The boiler induced draft fan is a key equipment in the boiler system, mainly used to extract flue gas from the furnace and discharge it into the atmosphere, maintain negative pressure in the furnace, and ensure stable combustion process. The following is a detailed introduction about the boiler induced draft fan:
---
**1. Main function**
-* * Maintain furnace negative pressure * *: prevent high-temperature flue gas leakage and ensure operation.
-* * Exhaust smoke * *: The exhaust gas after combustion is discharged into the atmosphere through a chimney.
-* * Balanced ventilation * *: Cooperate with the air supply fan to ensure the required amount of air for combustion.
-Energy saving and environmental protection: Some modern induced draft fans can be combined with waste heat recovery systems to reduce energy consumption.
---
**2. Structural composition**
-* * Impeller * *: mostly designed with a backward tilt or radial shape, resistant to high temperatures and corrosion (commonly used materials such as Q345, 16Mn, etc.).
-* * Chassis * *: Made of welded steel plates, lined with wear-resistant or anti-corrosion coatings.
-* * Bearing box * *: Supports the rotor and requires a good lubrication and cooling system.
-Couplings/Motors: Variable frequency motors are commonly used to regulate air volume.
-Adjusting the baffle: Controlling the smoke flow rate may use hydraulic couplings or variable frequency speed regulation.
---
**3. Job characteristics**
-High temperature environment: The processing temperature of flue gas is usually 150-200 ℃ (up to 400 ℃ or above).
-* * Dusty gas * *: It needs to withstand fly ash wear and tear, and anti-wear measures should be installed if necessary.
-Corrosive media: To deal with acidic gases such as sulfides, anti-corrosion design is required.
-High negative pressure operation: usually within the range of -1000~-3000 Pa.
---
**4. Common types**
-Centrifugal induced draft fan: The most commonly used, with high pressure and stable air volume.
-Axial flow induced draft fan: High flow, low pressure head scenario, high efficiency.
-* * Adjustable static blade/adjustable moving blade fan * *: Used for large boilers, with better regulation performance.
---
**5. Key selection points**
-Airflow and Wind Pressure: Calculated based on boiler evaporation rate, fuel type, and flue resistance.
-Temperature adaptability: Select materials based on the temperature of the flue gas.
-Efficiency and Power: Prioritize energy-saving models (such as efficiency>85).
-Explosion proof requirements: Gas boilers require explosion-proof motors.
-Noise Control: Compliant with environmental standards (usually ≤ 85 dB).
---
**6. Common faults and their solutions**
|* * Fault phenomenon * * | * * Possible cause * * | * * Solution * *|
|----------------------|-----------------------------|--------------------------------|
|Excessive vibration | Dust accumulation/wear on impeller, bearing damage | Dust cleaning, dynamic balance correction, bearing replacement|
|High bearing temperature | Insufficient lubrication, cooling system malfunction | Check oil level, clean cooler|
|Insufficient air volume | Small baffle opening, belt slippage | Adjust baffle, replace belt|
|Abnormal noise | Foreign objects entering, loose components | Shutdown inspection, tightening bolts|
---
**7. Maintenance and upkeep**
-Daily inspection: bearing temperature, vibration, and abnormal noise.
-* * Regular maintenance * *:
-Clean the dust accumulation on the impeller every month.
-Replace lubricating oil every quarter.
-Inspect the wear-resistant lining and seals annually.
-Long term disuse: It is necessary to clean the dust and regularly rotate the bearings to prevent corrosion.
---
**8. Energy saving renovation direction**
-* * Variable frequency speed regulation * *: Automatically adjust the speed according to the load, saving 20-40% electricity.
-Impeller: Adopting a three-way flow design to improve efficiency.
-Waste heat utilization: Install a heat pipe heat exchanger to recover heat from flue gas.
---
**9. Precautions**
-After shutdown, wait for the fan to cool down before maintenance.
-Ensure that the CO concentration meets the standard before entering the flue to prevent poisoning.
-It is strictly prohibited to clean the impeller or adjust components during operation.
---
If more specific parameter calculations (such as wind volume, power) or fault diagnosis are needed, detailed information such as boiler model and fuel type can be provided for further analysis.
