STEAM BOILER CLEANING: REMOVING MAGNETITE LAYERS
A steam boiler is commonly made of carbon steel and the surface of the water side of the boiler must be kept
free of undesirable deposits.
Deposits have a lower thermal
conductivity than steel and make it...
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STEAM BOILER CLEANING: REMOVING MAGNETITE LAYERS
A steam boiler is commonly made of carbon steel and the surface of the water side of the boiler must be kept
free of undesirable deposits.
Deposits have a lower thermal
conductivity than steel and make it
necessary to raise the temperature on
the combustion side of the boiler.
Thus
more fuel is needed to generate steam.
The heat transfer efficiency (ratio of fuel
consumed to steam generated) reduces.
Steam has the very important
characteristic that at a specific elevated
temperature it reacts with the iron ions
on the boiler wall steel on the water
side, to form a uniform layer of iron
oxide (Fe3O4), known as magnetite.
In a
reducing atmosphere at temperatures
above 100°C where the water acts as an
oxidising agent, the electrochemical
reaction takes place and a layer of
magnetite is formed.
This magnetite layer is a typically black,
extremely thin adherent film that
passivates the steel surface and
therefore protects it from corros
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