Packing Mall carbon molecular sieve (CMS)has the characteristics of high strength, large nitrogen production, and high nitrogen recovery rate. Additionally, the nitrogen concentration can be as high as 99.999% at 0.75~0.8 MPa. Through the regeneration of carbon molecular sieve, it has the advantages of long service life. Its regeneration is mainly to desorb the gas molecules adsorbed in its microporous structure and restore its adsorption capacity. The common regeneration methods are as follows:
Depressurization Desorption Regeneration
This is a common regeneration method in the pressure swing adsorption (PSA) process. The adsorption of gas by carbon molecular sieve is carried out under a certain pressure. When the adsorption is saturated, the pressure in the adsorption tower is reduced. According to the adsorption equilibrium principle, when the pressure is reduced, the amount of gas adsorbed on the carbon molecular sieve decreases, and the originally adsorbed gas molecules will be desorbed from the micropores of the carbon molecular sieve, and the desorbed gas will be discharged from the adsorption tower, thereby regenerating the carbon molecular sieve. For example, in a nitrogen generator, when the carbon molecular sieve in the adsorption tower adsorbs oxygen and other impurity gases to saturation, the adsorbed oxygen and other gases are quickly desorbed by rapid pressure reduction to prepare for the next adsorption process. This method is relatively simple to operate, has low energy consumption, and has a fast regeneration speed. It is suitable for occasions with high requirements for regeneration efficiency.
Vacuum Desorption Regeneration
On the basis of desorption by pressure reduction, the adsorption tower is further evacuated. Vacuuming can further reduce the pressure in the adsorption tower and reduce the gas partial pressure, which is more conducive to the desorption of gas molecules from the surface of the carbon molecular sieve. Compared with simple desorption by pressure reduction, vacuum desorption can make the regeneration of carbon molecular sieve more thorough. For some application scenarios with high requirements for gas purity, such as the preparation of high-purity nitrogen, vacuum desorption regeneration can improve the regeneration effect of carbon molecular sieve, thereby improving the purity of product gas. However, this method requires equipment such as vacuum pumps, which increases equipment investment and operating costs.
Heating Desorption Regeneration
According to the thermal effect of the adsorption process, the adsorption process is usually exothermic, so the desorption process is endothermic. By heating the saturated carbon molecular sieve, energy can be provided for the desorption of gas molecules, making it easier for gas molecules adsorbed on the carbon molecular sieve to overcome the adsorption force and desorb. Generally, the carbon molecular sieve is heated to a certain temperature (usually around 100℃-300℃, the specific temperature depends on the type and use of the carbon molecular sieve) and maintained for a period of time to ensure that the gas molecules are fully desorbed. However, the energy consumption of heating desorption regeneration is high, and special heating and cooling equipment is required. The operation process is relatively complicated. At the same time, frequent heating and cooling may affect the service life of the carbon molecular sieve, so comprehensive consideration is required in practical applications.
Flushing Gas Regeneration
non-adsorbed or difficult to adsorb gas (such as nitrogen, etc.) is introduced into the adsorption saturated carbon molecular sieve bed, and the adsorbed gas molecules are replaced by flushing gas to achieve the regeneration of the carbon molecular sieve. This method can improve the regeneration effect to a certain extent, especially for some gases that are difficult to desorb by simple pressure reduction or heating. However, the use of flushing gas will increase gas consumption, and the flow rate and time of flushing gas need to be reasonably controlled to achieve better regeneration effect and economic benefits.
