Views: 8 Author: Site Editor Publish Time: 2021-06-11 Origin: Site
Liquid nitrogen (often written as LN2) is a liquid form of nitrogen formed at low temperatures. Nitrogen has a boiling point of -196°C, and liquid nitrogen will be formed if the temperature is below this under normal atmospheric pressure; if it is pressurized, liquid nitrogen can be obtained at a higher temperature. In industry, liquid nitrogen is obtained by fractional distillation of air. After the air is purified, it is liquefied in a pressurized and cooled environment, and separated by the different boiling points of the components in the air. Nitrogen (78.09% of the air volume) is released first (and not liquefied), then argon, which accounts for 0.93% of the air, and finally oxygen, which accounts for 20.95%. Tianmao Gas reminds you that the natural evaporation consumption of liquid nitrogen is 1-1.25 liters per day and night, so do not cover the liquid nitrogen container too tightly to prevent explosion. The explosion of the liquid nitrogen tank may be caused by high temperature, impact, and extrusion. An explosion can occur if the internal pressure increases or the strength of the cylinder decreases.
1. External environmental impact
High temperature and high pressure
Liquid nitrogen is made by air compression and cooling, and gasification can be restored to nitrogen. When each liter of liquid nitrogen is converted, the temperature will rise by 15°C and the volume expansion will be about 180 times. When the external temperature and pressure exceed the cooling temperature and pressure that the tank can withstand, an explosion will occur.
Collision and vibration
The tank body of the liquid nitrogen container is designed with a special shock-proof design. In addition to static storage, the transport liquid nitrogen tank can also be transported and used in a filled state. However, after the tank body of the liquid nitrogen tank receives a very strong collision and vibration, it will cause damage to the tank body insulation layer or other parts, so that the external environment will directly affect the vapor and cause an explosion.
Poor sealing and ventilation
If the environment where liquid nitrogen is used and stored is not well ventilated, it will cause the concentration of nitrogen and hydrogen monoxide in the room to accumulate, and if it reaches the explosion limit, it will cause an explosion.
2. Quality factors
Improper selection of materials
Liquid nitrogen containers are generally made of pure aluminum foil and stainless steel cold- and hot-rolled steel plates. If the specifications and quality of these materials do not meet the requirements of the norms and standards, and cannot meet the withstand conditions of frozen liquid nitrogen, an explosion may occur.
The liquid nitrogen tank has both inner and outer tanks. Once the outer reflective material and heat insulating material of the inner tank fall off, the adjacent reflective material will directly contact the outer tank, causing the liquid nitrogen in the inner tank to expand and vaporize, or even explode.
Valves, meters and other accessories are obsolete and aging
In the long-term use process, if the valves, meters and other accessories of the liquid nitrogen tank are not frequently checked and replaced, once these accessories are old and aging, the temperature of the liquid nitrogen will rise or leak, which may cause an explosion.