At present, there are three kinds of air separation nitrogen generators commonly used in industry, namely cryogenic air separation method, molecular sieve air separation method (PA) and membrane air separation method. Today, let's talk about the cryogenic air separation nitrogen generator. Nitrogen production by cryogenic air separation is a traditional method with a history of nearly several decades. It uses air as raw material, compresses, purifies, and then liquefies the air into air through heat exchange.
A mixture of liquid oxygen and liquid nitrogen is a mixture of liquid oxygen and liquid nitrogen. The boiling point of liquid oxygen is different (at 1 atmosphere pressure, the boiling point of the former is -183°C, and the boiling point of the latter is -196°C). By distillation of liquid air, they are separated to obtain nitrogen. The cryogenic air separation nitrogen generator is complex, occupies a large area, has high infrastructure costs, a large one-time investment in equipment, high operating costs, slow gas production (12-24 hours), high installation requirements, and a long cycle. Considering the comprehensive equipment, installation and infrastructure factors, the investment scale of the PSA unit with the same specification is 20%~50% lower than that of the cryogenic air separation unit. Cryogenic air separation nitrogen generators are suitable for mold nitrogen, but small and medium-sized mold nitrogen is uneconomical.
Molecular sieve nitrogen generation by air separation (PSA or pressure swing adsorption): It is competitive on nitrogen generators below 3000Nm3/h, and is more and more popular with medium and small nitrogen users. PSA nitrogen has become a medium and small nitrogen user welcome method. Since the carbon molecular sieve is used as the adsorbent, the adsorbent is used in the air, and the pressure swing adsorption principle is used to selectively adsorb oxygen and nitrogen with the carbon molecular sieve to realize the method of nitrogen separation. This process is a nitrogen production method developed rapidly in the 1970s. The process is simple, high degree of automation, short gas production time (15-30 minutes), low energy consumption, and can be adjusted in a wide range of molecular sieve nitrogen generators according to user needs, easy operation and maintenance, and low operating costs. The equipment is highly adaptable.
Membrane air separation nitrogen production method (hollow fiber membrane separation): using air as raw material, under certain pressure conditions, using different properties of gases such as oxygen and nitrogen, which have different permeability in the membrane, so as to realize the separation of oxygen and nitrogen . Compared with other nitrogen generators, it has the advantages of simple structure, small size, no switch valve, less maintenance, faster gas production (≤3 minutes), convenient capacity expansion, etc., especially suitable for medium , Small nitrogen users, with the best performance-price ratio. The nitrogen purity is above 98%, and its price is more than 15% higher than that of the PSA nitrogen generator of the same specification.
