What are the criteria for selecting refractory materials for lime vertical kiln equipment
The refractory materials of lime vertical kilns directly affect the lifespan, thermal efficiency, and operational stability of the kiln body. The selection should comprehensively consider factors such as high temperature resistance, erosion resistance, thermal shock stability, and economy. The following are the key selection criteria:
1. High temperature resistance performance
The temperature of the vertical kiln calcination zone usually reaches 1100~1300 ℃, and the refractory material needs to have a high load softening temperature (≥ 1500 ℃) and a low high temperature creep rate. Common materials include:
High alumina brick (Al ₂ O ∝ ≥ 65%): suitable for calcination belts, with excellent high temperature resistance.
Magnesium aluminum spinel brick: Strong resistance to alkaline erosion, suitable for high activity lime production.
2. Chemical resistance
The CaO and fuel ash (such as SiO ₂, K ₂ O) produced by the decomposition of limestone are prone to react with refractory materials, leading to erosion or nodulation. Prioritize selecting refractory materials with low porosity (<18%) and high density (≥ 2.8g/cm ³) to reduce infiltration erosion.
3. Thermal shock stability
Temperature fluctuations inside the kiln can easily lead to cracking of refractory materials. Magnesia chromium bricks or zirconium containing silicon mullite bricks are suitable for preheating and cooling zones due to their low coefficient of thermal expansion and outstanding thermal shock resistance.
4. Mechanical strength and wear resistance
The falling of materials and the erosion of airflow require refractory materials to have high compressive strength (≥ 50MPa) and wear resistance. The application effect of silicon carbide composite bricks in the lower part of the kiln body is significant.
5. Economy and maintenance costs
Taking into account the initial cost and service life, layered material selection (using high-end refractory materials for calcination belts and ordinary materials for other areas) can optimize costs.
The refractory materials for lime vertical kilns need to be scientifically selected based on the kiln structure, process temperature, and raw material characteristics, and combined with regular maintenance (such as spray repair technology) to extend their service life and ensure efficient and stable operation.
