This article's table of contents introduction:
- Breakdown of the Specification
- Typical Applications
- Key Technical Specifications You Need to Provide
- Example Manufacturer / Model (Conceptual)
- Critical Safety & Engineering Notes
This appears to be a highly specific industrial equipment specification. You are describing a Centrifugal Blower Fan designed for a Stainless Steel Industrial Boiler, used for Secondary Air supply, and rated as Explosion Proof.
Below is a breakdown of what this specification means, the typical applications, and key engineering considerations.
Breakdown of the Specification
- Stainless Steel (SS304/SS316):
- Why: The fan housing, impeller, and shaft are made of stainless steel. This is critical for corrosion resistance (resistance to flue gases, moisture, and acidic condensate) and for high-temperature environments.
- Application: Used in biomass boilers, waste-to-energy plants, or chemical processing where corrosive gases or high humidity are present.
- Industrial Boiler:
- Context: This is not a residential fan. It is for large-scale steam generators or hot water boilers used in power plants, manufacturing, or district heating.
- Secondary Air:
- Function: In boiler combustion, air is split into Primary Air (for fuel conveying and initial combustion) and Secondary Air (injected above the fuel bed to ensure complete combustion of volatile gases).
- Fan Role: Provides a high-pressure, high-velocity air stream to mix with unburned gases, reducing emissions (CO, NOx) and improving thermal efficiency.
- Explosion Proof:
- Critical Feature: The fan motor, electrical connections, and sometimes the fan housing are designed to contain any internal spark or explosion, preventing it from igniting external flammable gases (e.g., methane, hydrogen, or fly ash clouds).
- Standards: Typically built to ATEX (Europe), IECEx (International), or NEC/UL (North America) standards. The motor will likely be a TEFC (Totally Enclosed Fan Cooled) or XP (Explosion Proof) motor rated for Class I, Division 1 or 2 (gas) and Class II (dust).
- Centrifugal Blower Fan:
- Type: This uses a centrifugal (radial) impeller. The air enters axially and exits radially at high pressure.
- Wheel Types for this application:
- Backward Inclined (BI) / Backward Curved (BC): High efficiency, non-clogging, good for clean secondary air.
- Radial Blade (RB) / Paddle Wheel: For extremely dirty or particulate-laden air (less common for clean secondary air, but can handle high pressures).
- Airfoil: Highest efficiency, but expensive; used in large power plants.
Typical Applications
- Biomass & Wood Pellet Boilers: Secondary air fans inject hot air over the flame to burn off tars and volatiles.
- Coal Fired Boilers (CFB/Pulverized Coal): Over-fire air (OFA) fans for NOx reduction.
- Waste Incineration Plants: High-temperature resistant SS fans for secondary combustion air to ensure complete destruction of dioxins and furans.
- Chemical Recovery Boilers (Pulp & Paper): Handles corrosive sulfur compounds (SS316L required).
- Heat Treatment Furnaces: Supply air for afterburners.
Key Technical Specifications You Need to Provide
To purchase or quote this fan, an engineer will need the following data. You should have these ready:
| Parameter | Unit (Metric) | Notes |
|---|---|---|
| Air Volume (Flow Rate) | m³/hr or CFM | Maximum required at design temperature |
| Static Pressure | Pa, mmH2O, or inWG | Pressure needed to overcome boiler backpressure |
| Air Temperature | °C or °F | Critical for material selection (e.g., 20°C ambient vs 200°C preheated air) |
| Gas Type | - | Clean ambient air? Or recirculated flue gas? (FGR) |
| Explosion Proof Class | Zone 1/2, Div 1/2 | Gas group (e.g., IIB T3) |
| Material Grade | SS304 vs SS316 | 316 for chlorides, 304 for standard hot air |
| Motor Power | kW or HP | Determined by fan curve |
| Drive Type | Direct vs Belt | Direct drive for constant speed; Belt drive for variable volume control |
Example Manufacturer / Model (Conceptual)
While I cannot buy/sell, here is how you would search for this:
"SS304 Backward Curved Centrifugal Fan, 15 kW, 50,000 m³/hr @ 2000 Pa, ATEX Ex d IIC T4, Secondary Air for Biomass Boiler"
Common manufacturers include:
- New York Blower (USA)
- Chicago Blower (USA)
- Greenheck (USA)
- AirPro Fan & Blower (India)
- Elektror (Germany)
- Howden (Global)
Critical Safety & Engineering Notes
- Temperature Rating: The explosion-proof rating is for the motor and electricals, not the fan casing. The casing must be rated for the process temperature (e.g., 400°C stainless steel).
- VFD Compatibility: If using a Variable Frequency Drive (VFD) for speed control, the motor must be inverter-duty (Explosion Proof VFD motor). A standard XP motor cannot be run on a VFD without special filters.
- Shaft Seal: Ensure a high-temperature shaft seal (e.g., graphite or lip seal) prevents hot gas leakage to the bearing housing.
- Spark Resistant Construction: Even though it is "Secondary Air" (usually clean), explosion-proof construction often includes spark-resistant impellers (non-ferrous tips like aluminum bronze or nickel-on-stainless) to prevent ignition in case of impeller contact.
Summary: You are looking at a heavy-duty, corrosion-resistant, high-pressure fan intended for safe operation in a hazardous environment. It is a critical component for boiler efficiency and emissions control.
