Hot corrosion is continuously occurring in exhaust valve passages where the products of combustion after their chemical reaction deposit as the gas cools, on the walls of the valve passages. The residual fuel used in main engines in todays standards have a maximum sulphur content of 3.5 percent M/M.
During combustion this sulphur combines with the oxygen from the air for combustion to form sulphur di oxide and is represented by the following equation
S + O2 = SO2 ————–(1)
Simultaneously the hydrogen in the fuel is combining with oxygen from the air for combustion to form water vapour and is given by the following equation.
H2+2O2 = 2H2O————(2)
The water vapour cools down to its dew point to combine with the sulphur di oxide to form a weak acid named sulphurous acid and is given by the equation
This is how hot corrosion occurs.
- You must login to post comments
Please login first to submit.