How does an open feedwater heater remove oxygen from the water?

An open feedwater heater removes oxygen from water primarily through the combination of both tray deaerators and spray deaerators. In this process, the feedwater is brought into contact with steam, which aids in the removal of dissolved gases, including oxygen, from the water.

In a tray deaerator, the feedwater flows downward through a series of trays, while steam is introduced from below, creating conditions that facilitate the escape of dissolved gases. The design allows for an effective transfer of heat and mass, which enhances the removal of oxygen from the water.

The spray deaerator, on the other hand, uses a different mechanism where the water is sprayed into a steam chamber, creating a larger surface area for the steam to interact with the water. This setup also promotes the efficient removal of dissolved gases.

By utilizing both methods, an open feedwater heater can achieve superior deaeration, ensuring that the feedwater is kept free of oxygen, which is crucial for preventing corrosion in boiler systems and maintaining efficiency. The combination of tray and spray methods leverages the strengths of both approaches, resulting in more effective degasification.