The Main Functions of a Boiler Economizer Include

1. Improving Boiler Efficiency
   By recovering waste heat from flue gases to preheat boiler feedwater, it reduces fuel consumption and enhances thermal efficiency.

2. Lowering Exhaust Gas Temperature
   It absorbs heat from the flue gases, reducing the exhaust gas temperature and thereby minimizing heat loss.

3. Saving Fuel
   Utilizing waste heat to preheat feedwater decreases fuel usage, leading to energy savings.

4. Reducing Environmental Pollution
   Lowering the exhaust gas temperature reduces the emission of pollutants, lessening environmental impact.

5. Increasing Boiler Output
   Preheating feedwater shortens heating time, improving steam production and operational efficiency.

6. Protecting Boiler Equipment
   It reduces the damage caused by high-temperature flue gases to downstream equipment, extending the lifespan of the system.

7. Lowering Operating Costs
   By saving fuel and reducing maintenance expenses, it decreases overall operating costs.

In summary, an economizer enhances the economic and environmental performance of a boiler by recovering waste heat, improving efficiency, saving fuel, and reducing pollution.