Main causes of refractory damage in glass furnaces

The damage mechanism of glass furnace refractory materials mainly includes chemical erosion, mechanical damage, thermal damage and other factors. The main damage mechanisms are analyzed as follows:

Chemical erosion

In the high-temperature working environment of the glass furnace, the refractory material reacts chemically with molten glass, alkali metal oxides in the glass, as well as fly ash and gas-phase substances (such as SO₂, Na₂O, etc.), which leads to the gradual destruction of the refractory material:

Alkaline erosion: Alkali metal oxides (e.g. Na₂O, K₂O) in glass raw materials penetrate the refractory material at high temperatures and react with its components (e.g. SiO₂ or Al₂O₃) to form compounds with low melting points, leading to structural failure.

Liquid glass erosion: molten glass is in direct contact with the refractory material, dissolving or etching its surface, reducing the strength and service life of the refractory material.

Mechanical damage

In the working environment of a glass furnace, the refractory material may be subjected to mechanical stresses such as high temperature glassy liquid flow, particle washout and impact, resulting in abrasion and cracking:

Wear and tear due to abrasion: High velocity flow of glassy liquid or flow of gases containing particles accelerates surface wear of refractory materials.

Particle impact: suspended particles hit the surface of the refractory material, causing surface rupture and localized damage.

Thermal damage

Temperature fluctuations and high-temperature environment in a glass furnace affect the thermal stability and structural integrity of refractory:

Heatstroke damage: Uneven temperature distribution in the glass furnace and rapid heating or cooling can lead to stress cracks in the refractory material due to differences in thermal expansion coefficients.

Melting point damage: When the local temperature exceeds the melting point of the refractory, the material may soften, flow or even melt.

Crystal Transformations: Some minerals (e.g. quartz) in refractory materials undergo crystalline changes at high temperatures accompanied by volumetric expansion or contraction, resulting in structural damage.

Structural erosion and cracking

Vapor phase erosion: Volatile components (e.g. sulfides, alkali metal oxides) in a high-temperature environment can form substances with low melting points on the surface of refractory materials, which leads to structural weakening of the surface.

Peeling phenomenon: prolonged chemical erosion, thermal stress or mechanical stress can cause the material to gradually peel away from the surface and lose its protective effect.

Melt penetration

Liquid molten glass can penetrate the refractory material through capillaries, accelerating chemical reactions and material degradation. Penetrated liquid glass at high temperatures can change the microstructure of the material, reducing strength and erosion resistance.

Decision measures

Selection of high-performance refractory materials: use high-purity high-density alumina, zirconia, fused zirconia corundum and other refractory materials such as high alumina bricks, silica bricks, AZS bricks, etc. to improve chemical erosion resistance and thermal shock resistance.
optimization of furnace design: reduction of direct contact between refractory and high-temperature glass liquid, improvement of temperature distribution and reduction of local temperature difference.
control of operating conditions: stabilizing the oven temperature, preventing sudden temperature rises and falls, and reducing damage from thermal shock.
regular maintenance and repair: replace the refractory material in the damaged area in time to prevent localized damage from expanding.

In this way, the service life of refractories for glass furnaces can be extended and their efficiency can be improved.