Boiler Bed Material
Boiler Bed Material
Boiler Bed Material—also commonly called boiler bed sand or refractory bed material—is a specialized granular product essential for fluidized bed combustion (FBC) and atmospheric/circulating fluidized bed combustion (AFBC/CFBC) boilers. The main function is to create a stable and efficient fluidized “bed” for thorough fuel combustion and effective heat transfer.
Composition
- Primary constituents: High-purity silica (SiO₂, typically 60–70%), moderate alumina (Al₂O₃, 30–40%), and very low iron (Fe₂O₃ < 1.5–2.5%). Alkalies (Na₂O + K₂O) are kept under 1% to minimize slagging and clinker formation.
- Other materials: Some variants use crushed or blended refractory minerals (like fireclay-based or ceramic aggregate types) for enhanced heat resistance and fluidization.
- Color and texture: Beige or off-white, granular or powdered, with a highly dense texture and minimal dust.
Key Physical Properties
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Property
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Typical Range
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|---|---|
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Particle Size
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0.85–2.36mm (sometimes up to 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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~2.00g/cm³
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Fusion Temp
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>1,300°C (often up to 1,400°C)
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Moisture
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As low as possible, highly dried
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Abrasion Resistance
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High
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Packaging
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40–50kg HDPE or BOPP bags, 1MT jumbo bags, bulk
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Composition & Characteristics
- Core Ingredients: High-purity silica (SiO₂, usually 60–70%), moderate alumina (Al₂O₃, 30–40%), very low iron content (Fe₂O₃ <1.5–2.5%). The product is largely free of contaminants, with low alkalis (Na₂O + K₂O <1%), moisture, and dust.
- Physical Form: Granular or powdered, beige to off-white color, dense, and highly screened for uniform particle size.
- Particle Size: Typically ranges 0.85–2.36mm, with strict control to match boiler design and fuel needs.
- Fusion Temperature: Usually >1,300°C (often up to 1,400°C), allowing stable operations without risk of agglomeration or melting.
- Bulk Density: Usually 950–1,100kg/m³; particle density about 2.00g/cm³.
- Packaging: Supplied in 40–50kg HDPE/BOPP bags, 1MT jumbo bags, or in bulk.
Application & Usage
- Industries: Power generation, cement, and any sector using FBC-type boilers.
- How Used: Charged directly into the boiler bed. Forced air is passed upward to fluidize this material—creating an ideal environment for mixing and burning fuel.
- Customizable: Suppliers can adjust grain size, chemistry, and packaging to suit specific operational needs.
Selection & Purchasing
- Compatibility: Precision in particle sizing and chemistry is crucial—wrong specification may cause poor fluidization, increased clinker/ash, or erosion.
- Standards: Manufactured per technical and quality standards (BHEL, ASTM, IS, BS, etc).
- Price: Commonly ranges from ₹1,500 to ₹5,500 per tonne in India, varying by purity, size, and packaging.
- Packaging: Supplied in 40–50kg HDPE/BOPP bags, 1MT jumbo bags, or in bulk.
Summary
Boiler bed material is a high-silica sand blend, engineered and graded for resilience at high temperatures and effective heat transfer within FBC/CFBC/AFBC boilers. Its role is critical in supporting optimal combustion, minimizing slag/ash problems, and protecting expensive boiler components, which in turn ensures efficient operation and lower maintenance.