Refractory Bed Material
Refractory Bed Material
Refractory Bed Material also known as boiler bed material or boiler bed sand—is a specially formulated, heat-resistant granular aggregate critical for fluidized bed boilers, including FBC, AFBC, and CFBC types. Its main function is to maintain a stable, high-temperature bed that supports efficient fuel combustion, effective heat transfer, and long-term boiler durability.
Composition & Chemical Properties
- High-Purity Silica (SiO₂): Usually 60–70%, providing primary heat resistance and structural stability.
- Alumina (Al₂O₃): 30–40%, enhancing refractory qualities and thermal shock resistance.
- Low Iron Oxide (Fe₂O₃): Less than 1.5–2.5%, essential to minimize slagging, fouling, and agglomeration.
- Low Alkalis (Na₂O + K₂O): Below 1% to avoid chemical reactivity and extend boiler life.
- Additional Minerals: Trace amounts of TiO₂ (≤1%), fire clay, or other blend agents for customized formulations.
- Moisture: As low as possible, highly dried to not impact fluidization.
Physical Characteristics
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Property
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Typical Range
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Particle Size
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0.85–2.36mm (custom: 0.6–2.8mm)
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Bulk Density
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950–1,100kg/m³
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Particle Density
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~2.0g/cm³
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Fusion Temperature
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>1,300°C (often up to 1,400°C)
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Initial Deformation Temp (IDT)
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>1,300°C
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Form
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Granular or powdered, off-white/beige, screened and dust-free
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Sphericity
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Sub-angular to rounded, for perfect fluidization
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Packaging
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40–50kg HDPE/BOPP bags, 1MT jumbo bags, bulk
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Key Features & Benefits
- Perfect Fluidization: Uniform, controlled grain size and high purity enable smooth bed movement, maximizing combustion efficiency and heat transfer.
- Thermal & Mechanical Stability: : High resistance to abrasion, erosion, and thermal cycling, preventing tube wear and prolonging bed life.
- Clinker/Slag Resistance: Low impurity levels minimize the risk of bed agglomeration and slag.
- Customizable: Can be tailored for fuel type, boiler design, and operational requirements.
- Fuel Flexibility: Compatible with coal, lignite, biomass, petcoke, and waste fuels.
- Tube/Erosion Protection: Reduces direct impact and abrasion on expensive boiler tubes.
Typical Applications
- Used in FBC, AFBC, and CFBC boilers across power, cement, chemical, waste-to-energy, and other industrial sectors.
- Also utilized for heat-resistant linings in kilns and reactors.
Selection & Quality Considerations
- Must match the specified particle size and chemical composition for the design fuel and boiler type—incorrect specs risk poor fluidization, increased ash, or wear
- Produced to conform with technical standards (BHEL, ASTM, IS, BS).
- Price (India, 2025): ₹1,500–₹5,500 per tonne, depending on composition, grade, packaging, and location.
- Fuel Flexibility: Supports combustion of coal, lignite, biomass, petcoke, and waste fuels in FBC systems.
Summary
Refractory bed material is a high-silica, moderate-alumina, low-iron aggregate—processed, screened, and quality-tested for heat duty, chemical stability, and physical endurance. This material is essential for safe, clean, and reliable fluidized bed boiler operation, ensuring efficient fuel combustion, optimal energy conversion, and long boiler service life.