Cryogenic Nitrogen Generator

In a cryogenic nitrogen generator (using a dual-column system as an example), air is first drawn in through a series of filtration, compression, precooling, and purification processes. During precooling and purification, moisture, carbon dioxide, and hydrocarbons are removed from the air. The treated air then enters the cold box where it is cooled to liquefaction temperature through a plate heat exchanger before entering the bottom of the lower column.

The liquid air at the bottom is super-cooled and directed into the condenser at the top of the lower column (higher pressure). The evaporated oxygen-rich air is then introduced into the upper column (low-pressure) for further fractionation. The oxygen-rich liquid air at the bottom of the upper column is directed to the condenser at its top. The evaporated oxygen-rich liquid air is rewarmed through the cooler and main heat exchanger, then extracted midway and sent to the expander system。

The expanded cryogenic gas is rewarmed through the main heat exchanger before leaving the cold box. A portion is vented while the remainder serves as warm gas for the purifier. High-purity liquid nitrogen obtained at the top of the upper column (low-pressure) is pressurized by a liquid nitrogen pump and sent to the top of the lower column (high-pressure) to participate in fractionation. The final high-purity nitrogen product is drawn from the top of the lower column (high-pressure), rewarmed by the main heat exchanger, and then discharged from the cold box into the user's pipeline network for downstream production.