Purpose of a Deaerator
The main purpose of a deaerator is to remove dissolved gases (especially oxygen and carbon dioxide) from the feedwater before it enters the boiler.
If these gases are not removed, they can cause serious corrosion in the boiler and steam system. Oxygen leads to rusting, while carbon dioxide can create acidic conditions.
▪️How Steam Helps in Deaeration
Steam is used to heat the feedwater and remove dissolved gases.
Here’s how it works:
▪️Raising Feedwater Temperature
Why Heat the Water? Gases like oxygen and carbon dioxide dissolve less in hot water compared to cold water. So, if we heat the water, these gases are forced out.
◽Role of Steam: The steam heats the incoming feedwater to a high temperature, usually close to its boiling point (or saturation temperature). This high temperature helps reduce the solubility of these gases.
▪️Stripping Action of Steam
Scrubbing Out the Gases: When steam is introduced, it bubbles through the feedwater. This creates a stripping or scrubbing effect, which pushes the dissolved gases out of the water.
Venting the Gases: As steam bubbles through the water, it lifts the dissolved gases to the top of the deaerator. These gases are then vented out of the deaerator to the atmosphere, which prevents them from re-entering the feedwater.
Protecting the Boiler System
Corrosion Prevention: By removing oxygen and carbon dioxide, the deaerator protects the boiler and piping from corrosion. This is important because corrosion can cause leaks, reduce efficiency, and lead to costly repairs.
Reducing Maintenance Costs: When corrosion is minimized, the boiler and steam system last longer and require less maintenance.
▪️Improving Boiler Efficiency
Stable Temperature: Heated feedwater reduces temperature fluctuations in the boiler. This makes the system more efficient because it doesn’t have to work as hard to heat the water each time.
Saving Energy: By feeding preheated and de-aerated water into the boiler, energy consumption is reduced, leading to lower operational costs.
