Nitrogen liquefaction is a process involving several key steps, mainly including the following aspects:
1. Raw material preparation
First, high-purity nitrogen needs to be prepared as raw material. In nature, nitrogen is the main component of the atmosphere, accounting for about 78% of the total volume. However, nitrogen extracted directly from the air contains impurities such as oxygen, water vapor and other gases. Therefore, before liquefaction, the nitrogen must be purified to ensure that its purity reaches the required level. This usually involves the use of adsorbents or other purification technologies to remove impurities.
2. Compression
Next, the purified nitrogen needs to be compressed. This is because the liquefaction of gas depends not only on temperature, but also on pressure. According to the gas law, increasing the pressure of the gas helps to lower its boiling point, making liquefaction possible. In the process of nitrogen liquefaction, it is usually necessary to compress the nitrogen to more than several atmospheres.
3. Cooling
The compressed nitrogen then needs to be cooled to extremely low temperatures. This is because the critical temperature of nitrogen is low, about -147°C. Only below this temperature can nitrogen be liquefied. The cooling process is usually divided into several stages, first pre-cooling and then deep cooling. Pre-cooling can initially reduce the temperature of nitrogen and reduce the load of the subsequent deep cooling process. Deep cooling uses a refrigeration system to further cool the nitrogen to the liquefaction temperature.
4. Liquefaction
When the nitrogen is cooled to a low enough temperature, it will begin to liquefy. This process usually occurs in a special liquefier, where the nitrogen is further cooled under high pressure until it turns into a liquid state. The liquefied nitrogen can be stored in an insulated container to prevent it from vaporizing rapidly.
5. Storage and transportation
The liquefied nitrogen needs to be properly stored and transported. Because the boiling point of liquid nitrogen is extremely low, special insulating materials and containers are required to prevent heat from entering, thereby preventing the liquid nitrogen from vaporizing rapidly. In industrial production, liquid nitrogen is usually stored in large insulated storage tanks or transported to the place of use through insulated pipelines.
In summary, nitrogen liquefaction is a process involving multiple key steps, including raw material preparation, compression, cooling, liquefaction, storage and transportation. Each step is crucial, and any improper link may lead to liquefaction failure or inefficiency.
