Vacuum deaerator

In power plant, demineralized water should go through deaeration process to remove dissolved oxygen. Or else, oxygen would cause tubes and equipment corrosion, which results in increased Fe content in feedwater. Formation speed of iron oxide scale is proportional to Fe content. Because iron oxide scale has a bad thermal conductivity, tube failure happens when oxygen corrosion is serious. In China, deaeration is a must for steam boiler with output higher than 2tph or hot water boiler with temperature higher than 95℃.

Deaeration is a key process for feed water treatment in power plant. There are thermal deaeration and chemical deaeration methods to achieve that. Vacuum deaerator is one of the many. It make feedwater flashed in vacuum environment to remove oxygen, nitrogen, carbon dioxide, etc.

Vacuum deaerator working principle:

According to Henry’s Law, amount of gas dissolved in liquid is proportional to its partial pressure above the liquid. If partial pressure of steam above feed water increases, partial pressure of dissolved gas will decrease. When feed water is flashed into steam, gas dissolved in water has to be released to keep proportional to its partial pressure in vapor. When steam above water becomes saturated, gas dissolved in water is nearly all released.

Vacuum deaerator could work under 30~60℃. Deaeration is done at low water temperature. Low grade waste heat could be used to heat deaerator water by steam jet heater. Vacuum deaerator has a good performance for boiler used for heating purpose, or boiler with a wide varying load. Vacuum could be achieved by steam jet ejector or water jet ejector.

Vacuum deaerator advantages:

1. It could remove not only oxygen, not also carbon dioxide, H2S, etc.
2. Stable performance, easy operation.
3. Quick start-up.
4. Load could vary within 0~120% without influence on deaeration.
5. Installation at a high or low level is both acceptable.

Vacuum deaerator parameter: