220 Nm3/H High Quality PSA Nitrogen Generation System For SMT Industry , Purity

Taking the clean compressed air as raw material and carbon molecular sieve as adsorbent, PSA nitrogen generation is a new technology of nitrogen which adopts the pressure swing adsorption principle to obtain the nitrogen with purity of 98% to 99.99%. Under the principle, the carbon molecular sieve full of micropore would selectively adsorb the gas molecules.Carbon molecular sieve is made through a series of processing, molding and sintering after grinding the hard coal. The crystal particle of the activated carbon molecular sieve has countless microporous caves after molding. Diameter of the cave is controlled between oxygen molecules and nitrogen molecules. (Note: the diameter of oxygen molecules is smaller than nitrogen molecules).

The gas molecules with diameter less than that of the cave can enter the cave, while those molecules whose diameter larger than the cave will be obstructed outside the cave. The cave plays a role of sieving the molecules. A large number of molecular sieve piles up in the adsorption tower. At the beginning of operation, the air pressure in the adsorption tower is atmospheric (i.e. gauge pressure is 0MPa); when the air of 0.7 to 0.8MPa pressure enters into the carbon molecular bed, the partial pressure of oxygen in the molecular sieve cave (Note: air pressure consists of the partial pressure of various gases; the air pressure is higher, the partial pressure of the corresponding gas is higher) has pressure difference with that outside the cave, therefore, oxygen molecules outside has the trend to enter into the molecular sieve cave. With the promotion of this force, lots of oxygen molecules can rapidly enter into the cave. (Note: the bigger the pressure difference is, the more quickly oxygen molecules enter into the molecular sieve cave.) Large amounts of oxygen molecules enter into the molecular sieve cave. While the nitrogen molecules cannot enter because their diameter is greater than that of the molecular sieve cave. The nitrogen molecules concentrate in the gas phase outside the molecular sieve, thus separating nitrogen and oxygen from the air. Because the molecular sieve cave has a certain volume, more and more oxygen molecules enter into the molecular sieve after the adsorption tower works for a certain time, and the oxygen partial pressure inside the molecular sieve cave is higher and higher. When the oxygen partial pressure inside and outside the molecular sieve cave is equal, oxygen has no flow trend and it only freely expands inside and outside the molecular sieve cave, which is the saturation for molecular sieve’s oxygen -adsorption. (The maximum oxygen-adsorption capacity of carbon molecular sieve increases with the adsorption pressure rises and vice versa. So the adsorption pressure should be controlled in a higher range of pressure, which normally is 0.7 ~ 0.8MPa, to achieve better adsorption effect). When the adsorption of the molecular sieve in the adsorption tower reaches saturation, oxygen molecules inside the molecular sieve cave shall be emitted for preparation of the next operation.

After the end of the operation when the exhaust gas is emitted by the adsorption tower, the average pressure of the carbon molecular sieve layer drops from 0.3 ~ 0.6MPa to normal pressure. The oxygen partial pressure inside the carbon molecular sieve cave is greater than that of the external, and the oxygen flows outward from the cave, releasing the adsorbed oxygen molecules from the molecular sieve cave. That’s all for the PSA nitrogen generation process.

Nitrogen flow: 0-2,000Nm3/h O2: ≤1ppm Dew point: ≤-70℃  Nitrogen purity: 99.99%-99.999%