Tailored fuel treatment enables optimizing the operation of heavy-fueled gas turbines

The combustion of heavy fuel oil (HFO) in gas turbines (GT) generates some operational constraints and expenses which are too often accepted fatalistically. A first development has addressed the technical challenge caused by the deposition of ash on the hot parts of the turbines. Indeed, the combustion of HFO significantly increases the volume of ash as one must treat the fuel with a ``vanadium inhibitor'' that acts as an ash modifier preventing hot corrosion by vanadium. This fouling effect is the most serious drawback of HFO operation as it progressively shrinks the performances and reduces the availability of the machines. To tackle this issue, a genuine bimetallic vanadium inhibitor has been developed and field tested step by step between 2015 and 2018. The last step that took place at Yugadanavi in March -April 2018 has allowed validating a ready-to -use version of this bimetallic inhibitor product. Upon the completion of this program, the rate of power degradation during HFO operation has been halved and the GT availability significantly increased while the emission of particulates has been substantially reduced. As a further improvement effort, the teams have tested in the field the effect of changing the temperature of the HFO on its viscosity and monitored the impact induced on the quality of fuel atomization that underlies namely the level of particulate emissions. This second program devoted to the optimization of HFO heating, has enabled defining a rational minimum temperature of the fuel which establishes a fair compromise between atomization effectiveness and thermal energy consumption. This paper summarizes the main outcome of this multi -year collaborative test program.