What is a VPSA or VSA Oxygen Generator?

1. Air Blower: The air blower is the primary equipment responsible for introducing atmospheric air into the VPSA or VSA bed. Unlike PSA oxygen generators that work at higher pressures, VPSA/VSA systems operate at low pressure

1. Operating Pressure Range: 0.3 to 0.5 Barg.
2. Type: Oil-free blowers are essential to prevent oil vapours or particles from contaminating the molecular sieves.
3. Function: The blower pushes a continuous stream of air through the system, ensuring that the feed gas supply to the molecular sieve bed remains steady and uncontaminated.
   

2. Air Cooler: As the air exits the air blower, its temperature rises due to compression and friction. High air temperatures are detrimental to molecular sieves and can reduce adsorption efficiency. Therefore, the air cooler plays a vital role in conditioning the feed air.

1. Cooling Methods
   1. Air-to-air heat exchangers (for dry climates or when water is scarce).
   2. Water-cooled heat exchangers (for higher cooling capacity).
2. Target Temperature: Cooled down to ambient
   conditions, typically 20°C to 30°C.
3. Purpose: Ensures optimal adsorption performance and prolongs molecular sieve life.

3. VPSA or VSA Bed: The adsorption bed is the heart of the VPSA/VSA oxygen generator. This pressure vessel is tightly packed with zeolite molecular sieves and activated alumina, to separate oxygen from the other gases in the air.

1. Adsorption Process:
   1. Nitrogen molecules are selectively adsorbed by the zeolite.
   2. Oxygen molecules pass through the bed and are collected for use.
2. Automation: Controlled entirely via valves and PLC (Programmable Logic Controller) for seamless cycling between production and regeneration.
3. Design Considerations: Proper packing density and distribution are crucial to maintain high purity and consistent oxygen output.

4. Vacuum Pump: The vacuum pump is what differentiates VPSA/VSA systems from PSA systems. Instead of using high-pressure purge gas for regeneration, a vacuum is applied.

1. Regeneration Role: Removes the adsorbed nitrogen and other residual gases from the molecular sieve bed.
2. Vacuum Range: 0.5 to 0.55  bar(a)
3. Advantage: Reduces energy consumption and increases oxygen recovery efficiency compared to PSA systems.

5. Oxygen Booster: The Oxygen coming out of the VPSA/VSA bed is at low pressure (0.3-0.5 Barg), which is insufficient for most industrial applications. The oxygen booster compresses this low-pressure oxygen to the required delivery pressure.

1. Type: Oil-free reciprocating compressors are preferred to prevent contamination.
2. Pressure Output: Depends on application; can range from a few bars to higher levels for specific processes.

6. Oxygen Tank: Oxygen generation in VPSA/VSA systems is cyclic, meaning oxygen is produced in intervals rather than continuously. However, industrial applications require a steady and uninterrupted supply.

1. Function: The oxygen tank stores the produced oxygen and balances supply-demand fluctuations.
2. Sizing: Determined by the system’s cycle time and the customer’s continuous oxygen consumption rate.
3. Benefit: Acts as a buffer, ensuring stable downstream oxygen flow and pressure.

7. Oxygen Analyser: Maintaining consistent oxygen purity is critical for both safety and process efficiency. The oxygen analyser continuously monitors the oxygen content in the storage tank.

1. Purity Range: Typically 90-95% for VPSA/VSA systems.
2. Automation Trigger: If the oxygen purity falls below the desired level, the PLC either stops production or initiates the regeneration cycle.
3. Advantage: Ensures the end user always receives oxygen within the specified purity limits.