Induced Draft Fan – Purpose-Built for Flue Gas Duty in Boilers, Furnaces, and Combustion Systems
Engineering & Application Overview
Combustion systems actively need to maintain negative pressure in the combustion chamber to cool down the facilities. For example, a boiler, rotary kiln, thermal oxidizer, or coal-fired furnace. Otherwise, those facilities need to face so many consequences that are mentioned below:
- Increase the smoke pressure.
- Combustion air will not be distributed properly.
- Hot flue gas returns to the boiler house. Which directly violated safety and legal standards.
A general centrifugal fan is not suitable for this task. The reason is that the exhaust gas from the combustion system is not clean air; it has combustion products, fly ash, sulfur compounds and moisture mixtures at high temperatures of around 150 to 450 degrees Celsius. Those particles can damage the impeller and an ordinary house casing over time
Induced Draft Fan are specially engineered to handle this task. This fan is installed on the exhaust side after the furnace, economizer, air preheater, and pollution control equipment. It extracts hot flue gas through the entire system and generates suction pressures that can maintain a stable combustion draft.
Some of the special engineering characteristics are given below:
- Impeller: It has erosion-resistant geometry and special materials for ash-mixed gases.
- Shaft sealing: Specially engineered for negative-pressure operation, which can resist air from entering the bearing housing and stable draft control.
- Bearing arrangement: It is rated for operating in high temperatures.
- Speed control: Inlet Guide Vanes (IGV) or VDF that keep furnace draft stable based on boiler load changes.
A standard Induced Draft Fan comes with 2 kinds of impellers, which need to be chosen based on their needs. The backward inclined impeller is suitable for moderate-dust flue gas and delivers 75% to 85% efficiency. On the other hand, the radial blade impeller is designed for heavy ash-laden or sticky gas. Its fouling resistance is prioritized over achieving peak efficiency. It is engineered for high pressure and airflows with high-temperature capabilities.
This unit is the engineered solution for the most demanding gas-handling duty in any combustion system.
Primary Industrial Uses
Core Technical Specifications
- Airflow Range: 500 ~ 300,000 m³/h
- Total Pressure: 2,000 ~ 28,500 Pa
- Efficiency: 55%~85% (backward inclined: 75%~85%; radial blade: 55%~70%)
- Blade Geometry: Backward Inclined (moderate-dust duty) or Radial Blade (heavy ash-laden duty) - application dependent
- Impeller Diameter: 350 ~ 2,100 mm
- Motor Power: 3 ~ 1,000+ kW
- Max Temperature: Up to 600°C
- Vibration: ≤ 3.0 mm/s (ISO 10816-3 / ISO 14694)
- Operating Pressure Mode: Negative pressure (suction side) - sustains combustion chamber draft
- Shaft Sealing: Engineered for negative-pressure operation - prevents air in-leakage at bearing housing
- Body Material: Carbon Steel (standard), SUS304, SUS316, wear-resistant alloys, erosion-resistant coating (as specified by flue gas composition)
- Blade Material: As per order specification
- Customization: Available
Specification Table
|
Model: |
W-Series |
Type: |
Induced Draft Fan |
|
Impeller type: |
Backward Inclined or Radial Blade |
Electric Current Type: |
AC |
|
Motor Power (KW): |
3 ~ 1,000+ kW |
Power Supply: |
As customer requires. |
|
Speed (RPM): |
480 ~ 2,975 |
Pressure (Pa): |
2,000 ~ 28,500 |
|
Efficiency (%): |
55% ~ 85% |
Temperature (F): |
Up to 600°C / 1,100°F |
|
Packaging: |
Wooden Package |
Origin: |
P.R. China |
|
Delivery: |
All over the world |
Warranty: |
18 months |
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