Product Category
Analysis of problems in cryogenic storage tanks
Date: Feb 06, 2020
The cryogenic storage tank manufacturers summarize the following points and analyze the common problems of cryogenic containers in periodic inspection:
1. Loss of vacuum.
Cryogenic vacuum storage tanks are classified into vacuum powder type and high-vacuum multi-layer insulation type according to the type of vacuum. There are many factors that can affect vacuum loss, including:
The first is the influence of thermal insulation materials (powder pearl sand, thermal insulation aluminum foil, adsorption materials, etc.) in the interlayer. Due to different physical properties and physical shapes of thermal insulation materials, their thermal conductivity is also different. In addition, the same thermal insulation materials have different thermal conductivity when they are at different degrees of vacuum. The basic rule is that as the vacuum decreases, the thermal conductivity increases.
The second is the effect of vacuum sandwich gas. As the degree of vacuum decreases, the gas content in the vacuum interlayer increases, and the thermal conductivity increases.
The third is the effect of the outgassing phenomenon of various materials in the interlayer, which is what we call the vacuum outgassing rate of the vacuum interlayer. Over time, outgassing of the material is inevitable, which in turn leads to a reduction in vacuum.
The fourth is the effect of temperature. In the case of stable heat transfer, the thermal conductivity of thermal insulation materials such as interlayer pearlescent sand decreases with decreasing temperature.
2. Failure of safety accessories.
The reasons for the failure of the safety accessories of the cryogenic storage tank are: the safety valve calibration period is exceeded, the internal pressure of the tank is too high, and the vacuum degree exceeds the safe range. There is a leak at the connection part of the safety accessory, and some quality problems of the safety accessory, for example, it is found that the vacuum gauge of the container fails during the inspection due to quality problems, and the vacuum cannot be measured.
3. Leakage and icing of external pipelines and valves.
Judging from the regular inspection of cryogenic containers in recent years, there are many problems with externally connected pipes. The main problems are the leakage of welds in external pipes and the phenomenon of frost cracking of the pipes. The cause of the leakage, from the installation point of view, the external pipeline of the cryogenic pressure vessel is installed on-site, whether the welding conditions on site meet the welding requirements, and the quality level of the installation unit and the operator is uneven. Sex, there are some security risks. From the perspective of the use process, the main reason is that the sealing performance of the connection is not good, or due to repeated filling, there is a change in temperature difference between the connection of the nozzle and the casing, which causes alternating stress between the connection portion of the nozzle and the casing and the sealing surface of the valve. And cause a leak.
1. Loss of vacuum.
Cryogenic vacuum storage tanks are classified into vacuum powder type and high-vacuum multi-layer insulation type according to the type of vacuum. There are many factors that can affect vacuum loss, including:
The first is the influence of thermal insulation materials (powder pearl sand, thermal insulation aluminum foil, adsorption materials, etc.) in the interlayer. Due to different physical properties and physical shapes of thermal insulation materials, their thermal conductivity is also different. In addition, the same thermal insulation materials have different thermal conductivity when they are at different degrees of vacuum. The basic rule is that as the vacuum decreases, the thermal conductivity increases.
The second is the effect of vacuum sandwich gas. As the degree of vacuum decreases, the gas content in the vacuum interlayer increases, and the thermal conductivity increases.
The third is the effect of the outgassing phenomenon of various materials in the interlayer, which is what we call the vacuum outgassing rate of the vacuum interlayer. Over time, outgassing of the material is inevitable, which in turn leads to a reduction in vacuum.
2. Failure of safety accessories.
The reasons for the failure of the safety accessories of the cryogenic storage tank are: the safety valve calibration period is exceeded, the internal pressure of the tank is too high, and the vacuum degree exceeds the safe range. There is a leak at the connection part of the safety accessory, and some quality problems of the safety accessory, for example, it is found that the vacuum gauge of the container fails during the inspection due to quality problems, and the vacuum cannot be measured.
3. Leakage and icing of external pipelines and valves.
Judging from the regular inspection of cryogenic containers in recent years, there are many problems with externally connected pipes. The main problems are the leakage of welds in external pipes and the phenomenon of frost cracking of the pipes. The cause of the leakage, from the installation point of view, the external pipeline of the cryogenic pressure vessel is installed on-site, whether the welding conditions on site meet the welding requirements, and the quality level of the installation unit and the operator is uneven. Sex, there are some security risks. From the perspective of the use process, the main reason is that the sealing performance of the connection is not good, or due to repeated filling, there is a change in temperature difference between the connection of the nozzle and the casing, which causes alternating stress between the connection portion of the nozzle and the casing and the sealing surface of the valve. And cause a leak.
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