Concerning the temperatures and chemical reactions of the fuel, the processes of combustion of an alternate engine and of a gas turbine, both fed with fuel oil or oil crude, are very similar.
In both gas turbines and engines, the temperatures at the combustion chambers are approximately of 2,000 ºC.
The temperature at the engines exhaust valves is of 400-450ºC and the one at the engine’s turbo-compressor inlet is between 500 and 600 ºC.
The temperature at the gas turbine inlet is 1,000-1,300 ºC and the exit temperature is between 450 and 600ºC.
In regard of the corrosion / corrosion neutralization, the gas turbine blades would be the equivalent to the exhaust valves of an engine using heavy fuel oil since both of them are within the temperature range where the Vanadium or Sodium corrosive reactions take place.
At the time of combustion, the SOLUBLE Magnesium carboxylates / Magnesium Organic salts of Fatty acids (molecules - trade secret) organic salts soluble in hydrocarbons react with Vanadium Oxides forming Magnesium Vanadates with high melting points (over 1,200ºC), which are solid and non-corrosive at the gas turbine gases' internal temperature, carried away by the combustion gas stream without being deposited in the circuit.
The V2O5 (Vanadium pentoxide) is neutralized obtaining alkaline-earth vanadates of high fusion point, at the same moment of combustion, which:
- eliminates corrosion due to V2O5.
- eliminates the presence of Sodium vanadates of low melting point, neutralizing the corrosion and incrustations in the combustion chamber and the gas turbines' blades.
The action of fixing heavy metals (Vanadium), is also translated into a decrease in the oxidation from SO2 to SO3 (formed from the fuel oil’s Sulphur) because the catalytic action over the reaction is minimized; as a consequence, the formation of Sodium sulfate is reduced (Na2SO2) that melts at 888 ºC and also diminishes the appearance of Sulphuric acid condensation when the combustion gases cool down and, along with it, cold corrosion.
In addition, since the "rb bertomeu" additives are completely soluble (containing molecules of Mg, no particles), they can be added to the fuel in the storage tank by injecting it directly, by a metering pump, into the HFO receiving pipe when the HFO is unloaded. As a total dissolution of the additive occurs, there is no risk of separation / sedimentation of Magnesium in the bottom of the tank.
Other benefits are:
a) De-emulsionates and decants water contained in the heavy fuel oil, that must be removed periodically from the storage tank by bleeding or centrifugation in the heavy fuel oil purifiers, so that the quantity of Sodium salts will be strongly reduced. This way Sodium sulphate (melts at 888ºC) and vanadate formation is minimized.
b) Achieves a perfect pulverisation of the fuel oil in order to eliminate residual carbons which could act as base of adhesion for residual saline.
This document is an extract of RB7 - 'Fuel oil and its corrosive effects in the industrial combustion'
You can find more information about this topic at the following Technical Documents:
RB8 'Additives “rb bertomeu” vs corrosion due to Vanadium and Sodium from heavy fuel oil or crude oil'
RB27 'Actions of the fuel oil addtivies “rb bertomeu” '