The invention relates to corrosion inhibitors for gas turbine, in particular for high temperature corrosion inhibitors associated to vanadium in the presence of sodium and/or potassium for the combustion.

Yttrium and magnesium are well known corrosion inhibitors for Vanadium in liquid fuel . For example US00RE61 17E and US 20100199546 Al di sclo se methods for regulating vanadium inhibitor in a gas turbine. In addition, US 2014 / 03 1 5 136 di sclo ses a method of operating a gas turbine to inhibit vanadium corrosion.

These two additives are typically used in oil- soluble solution and mixed into the fuel prior to inj ection into the combustion chambers.

Vanadium corrosion at high temperature is usually inhibited by magnesium to form Mg3 V208 (refractory) . However, in presence of a significant amount of sodium or potassium in the flammable mixture (of the order of > 1 ppm in air or oil or water), magnesium is not effective. Actually vanadium tends to form compounds with sodium which may foul the blades in gas turbine and which induce irreversibl e lo ss of performance in gas turbine due to non-washable deposits .

Thus the problem solved by the present invention i s to ensure a corrosion inhibitor inj ection in an effective way preventing problem known.

The Yttrium has proved to be more effective reactive than magnesium compared to the Vanadium in presence of sodium or potassium in heavy oil . During reaction it can form YV04 preventing Sodium reaction with vanadium . Therefore using Yttrium one can prevent non-washable deposits in blades or in hot gas paths in gas turbine .

Features and advantages of the invention will become apparent from the following description, in view of the appending drawing illustrating embodiments of a method and installation according to the invention.

The invention is a method of inj ection of Yttrium and/or Magnesium which can be used in a gas turbine combustor. Yttrium i s highly solubl e in water and allows it to be easily transportable . Thus it is stored in the form of Yttrium nitrate or sulfate in a concentrated aqueous solution (in example 70% saturation) and inj ected using either a dosing pump or venturi nozzle. One example of a method of inj ection of Yttrium and/or

Magnesium will now be described.

According to a first embodiment, a premixed inj ection i s carri ed out using water solubilized or solid Yttrium salt or Magnesium salt premixed with liquid in a dedi cated tank equipped with a dynamic mixer. Then inj ection of mixed solution i s inj ected on liquid fuel system or air atomizing or water inj ection, or a dedicated nozzl e installed in combustion chamber or emul sion of water and liquid fuel system . The advantage of this method is to ensure the optimal mixing of additives in liquid before inj ection.

According to another embodiment, a direct inj ection method i s used using water solubilized or solid Yttrium salts or Magnesium salts. Inj ection can be performed through an on-line optimized mixer (for example static or dynami c ) with di stributor in the following systems : liquid fuel system or liquid and water emul sion or air atomizing or water inj ection, or a dedicated nozzle installed in combustion chamber. The advantage of thi s method i s cost.

In both methods, the sodium, potassium and vanadium percentage can be measured in fuel . Depending on ppm quantity measured a controller regulates inj ection either Yttrium or Magnesium flow rate .

In example : If (vanadium > 0, 5ppm AND sodium + potassium % is greater than l ppm) then inj ection of YTTRIUM el se inj ection of Yttrium or Magnesium depending on end user choice.

If vanadium < 0, 5 ppm no inj ection. - the fuel upstream of the combustion chambers using a mixer (for example static or dynamic) which is effective to ensure a stable mixture (or even to create an emul sion) these two immi scible liquids .

- The water inj ection system upstream of the combustion chamber of the gas turbine using a mixer between water solubl e liquids. Thi s route of inj ection may be used only for machines that contain a water inj ection system (eg. to increase power or to reduce emi ssions of nitrogen oxides NOx) .