Why Boiler Feedwater Need to Deaerate

Oxygen is the most aggressive dissolved gas among the common source of corrosion in a boiler system. Even small oxygen concentration can cause serious boiler corrosion problems. Therefore, the importance of eliminating oxygen as a source of pitting and iron deposition cannot be over-emphasized.

We know that one of the most serious aspects of oxygen corrosion is that it occurs as pitting. This type of corrosion can produce failures even though only a relatively small amount of metal has been lost and the overall corrosion rate is relatively low. The degree of oxygen attack depends on the concentration of dissolved oxygen, the pH and the temperature of the feedwater.

The influence of temperature on the corrosivity of dissolved oxygen is particularly important in closed heaters and economizers where the water temperature increases rapidly. Elevated temperature in itself does not cause corrosion. Small concentrations of oxygen at elevated temperatures do cause severe problems. This temperature rise provides the driving force that accelerates the reaction so that even small quantities of dissolved oxygen can cause serious corrosion.

Deaerator is a package unit capable of removing from the water all dissolved oxygen at all loads up to and including the rated capacity. The Deaerator can accomplish the following :

1. Oxygen & Carbon Dioxide removal from boiler feed water

2. Raise the temperature of the feedwater

3. Improve heat transfer in boiler

4. Utilize low pressure exhaust and flash steam

5. Common collection points for high & low temperature condensate returns

6. Economizing of overall operation with strong reduction in the chemical treatment costs.