Client Background
Industry: Iron & Steel Metallurgy
Equipment: 4 Maerz parallel-flow regenerative twin-shaft lime kilns (single kiln capacity: 600 TPD)
Material Characteristics: High-activity limestone, fuel sulfur content 0.8%-1.2%
Key Requirements:
Resolve refractory spalling caused by alternating kiln temperatures;
Extend kiln lifespan to 5+ years (original: 3 years);
Reduce kiln shell surface temperature to ≤180°C.
Key Challenges
Extreme Operating Conditions:
Cyclical combustion switching (24-30 times/day) with rapid temperature fluctuations (800°C → 1350°C → 800°C);
Synergistic erosion from fuel sulfur and CO₂ generated by limestone decomposition.
Structural Complexity:
40-meter kiln height requiring gradient material performance across preheating/calcining/cooling zones;
Complex shapes (e.g., arches, discharge gates) complicating installation.
Solutions
1. Material System Design
| Kiln Zone | Refractory Solution | Technical Advantages |
| Preheating Zone | Low-cement high-strength clay castables (Al₂O₃≥55%) | CO₂ resistance, thermal conductivity ≤1.2 W/m·K |
| Calcining Zone | Magnesia-alumina spinel bricks (MgO≥85%, Al₂O₃ 8-12%) | 3x sulfur resistance, withstands ≥200 thermal cycles |
| Cooling Zone | SiC composite wear-resistant castables (SiC≥30%) | Mohs hardness ≥8, resistant to clinker impact |
| Arch/Expansion Joints | Nano-porous ceramic fiber modules + phosphate sealants | Compensates thermal expansion, minimizes cracks |
2. Engineering Innovations
Rapid Repair Technology: In-situ hot repair materials (solidifies in 3 hours), reducing downtime by 70%;
Modular Construction: Prefabricated arch bricks improved installation efficiency by 40%.
Results
| Metric | Before | After | Economic Value |
| Calcining Zone Lifespan | 10 months | 18 months | Annual maintenance savings: RMB 3.2M |
| Kiln Shell Temperature | 220-250°C | ≤165°C | Reduced heat loss, saving RMB 1.5M/year in coal costs |
| Unplanned Shutdowns | 8 times/year | 2 times/year | Increased annual output by 21,000 tons |
| Refractory Energy Use | Baseline | ↓15% | Reduced CO₂ emissions by 420 tons/year |
Client Feedback
“The solution resolved chronic thermal shock damage in Maerz kilns and ensured continuous production.” – Client’s Equipment Management Director
