Principles of PSA nitrogen generator and carbon molecular sieve

2025-11-14 | More News

Carbon molecular sieve is a non-polar carbon material, the main component is elemental carbon, and the main raw material is phenolic resin. It’s an adsorbent for separating of oxygen and nitrogen in the air by modifying the pore structure. Nitrogen is produced by pressure swing adsorption (PSA) in industry, and it has a long service life and a wide range of applications.

So how does PSA carry out nitrogen purification? We will tell you in detail.

1. The basic process flow of PSA nitrogen production

After the air is compressed by the air compressor, after dust removal, oil removal, and drying, it enters the air storage tank, and enters the left adsorption tower through the air intake valve and the left suction intake valve. The tower pressure rises, and the oxygen molecules in the compressed air are removed. Carbon molecular sieve adsorption, the unadsorbed nitrogen passes through the adsorption bed, and enters the nitrogen storage tank through the left suction gas valve and the nitrogen gas production valve. This process is called left suction and lasts for tens of seconds.

After the left suction process is over, the left adsorption tower and the right adsorption tower are connected through the upper and lower pressure equalizing valves, so that the pressures of the two towers are equalized. This process is called equalizing pressure and lasts for 2 to 3 seconds. After the pressure equalization is completed, the compressed air enters the right adsorption tower through the air inlet valve and the right suction inlet valve.

The oxygen molecules in the compressed air are adsorbed by the carbon molecular sieve, and the enriched nitrogen enters the nitrogen gas through the right suction outlet valve and the nitrogen gas production valve. Tank, this process is called right suction, and the duration is tens of seconds.

At the same time, the oxygen adsorbed by the carbon molecular sieve in the left adsorption tower is depressurized and released back to the atmosphere through the left exhaust valve. This process is called desorption. Conversely, when the left column is adsorbing, the right column is also desorbing at the same time.

2. The adsorbents usually need as follows:

Activated carbon – To remove oil, to avoid carbon molecular sieves contacting oil impurities, blocking the pore size, resulting in a decrease in purity and nitrogen production.
Carbon molecular sieve — The key of nitrogen production, adsorb oxygen and produce high purity nitrogen from 99-99.9995%.
Activated alumina — High crush strength and strong water absorption capacity, which can protect the carbon molecular sieve (the quantity used is not much, just covering the height of the tower about 5-10 cm).

3. Adsorbent replacement

1) Activated carbon filter can effectively filter oil and prolong the service life of high-quality carbon molecular sieve. Activated carbon needs to be replaced every 3000 hours or 4 months. If the use cycle is not frequent, it can be considered that it must be replaced within 1 year.
2) The carbon molecular sieve decays by 5-8% every year. If the customer does not have high requirements for nitrogen production purity and nitrogen production, it is generally replaced once every 5 to 6 years; otherwise, we recommend replacing it once every 3 to 5 years.
3) Activated alumina can protect the carbon molecular sieve. For example, before replacing the carbon molecular sieve, we recommend that the bottom of the tower be covered with activated alumina.In addition to psa nitrogen generator, we also produce VPSA Oxygen Generators,PSA Oxygen Generators, storage tanks, heat exchangers and other products. If you are interested in psa nitrogen Systems or other products, please feel free to send an email to [email protected]. We will be very happy to serve you.

carbon molecular sieve capacity (KG)	purity/nitrogen capacity (Nm³/h) – Low purity				purity/nitrogen capacity (Nm³/h) – high purity
	96%	97%	98%	99%	99.95%	99.98%	99.995%	99.999%
120	55	50	45	40	20	15	13	10
150	75	70	65	50	20	20	15	13
180	80	80	70	60	30	22	20	15
210	105	100	90	80	30	25	25	18
240	115	110	100	90	40	30	27	20
275	130	120	110	100	45	35	30	23
300	150	140	130	110	45	40	35	25
336	170	160	140	120	60	45	40	28
360	180	170	150	130	65	48	42	30
420	200	190	170	150	70	55	45	35
444	210	200	180	160	75	50	50	37
480	230	220	200	170	80	60	55	40
516	250	230	210	180	85	65	55	43
540	270	260	230	200	90	70	60	45
600	290	270	240	220	100	75	65	50
624	300	280	250	230	105	80	70	52
660	330	310	280	250	110	85	75	55
720	360	350	320	280	120	90	80	60
840	390	370	330	300	140	100	90	70
900	430	400	360	320	150	110	100	75
960	460	440	410	370	160	120	110	80
1020	480	460	400	350	170	125	115	85
1080	500	470	420	380	180	130	120	90
1200	550	520	470	400	190	140	130	100
1250	630	600	540	480	200	150	140	105
1300	650	650	500	450	220	160	150	110
1350	650	630	570	490	230	170	150	115
1400	670	620	550	500	250	180	160	120
1500	720	680	600	550	260	190	170	130
1550	760	730	650	600	270	200	180	135
1600	770	720	680	580	280	210	190	140
1700	850	800	720	650	300	220	200	150
1800	930	880	780	700	330	240	210	160
1900	950	900	800	730	350	250	220	170
2000	1000	950	850	750	370	270	230	180
2100	1100	1050	950	850	400	280	250	190
2200	1150	1000	900	800	420	300	260	200