The reflux nitrogen in air separation equipment can carry away frozen water and carbon dioxide, mainly based on the physical characteristics of nitrogen, equipment operation mechanism, and the synergistic effect of self removal principle.
The polluted nitrogen discharged from the distillation tower is an unsaturated gas with high nitrogen content and basically no moisture or carbon dioxide. This characteristic gives it the ability to absorb impurities, providing a foundation for subsequent removal processes.
The pressure of polluted nitrogen is much lower than that of normal air, resulting in its actual volume being 3-4 times larger than that of normal air. Although the saturation content of water and carbon dioxide that can be accommodated by a unit volume of polluted nitrogen is relatively low, the increase in total volume significantly enhances its actual capacity to carry more impurities. Although the temperature of polluted nitrogen is lower than that of normal air, it compensates for the insufficient saturation content through its volume advantage. The synergistic effect of temperature and pressure enables nitrogen pollution to more effectively absorb and remove frozen impurities when passing through the heat exchanger.
In the heat exchanger of the air separation equipment, as the air temperature decreases, moisture and carbon dioxide gradually precipitate and freeze on the packing or fins of the heat exchanger. When the reflux nitrogen passes through these channels, frozen impurities will sublime or evaporate into the nitrogen and then be carried out of the equipment.
