Industrial nitrogen generator, how much do you know?
Nitrogen generator refers to equipment that uses air as raw material and uses physical methods to separate oxygen and nitrogen in it to obtain nitrogen. Nitrogen generators used in industry can be divided into three types according to different classification methods, namely cryogenic distillation (cryogenic air separation), molecular sieve air separation (PSA) and membrane permeation (membrane air separation). . This article focuses on molecular sieve air separation (PSA).
| PSA nitrogen production principle:
Nitrogen generator is a nitrogen production equipment designed and manufactured based on pressure swing adsorption technology. The nitrogen generator uses high-quality imported carbon molecular sieve (CMS) as the adsorbent and uses the pressure swing adsorption principle (PSA) at normal temperature to separate air to produce high-purity nitrogen. Usually, two adsorption towers are connected in parallel, and the imported PLC controls the automatic operation of the imported pneumatic valve to alternately perform pressurized adsorption and decompression regeneration to complete the separation of nitrogen and oxygen and obtain the required high-purity nitrogen.
| Technical indicators of PSA nitrogen generator:
Inlet temperature: ≤40℃ (requires cold dryer)
Minimum operating pressure: 0.5MPa
Normal pressure dew point: -40~-70℃/ctd
Nitrogen purity: 95-99.999%
Average regeneration gas consumption: ≤5%
Ambient temperature: 5~40℃
Switching cycle: 45-60S
Voltage/frequency: 220V/50HZ
| Workflow
1. Unequal potential equalization:
After adsorption tower A works for 50 seconds, the carbon molecular sieve approaches saturation and enters the 2-second inequality pressure equalization (valves V2, V3, V9, and V10 are all closed). The high-pressure semi-finished nitrogen from adsorption tower A enters adsorption tower B through V7 and V4. , so that the air pressure of the two adsorption towers is consistent, and all valves are closed after equalizing the pressure.
2. Tower A adsorbs, Tower B does not adsorb:
The compressed air is opened from the inlet and outlet valve V3 (only one of valves V3 and V4, and valves V5 and V6 are opened during operation, or they are closed at the same time) and enters the adsorption tower A through the pipeline to boost pre-adsorption, start the nitrogen production process, and open valve V5 to transport the finished product. Nitrogen enters the gas storage tank.
3. Tower B adsorption, tower A desorption:
The valves V4 and V10 open the compressed air to enter the adsorption tower B and start the adsorption work. The valves V6 and V9 open in a delayed manner to send nitrogen into the gas storage tank. At the same time, valve V1 is opened to discharge the impurities in tower A into the atmosphere (a trace amount of nitrogen at the top of the tower backflushes the impurities) until tower B completes the adsorption and all valves are closed to enter a pressure equalization state.
| Selection method of nitrogen generator
Air-to-nitrogen ratio: refers to how much m³/H of nitrogen is produced and how much m³/H of air is consumed? (Note: The above refers to the void-to-nitrogen ratio, which varies according to the performance and data of carbon molecular sieves from different manufacturers and is for reference only.)
PS: If the customer needs 50m³/H nitrogen with a purity of 99.9% in the workshop, what size air compressor is needed?
Calculation: Q=50*4.0=200m³/H=3.33m³/min. Through this flow rate, relevant air compressor equipment can be selected.
Note: For 99.999% purity, the air-to-nitrogen ratio is 1:8. Considering the economical issues of the entire system, our company recommends that the flow rate below 200m³/h can be matched with the nitrogen production host in one step. For flow rates above 200m³/h, it is recommended that the nitrogen be first The gas purity is reached to 99.9% through the PSA pressure swing adsorption nitrogen generator, and then the gas is purified to 99.999% through the purification device.
