The Pressure Swing Adsorption (PSA) nitrogen production technology is a high-tech method for obtaining nitrogen gas from compressed air, which has been widely applied in the industrial sector. PSA nitrogen production utilizes carbon molecular sieve to sieve and adsorb nitrogen and oxygen molecules from the air. When the pressure increases, the carbon molecular sieve with many uniform micropores adsorbs oxygen. When the pressure decreases, it desorbs oxygen, achieving the separation of oxygen and nitrogen. In fact, while the carbon molecular sieve adsorbs oxygen, it also adsorbs nitrogen. Due to the kinetic effect and the microporous characteristics of the carbon molecular sieve, the diffusion rate of oxygen in the micropores is much faster than that of nitrogen. PSA nitrogen production typically involves setting up two filled adsorption towers in the system, with carbon molecular sieve inside. One tower adsorbs to produce nitrogen, while the other tower desorbs and regenerates. The PLC program controller is used to control the opening and closing of pneumatic valves, enabling the two towers to alternate in cycles for continuous production of high-quality nitrogen gas.
The operation steps of a vacuum pressure swing adsorption nitrogen generator are divided into pre-startup checks, startup procedures, shutdown procedures, and maintenance steps. Operating the nitrogen generator according to the instructions can effectively extend its service life.
Nitrogen Generator Pre-Startup Inspection
1.1 Ensure the system and equipment are all in standby for activation in sequence.
Are all进出口 valves in the equipment in a fully closed position?
Is the power supply normal?
1.4 Are the air compressors and purification systems operating normally?
Is the cooling water functioning properly (some equipment is equipped with a cooling water recirculation system)?
1.6 Is the equipment itself clean and is the surrounding environment properly cleaned?
Nitrogen Generator Startup Procedure
2.1 Upon the compressor being started in accordance with the procedure and operating normally (air pressure ≥ 0.9 Mpa), open the gas storage tank's gas supply valve and ensure the gauge pressure of the supplied gas is between 0.8-0.9 Mpa; when the compressor starts in no-load condition, after normal operation, exhaust the oil and water from the air storage tank.
2.2 Open the freeze-dryer, pre-cool for 5-10 minutes, and promptly open the drain valve of the filter to drain the excess water.
2.3 Compressed air passes through an activated carbon filter into the air buffer tank. Once the tank's pressure reaches ≥0.8 Mpa, open the air inlet valve of the adsorption tower and ensure that all working systems are functioning properly.
2.4 Turn on the main power of the nitrogen generator, activate the PLC power inside the electrical control box, and press the nitrogen generator start button on the control panel or the start button on the human-machine interface. The control system will enter automatic operation mode. Observe whether the indicator lights are functioning properly, and check if the solenoid valves and pneumatic valves are switching correctly (determined by the changes in the pressure gauge readings).
After the 2.5 system is operational, turn on the nitrogen analyzer's power supply. The liquid crystal display sequentially shows the startup self-check, with the instrument model "-4N," software version U3-1, and analyzer preheat countdown 00019-00000. The nitrogen concentration is displayed as 79.000-99.99. All parameters of this instrument have been set at the factory; please do not adjust.
2.6 Adjust the intake valve size, gradually open the exhaust valve system, and set the pressure relief valve outlet pressure of the pneumatic control valve at around 0.5 Mpa (usually already adjusted upon factory shipment).
2.7 When the meter enters the testing phase, adjust the test flow system to initiate testing (adjust the sampling减压阀to 0.05-0.1Mpa, and regulate the sampling flow valve until you can feel air exiting at the probe outlet). After the meter operates normally, adjust the nitrogen analyzer's purity alarm, and observe if the purity alarm and the visual/audio alarms are functioning properly.
2.8 Open the不合格 gas vent valve, usually close the small nitrogen flowmeter's shut-off valve, adjust the flow to half of the rated flow, and perform small flow nitrogen production. After the gas meets the standard, slowly open the pure gas outlet shut-off valve, adjust the flow to the rated flow, close the vent shut-off valve, and the equipment can be used normally once it operates normally.
Nitrogen Generator Shutdown Procedure
3.1 Turn off the air compressor power and close the exhaust valve.
3.2 Turn off the cold dryer power.
3.3 Shut off the intake system valve.
3.4 Shut down the nitrogen generator PLC power supply and the power supply to the electrical control cabinet.
3.5 Turn off all power sources and switches.
3.6 Open the drain valve at the bottom of the gas storage tank and oil-water separator to release oil and water.
3.7 In case of an extended shutdown, the drain valves on all gas tanks within the system should be opened to relieve pressure before closing the system.
Important Precautions for Nitrogen Equipment in Operation
4.1 Regularly monitor the equipment's gauge air pressure.
4.2 Pay attention to check whether the pressure of each吸附塔is in normal condition.
4.3 After the equipment is normally powered on, pay attention to whether the air compressor, desiccant dryer, filter, and drain are operating normally.
4.4 Note that the export flow must not exceed the equipment's rated gas production capacity.
4.5 Under the premise of meeting the test requirements, the sampling flow should be minimized as much as possible.
4.6 The nitrogen recovery valve (regeneration valve) for the nitrogen generator should not be adjusted at will under normal circumstances.
4.7 When starting the flowmeter, open it slowly to avoid damaging the flowmeter.
On April 8th, when the equipment is in continuous operation, it is essential to regularly inspect the airtightness of the pipe connections and ensure no leakage occurs. Additionally, check the normal operation status of the pneumatic valves.
Nitrogen Equipment Maintenance
5.1 Follow the manual for maintenance and care.
The lifespan of the filter core is generally around 4,000 hours; it should be replaced promptly upon expiration.
The oxygen electrode of the nitrogen analyzer typically has a lifespan of about 1 year and should be replaced as needed.
5.4 Regularly replace the activated carbon in the activated carbon filter (with a lifespan of about 4,000 hours).
5.5 When equipment is not used for an extended period or used intermittently, it is recommended to power on the device at least once a month.
5.6 The carbon molecular sieve is a core component of nitrogen-producing equipment. To prevent contamination and ensure its functionality, strict control over the oil content in the air compressor is necessary, as well as keeping the drain valve clear and replacing the filter cores and activated carbon on a regular basis.
5.7 Storage, transportation, and handling of carbon molecular sieve do not pose any harm to humans. When filling the carbon molecular sieve, eye protection and a mask should be worn. After filling, wash any skin that has come into contact with the material.
5.8 In the event of nitrogen purity alarms and a decrease in adsorption pressure, etc., it is necessary to promptly identify the cause and eliminate the fault.
5.9 Regular System Leak Detection
5.10 Detected oil leakage in the air compressor; immediately notified the air compressor maintenance team for repair, and it can be used only after meeting the requirements.
On 5.11, if a large amount of black powder is ejected from the muffler exhaust port during operation, the machine should be immediately shut down to investigate the cause and prevent further carbon molecular sieve pulverization.
The above is information regarding the operation steps of a vacuum pressure swing adsorption nitrogen generator, for reference only. Please refer to the manufacturer's communication for specific procedures.
