How does an oxygen generator work?

Oxygen concentrators have become indispensable equipment in today's medical and industrial fields. Whether it is to help patients with breathing difficulties or to provide necessary oxygen supply in industrial production processes, it is crucial to understand how these devices work. But how exactly does an oxygen generator work?

The oxygen concentrator employs a selective adsorption technology to efficiently extract oxygen from nitrogen and other components found in ambient air, thereby generating high-purity oxygen. This innovative method finds essential applications in both medical and industrial sectors, ensuring a constant flow of pure oxygen.

If you are considering purchasing an oxygen concentrator or are simply interested in its functionality, this guide will provide clarity and detail.

What is an oxygen generator?

An oxygen concentrator is a specialized device that produces oxygen by employing air separation technology to extract oxygen from the air—often referred to as air separation equipment.

Categorically, it can be classified into four types based on its working principle: PSA oxygen generator, low-temperature oxygen generator, electrolyzed water oxygen generator, and oxygen-enriched membrane oxygen generator.

In terms of application, they can further be segmented into industrial oxygen concentrators, household oxygen concentrators, and medical oxygen concentrators.

What is an oxygen generator used for?

Industrial oxygen concentrators serve as crucial instruments in generating concentrated oxygen for a variety of commercial applications. In medical environments such as hospitals, they deliver oxygen for patient care and medical procedures. Additionally, sectors such as metallurgy, chemical manufacturing, waste management, and water treatment leverage these devices; oxygen plays a vital role in enhancing combustion, facilitating chemical processes, and managing waste. Thus, oxygen concentrators significantly elevate efficiency, sustainability, and productivity across varied industries.

Oxygen Concentrators and Oxygen Concentrators

While the terms might sound similar, there is a fundamental difference between medical and industrial oxygen concentrators. Primarily utilized in healthcare settings, medical oxygen concentrators draw ambient air, filtering out nitrogen to supply pure oxygen to users. They are tailored for personal use, providing a steady stream of oxygen for individuals with respiratory conditions.

Conversely, industrial oxygen concentrators operate on a larger scale and are often deployed in industrial applications. Regardless of their function, they adhere to the same principle of separating oxygen from nitrogen; the distinction lies in their output capacity. Industrial models are robust and designed to yield large volumes of concentrated oxygen, supplying multiple industries such as steel manufacturing, chemical processing, and wastewater treatment.

How an oxygen generator works

The air we breathe consists predominantly of nitrogen (around 78%) and oxygen (approximately 21%), along with trace amounts of other gases. The principle driving the oxygen concentrator is its ability to utilize the distinctions in molecular size and weight between nitrogen and oxygen atoms to capture purer oxygen, generally achieving purity rates of over 90%. This section will focus especially on the workings of the PSA oxygen concentrator.

PSA Oxygen Concentrator

Using PSA (Pressure Swing Adsorption) technology, we can generate high purity oxygen (93% ± 2). Under standard conditions, specific molecular sieves effectively adsorb the nitrogen, carbon dioxide, and moisture from the compressed air. The process involves two molecular sieve adsorption towers. By introducing high-pressure, dehydrated and filtered air into one of the towers, nitrogen and other impurities adhere to the sieve, enriching the oxygen concentration in the gas phase. This enriched gas is stored in an oxygen buffer tank while the molecular sieve in the other tower depressurizes, releasing previously adsorbed components. The cyclic operation of these two towers allows for stable and economical oxygen production.

Low temperature oxygen concentrator

This type of concentrator separates oxygen from air via cryogenic distillation. Initially, air is cooled to below 100 K to liquefy it. The differences in boiling points between oxygen and nitrogen at normal pressure enable nitrogen, which has a lower boiling point, to vaporize more easily than oxygen. In the distillation tower, higher temperature vapor continually interacts with lower temperature liquid, incrementally increasing the nitrogen in the vapor phase while boosting oxygen content in the liquid phase, achieving effective separation and high purity oxygen production.

Electrolyzed water oxygen generator

This generator utilizes electrolysis to split water into hydrogen and oxygen. When a power source is applied, it splits the water molecules within the electrolyzer, producing both gases. The hydrogen is typically expelled through drainage while the generated oxygen is directed to its intended application.

Oxygen-enriched membrane oxygen generator

This generator uses specialized membrane materials designed to selectively allow oxygen to pass through while restricting the movement of other gases, effectively separating oxygen from the surrounding air.

Since different types of oxygen concentrators operate based on their distinct principles, it’s important to choose based on parameters like purity, flow rate, and intended use. If you're unsure which to select, please feel free to reach out for assistance!

Chemical oxygen generation

This method relies on chemical reactions to produce oxygen. A classic example is the thermal decomposition of potassium chlorate (KClO3), which releases oxygen. Although this method can yield high-purity oxygen, it is usually not favored for large-scale production due to safety concerns and high operating costs.

Components of an oxygen generator

Understanding the components of an oxygen concentrator is critical to grasp its functionality. Below are the main components that constitute an oxygen concentrator:

Air compressor

The air compressor is the vital first element that provides the necessary air supply to the oxygen concentrator. It compresses ambient air and releases it under pressure, setting the stage for successful oxygen extraction in the later stages.

Air pre-treatment/filtration

Once the air is compressed, it undergoes a pre-treatment or filtration process to eliminate impurities and moisture. This combined system employs filters and air dryers to remove dust, oils, and water vapor, thus shielding the sieve beds from potential damage during the separation process.

Oxygen separation device

This component varies based on the specific technology used in the oxygen generator; it can be a PSA module, a membrane separator, or a cryogenic unit, serving as the core heart of the machine. Its primary function is to achieve oxygen extraction from the surrounding air.

In a PSA-based oxygen generator, the separation device comprises a sieve bed (filled with zeolite) and a network of valves to control pressure cycles. In membrane systems, it includes a semi-permeable membrane, while cryogenic units utilize a sophisticated arrangement of heat exchangers and distillation columns for air liquefaction and separation.

Oxygen concentrator working process

• Compression: Initially, we draw air into the oxygen generator and compress it, leading to increased pressure but retaining a mix of nitrogen and oxygen.

• Adsorption: The compressed air is then directed into the molecular sieve tower, where high pressure allows for selective absorption of oxygen, leaving nitrogen behind.

• Decompression: After a sufficient volume of oxygen has been adsorbed, we deactivate the gas flow and initiate a depressurization process to desorb the oxygen, yielding high purity oxygen.

• Recovery: The collected oxygen moves to a storage tank, while the pressure in the molecular sieve tower continues to drop to near atmospheric pressure.

• Regeneration: The molecular sieve through depressurization releases residual nitrogen, effectively regenerating the sieve for future use.

This cycle effectively enables continuous oxygen production, maximizing efficiency and minimizing production costs for users selecting a suitable oxygen concentrator.