Carbon molecular sieve (CMS) is a new type of non-polar adsorbents, which has the performance of absorbing oxygen molecules in the air under normal temperature and pressure, thus obtaining nitrogen-rich bodies. Use carbonMolecular sieveThe most remarkable feature of the new technology of nitrogen production by variable pressure absorption method is: N2The impurity content of the product is relatively low, N2Concentration and gas volume can be adjusted as needed, and O can be obtained through refining2High purity N with content less than 5PPm and dew point less than-60℃2.
In 1960s, carbon molecular sieve was firstly manufactured successfully in America and was promoted and applied soon. At first, carbon molecular sieve was used as the absorbant to separate oxygen from the air, and later it was gradually applied to the equipment for producing nitrogen.
By the end of 1970s S and the beginning of 1980s S, the demand for nitrogen in various countries around the world was continuously increasing, and the technology of pressure swing adsorption nitrogen production was gradually matured, which further promoted the development of carbon molecular sieve manufacturing technology.
By 1982, the output of nitrogen in America and Japan had exceeded that of oxygen one after another. At this time, the nitrogen produced by pressure conversion had already accounted for about 18% of the total output of nitrogen. As the market share of nitrogen produced by pressure conversion was larger and larger, all the major industrial countries in the world have invested funds in the research and development of carbon molecular sieves for pressure conversion, among which the United States, Japan and Germany are in the leading position in technology.
Until today, the main manufacturers of carbon molecular sieve in the world are still distributed in these countries. The famous companies are Calgon company and pulix company in America, igua company and Takeda Company in Japan, BF company in Germany, etc. Among them, American molecular sieve occupies a small market share in China, and German and Japanese molecular sieve manufacturers both have Agency companies in China, so it also occupies the largest market share.
In general, the molecular sieve can be divided into four stages according to the performance difference:
Due to the limitation of manufacturing process, the pore distribution of carbon molecular sieve in the first stage is very uneven, and only nitrogen with the purity of 97% and 98% can be produced, and the recovery rate is only 26% ~ 34%, high energy consumption.
The performance of the carbon molecular sieve in the second stage has been improved to some extent. Nitrogen with a purity of over 99.9% can be produced, but the energy consumption is quite astonishing and it does not have the condition of large-scale application, the recovery rate of the molecular sieve at this stage reaches 37% when the nitrogen with the purity of 97% and 98% is produced ~ 42%, has been widely used.
With the improvement of processing technology, molecular sieve in the third stage has made great progress in its performance. It can produce nitrogen with a purity of over 99.99% at one time, and the recovery rate reaches 40% when producing nitrogen with a purity of 99.5%, the representative molecular sieves, such as German BF-185, Japanese Takeda 3K-172, Iya 2GN-H and so on, all have this level. The third generation of molecular sieve is also the most widely used molecular sieve at present, which is chosen by most domestic manufacturers. What makes people feel proud of is that the domestic molecular sieve has made quite rapid progress in recent years, among which there are factories like Changxing Kebo, Weihai Huatai and so on. The performance of the molecular sieve produced is close to that of the imported molecular sieve, however, due to the limitation of conditions, domestic molecular sieves have poor reproduction. Simply speaking, the performance of each batch of molecular sieves has certain differences, which is not as stable as imported molecular sieves. The main reason is that the technology of activation pore-making and pore structure adjustment is not mature, and the performance of molecular sieve is easy to fluctuate. At the same time, it may cause the performance of molecular sieve to decline quickly, the performance may decline by about 15% in two to three years. But because the price of domestic molecular sieve has a relatively big advantage, and its performance is close to that of the third generation imported molecular sieve, it has been widely used. It is also difficult for users to distinguish which kind of imported molecular sieve is and which kind of domestic molecular sieve is, which gives some illegal manufacturers an opportunity to replace imported molecular sieve with domestic molecular sieve, deceiving users with low-price signboards to earn huge profits.
The fourth generation of molecular sieve was successfully developed by Japan igua company in 2001. Compared with the third generation of molecular sieve, its performance has been greatly improved, and it can produce nitrogen with a purity of more than 99.9995% at one time. When producing nitrogen with the purity of 99.99%, the recovery rate of nitrogen has reached an astonishing 32%, and its significance is more important in today's time when the energy is so tight. Compared with the nitrogen-making equipment which uses the fourth generation molecular sieve of iangu as the absorbant, the nitrogen-making equipment which uses its molecular sieve as the absorbant has obvious advantages in the aspects of equipment energy consumption, molecular sieve loading quantity, comprehensive economic indicators, etc, and with the improvement of the product's nitrogen purity, this advantage becomes more and more obvious.
