Deaerator tank

Word of the Month: Deaerator

 

What is a Deaerator?

A deaerator is a mechanical device which removes dissolved gases (such as oxygen and carbon dioxide) from condensate. It consists of a deaerating section, a storage tank, and a vent. It is connected to a boiler, and preheats condensate before it enters the boiler. By removing carbon dioxide completely and lowering oxygen levels, it prevents corrosion and damage to the boiler at little or no cost. Additional benefits of the deaerator include providing water storage capacity and reducing the thermal shock of preheating equipment within the boiler.

How Does It Work?

Low pressure steam is injected into the deaerator tank, and dissolved gases go out through the vent. To prevent the oxygenation and rusting of equipment within the high-pressure boiler, the dissolved oxygen level must be lower than 5 parts per billion (ppb). Meanwhile, the condensate left in the tank is heated to 230 degrees Fahrenheit, and if water levels are too low, makeup condensate is added to maintain water levels in the tank and supply it to the boiler. After that, the preheated water is ready to be transferred to the boiler, where the heating process continues!

“In the deaeration section, steam bubbles through the water, both heating and agitating it. Noncondensable gases and some steam are released through the vent.” -US Department of Energy

Why Do We Use It? 

The deaerator has three primary purposes:

  1. Storing and supplying water to the boiler
  2. Mixing make-up water with steam, bringing the temperature of the water up in order to prevent thermal shock within the boilers
  3. Removing dissolved oxygen and carbon dioxide to prevent corrosion

On campus in the CHCP, an important step in heating the water includes a stop in the deaerator tank. Before condensate from the CHCP plant enters a boiler, the deaerator tank removes dissolved gases (especially carbon dioxide) from the water so that it does not cause corrosion within the boiler. Thus, the equipment inside the boiler is protected and lasts longer!