consist in soot only or in ash plus soot, according to their ash-free or ash-forming character. Standard diffusion flame combustion systems are known as ``universal'' combustors, capable to burn both ash-free (naphtha, light and heavy distillates) and ash-forming (crude and heavy) fuels. In contrast, DLN systems are designed to burn gaseous fuels and light distillates. PMs in the range of a few parts per million represent a solid micropollutant, the measurement and abatement of which creates specific technical challenges. In order to fully characterize soot emission and investigate their reduction, GE has undertaken a multi-year investigation program covering (i) an exploratory engineering study starting from the EN13284-1 standard and (ii) the testing of a number of inorganic oxidation catalysts used in the form of fuel additives (''soot inhibitors''). In this framework, a joint work involving GE and Electricity Authority of Cyprus has been conducted in the first half of 2017 and a. full-scale test plan has been performed at the Vasilikos power plant in Cyprus, involving a Frame 6F.03 DLN2.6 that burns light distillate oil and is equipped with a DeNOx water injection system. Four types of soot inhibitor additives: cerium (IV) and (III), iron (III) and (II) were tested. This paper reviews the results of this field test and compares them with data previously acquired at other power plants featuring different liquid fuels and combustion systems. Its goal is to provide the gas turbine community with a better understanding of PM emissions and their abatement using various soot inhibitor candidates, in function of liquid fuel type and combustion system.