On 2018-08-08 14:48:54
Refractory selection of heat treatment furnace
Refractories are the basic materials used in the high temperature industry. The refractories (heavy refractory brick, light refractory brick, heat preservation cotton, refractory castable) used due to the influence of using position, temperature, operation mode, chemical erosion, etc Different, no one refractory can meet all the working conditions, so the main conditions and economic conditions should be taken as the supplement when choosing refractory. What are the specific requirements for refractories?
1. Resistance to temperature damage. In the process of use, the refractories will not cause damage to the furnace structure or refractory components due to the melting and softening of the materials. The corresponding properties include fire resistance, load softening temperature, creep resistance and high temperature strength. Therefore, it should have better high temperature resistance.
2. Resist the damage of thermal stress. In the intermittent production of industrial kilns, the lining or refractory parts have to go through the process of heating and cooling repeatedly, which is called "thermal shock". Even in the non intermittent and temperature stable furnace, there will be a large temperature difference between the hot side and the cold side of the refractory, both of which will cause a large stress in the material. The magnitude of stress is related to the thermal conductivity, expansion coefficient, elastic modulus, strength and many other properties of the material. The performance of refractories related to this is thermal shock resistance. Therefore, it is necessary to have the thermal shock resistance or thermal spalling resistance.
3. Resist the erosion of environmental medium. Refractory materials in the use process often inevitably contact with related media, such as metallurgical slag, molten metal, molten glass, cement clinker molten coal slag and corrosive gas. At high temperature, refractories will be corroded when contacting with these media. In addition, these media will infiltrate into the refractory along the pores and cracks of the refractory, causing damage to the internal composition and structure of the material. The factors that affect the corrosion resistance of refractories are the composition and structure of refractories. The corresponding performance is slag resistance. Therefore, the material is required to have high compactness, low porosity and strong impermeability.
4. Do not contaminate the bearing products. Refractories are used to make containers, industrial furnace linings or ceramic carriers for carrying some molten or sintered products at high temperature, such as steel ladle and tundish in iron and steel industry, lining of glass tank kiln, and burning plate (shed plate) and saggar for firing ceramic and electronic materials. If refractories react with molten steel and glass melt, the content of impurity elements and inclusions in molten steel will be increased, and stones or stripes will be formed in the glass. If the sintering plate of the electronic material reacts with the sintered electronic material, it will cause adhesion and affect the surface roughness of the electronic material. It is required that the chemical composition of refractory can react with solution.
5. Do not pollute the environment. Refractories shall not cause harm to the living environment of human beings in the process of production and use, and shall not produce harmful substances that pollute the atmosphere and water source, so as to facilitate the recycling and utilization of materials as much as possible. Magnesia chrome refractories are widely used as high-quality refractories, but because of the harm of hexavalent chromium to human body, especially the pollution of water source, magnesia chrome refractories have been listed as one of the varieties that should be eliminated, and new substitute products are being actively developed.
When discussing the impact of refractory production on the environment, we must also mention the energy consumption and the impact of CO2 on the climate. A large number of unburned or shaped refractories are used, and the necessary physical and chemical processes are completed by using the high temperature under the use conditions, so as to meet the requirements of use, i.e. the so-called "self adaptation", which is of great significance to reduce the energy consumption in the production of refractories.
Refractories are used in high temperature kilns. Refractories should play a certain role in energy saving and emission reduction of industrial furnaces. The insulating refractories with high thermal insulation performance and the insulating refractories which can be directly used in hot surface or directly contact with melt are very important for energy saving of various kilns and high temperature vessels.
Refractory is a kind of material that can be used at high temperature. In addition to high temperature resistance, it is also expected to have a strong resistance to erosion of various media such as melts, and a better resistance to temperature shock. At the same time, the products and environment it serves should be free from pollution or less pollution. In actual work, the main performance can be selected according to the specific use conditions to meet the use requirements.