With the rapid development of industrialization, boilers have become the core equipment in production and heating. In order to ensure the efficient and safe operation of the boiler, the treatment of feed water has become a crucial link. Among them, boiler feed water deoxygenation is a key step. So, why deoxygenate boiler feed water? How does the deaerator work? Next, we will delve deeper into this topic.

What is Boiler Thermal Deoxygenation?

Thermal deaeration: The thermal deaeration method is to remove the dissolved oxygen in the water by heating the feed water to the approximate boiling point.

Oxygen removal methods: chemical oxygen removal and thermal oxygen removal. Large-scale industrial production is usually used in combination, with thermal oxygen removal as the main and chemical oxygen removal as a supplement.

Advantages of thermal deoxygenation:

1. Most of the boiler feed water needs to be heated

2. As a physical method, there is no need to add any chemical agents, so it will not reduce the quality of water vapor or cause pollution.

Why should boiler feed water be deaerated?

Deoxygenation of boiler feed water is an effective measure to prevent boiler corrosion.

Gas Dissolution: When boiler feed water comes into contact with air, some gases, especially oxygen, dissolve into the water.

Corrosive Effect of Oxygen: Oxygen that has not been removed is the main source of corrosion in the water supply system, and it will corrode the system and its components if it exists for a long time.

Effect of Iron Oxide: Iron oxide produced by corrosion will enter the boiler and form iron scale that is difficult to remove on the boiler tube wall and heating surface, which reduces heat transfer efficiency and increases frictional resistance.

Safety hazard: Over time, corrosion may create small pits on the inner wall of the pipeline, which can lead to pipeline leakage or explosion in severe cases.

Working Principle of Deaerator

1. Thermal deoxygenation is a process of heat transfer and mass transfer. To ensure the ideal deoxygenation effect, the following conditions must be met:

Heating conditions: heat the water to the saturation temperature under the pressure of the deaerator to ensure that the pressure of the water vapor on the water surface is close to the full pressure on the water surface;

Gas discharge: discharge the gas escaping from the water in time to reduce the partial pressure of various gases on the water surface to zero or minimum;

Contact efficiency: the water to be deaerated and the heating steam should have sufficient contact area, and the two flow in reverse.

2. The segregation of gas from water is mainly divided into two key stages:

Initial deoxygenation: At this stage, there is a large amount of gas. Due to the large unbalanced pressure difference, the gas escapes in the form of small bubbles to overcome the viscosity and surface tension of water. Removes 80% to 90% of air in water.

Deep deoxygenation: At this stage, there is still a small amount of gas in the water, and the unbalanced pressure difference decreases, making it difficult for the gas to escape against the resistance of the water. At this time, increasing the contact area between steam and water or making water form a film can help the gas escape. In addition, steam bubbling enables gas to attach to the bubbles and escape from the water.

Conclusion

Generally speaking, boiler feed water treatment is not a simple process, it involves many aspects of scientific principles and practical experience. Ensuring that the oxygen in the feed water is effectively removed is of vital significance to prolonging the service life of the boiler, reducing maintenance costs and ensuring the safe operation of the plant. Therefore, for everyone involved in boiler operation and management, it is a responsibility that cannot be ignored to deeply understand and master this process.