How To Avoid Boiler Tube Corrosion
Water tube corrosion problem occurred in industrial hot water boiler is very serious, but the users of heating boilers usually not aware of the possibilities of corrosion. They have little idea what will causes it and lack the experience to avoid it.
Corrosion in heating boiler and power plant boiler
Corrosion of water tube exist in almost every industrial boiler, especially in low pressure heating boilers or horizontal fire tube type boiler, which usually operate at a lower steam pressure. However, in power plant boiler, the corrosion is not very often. This is because operators of power boilers realize the importance of proper water and take care to avoid such problems.
Reasons of water tube corrosion
Scale is not a major factor in low pressure boilers, although a large quantity of scale in the tube will also affect the normal operation of boiler. Many boiler owners completely drain their boilers once or twice a season under a mistaken belief that the water in the boiler is dirty. Actually, it is discouraged because we can only drain small quantities of water from the boiler, which is not very useful to industrial boiler.
We all know that steel does not corrode in dry air, or if air is kept away, but will corrode in the presence of moisture. So we can get that oxygen is the most important factor leads to corrosion.
Methods on avoid the tube being corroded
In larger boilers, such as power plant boiler or circulating fluidized bed boiler, air is removed from the feed water by being heated to the boiling point and venting off the gas and oxygen. The second method on avoid corrosion is to pass the feed water through a de-activator, which is a tank containing steel scrap, such as turnings or wires. Besides, we can use sodium sulfide or other chemical material in large boilers to remove oxygen. But it is not recommended for heating boilers because it must be closely controlled
Besides these, the protective coatings on the tube are commonly used to prevent rusting during storage and transit, that will cause corrosion if left on the tubes during operation of the boiler, which should be boiled out the boiler with an alkaline cleaner after installation.
