Introduction to three principles for designing liquid nitrogen generators

　　Nitrogen is a commonly used inert gas, low in price, easy to produce and non-toxic. It is commonly used as chromatographic carrier gas, purging, and protection in the laboratory. There are three main sources of nitrogen in the laboratory, one is cylinder gas, the other is pipeline gas, and the third is liquid nitrogen generator. Cylinder gas is of high quality, but steel cylinders are pressure vessels. Certain qualifications are required for transportation and storage. It is troublesome and expensive to replace in remote areas. Pipeline gas is large-scale nitrogen production and unified dispatch and use, which is suitable for large factories or industries where gas users are concentrated. In the park, the amount of gas used is large, and the construction cost is high; the liquid nitrogen generator is for on-site nitrogen production, mostly for small gas stations or laboratory instruments or small production lines. The use is flexible and the cost is controllable. There are no special requirements for transportation and storage. Choose for more and more laboratory users.

　　There are three types of liquid nitrogen generators according to their principles. The brief introduction is as follows for your reference:
　　1. PSA pressure swing adsorption nitrogen production. Using the difference in the adsorption capacity of nitrogen and other gas molecules in molecular sieves, the accumulation of concentration differences is formed, and high-purity nitrogen is produced at the end of the molecular sieve column.
　　2. Electrochemical method for producing nitrogen. High-pressure air is introduced into the cathode of the hydrogen electrolysis cell (the side where hydrogen is produced). Under the action of the catalyst, hydrogen and oxygen form a micro fuel cell to complete the oxidation-reduction reaction to produce water. The macroscopic performance is that the oxygen in the air is removed, and the remaining Nitrogen.
　　3. Nitrogen production by membrane separation. The high-pressure air passes through the hollow fiber membrane module, and the difference in diffusion speed of nitrogen and oxygen molecules accumulates, forming high-purity nitrogen at the output end of the membrane module. The purity of the formed product gas can reach 99%, and the gas flow rate is >5000ml/min, and can be accumulated. The use does not affect the quality of the product, and the gas device can be expanded infinitely without considering other restrictions.
　　In the laboratory, it is mainly used for purging, protecting, replacing oxygen, etc. that do not require particularly high gas purity. The main advantage of this type of generator is that it has a large flow rate. Laboratory-grade products are generally around 50L/min, and can be expanded at will, while having a long life.