Common industrial air separation machines

1. Nitrogen production by cryogenic air separation:

Nitrogen production by cryogenic air separation is a traditional method for nitrogen production, which has a history of several decades. It takes air as raw material, after compression, purification, and then uses heat exchange to liquefy air into liquid air. Liquid air is mainly a mixture of liquid oxygen and liquid nitrogen. Nitrogen can be obtained by separating liquid oxygen and liquid nitrogen with different boiling points (at 1 atmospheric pressure, the boiling point of the former is - 183 ℃, the latter is - 196 ℃). The cryogenic air separation nitrogen generator is complex, covers a large area, has high capital construction cost, high equipment one-time investment, high operation cost, slow gas production (12-24 h), high installation requirements and long cycle. Considering the factors of equipment, installation and infrastructure construction, the investment scale of PSA plant with the same specification for equipment below 3500nm3 / h is 20% - 50% lower than that of cryogenic air separation unit. Cryogenic air separation nitrogen generator is suitable for large-scale industrial nitrogen production, but medium and small-scale nitrogen production is not economical.

2. Nitrogen production by molecular sieve air separation (PSA or PSA type)

PSA has become the preferred method for small and medium-sized nitrogen users because it is competitive among nitrogen generators below 3000nm3 / h. Because, using air as raw material, carbon molecular sieve as adsorbent, using pressure swing adsorption principle, using carbon molecular sieve to selectively adsorb oxygen and nitrogen to separate nitrogen and oxygen is generally called PSA nitrogen production. This method is a new nitrogen production technology developed rapidly in the 1970s. Compared with the traditional nitrogen production process, the process is simple, highly automated, fast gas production (15-30 minutes), low energy consumption, product purity can be adjusted in a large range according to the needs of users, easy operation and maintenance, low operation cost and strong adaptability of the device.

3. Nitrogen production by membrane air separation (hollow fiber membrane separation)

Using air as raw material, under a certain pressure, oxygen and nitrogen and other gases with different properties have different permeation rates in the membrane to separate oxygen and nitrogen. Compared with other nitrogen generators, it has the advantages of simpler structure, smaller volume, no switching valve, less maintenance, faster gas production (≤ 3 minutes), and convenient capacity increase. It is especially suitable for medium and small nitrogen users with nitrogen purity ≤ 99.5%, and has the best function price ratio. When the purity of nitrogen is above 98%, the price of PSA nitrogen generator with the same specification is more than 15%.