What Conditions Need to Be Controlled for the Production of Nitrogen Using Carbon Molecular Sieves?
Carbon molecular sieve air compression purification process
Purifying the raw air before entering the carbon molecular sieve adsorption tower is necessary because particles and organic atmosphere entering the adsorption tower can block the micropores of the carbon molecular sieve and gradually reduce its separation performance.
There are methods to purify the raw air: 1) keeping the intake of the air compressor away from places with dust, oil mist, and organic atmosphere; 2) purifying the raw air with equipment such as a refrigerated dryer and adsorbent cleaning system before entering the carbon molecular sieve adsorption tower.
Concentration and production rate of nitrogen gas using carbon molecular sieve
The N2 concentration and production rate of nitrogen gas produced with carbon molecular sieve can be adjusted according to the user’s needs. When the production time and operating pressure are determined, lowering the production rate will increase the N2 concentration, and vice versa. Users can adjust according to their actual needs.
Carbon molecular sieve equalization time
During the process of producing nitrogen with carbon molecular sieve, when an adsorption tower is finished adsorbing, the pressurized gas inside the tower can be injected from both top and bottom into another regenerated adsorption tower to make the two towers have the same gas pressure. This process is called equalization. By choosing an appropriate equalization time, energy can be recovered, and the impact on the molecular sieve inside the adsorption tower can be reduced to extend the lifespan of the carbon molecular sieve. The equalization time is usually selected as 1 to 3 seconds, according to the switching speed of the valve.
Carbon molecular sieve production time
Due to the different adsorption and diffusion rates of oxygen and nitrogen in carbon molecular sieve, the adsorption of O2 reaches a balance in a short time, at which time the adsorption of N2 is very small. Therefore, a shorter production time can effectively improve the production rate of carbon molecular sieve, but it also increases the frequency of valve operation, so the performance of the valve is also important. Generally, the adsorption time is selected as 30 to 120 seconds. For small high-purity nitrogen generators, a shorter production time is recommended, while for large low-concentration machines, a longer production time is recommended.
Carbon molecular sieve operating pressure
The carbon molecular sieve has both kinetic and equilibrium adsorption effects. The higher the adsorbate pressure, the higher the adsorption capacity. Therefore, pressurized adsorption is favorable. However, if the adsorption pressure is too high, the requirements for the selection of the air compressor are also increased. In addition, the two processes of atmospheric regeneration and vacuum regeneration have different requirements for the adsorption pressure. Considering all factors, it is recommended that the adsorption pressure of the atmospheric regeneration process be selected as 5 to 8 kg/cm2, and the adsorption pressure of the vacuum regeneration process be selected as 3 to 5 kg/cm2.
Carbon molecular sieve operating temperature
Choosing a lower adsorption temperature as the adsorbent is beneficial to the performance of the carbon molecular sieve. Therefore, reducing the adsorption temperature is beneficial for the process of producing nitrogen using a carbon molecular sieve when conditions permit.
