What conditions are required for carbon molecular sieve nitrogen production?
1. Air compression and purification process
The pure raw air needs to enter the carbon molecular sieve adsorption tower. This is very necessary because particles and organic gases entering the adsorption tower will clog the micropores of the carbon molecular sieve and gradually reduce the separation performance of the carbon molecular sieve.
The methods for purifying the raw air include: 1. Keeping the air intake of the air compressor away from places with dust, oil mist, and organic gases; 2. Through cold dryers, adsorbent purification systems, etc., and finally, the processed raw air enters the carbon molecular sieve adsorption tower.
2. Concentration and production volume of the product nitrogen
The N2 concentration and production volume of nitrogen produced by carbon molecular sieve can be adjusted arbitrarily according to the user’s needs. When the production time and operating pressure are determined, reducing the production volume will increase the N2 concentration, and vice versa. Users can adjust according to actual needs.
3. Equalization time
In the carbon molecular sieve nitrogen production process, when one adsorption tower finishes adsorption, the pressurized gas inside this adsorption tower can be injected from both the upper and lower directions into another regenerated adsorption tower, and make the gas pressure of the two towers the same. This process is called equalization of the adsorption tower. Choosing an appropriate equalization time can not only recover energy but also reduce the impact on the molecular sieve inside the adsorption tower, thereby extending the service life of the carbon molecular sieve. The switching speed of the reference valve is generally selected as an equalization time of 1 to 3 seconds.
4. Production time
Due to the different adsorption diffusion rates of oxygen and nitrogen by carbon molecular sieve, the adsorption of O2 reaches equilibrium in a short time. At this time, the adsorption amount of N2 is very small. A shorter production time can effectively increase the production rate of carbon molecular sieve, but it also increases the frequency of valve operation. Therefore, the performance of the valve is also very important. Generally, the adsorption time is 30 to 120 seconds. Small high-purity nitrogen production machines are recommended to use a short production time, while large low-concentration ones are recommended to use a long production time.
5. Operating pressure
Carbon molecular sieve has both kinetic effect and equilibrium adsorption effect. When the partial pressure of the adsorbate is high, the adsorption capacity is also high. Therefore, pressurized adsorption is beneficial. However, if the adsorption pressure is too high, the selection of the air compressor also increases. In addition, the two processes of normal pressure regeneration and vacuum regeneration have different requirements for the adsorption pressure. Considering all factors, it is recommended that the adsorption pressure of the normal pressure regeneration process be selected as 5 to 8 kg/cm2; the adsorption pressure of the vacuum regeneration process be selected as 3 to 5 kg/cm2.
6. Operating temperature
A lower adsorption temperature when choosing the adsorbent is beneficial to the performance of the carbon molecular sieve. In the nitrogen production machine process, it is beneficial to adopt a lower adsorption temperature under certain conditions.
