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Matters needing attention when using tungsten-rhenium thermocouple
2012-3-3 10:32:23

从事化工行业的朋友应该不陌生吧,而你们了解钨铼热电偶的特点吗?不管大家了不了解,我在这里在做一个介绍,钨铼热电偶的特点是:热电极丝熔点高(3300℃),蒸气压低,极易氧化;在非氧化性气氛中化学稳定性好。 Tungsten-rhenium thermocouples are no strangers to the chemical industry. Do you know the characteristics of tungsten-rhenium thermocouples? Regardless of everyone's understanding, I will make an introduction here. The characteristics of tungsten-rhenium thermocouples are: High melting point (3300 ℃), low vapor pressure, easy oxidation; good chemical stability in non-oxidizing atmosphere. Large electromotive force and high sensitivity, the main thing is cheap. At present, when measuring temperatures above 1600 ° C, the non-contact method is often used. However, the error of this method is relatively large. If the contact method is used, the real temperature can be accurately measured. Among high-temperature thermocouples, high-temperature noble metal thermocouples (platinum-rhodium thermocouples) are expensive and the highest temperature can only be below 1800 ° C. Tungsten-rhenium thermocouples not only have a high temperature measurement limit, but also have good stability. Therefore, tungsten-rhenium thermocouples Even widely used in various industries. China has abundant tungsten resources. Tungsten-rhenium thermocouples are cheap and can partially replace high-temperature precious metal thermocouples (platinum-rhodium thermocouples).

The maximum operating temperature of tungsten-rhenium thermocouples can reach 2800 ° C. However, when the temperature is higher than 2300 ° C, the data is scattered. Therefore, the best use temperature is around 2000 ° C. Tungsten-rhenium thermocouples are extremely susceptible to oxidation and are suitable for use in inert or dry hydrogen, or they can be isolated from oxygen with a dense protective tube. Can not be used in carbon-containing atmosphere (such as in a hydrocarbon-containing atmosphere, the temperature exceeds 1000 ℃ will be corroded). Tungsten or tungsten thorium is easy to form stable carbides in a carbon-containing atmosphere, which reduces its sensitivity and causes brittle fracture. In the presence of hydrogen, it will accelerate carbonization. The anti-oxidation problem of tungsten-rhenium thermocouples has always been a topic of concern to scholars at home and abroad, and is committed to research and solution. Our company has adopted the international advanced manufacturing process and successfully developed the assembled high temperature and high pressure tungsten rhenium thermocouple. The temperature range of this product is 0 ~ 1800 ℃, which is widely used in metallurgy, coking, chemical furnaces, heat treatment, glass, etc. Industry, it has the advantages of high accuracy, low price, stable performance, and is not restricted by the working environment atmosphere. It is an ideal product to replace platinum and rhodium thermocouples. The tungsten-rhenium thermocouple produced by our company has been widely used in many units, and its performance has reached the level of similar products at home and abroad. ,首先要根据窑炉的结构,工作温度,发热原件及所烧成产品等实际情况,进行总体考虑,选择适用的保护管,保护管的耐热度要留有足够的余量。 The choice of protection tube, the use of tungsten-rhenium thermocouple , first of all, according to the actual structure of the kiln structure, operating temperature, heating elements and fired products, and overall considerations, select the appropriate protection tube, the heat resistance of the protection tube Leave enough margin. 1. The ultra-fine corundum tube (Al2O3) contains more than 99.5% corundum. The protective tube has high density and excellent resistance to chemical corrosion. It can be used for a long time up to 1650 ° C. It is easy to cause carbonization in a graphite furnace above 1300 ° C. Used in oxidation, reduction, vacuum and inert gas. 2. Recrystallized silicon carbide tube (SiC) The protection tube has strong thermal shock resistance, good thermomechanical properties, strong chemical resistance, and poor density. It can be used for a long time up to 1650 ° C. It is suitable for oxidation, reduction, vacuum and Use in inert gas. 3. Zirconia tube (ZrO2) The protective tube has strong corrosion resistance and good heat resistance. It can be used for a long time at 2000 ℃, and it is suitable for use in oxidation, reduction, vacuum and inert gas. 4. Molybdenum tube (Mo) The protective tube has good mechanical properties and thermal shock resistance at high temperatures, does not resist oxidation, and can be used for a long time up to 1800 ° C. It is suitable for use in reduction, vacuum and inert gases. 5. MoSi tube This protective tube has good mechanical properties at high temperatures, excellent thermal shock resistance and corrosion resistance, and good density. It can be used for a long time up to 1650 ° C. It is suitable for oxidation, reduction, vacuum and inert gas. Use. 6. Tantalum tube (Ta) The protective tube has good high temperature resistance, high temperature resistance to corrosion and thermal shock, and does not resist oxidation. It can be used for a long time up to 2300 ° C. It is suitable for reduction, vacuum and inert gas. 7. Tungsten tube (W) The protective tube has good high temperature resistance, high temperature resistance to corrosion and thermal shock, and does not resist oxidation. It can be used for a long time up to 2300 ° C. It is suitable for reduction, vacuum and inert gases.

在安装过程中需要特别注意,热电偶的安装插入孔必须安装定位保护套,对钼、钨、钽保护管制作的热电偶,安装过程中需特别小心,该保护管常温下硬而脆,很容易造成脆断。 Attention during installation and use: 1. Tungsten-rhenium thermocouples need special attention during the installation process. The installation insertion holes of the thermocouples must be installed with positioning protective sleeves. For thermocouples made of molybdenum, tungsten, and tantalum protective tubes, the installation process Special care should be taken in this protection tube. The protection tube is hard and brittle at room temperature, which can easily cause brittle fracture. 2. During the use of tungsten rhenium thermocouples or during maintenance after use, if the thermocouples are not damaged, disassembly and assembly of tungsten rhenium thermocouples is forbidden, and as far as possible, do not touch the hot end of the thermocouple, because tungsten rhenium thermocouples have passed through Later, the even wire became very brittle, so it was easy to cause the even wire to become brittle during the vibration process.