Application of Cross Temperature Measurement Technology in WISCO Double Bell Top Blast Furnace
Luoyang leipu electromechanical equipment co., ltd.-cross temperature measurement
Thermocouple across temperature of blast furnace-special thermocouple for iron and steel metallurgy industry-Jiangsu Huanya Electric Heating Instrument Co., Ltd.
Reference materials "
Brief introduction of KG type cross temperature measuring device for blast furnace
I. Overview of Cross Temperature Measuring Device for Blast Furnace
Because of its accuracy and digitalization, the cross temperature measuring device of blast furnace plays an extremely important role in understanding the distribution of top gas, improving utilization coefficient and reducing coke ratio. However, the design of the existing cross temperature measuring device for blast furnace is unreasonable, which makes it difficult for blast furnace operators to obtain smelting information continuously and accurately for a long time, which has an important impact on production and even the smooth operation of blast furnace. Therefore, operators are eager to transform and improve the existing cross temperature measuring device of blast furnace.
Second, the present situation of cross temperature measuring device for blast furnace
At present, the cross temperature measuring devices for blast furnaces used in major domestic steel mills are mainly divided into two categories:
1. One is the anhydrous cross temperature measuring device of blast furnace. The cast composite pipe structure is adopted, and the hot spots for temperature measurement are buried inside.
2. The other is a cross temperature measuring device for water-cooled blast furnace. A large amount of water is introduced into the body, which reduces the temperature of the body, thus ensuring that the equipment can be used in ultra-high temperature environment and prolonging the service life. This cross temperature measuring device is made of welded steel plate, and the inside is welded enough to form a cooling water tank.
Based on various working conditions, the two kinds of cross thermometers with water cooling are obviously better than those without water cooling, because the cross thermometers without water cooling have high body temperature and low strength at high temperature. Due to the alternating action of high-temperature gas and water pumped from the top of the furnace, the cross thermometer will be deformed and broken under frequent quenching and heating environment (as shown in figure 1). However, if the design of water-cooled cross thermometer is unreasonable and the welding quality is not high, water leakage will easily occur, which will bring great harm to blast furnace.
Figure 1 (cross thermometer without water cooling produced by domestic manufacturers)
The existing water-cooled cross temperature measuring device is easy to warp and deform.
In the process of blast furnace production, water is often pumped from the top of the blast furnace to cool the blast furnace, which will lead to excessive temperature difference between the upper and lower sections of the cross temperature measuring device, thus generating a large amount of thermal stress in the cross temperature measuring device, making the cross temperature measuring device tilt upward and even touch the chute (as shown in Figure 2).
Figure 2 (The water-cooled cross temperature measuring device produced by domestic manufacturers is deformed upwards)
The existing water-cooled cross temperature measuring device is prone to water leakage.
(1) Weld is too long. There are ten welds in the water tank, each of which is 4-6 meters long. It is difficult to guarantee the welding quality. Any welding defect will lead to water leakage in the water tank; (2) The cross section of the water tank is small, and the weld is particularly long. During the welding process, the long water tank is bent and deformed due to a lot of heat. In the process of correcting the water tank, tiny cracks will inevitably be pulled out between the weld and the steel plate, leading to water leakage in the water tank; ③ Pressure failure. Because the cross temperature measuring device is very long, it is not easy to anneal after welding, and the thermal stress generated during welding is not easy to eliminate; Even if the thermal stress is eliminated in the manufacturing process, it will reappear due to too many welds in the frequent quenching and heating environment. Under the combined action of thermal stress and corrosive medium at a certain temperature, the water tank, especially between the steel plate of the water tank and the weld, cracks and leaks (as shown in Figure 3). The phenomenon of stress corrosion is complicated. When the stress does not exist, the corrosion rate is very slow. When the stress reaches a certain level, the metal will break without serious corrosion. This kind of fracture is brittle without obvious signs. (4) The water tank is rectangular, and cold water will stagnate at its four corners, which is prone to local boiling, so the four corners of the water tank are often burned and leaked.
Fig. 3 (The water-cooled cross temperature measuring device produced by a domestic manufacturer was burnt and cracked)
The thermocouple of that exist cross temperature measuring device is not easy to replace.
Because the end of the thermocouple protective sleeve of the existing cross temperature measuring device must be bent, the thermocouple can sense the temperature of high temperature gas. In use, thermocouples are easily damaged. The damaged thermocouple can only be replaced after the whole cantilever is pulled out of the blast furnace when the blast furnace is slack. Once coking seriously blocks the thermocouple well, the thermocouple can't be pulled out or broken in the well, so even if the cross thermometer is watertight, reinstallation is just a decoration.
Three. KG type cross temperature measuring device for blast furnace (as shown in Figure 4)
Based on the above, the existing water-cooled cross temperature measuring device is reformed, which overcomes the shortcomings of easy upward deformation, easy water leakage and inconvenient thermocouple replacement, and doubles its continuous service life. On the basis of the existing water-cooled cross temperature measuring device, KG water-cooled cross temperature measuring device retains the water-cooling function, but its structure is more reasonable. The advantages are as follows: (1) The thermocouple is made of high-temperature resistant alloy tube, and the front end is completely sealed, so that the thermocouple is not in direct contact with gas, and it is not easy to be damaged. Even if it is damaged, it can be replaced during the operation of the blast furnace, without affecting the normal use of equipment and the normal production of the blast furnace; ② The body is made of high-temperature resistant stainless steel fluid pipe, and only the front end is welded, so as to realize water-cooling and reliable sealing, and only a small amount of welding makes the body more stable and less prone to water leakage; (3) The cross section of the cross temperature measuring device is circular, and there is no dead angle when cooling water circulates, which greatly improves the cooling effect of the cross temperature measuring device. Even if the pipes and materials in the blast furnace collapse, the KG type cross temperature measuring device of the blast furnace can completely resist. To sum up, the service life of KG type cross temperature measuring device for blast furnace is more than twice that of similar products.
Fig. 4 (KG type cross temperature measuring device for blast furnace produced by our company)
Photo of thermowell exposed outside the shell and burned out.
Thermowells are not exposed to the outside, so as not to burn out thermocouples and thermowells.
Good luck! If you have any questions, ask them. This is helpful and I hope to adopt them.