Product 12: understanding the Corundum-mullite ceramic heat storage body

Corundum-mullite ceramic regenerators are high-performance refractory heat storage materials made from corundum (Al₂O₃) and mullite (3Al₂O₃·2SiO₂) as core components, with the addition of special modifying additives. They are produced through precise batching, molding, and high-temperature sintering. With their excellent high-temperature resistance, heat storage efficiency, and structural stability, they have become a core material in industrial energy conservation and high-temperature heat exchange, widely used in high-energy-consuming industries such as steel, non-ferrous metals, building materials, and chemicals. They are a crucial supporting material for achieving "dual carbon" targets and promoting the energy efficiency upgrade of industrial kilns.

I. Corundum-Mullite Ceramic Heat Regenerator: Core Properties (Physical, Chemical, Thermal)

The superior performance of corundum-mullite ceramic heat regenerators stems from their unique composition and microstructure. Their physical, chemical, and thermal properties are strictly controlled to adapt to the harsh operating conditions of high-temperature industries. Specific parameters, based on mainstream industry standards and measured data, are as follows:

(I) Physical Properties

Physical properties directly determine the structural stability and heat exchange efficiency of the heat regenerator. Key indicators are as follows:

- Appearance and Structure: Products are mostly spherical, honeycomb-shaped (square, round, hexagonal), or block-shaped, with a smooth surface and no obvious pore defects. The interior exhibits a uniform, dense, or porous structure. Spherical heat regenerators commonly range from Φ16mm to Φ32mm and can be customized according to customer needs. Honeycomb heat regenerators have a pore density ranging from 16 CPSI to 60 CPSI, adaptable to different flue gas operating conditions.

- Density-related properties: Bulk density ranges from 1.9 g/cm³ to 3.0 g/cm³ (increasing with Al₂O₃ content), bulk density is 1350 kg/m³ to 1750 kg/m³, and porosity is controlled at 35%-45%, ensuring structural strength while reserving sufficient heat storage space, balancing heat storage capacity and air permeability.

- Strength performance: Excellent room temperature pressure resistance; Φ25mm spherical products have a pressure resistance ≥3.0 KN/piece, with high-end models reaching 5.0 KN/piece; outstanding wear resistance, with an wear rate ≤0.3%, able to withstand the erosion and wear of high-temperature airflow and dust, preventing pulverization and peeling during use, and extending service life.

- Specific Surface Area: The specific surface area of ​​spherical heat regenerators can reach 200m²/m³-240m²/m³, while that of honeycomb heat regenerators can reach up to 1050m²/m³ per unit volume. This ultra-large specific surface area enhances gas-solid heat exchange efficiency, accelerates heat transfer, and is suitable for the frequent reversing requirements of regenerative burners.

(II) Chemical Properties

The material is chemically stable, with strong corrosion resistance and oxidation resistance, making it adaptable to complex industrial flue gas environments. Its core characteristics are as follows:

- Stable Composition: The core components are Al₂O₃ and SiO₂. The Al₂O₃ content ranges from 65% to 95%, and the SiO₂ content can reach up to 90%. Different component ratios correspond to different models (such as KT-A65, KT-A95, etc.) to adapt to different operating temperature requirements. It does not contain easily volatile or easily oxidized components, does not produce harmful gases at high temperatures, and is environmentally friendly and pollution-free.

- Excellent corrosion resistance: Resistant to the erosion of acidic and alkaline flue gases and molten slag, especially resistant to the scouring of flue gases containing corrosive components such as V₂O₅ and Na₂O, with a corrosion rate reduced by more than 60% compared to ordinary cordierite regenerators; it maintains structural integrity and does not undergo chemical reactions or deterioration even in the complex flue gas environments of steel and glass kilns.

- Strong oxidation resistance: Does not readily react with oxygen at high temperatures, exhibiting no oxidation or peeling; it also withstands reducing atmospheres (such as blast furnace gas and converter gas environments) without pulverizing or cracking, making it suitable for the complex combustion conditions of industrial kilns.

- Chemical inertness: Does not chemically react with the heated medium (air, gas, molten metal, etc.), and will not contaminate the product or medium; suitable for high-temperature heat exchange applications in food and pharmaceutical industries, and also adaptable to the stringent requirements of non-ferrous metal smelting.

(III) Thermal Properties

Thermal properties are the core advantage of a heat storage body, determining its heat storage and release efficiency and high-temperature adaptability. Key indicators are as follows:

- High-temperature resistance: Operating temperature range 1400℃-1750℃, increasing with Al₂O₃ content. Models with 95% Al₂O₃ content can reach 1750℃. It has a high high-temperature load softening temperature, no significant thermal deformation, and can operate stably under high-temperature conditions for extended periods, meeting the high-temperature requirements of various industrial kilns.

- Heat Storage and Release Efficiency: Specific heat capacity reference value 0.9kJ/(kg·K)-1.2kJ/(kg·K), high heat storage density, with a heat storage capacity per unit volume 1.2-1.5 times that of ordinary heat storage materials; moderate thermal conductivity (1.8-2.5W/(m·K)), fast heat storage and release speed, capable of frequent reversal 20-30 times/h, with a temperature efficiency of over 90%. High-temperature flue gas can be cooled to 130℃-150℃ after passing through the heat storage bed, resulting in outstanding waste heat recovery efficiency.

- Excellent Thermal Shock Stability: After a 1100℃ water-cooling cycle test, it can withstand more than 25-30 rapid cooling and heating cycles with a strength retention rate greater than 85%, without cracking or peeling; it can adapt to the frequent start-up and shutdown of industrial kilns and temperature fluctuations, avoiding damage caused by thermal shock, extending the service life to 1.5-2 times that of traditional heat storage materials, with some high-end products having a cycle life exceeding 15,000 cycles. - Low coefficient of thermal expansion: The coefficient of thermal expansion (20-1000℃) is 4.5×10⁻⁶/℃-6.5×10⁻⁶/℃, resulting in good volume stability at high temperatures, low reheat shrinkage, and no significant shrinkage deformation. This avoids structural damage caused by uneven thermal expansion, ensuring the sealing and heat exchange stability of the heat storage system.

II. Core Features of Corundum-Mullite Ceramic Regenerators

Based on the properties mentioned above, corundum-mullite ceramic regenerators possess four core advantages over ordinary ceramic regenerators (such as cordierite and high-alumina ceramics): high efficiency, stability, durability, and energy saving. These advantages address frequently searched pain points by Google users, specifically:

1. High Heat Exchange Efficiency and Significant Energy Savings

The ultra-large specific surface area and reasonable pore structure create strong turbulence in the regenerator, effectively breaking through the surface boundary layer. Combined with a small conduction radius and low thermal resistance, this significantly improves heat exchange efficiency. It enables deep recovery of waste heat from high-temperature flue gas, reducing the exhaust volume of regenerable furnaces by 20%-50%, lowering the exhaust temperature to below 150℃, and achieving fuel savings of 20%-50%. Simultaneously, it shortens billet heating time by 50%, increases output by 15%-20%, and reduces oxidation loss by 30%-50%, offering both energy savings and improved quality, meeting the industrial demand for energy conservation and cost reduction.

2. Strong High-Temperature Stability and Long Service Life

Leveraging the excellent high-temperature properties of corundum and mullite, the product can operate stably for extended periods at temperatures ranging from 1400℃ to 1750℃. It features a high softening temperature under high-temperature loads and a low coefficient of thermal expansion, eliminating the risk of deformation and cracking. Simultaneously, it possesses exceptional thermal shock resistance, wear resistance, and corrosion resistance, withstanding high-temperature erosion, flue gas corrosion, and frequent thermal shocks. Its service life reaches 6-12 months, with some high-end products extending to over 3 years, significantly exceeding that of ordinary heat storage materials (3-6 months). This substantially reduces replacement costs and downtime losses, making it suitable for continuous industrial production needs.

3. Reasonable Structure and Wide Adaptability

The product comes in various forms (spherical, honeycomb, block) and a full range of specifications. Spherical heat storage elements have strong airflow capacity; even increased resistance due to ash accumulation does not affect heat exchange performance. Honeycomb heat storage elements have low airflow resistance and shallow heat penetration, making them suitable for different types of industrial kilns and heat storage systems. Component ratios and specifications can be customized according to different industries and operating conditions (temperature, flue gas composition, airflow velocity), adapting to various harsh environments such as high dust, strong corrosion, and high-frequency reversal. It is highly versatile and can be installed and used without large-scale modifications to existing equipment.

4. Environmentally Friendly and Pollution-Free, Aligning with Dual-Carbon Goals

The production process utilizes high-temperature sintering, resulting in no harmful gases or wastewater emissions. The product itself contains no heavy metals or other harmful substances and is recyclable after disposal, meeting environmental protection requirements. During use, it significantly reduces heat loss and NOx emissions from industrial kilns (by more than 40%), while simultaneously recovering waste heat, reducing fossil fuel consumption, and decreasing carbon emissions. This aligns with the national "dual-carbon" strategy and policies for improving the energy efficiency of industrial kilns, making it a core supporting material for green industry. It has strong policy adaptability and continuously increasing market demand.