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.