Silica Boiler Water Treatment

Acmite sodium ferrous silica na 2 fe 2 o 3 4sio 2 and crust fe si can be formed from corrosion result.

Silica boiler water treatment.

Another source of turbine deposition is the vaporization of salts present in boiler water. Treatment of water makeup condensate or both before it enters the boiler to reduce or eliminate chemicals such as hardness or silica gases or solids. For most dissolved solids found in boiler water it is negligible by comparison to mechanical carryover at pressures less than 2000 psig 13 8 mpa. The most significant factor is to maintain low silica concentrations in the boiler water.

It is not affected by boiler design. Maximum boiler water silica allowable to mantain less than 0 02 ppm silica in the steam. An exception is silica for which vaporous carryover can be substantial at lower pressures. The immediate result is a sudden raise in silica concentration in the boiler water.

Silica this may be the blowdown controlling factor in softened waters containing high silica. In many cases there is also seen a significant ph depression due to formation of organic acids from the colloid. Silica content of the boiler water is not as critical for steam systems without steam turbines. Natural waters generally contain about 5 8 mg l of silica si0.

Deposits common feedwater contaminants that can form boiler deposits include calcium magnesium iron copper aluminum silica and to a lesser extent silt and oil. Vaporous carryover depends on pressure and on boiler water chemistry. Little aluminum content in feedwater can cause high deposit of silica in boiler water. Another important source of silica in water is the sand watertreatments filter when water treated by lime soda process is filtered through a sand water filter a good amount of silica dissolves in it forming calcium and magnesium silicates due to alkaline nature of waters.

High boiler water silica content can result in silica vaporization with the steam and under certain circumstances siliceous scale. Vaporization of boiler water salts. Any chemical treatment in the attemperating water should be volatile. Silica removal is deployed for a variety of industrial applications including treatment of raw water cooling tower makeup water boiler feed and blow down water.

Therefore feedwater treatment must be controlled to eliminate aluminum and silica. Treatment of the boiler feed water boiler water steam or condensate with corrective chemicals. Water treatment of silica. Therefore good internal boiler water treatment programs are necessary.