Liquid nitrogen supply and PSA on-site nitrogen generation are two mainstream nitrogen supply modes in the industrial field, and their operation cost differences directly affect the long-term economic benefits of enterprise production. Liquid nitrogen generators mainly rely on industrial liquid nitrogen purchase, transportation, vaporization and on-site storage to realize nitrogen supply, while PSA nitrogen generators adopt on-site compressed air separation to produce nitrogen independently. The two modes have obvious differences in initial investment, daily operating cost, maintenance cost and loss cost, and are suitable for different production scale and gas consumption scenarios.

In terms of daily operating costs, PSA nitrogen generators have significant economic advantages in long-term and large gas consumption scenarios. The operating cost of PSA equipment mainly includes electricity consumption, compressed air consumption and regular replacement cost of filter elements and molecular sieves. The power consumption per cubic meter of qualified nitrogen is extremely low, and the consumables have a long service life, with low annual maintenance cost. In contrast, the operation cost of liquid nitrogen mode is high and unstable, including liquid nitrogen raw material purchase cost, special refrigeration transportation cost, on-site storage tank heat loss and vaporization loss cost. The unit cost of liquid nitrogen gasification is much higher than that of PSA on-site nitrogen production, and the price of liquid nitrogen is affected by market supply and demand, with large cost fluctuation.

In terms of initial investment and scenario adaptability, liquid nitrogen mode has low early-stage investment, only needing to be equipped with liquid nitrogen storage tanks and vaporizers, which is suitable for small-batch, intermittent and low-frequency nitrogen demand. PSA nitrogen generators require a certain initial equipment investment, but there is no subsequent repeated gas purchase cost, and the cost advantage becomes more obvious with the increase of service life and gas consumption. In addition, liquid nitrogen has unavoidable vaporization loss during storage and transportation, resulting in idle waste of cost, while PSA nitrogen generators produce gas on demand without loss. Comprehensive comparison shows that for enterprises with stable and continuous nitrogen demand, PSA nitrogen generators can save more than 40% of annual nitrogen supply cost compared with liquid nitrogen supply mode.