The purpose of deoxygenating boiler feed water

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The international standard \"GB1576-85 Quality Standards for Water in Low-Pressure Boilers\" specifies that hot water boilers must be deoxygenated, while for steam boilers with a capacity of >2 T/h or ≤2 T/h, deoxygenation should be carried out as much as possible or necessary anti-corrosion measures should be taken. Corrosion caused by dissolved oxygen: The dissolved oxygen in boiler water forms a corrosion cell together with the iron metal of the boiler. The electrode potential of iron is lower than that of oxygen; in this corrosion cell, iron acts as the anode, losing electrons to become ferrous ions, while oxygen acts as the cathode where reduction occurs. This cathodic depolarization effect caused by dissolved oxygen leads to corrosion of the boiler’s iron components. In addition, oxygen causes iron hydroxide dissolved in water to precipitate, reducing the concentration of ferrous ions and thereby intensifying the corrosion. When water contains dissolved oxygen, it causes corrosion of the furnace body; as the oxygen concentration increases, the rate of corrosion accelerates. Typically, many small bulges form on the metal surface, with diameters ranging from 1 to 25 millimeters. It most commonly occurs in the water supply pipes and boiler economizers, and to a lesser extent in the downcomers as well.