Nitrogen, due to its stable chemical properties, plays a dual role as both a "safety guard" and a "process raw material" in industrial systems. Used in the chemical industry for nitrogen sealing of storage tanks and pipeline purging and replacement, it is a standard equipment for explosion and oxidation prevention; Used as a protective gas for bright annealing of steel in the metallurgical industry to avoid high-temperature oxidation and peeling; The electronics and lithium battery industry requires 99.999% high-purity nitrogen to provide an oxygen free environment for chip packaging and battery injection. In addition, nitrogen filling for food preservation, laser cutting assisted gas, liquid nitrogen freezing for medical purposes, and other scenarios are also widely used.
In industry, nitrogen and oxygen are usually produced in the same source, and the core depends on the technical route of the oxygen production equipment. The deep cryogenic air separation unit (KDON series) can simultaneously produce high-purity oxygen and pure nitrogen, while the PSA pressure swing adsorption oxygen generator can only produce oxygen, and the adsorbed nitrogen is directly discharged and cannot be recovered as qualified products.
The pure nitrogen production of cryogenic air separation follows clear engineering laws. The proportion of nitrogen in the air component is about 78%. Theoretically, for every 1 Nm ³/h of oxygen produced, the corresponding native nitrogen is about 3.7-3.8 Nm ³/h. However, due to the limitation of distillation reflux conditions, the actual amount of pure nitrogen that can be extracted is lower than the theoretical value. In mainstream industry designs, the ratio of pure nitrogen to oxygen production is approximately 2.5-3.5:1, with a typical configuration of 3:1. For example, the KDON-1000/3000 device produces 1000 Nm ³/h of oxygen and 3000 Nm ³/h of pure nitrogen.
It should be noted that the higher the amount of pure nitrogen extracted, the better. Excessive extraction will weaken the reflux ratio of the upper tower, resulting in a decrease in oxygen extraction rate and fluctuations in purity. Each set of devices has an optimal operating equilibrium point, and it is necessary to make economic matching between oxygen and nitrogen production based on the actual gas demand of users.
