Impurities in natural water and their hazards to Industrial boilersImpurities in natural water and their hazards to Industrial boilers
1. Suspended Impurity
The suspended impurity refers to impurities which particle diameter is above 0.1 um. the turbidity and chrominance of natural water is caused by these impurities. The suspended matter is unstable state in water, the lighter substance floats on the water surface (such as grease), heavier substances will sink when they are still (such as sand, clay, animal and plant corpse fragments and fibers, etc.).
The existence of suspended matter will influences boiler and ion exchange equipment runs safely and economically.
Depositing in ion exchanger, it will contaminate the ion resin, thereby influence the water quality, decrease the exchanging capacity.
if the suspended matter enters into boiler, it will deposit in the drum, cause the deteriorate of heating transfer, thereby the metal will be accidentally damaged by overheating.
2. Colloidal Impurity
Colloidal substance refers to those particle diameter of 1 nm -100 nm
there are mainly two kinds of colloids in natural water,
one is mineral colloids, such as silicon, iron and aluminum; the other is organic colloid formed by humus after decay of animals and plants.
Since the surfaces of the colloids have same charge, their particles repel each other, so the particles cannot grow and cannot sink by gravity. Therefore, it can be stably exist in water.
the existence of the colloidal substance will form a hard scale that is difficult to remove, and the boiler water will generate a large amount of foam, cause boiler priming effect, which will influence the normal operation of boiler.
3. Dissolved Substances
The dissolved substances in water are mainly gas and mineral salts, which existing in a molecular or ionic state and have a particle size of 1 nm or less.
The gases dissolved in the water are in a molecular state, and the harmful gases that may cause boiler corrosion are mainly oxygen and carbon dioxide gas, and some hydrogen sulfide gas sometimes.
the Oxygen in water is dissolved from atmosphere, the carbon dioxide and hydrogen sulfide are produced by decomposition or oxidation of organic matter.
mineral salts existing in water are present in ionic state. They are produced by dissolution of minerals in the formation.
The salts dissolved in natural water are mainly calcium, magnesium, manganese, iron, silicon, aluminum, phosphorus bicarbonate, chloride and sulfate. If these impurities are not removed, it will cause boiler fouling, corrosion and pollution of steam quality, cause overheating deformation of boiler metal, corrosion perforation, shortening the service life of boiler, wasting fuel, reducing the heating efficiency of boiler. In severe cases, it may even cause accidents