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High temperature insulation wool industry classification

Views: 0     Author: Site Editor     Publish Time: 2020-10-28      Origin: Site

Compared with traditional refractories, the density of high temperature insulation wool is very low, so its heat capacity is very low (based on the insulation quality in the furnace). With the development of related industries, people's demand for high temperature insulated wool is increasing, and the requirements are also increasing. This requires us to have a deeper understanding of it in order to find its value more. So do you know what kind of material it is? What are its characteristics? Next, we will introduce to you some high temperature insulation wool related content, I hope you can better understand.

 

The points are as follows:

※ What is high temperature insulation wool

※ High temperature insulated wool classification

※ Material property

※ Conclusion

 

What is high temperature insulation wool

High temperature insulation wool, commonly known as ceramic fiber cotton, also known as ceramic insulation materials and ceramic fiber blankets, is one of the main components of high temperature insulation materials. It is a synthetic mineral wool with high temperature resistance over 1000 C. High temperature insulation wool is made of synthetic materials and aromatic polyamides. In addition to fiberboard, various other products can also be made from high-temperature wool. These include vacuum plates and parts. In addition to being used as insulating plates, these products can also be used in, for example, burner components or kilns. Therefore, it has a wide range of applications. However, although this material has excellent heat resistance, it does not have the same strength or durability as glass fiber felt.

 

High temperature insulated wool classification

High temperature insulating cotton (HTIW) belongs to artificial mineral fibers, including mineral wool and glass wool. Minerals and glass wool are used at temperatures below 650 degrees Celsius, with a few exceptions. When the applied temperature is higher than 1000 C, the material is called high temperature wool. Therefore, it includes alkaline earth silicate wool (AES-wool), aluminium silicate wool (ASW) and alkaline earth silicate wool (AES-wool).

 

(1) Polycrystalline wool (PCW).

The production principle of alkaline earth silicate wool (AES wool) is the same as that of ASW wool. The raw materials are SiO 2, CaO and/or MgO. CaO and MgO reduce the melting temperature of SiO 2 and ensure the low biological durability of the fibers. Biological resistance is low, and fibers are classified as "bio-soluble". The body can dissolve AES fibers in a few weeks.

 

(2) Aluminum silicate powders (Al 2O 3 and SiO 2 and possibly ZrSiO 4) are melted in a resistance arc furnace with carbon electrodes. The melt is discharged from below the melting unit and blown or ejected through compressed air on the rotating disc. The fibers are several centimeters long, 2-4 microns in diameter and end with a teardrop-like head. These head and non-fibrous materials are called "shooting". The teardrop-like head often breaks. The injection rate of crude fibers is 40-60%. The decrease of injection content in the finished product reduces the thermal conductivity and improves the insulation effect.

 

(3) Polycrystalline wool

Polycrystalline cotton (PCW) is produced in different ways. The content of Al2O3 in this fiber type is at least 72%. Because of the high surface tension, the melt cannot be blown into the fibers. Therefore, PCW is generated by sol-gel method. Water soluble gel fibers were obtained and then treated in a continuous furnace. The product is ceramic fiber.

 

Material property

The characteristics of high temperature insulating wool are low thermal conductivity, low bulk density and low heat capacity. Therefore, high temperature wool can be used to construct a very energy-saving, regular operating system, which can be quickly heated and cooled.

 

1. Contraction

All high temperature insulating cotton shrinks at high temperature. If necessary, the newly installed insulation must be added within days or weeks after the start of operation. This figure shows the typical long-term behavior of ASW at different temperatures. Depending on temperature, most contractions occur in the first hour and days of operation, and then the process slows down significantly.

Corrosive components in furnace atmosphere can significantly increase shrinkage (e.g. alkali). These corrosive components enter the furnace through cargo. In this case, contraction will not stop. Although it will slow down, it will continue to depend on the number of corrosive media and diffusion mechanisms. AES and ASW recrystallize at temperatures higher than 900 C. When used continuously at temperatures higher than 900 C, these materials produce crystalline SiO 2 and the glass structure disappears. As a result, materials lose flexibility over time. Higher working temperature can accelerate the process.

 

2. Thermal conductivity

The thermal conductivity depends on the density and preferred orientation of the fibers. The material type has little effect on the thermal conductivity at high temperature.

3. Elasticity

Elasticity is the characteristic of needle-punched blankets. Elasticity varies with compression (the point at which the fibers break) and heat load (recrystallization). 7Elastic behavior is important for the use of modules. Pre-compression in the module and therefore in the furnace wall cancel out the shrinkage at high temperature. The use of modules has other advantages. The bulk density of the material is high, and the thermal conductivity decreases at high temperature, so the heat transfer decreases. The preferred fiber direction is perpendicular to the furnace wall. Therefore, modular systems can withstand up to 30 m/s of traffic. If the rubber cloth is installed in layers, it should not exceed 10 meters per second, otherwise the fibers in the material will be blown away/eroded.

 

4. Corrosion

The chemical properties of ASW and PCW are stable and can withstand acid atmosphere. AES wool can't. People often neglect that the dew point of acid is higher than that of water. For example, sulfuric acid condenses at about 160 degrees Celsius. Equally important is the condensate of pure water on the wall. AES should not be used under such conditions (nor in HF, H3PO4, H2SO4, NaOH, KOH, etc.).

 

Conclusion

Because of its excellent thermal shock resistance and low thermal conductivity, high temperature insulated wool is superior to glass wool and rock wool. Its potential to replace these products is expected to have a positive impact on its global demand. It is an accumulation of fibers of different diameters and lengths, so they are increasingly used in various end-use industries, so its development is bright. If you want to know more about this product, please contact us in time. Our company is committed to the production of high temperature insulation wool related substances. We will provide you with the latest information about it.


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