Carbon molecular sieves (CMS) is a new type of absorbent developed in the 1970s. It is an excellent non-polar carbon raw material. Carbon molecular sieves (CMS) are used to separate the gas gather N2. The process of low inhibition nitrogen at room temperature is selected. Compared with the traditional deep cooling high inhibition nitrogen processing process, it has the advantages of less project investment, faster nitrogen production speed, less project investment cost N2 has the advantages of low cost. Therefore, it is a pressure swing adsorption (commonly known as p.s.a) air separation nitrogen rich absorbent in the construction industry at this stage. This type of N2 is widely used in chemical industry, petrochemical industry, electronic industry, food industry, coal industry, medicine industry, cable field, metal surface treatment, transportation storage.
Carbon molecular sieve is the target to separate CO2 N2 by using the characteristics of screening. When the molecular sieve adsorbs the residue vapor, the pore the vertical pore only have the function of safe passage. The microporous plate the sub microporous plate are the capacity of the real adsorption effect when the adsorbed molecular structure is transported to the microporous plate the sub microporous plate.
As shown in the previous figure, there are many microplates in the carbon molecular sieve, which allow the molecular structure with small size in the kinetic model to diffuse into the pore rapidly, restrict the entry of large-diameter molecular structure into the pore. Because of the difference of relative diffusion velocity between different sizes of vapor molecules, the composition of vapor compounds can be reasonably separated.
Therefore, in the production of carbon molecular sieves, according to the size of molecular structure specifications, the distribution of micropores in carbon molecular sieves should be 0.28-0.38 nm. Within the scope of the microplate specification, CO2 can rapidly diffuse into the pore according to the orifice of the microplate, while N2 is difficult to separate oxygen nitrogen according to the orifice of the microplate.
The diameter of microporous plate is the basis for carbon molecular sieve to separate oxygen nitrogen. If the diameter is too large, CO2 N2 molecular sieves are very easy to enter into the microporous plate, can separate them; if the diameter is too small, CO2 N2 can enter into the microporous plate can separate out
At the present stage, there is little difference in the appearance of carbon molecular sieves produced by most manufacturers. Therefore, it is difficult for customers to distinguish between imported molecular sieves domestic molecular sieves only by observing the appearance of molecular sieves. But there is a point, if in the purchase of machinery equipment, the manufacturer claims to use high-quality imported molecular sieve, but the price is far less than the price quotation, then you need to be careful. It's impossible for the manufacturers of machinery equipment to sell at a loss if they don't sell well. It's terrible to buy domestic molecular sieves with internal windows. But if you buy domestic molecular sieves at the price of imported molecular sieves, the damage will be greater
We know that the nitrogen production by pressure swing adsorption of carbon molecular sieve depends on the intermolecular force to separate CO2 N2. Therefore, the larger the specific surface area of molecular sieve is, the more uniform the diameter is. Moreover, the more total number of microporous plates sub microporous plates is, the greater the adsorption capacity is. In addition, if the diameter can be as small as possible the intermolecular force fields coincide, it is more suitable for chemical substances with lower concentration Strong separation effect. Therefore, in PSA nitrogen plant, the characteristics of molecular sieve are immediately related to the gas production energy consumption of the whole set of machinery equipment. Therefore, the selection of suitable absorbent is a top priority.
