Preventing corrosion through deaeration
Hot water and steam boilers heat factories, offices, schools and homes throughout the world. Is has been a tested method of heat transfer for more than a century. But the process of steam boiling has a side effect that can contaminate the inner workings of the boiler itself and the heat transfer pipes. The byproduct is dissolved oxygen and carbon dioxide.
When water reaches a boiling point, it releases microscopic oxygen bubbles. The bubbles attach themselves to the metal linings of the boiler’s inner walls. The process of oxidation comes into play and begins to corrode the metal. Oxygen level is one of the three factors of iron or steel corrosion. Higher oxygen levels increase the amount of metal that may be corroded.
Dissolved carbon dioxide also has a negative effect. When carbon dioxide combines with water it creates carbonic acid. This acid is harmful to metal and slowly eats is away. When combined with oxidation, carbonic acid will eventually lead to boiler failure.
Luckily, manufacturers have solved the problem of how to remove oxygen and carbon dioxide gases from the boiler system. The process is referred to as deaeration. There are two main methods of deaeration, both of which incorporate the use of deaerator spray nozzles.
Feed water, or incoming water, is fed into a deaeration tank and heated to the saturation point or boiling point. In the first method, the water falls through a series of metal trays. Many metal trays all the most metallic surface area for the dissolved gases to collect upon. Steam is then sprayed on the trays through a series of deaerator spray nozzles to clean them. The gases are then vented outside the tank and the deaerated water falls to the bottom of the tank and into the boiler. In the second method, trays aren’t used. deaerator spray nozzles spray steam to the top layer of water, releasing the gases. The gases are then vented outside the tank.
Because the deaerator spray nozzles are an integral part of the process, they need occasional maintenance, including replacement. Fortunately, replacement nozzles are accessible from a reputable supply dealer and can be replaced routinely.