Nitrogen production types include pressure swing adsorption, membrane separation and cryogenic air separation. Nitrogen generator is a nitrogen equipment designed and manufactured according to pressure swing adsorption technology. The nitrogen machine uses high-quality imported carbon molecular sieve as adsorbent and uses the principle of room temperature pressure swing adsorption to separate air to produce high-purity nitrogen. Usually, two adsorption towers are connected in parallel, and the imported PLC controls the automatic operation of the imported pneumatic valve to alternately carry out pressurized adsorption and decompression regeneration to complete nitrogen and oxygen separation and obtain the required high-purity nitrogen.
The first method is nitrogen production by cryogenic process
This method first compresses and cools the air, and then liquefies the air. Using the different boiling points of oxygen and nitrogen components, gas and liquid contact on the tray of the distillation column for mass and heat exchange. The oxygen with high boiling point is continuously condensed from the steam into a liquid, and the nitrogen with low boiling point is continuously transferred to the steam, so that the nitrogen content in the rising steam is continuously increased, while the oxygen content in the downstream liquid is higher and higher. Therefore, oxygen and nitrogen are separated to obtain nitrogen or oxygen. This method is carried out at a temperature lower than 120K, so it is called cryogenic air separation.
The second is to use pressure swing adsorption to produce nitrogen
Pressure swing adsorption method is to selectively adsorb oxygen and nitrogen components in the air through adsorbent, and separate the air to obtain nitrogen. When the air is compressed and passes through the adsorption layer of the adsorption tower, oxygen molecules are preferentially adsorbed, and nitrogen molecules remain in the gas phase to become nitrogen. When the adsorption reaches equilibrium, the oxygen molecules adsorbed on the surface of the molecular sieve are removed by decompression to restore the adsorption capacity of the molecular sieve, that is, adsorbent analysis. In order to continuously provide nitrogen, the unit is usually equipped with two or more adsorption towers, one for adsorption and the other for analysis, and switched for use at an appropriate time.
The third method is to produce nitrogen by membrane separation
Membrane separation method is to separate nitrogen rich gas from mixed gas by using the permeability selectivity of organic polymerization membrane. The ideal film material should have high selectivity and high permeability. In order to obtain an economical process, a very thin polymer separation membrane is required, so it needs support. Armor piercing projectiles are usually flat armor piercing projectiles and hollow fiber armor piercing projectiles. In this method, if the gas production is large, the required film surface area is too large and the film price is high. Membrane separation method has simple device and convenient operation, but it is not widely used in industry.
To sum up, the above is the main content of several ways of nitrogen production. Cryogenic air separation can produce not only nitrogen, but also liquid nitrogen, which can be stored in liquid nitrogen storage tank. The operation cycle of cryogenic nitrogen production is generally more than one year, so standby equipment is generally not considered for cryogenic nitrogen production. The principle of nitrogen production by membrane air separation is that the air enters the polymer membrane filter after being filtered by the compressor. Due to the different solubility and diffusion coefficient of different gases in the membrane, the relative permeation rate in different gas membranes is different. When the purity of nitrogen is greater than 98%, the price is more than 15% higher than that of PSA nitrogen generator of the same specification.
Post time: Jan-18-2022