The nitrogen generator uses high-quality carbon molecular sieves as the adsorbent and employs the pressure swing adsorpt

The nitrogen generator uses high-quality carbon molecular sieves as the adsorbent and employs the pressure swing adsorption (PSA) principle at room temperature to separate air and produce high-purity nitrogen.

Typically, two adsorption towers are connected in parallel, with PLC-controlled inlet pneumatic valves operating automatically. They alternately perform pressure adsorption and depressurization regeneration to complete nitrogen-oxygen separation and obtain the required high-purity nitrogen.

The principle of PSA nitrogen generation: Carbon molecules can simultaneously adsorb oxygen and nitrogen from the air, and the adsorption capacity increases with increasing pressure. Furthermore, the carbon molecular sieve adsorbs oxygen very quickly, reaching over 90% adsorption in about one minute; at this point, the nitrogen adsorption capacity is only about 5%, so the majority of the adsorbed gas is oxygen, and the remainder is predominantly nitrogen.

The nitrogen generator's workflow is achieved by a programmable logic controller (PLC) controlling three 2-position 5-way pilot solenoid valves, which in turn control the opening and closing of eight pneumatic pipeline valves. The three 2-position 5-way pilot solenoid valves control the left suction, equalization, and right suction states, respectively. The timing sequence for left suction, pressure equalization, and right suction is stored in the programmable controller. In the power-off state, the pilot gas from all three 2-position 5-way pilot solenoid valves is connected to the closed port of the pneumatic pipeline valve. When the process is in the left suction state, the solenoid valve controlling left suction is energized, and the pilot gas connects the opening ports of the left suction inlet valve, left suction gas generator valve, and right exhaust valve, causing these three valves to open and completing the left suction process. Simultaneously, the right adsorption tower desorbs. When the process is in the pressure equalization state, the solenoid valve controlling pressure equalization is energized, and the other valves are closed. The pilot gas connects the opening ports of the upper and lower pressure equalization valves, causing these two valves to open and completing the pressure equalization process. When the process is in the right suction state, the solenoid valve controlling right suction is energized, and the pilot gas connects the opening ports of the right suction inlet valve, right suction gas generator valve, and left exhaust valve, causing these three valves to open and completing the right suction process. Simultaneously, the left adsorption tower desorbs. In each process segment, all valves except those that should be open should be closed. To ensure the complete release of oxygen from the molecular sieve during depressurization into the atmosphere, nitrogen gas is used to purge the desorption tower through a normally open backflush valve, expelling the oxygen from the tower. This process, called backflush, occurs simultaneously with desorption.

The nitrogen generator in our factory operates using a Siemens S7-200 programmable controller. This controller first controls solenoid valves, which then control the opening and closing of eight pneumatic pipeline valves in towers A and B. The solenoid valve timing sequence is stored in the programmable controller. During years of operation of our nitrogen generator, the main problems have been low gas production pressure and high oxygen content.

1. Low incoming gas pressure naturally results in insufficient production pressure.
2. High on-site gas consumption, leading to insufficient production and increased pressure.
3. Clogged filters and valves in the incoming gas pipeline reduce gas flow, resulting in nitrogen production far less than consumption and low system pressure.
4. Leaks in the gas supply network further reduce pressure.
5. Abnormal control of the nitrogen generator's valve circuit or mechanical jamming.

1. Low original compressed air pressure leads to poor pressure swing adsorption (PSA) effect and ineffective deoxygenation.
2. Malfunction of the pilot solenoid valves or pneumatic valves controlling the left and right towers. For example, some valves may have delayed opening and closing times or be jammed. This will cause air leakage, leading to erratic operation of the two towers, poor nitrogen generation, and high oxygen content.
3. Proper air consumption control is essential. Excessive air flow will also result in poor nitrogen generation.
4. Failure to replace the carbon molecular sieve and filter element for a long time will also lead to high oxygen content.
5. Control circuit malfunction causing solenoid valve failure, resulting in inability to open or close properly and causing oxygen content issues.