Twin Shaft Lime Kiln
Regenerative alternating operation with severe thermal cycling; high-alumina brick in general zones and magnesia–alumina spinel brick in high-temperature switching areas.
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Get PriceRegenerative alternating operation with severe thermal cycling; high-alumina brick in general zones and magnesia–alumina spinel brick in high-temperature switching areas.
Axial moving bed with clear longitudinal zones; high-alumina brick (tail), anti-spalling brick (transition), spinel brick (burning), and castable (kiln hood).
Ring-shaped continuous flow with zoned heating; high-alumina brick in preheating, alumina/phosphate bricks in calcining, and magnesia-based materials in burning zones.
Vertical counter-current kiln with strong thermal gradient; uses high-alumina brick in upper zones and anti-spalling/alkali-resistant refractory in the lower and discharge areas.
Non-uniform vertical firing with high chemical attack; high-alumina brick (upper), anti-spalling brick (middle), and silica/alumina brick (lower high-temperature zone).
Twin shaft (PFR) kilns have high thermal efficiency and require materials resistant to thermal cycling and alkali attack. Recommended zones:
Rotary lime kilns operate at 1100–1300°C. Main challenges: alkali attack, mechanical wear, coating formation.
Annular shaft kilns have a central inner cylinder and outer shell. Refractory selection focuses on uniform heating and resistance to lime dust abrasion.
Traditional vertical kilns. Simple refractory design but require good abrasion resistance and thermal insulation.
These kilns use coal, gas or oil. Severe temperature fluctuations and ash attack require robust materials.
| Kiln Type / Zone | Operating Conditions | Common Materials | Recommended Materials |
|---|---|---|---|
| Twin shaft – calcining zone | 1200–1300°C, thermal cycling, severe alkali attack | Magnesia Brick | Magnesia Alumina Spinel Brick, SiC Castable |
| Rotary – burning zone | ≥1300°C (flame >1800°C), coating formation, alkali & sulfur corrosion | Direct-bonded Magnesia Chrome brick | Magnesia-iron Spinel Brick (chrome-free) |
| Annular shaft – calcining zone | 1200–1300°C, high dust load, uniform heating requirement | High Alumina Brick (70-75% Al2O3), Mullite Brick | Magnesia Alumina Brick |
| Single shaft – calcining zone | >1200°C, alkali attack, moderate abrasion | High Alumina brick (Al 55–65%) | Magnesia-chrome brick (as per user specification) |
| Mixed firing – burning zone | 1300–1450°C, fluctuating temperature, ash & slag corrosion | High-alumina brick (Al≥70% ) | Magnesia-alumina spinel brick (as per user) |
| Cooling zone (all types) | 800–1200°C, Abrasion, erosion, thermal shock, and moderate alkali attack. | High Alumina Brick (Al 55–70%), Dense Fireclay Brick, Phosphate‑bonded High Alumina Brick | SiC Castable, Corundum Mullite Castable, Magnesia Alumina Spinel Brick |
Magnesia‑spinel brick or SiC‑based castable offers excellent resistance to thermal cycling and alkali attack. High‑alumina brick (70% Al₂O₃) is also a cost‑effective alternative.
Use high‑alumina brick with low porosity (≤16%) and smooth surface. Proper burner adjustment and raw material sizing also help reduce ring formation.
Silicon carbide (SiC) castable or steel‑fiber reinforced corundum castable provides superior abrasion resistance under falling lime temperature.
For moderate temperatures, fireclay brick works well. However for calcining zones above 1000°C, upgrade to high‑alumina brick (55–65% Al₂O₃) for longer life.
Mixed firing kilns experience more severe temperature fluctuation and ash corrosion; thus higher grade materials (SiC, 70%+ Al₂O₃) are recommended for combustion chambers and the calcining zone.