1. Relative Positions of Superheater, Economizer, and Air Preheater

In a typical boiler system, these three heat exchangers are arranged in the following sequence based on heat recovery efficiency:

1. Economizer – Located at the boiler's rear section before the flue gas exits. It captures waste heat from the exhaust gases to preheat the boiler feedwater, reducing the heat load on the boiler and improving overall efficiency.
2. Air Preheater – Positioned after the economizer, it uses residual flue gas heat to warm the incoming combustion air. This increases air temperature, accelerates fuel combustion, and enhances efficiency.
3. Superheater – Usually found in the radiant section or convection section after the evaporator. Its primary function is to further heat the steam beyond its saturation temperature, producing high-temperature, high-pressure superheated steam for turbines or other power equipment.

This arrangement maximizes waste heat recovery, improves boiler efficiency, and reduces fuel consumption and emissions.

2. Functions of Superheater, Economizer, and Air Preheater

1. Superheater

   • Increases steam temperature beyond saturation, producing superheated steam.
   • Supplies high-temperature steam to turbines, improving thermal efficiency.
   • Prevents steam condensation, reducing corrosion in pipelines and equipment.

2. Economizer

   • Recovers waste heat from flue gases, raising the temperature of feedwater and reducing fuel consumption.
   • Lowers exhaust gas temperature, increasing boiler efficiency.

   • Protects the boiler’s heating surfaces, reducing thermal stress and extending equipment lifespan.

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3. Air Preheater

   • Uses waste heat to preheat combustion air, improving fuel combustion efficiency.
   • Enhances fuel burning efficiency, reducing unburned carbon emissions.
   • Lowers exhaust gas temperature, minimizing energy losses.

3. Optimizing the Layout of Superheater, Economizer, and Air Preheater

To maximize heat recovery, the optimal placement of these components should focus on:

• Lowering exhaust gas temperature – Properly designed economizers and air preheaters maximize heat recovery, reducing flue gas temperature to an economically viable minimum.
• Optimizing combustion – The air preheater raises combustion air temperature, ensuring complete fuel combustion and reducing energy losses.
• Preventing corrosion – Controlling the minimum wall temperature of the economizer and air preheater prevents low-temperature corrosion, extending equipment service life.

Conclusion

The superheater, economizer, and air preheater are indispensable in boiler systems. Their proper arrangement and efficient heat exchange processes significantly improve boiler efficiency, lower operating costs, and enhance the economic benefits of industrial production.