The glass furnace is thermal equipment for melting glass made of refractory materials. When choosing refractory materials for glass kilns, consideration should be given to the type of kiln, the location of use, the mechanism of damage, the types of molten glass, and the types of pigments. Refractories for glass kilns should first be able to resist the erosion of glass melt and gaseous substrates and should have a sufficiently high load softening temperature and thermal stability.
Generally, it is hoped that the refractory materials in various parts of the kiln do not show local premature corrosion, so as to ensure that the entire kiln has a sufficiently long service life. However, due to the different mechanical, physical, and chemical conditions of each part of the glass furnace, the properties of the refractory materials used must be adapted to it. At the same time, it is required not to adversely affect other types of adjacent bricks.
The glass kiln refractory bricks mainly include clay bricks, silica bricks, fused zirconia corundum bricks, fused corundum bricks, magnesia refractories, including magnesia refractories for regenerators. In addition, zirconia bricks have excellent properties such as high-temperature resistance, good thermal shock resistance, and corrosion resistance to molten glass. Alumina-Zirconia-Silica (AZS) fused-cast bricks and fired bricks have good corrosion resistance to molten glass and can be used for the wall and upper structure of glass kilns. Of course, there are also heat-insulating refractory materials for energy saving and heat preservation to save production costs.
What are the index performances that need to be considered when choosing refractories for glass kilns?
When selecting and purchasing refractory for glass furnace, what are the index performances that should be considered first?
(1) Organizational structure
Refractory material is a heterogeneous body composed of solid phases (including crystal and glass phases) and pores. The macroscopic structure of the product is the main factor that affects its high-temperature use properties.
① porosity
In refractory materials, there are often many pores of different sizes and shapes. The open pores (also known as apparent pores) that are in communication with the atmosphere, the interpenetrating pores are called communicating pores, and the ones that are not in communication with the atmosphere are called closed pores. The porosity is usually used to reflect the compactness of the refractory, that is, the percentage of the volume of the pores in the brick to the total volume.
Porosity is the basic technical index of refractory materials, it almost affects the performance of refractory products. The smaller the porosity, the better the corrosion resistance of the refractory and the higher the structural strength. The higher the porosity, the lower the thermal conductivity of the material.
②Bulk density
Bulk density is the mass of refractory material per unit volume (total volume including pores). It directly reflects the compactness of refractory products and is an important indicator to measure the quality of refractory materials and dense refractory products. Generally speaking, the higher the bulk density, the lower the porosity, and the better a series of properties such as strength and high-temperature load softening temperature.
③True density
The true density refers to the ratio of the mass of a porous material to its true volume (without pores). The true volume refers to the volume of the solid material in the porous body. Its value has nothing to do with density and porosity but is related to the chemical mineral composition of refractory materials.
(2) Thermal properties
① Thermal expansion
When the refractory is heated, the property that its volume expands with the increase in temperature is called thermal expansion. It is usually expressed by linear expansion coefficient or volume expansion coefficient.
When using refractory materials, we must pay great attention to their thermal expansion. Expansion joints should be reserved in the furnace structure according to the thermal expansion characteristics of refractory materials. When igniting the kiln, it is necessary to formulate a reasonable heating curve and adopt necessary measures such as adjusting the brace according to the thermal expansion of the refractory material.
② Thermal conductivity
Thermal conductivity represents the size of the thermal conductivity of the refractory material, expressed in terms of thermal conductivity. The so-called thermal conductivity refers to the rate of heat flow through a unit area of a material under a unit temperature gradient. It mainly depends on the chemical composition and organizational structure of the material.
③Heat capacity
Heat capacity, also known as specific heat capacity, refers to the amount of heat required to heat 1 kg of refractory materials to raise the temperature by 1°C under normal pressure. It is of great significance when designing and controlling the heating and heat storage capacity of the furnace.
For more product information and prices of furnace bricks for glass kilns, please contact us. Our Refractory for Glass Furnace and services will not let you down.
