The main components of air are nitrogen and oxygen. By utilizing the different adsorption properties of nitrogen and oxygen on zeolite molecular sieve (ZMS) at ambient temperature (oxygen passes through while nitrogen is adsorbed), an appropriate process is designed to separate nitrogen and oxygen to produce oxygen. Nitrogen has a stronger adsorption capacity on zeolite molecular sieve than oxygen (nitrogen interacts more strongly with the surface ions of the molecular sieve). When air passes through an adsorption bed filled with zeolite molecular sieve adsorbent under pressure, nitrogen is adsorbed by the molecular sieve, while oxygen, being less adsorbed, is enriched in the gas phase and flows out of the adsorption bed, thereby separating oxygen from nitrogen to obtain oxygen. When the molecular sieve becomes nearly saturated with adsorbed nitrogen, the airflow is stopped, and the pressure in the adsorption bed is reduced. The adsorbed nitrogen is then desorbed, regenerating the molecular sieve for reuse. By alternating between two or more adsorption beds, oxygen can be produced continuously.

The boiling points of oxygen and nitrogen are close, making them difficult to separate, and they tend to be enriched together in the gas phase. Therefore, pressure swing adsorption (PSA) oxygen generation units typically produce oxygen with a concentration of 90-95% (the maximum oxygen concentration is 95.6%, with the remainder being argon), also known as oxygen-enriched air. In comparison, cryogenic air separation units can produce oxygen with a concentration of 99.5% or higher.

VPSA Oxygen Generator Process
The adsorption beds in a pressure swing adsorption (PSA) air separation oxygen generation unit must include two operational steps: adsorption and desorption. To continuously obtain product gas, oxygen generation units are typically equipped with two or more adsorption beds. For energy efficiency and stability, additional necessary auxiliary steps are also incorporated. Each adsorption bed generally undergoes steps such as adsorption, pressure release, evacuation or depressurization regeneration, purge displacement, and pressure equalization and repressurization, operating in a cyclical manner. At any given time, each adsorption bed is in a different operational step. Under the control of a PLC, the beds switch at timed intervals, coordinating their operations with staggered timing to ensure smooth operation of the PSA unit and continuous production of product gas. For practical separation processes, other trace components in the air must also be considered. Carbon dioxide and moisture generally have much stronger adsorption capacities on common adsorbents compared to nitrogen and oxygen. Suitable adsorbents (or the oxygen generation adsorbent itself) can be added to the adsorption bed to adsorb and remove these impurities.
◆ The number of adsorption towers required for an oxygen generation unit depends on the scale of oxygen production, adsorbent performance, and process design philosophy. Multi-tower operations tend to offer better stability but require higher equipment investment. The current trend is to use high-efficiency oxygen generation adsorbents to minimize the number of adsorption towers and adopt short operational cycles to improve unit efficiency and reduce investment costs as much as possible.

VPSA Oxygen Generator Technical Features
1. Simple process flow;
2. Oxygen production scale below 10,000 m3/h, lower power consumption for oxygen generation, and smaller investment;
3. Minimal civil engineering requirements, shorter installation period compared to cryogenic units;
4. Low operation and maintenance costs;
5. High degree of automation, convenient and quick start-up and shutdown, and fewer operators required;
6. Strong operational stability and high safety;
7. Simple operation, with major components sourced from internationally renowned manufacturers;
8. Use of original imported oxygen generation molecular sieve with superior performance and long service life;
9. Strong operational flexibility (excellent load adaptability and fast switching speed).

VPSA Oxygen Generator Technical Specifications
Production scale: 100-10,000 Nm3/h
Oxygen purity: ≥90-94%, adjustable within the range of 30-95% based on user requirements.
Power consumption for oxygen generation: When oxygen purity is 90%, the power consumption (useful work) per unit of pure oxygen is 0.32-0.37 kWh/Nm3.
Oxygen pressure: ≤20 kPa (can be pressurized)
Annual operational rate: ≥95%

For decades, Hangzhou Lecheng Gas Equipment Co., Ltd. has been dedicated to the research, development, and production of small and medium-sized air separation equipment, accumulating extensive experience in production, R&D, and installation. For more information about VPS oxygen generators, please feel free to contact us.