VPSA oxygen generation plant is generally composed of blowers, vacuum pumps, adsorption towers, storage tanks, pressure-equalized buffer tanks and control valves in the pipeline, which are managed by computer programs to achieve oxygen separation from the air. Below is the major composition of a 4000m3/h VPSA (Vacuum Pressure Swing Adsorption) oxygen unit.

1.Suction Air Filter

The suction air filter consists of an inner and an outer filter to remove mechanical impurities in the air. A differential pressure gauge is installed to indicate whether the filter is due for maintenance.  

2. Centrifugal Air Blower and Vacuum Blower

The air blower used in the oxygen unit is a Roots blower whose design flow rate is 50,000Nm3/h, serving to feed air into the adsorption beds. The vacuum blower is a Roots blower with a design flow rate of 65,500Nm3/h, which provides vacuum conditions for the adsorbent regeneration and exhaust gas discharge. Both blowers are driven by a motor. A sealing water system is also equipped in the vacuum blower for sealing, lubrication and cooling purposes.

3. Sealing Water System

The sealing water is delivered from the equipment to the pipelines at the inlet of the vacuum blowers. Its pressure is controlled by pressure regulating valves. When the vacuum blower is running, the globe valve is opened to supply sealing water and it is closed when the oxygen plant shuts down. When the inlet valve is open, the drain valve is closed. Conversely the drain valve opens to relieve pressure for the inlet valve to make sure that no water is sent to the vacuum blower. The sealing water flow is controlled by the flow control valves and any water flow below the set value will lead to the shutdown of the VPSA oxygen equipment.

During normal operation, the sealing water is carried by the nitrogen to the vacuum separation silencer for discharge. When the vacuum blower is stopped, the remaining water is discharged through the discharge pipes back to the rack. The drain valve closes when the vacuum blower is operating and opens reversely.

4. Double Adsorption Beds

The two adsorption beds are equipped with 13X and specialized VPSA oxygen molecular sieve which are used to adsorb moisture, CO2, hydrocarbons and nitrogen in the air respectively. The two adsorbents are distributed radially in the adsorption bed to reduce the impact of the axial airflow on the molecular sieve. The molecular sieve is sealed and compressed with an adhesive membrane to prevent the molecular sieve from moving up and down. Meanwhile, introducing oxygen to the protective layer.

5. Automatic Switching Valve

It has the remarkable merits of more than 1,500,000 times of fault-free cutoffs.

6. Instrument Air Compressor System

VPSA oxygen system uses instrument compressors and supporting dryers to provide instrument air.  With a power of 37kW, each unit is able to provide 3.8Nm3/min air to the VPSA oxygen system.

7. PLC System

The complete set of VPSA oxygen equipment is equipped with specialized operating program, and the operation interface of the control system can be entered through the operation platform software. This computer system does not affect the operation of the oxygen plant even if the PC crashes; Moreover, under the condition of perfect communication, it can be connected in a remote way from anywhere in the world to achieve unattended operation on the whole.

8. Auxiliary Equipment of Blower

The ancillary equipment of the blower includes inlet and outlet silencers, vacuum separation silencers and discharge silencers, among which the separation silencer is used to separate the exhaust gas from sealing water at the outlet of the vacuum blower. The exhaust gas（N2, Ar and other components）is directly discharged to the atmosphere and the sealing water is sent to the water collection well for nitrogen sealing.

9. Oxygen Compressor System

According to the oxygen capacity of VPSA oxygen units and the user's requirements, vertical 2-stage and 3-phase piston compressors could be used. The discharge capacity of each oxygen compressor is 5000Nm3/h and the nominated outlet pressure is 0.8MPa.