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Principle and Technology of Liquid Nitrogen Freezing

Editor:adminClick: Time:2017-10-18 09:43

Liquid nitrogen freezing principle and process: liquid nitrogen is a relatively ideal refrigerant, colored transparent, slightly lighter than water, inert, no corrosion, vibration, spark is stable, an atmospheric pressure, liquid nitrogen vaporization The temperature is -195.81t, the latent heat of vaporization is 47.9kcal / kg. Due to the development of space technology and steelmaking industry, a large number of oxygen by-products - nitrogen liquid liquefied liquid nitrogen has been widely used as a kind of cryogenic cold source. Medicine, laser, superconductivity, food, biological and other industrial production and scientific research. In the 20th century, the liquid nitrogen refrigerant direct gasification and refrigeration construction of underground construction has become a new method of soil freezing, which has opened up a new way to improve the freezing speed of the strata.
Liquid nitrogen freezing has the advantage of simple equipment, construction speed, suitable for local special treatment and rapid rescue and rapid construction. For example, the northern suburbs of Paris water supply tunnel, built in the ground 3m deep, when the current into the 70m, encountered flow sand can not pass, the use of liquid nitrogen freeze, the process system is liquid nitrogen from the ground tank through the pipeline to the work surface.
Liquid nitrogen in the freeze after the vaporization of heat, the gas nitrogen discharged from the ground by the release of the atmosphere, the freezing time only 33 hours, frozen soil speed of 254m / day and night, 10 times faster than conventional salt water freeze. Other liquid nitrogen frozen like a British groundwater working surface frozen soil Edinburgh's sewer, London Post Office of the harbor wells, the United States held l a water sand; a watertight sandstone; 9 a marl; 4 a well; Surface construction, a subway project in Japan to 5 a liquid nitrogen Q letter car; 6 a liquid nitrogen 黼; 7 a frozen tube; 8 a liquid nitrogen vaporization filling and the former Soviet Union New Coriolis test construction. In the case of
The relationship between the boiling point of nitrogen and the pressure of liquid nitrogen can be calculated according to the enthalpy-pressure diagram of nitrogen. Such as liquid nitrogen vaporization pressure is 0.12MPa, from the liquid vaporization into the gaseous enthalpy increase of 47.6kcal / kg. The vaporization process is isothermal endothermic process, the corresponding vaporization temperature of -193.92 ℃, followed by nitrogen overheating further cooling, sensible heat is 0.25keal / kg true C. If the temperature to -60t, then overheating refrigeration 34kcal / kg, then the liquid nitrogen at 0.12MPa pressure vaporization, to-60'C, cooling capacity of 81.6kcal / kKo.
Liquid nitrogen, liquid argon and other gases are generally used Dewar jar, which is because the Duwa tank gas supply and cylinder gas supply with a large storage capacity, high purity gas, convenient transportation, high security and cost-effective advantages. So now customers use Duwa cans are very common. Here to introduce the use of the process in the Dewa need to pay attention to the convenience of contact with the user to understand.
1. Dewar tank gas in the tank when the pressure is too high, will be out of pressure discharge gas. So keep the storage at the ventilation, to avoid excessive gas concentration caused by suffocation.
2. Dewa tank containing the gas (liquid nitrogen, liquid oxygen, liquid argon or liquid carbon dioxide) minimum temperature can be minus 196 degrees, so use the skin to avoid direct contact with the liquid gas to prevent frostbite.
3. Because of the large amount of gas used in the valve and pipe icing, to use water after pouring fold, must not be violent fold.
4. Dewa pots should be placed vertically during use and transport to avoid tilting. To prevent the discharge of liquid from the safety valve, causing frostbite and damage to the dam. In the use of the process, open and close the valve when the intensity can not be too large.
Security is the first for everyone, and only the protection of life and property we can talk about the value of life, so in the use of Duwa pots we have a lot of attention to safety.
If you are interested in the liquid nitrogen tanks or need other model, please click on our online customer service, or call us. Pchao, provide  different model of the liquid nitrogen container.
Welcome sending your inquiry: Phone : +8613569413718  

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