DEAERATOR TANK DESIGN & ENGINEERING FOR FOR BOILER

Designing a deaerator tank for a boiler involves several key considerations to ensure efficient operation and maintenance. Here are the fundamental aspects to focus on:

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Purpose of a Deaerator Tank

A deaerator tank is primarily used to remove dissolved gases (such as oxygen and carbon dioxide) from boiler feedwater. This helps prevent corrosion in the boiler and piping system, as well as improves boiler efficiency by minimizing the presence of non-condensable gases.

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Key Design Considerations

1. Sizing and Capacity:

   • Storage Capacity: Determine the required storage capacity based on the boiler's feedwater flow rate and the time required to remove dissolved gases.

   • Boiler Size: The size of the boiler and its steam generation rate will influence the size of the deaerator tank.

2. Operating Temperature:

   • Typically, deaerator tanks operate at temperatures close to the steam saturation temperature corresponding to the operating pressure of the boiler. This enhances the removal of dissolved gases.

3. Operating Pressure:

   • The deaerator operates at a slightly higher pressure than the boiler to ensure that the feedwater is supplied without cavitation and to facilitate the removal of gases.

4. Design Features:

   • Spray Nozzles: Used to spray the feedwater into the tank, creating a large surface area for efficient steam stripping of dissolved gases.

   • Steam Inlet: Properly designed steam distribution system to ensure uniform heating and stripping of gases.

   • Vent System: To remove non-condensable gases (mainly oxygen and carbon dioxide) from the top of the tank.

   • Internal Components: Baffles or trays to enhance the contact time between steam and water for effective degassing.

5. Material Selection:

   • Choose materials that are compatible with the feedwater and the operating conditions (typically stainless steel or carbon steel with suitable coatings).

6. Safety Considerations:

   • Provide for pressure relief and venting to ensure safe operation under all conditions.

7. Maintenance and Access:

   • Design the tank for easy inspection, cleaning, and maintenance of internal components.

Design Process

• Calculate Feedwater Flow Rate: Based on boiler capacity and steam generation rate.

• Determine Required Storage Time: Typically, 10-30 minutes of storage is recommended for effective degassing.

• Select Operating Conditions: Temperature and pressure should be chosen to maximize efficiency.

• Design Internal Components: Ensure proper placement of spray nozzles, steam inlets, and vents.

• Consider Local Codes and Standards: Comply with local regulations and industry standards for boiler feedwater systems.

Conclusion

Designing a deaerator tank requires careful consideration of these factors to ensure optimal performance, longevity, and safety of the boiler system. Consulting with experienced engineers and referring to industry guidelines (such as ASME Boiler and Pressure Vessel Code) can provide additional insights into best practices and standards for deaerator tank design.