Enhancing Air Separation Units with Precision Gas Measurement Equipment

• Air intake - The first step in an ASU is to draw air into the unit so it can be separated. Dust is filtered out of the air before it is sent to the compression stage.
• Compression - After the air is filtered, it is compressed to increase its pressure. Compression is necessary for the cooling and separation processes.
• Purification - The compressed air may be purified to remove moisture, carbon dioxide, or other gas or chemical impurities. Purification ensures the high purity of the separate gases and mitigates potential problems affecting the cryogenic equipment.
• Cooling - The compressed air needs to be cooled if cryogenic distillation will be used to separate its components. This is typically done with a series of refrigeration cycles and heat exchangers. The air is liquefied for the distillation process which is based on the different boiling points of the different components in the compressed air.

• Separation - Separation is performed using either cryogenic distillation or non-cryogenic methods. We will look at these options in more detail in the next section.
• Recovery - The separated gases are collected for use in industrial processes. Nitrogen is usually produced in higher volumes than oxygen or argon. The gases can go through additional purification processes if necessary for a specific application.
• Storage and distribution - After purification, the gases may be stored in their gas or liquid state in tanks for transfer to other locations. Distribution can be provided directly to end-users with gases fed into industrial processes or equipment.

• Cryogenic distillation - Cryogenic distillation requires air to be cooled to very low temperatures. Cryogenic typically indicates temperatures below 120 degrees Kelvin or more than -243 degrees Fahrenheit. After cooling, the air is expanded in a distillation column where components are separated based on their different boiling points. For example, nitrogen liquefies at a lower temperature than oxygen. This type of ASU can produce oxygen with a purity of up to 99.5%.
• Pressure swing adsorption (PSA) - PSA is a non-cryogenic air separation method utilizing absorbent materials to absorb nitrogen from compressed air. The cycle-based process swings the absorbent material from high to low pressure. The absorbed nitrogen is released to enable the production of purified oxygen. PSAs produce lower purity oxygen, typically from 90 to 95% pure. They are often used in smaller operations or in locations that cannot support cryogenic units.
• Membrane separation - This non-cryogenic technique uses membrane technology that employs selection permeation to separate gases according to chemical properties of molecule size. A specially designed membrane separates air components based on how quickly specific gases pass through it. This method can produce oxygen or nitrogen without cryogenics and offers an energy-efficient and compact solution for small operations.
• Vacuum pressure swing adsorption (VPSA) - VPSA operates similarly to PSA separation. It employs a vacuum which allows oxygen production at lower pressures than the PSA method.

• Manufacturing - ASUs are used in many processes in industries like steel, chemical, and petrochemical manufacturing. Large volumes of oxygen and nitrogen are required for these processes.
• Healthcare - ASUs are vital for producing oxygen for patient treatment in the healthcare sector. Impurities can be extremely detrimental for patient well-being and need to be avoided at all costs.
• Energy production - Oxygen and nitrogen are essential for multiple energy generation processes such as combustion and purging during energy production. Consistent access to these gases enables smooth energy production for business and residential use.
• Semiconductor and electronics - Very pure nitrogen and argon are required in the production of electronic components and semiconductor chips. Impurities may cause contamination and lead to inferior products.
• Food and beverage - The food and beverage industry uses nitrogen and carbon dioxide for refrigeration and packaging to preserve freshness during shipping.

Impact on industrial processes

Gas purity affects product quality and the operational efficiency of industrial processes.

• Product quality - Impurities in gas can result in defects, contamination, or unexpected reactions that degrade product quality. Consistency and performance often relies on the ability to ensure the use of high-quality gases. Fields such as healthcare, pharmaceutical production, food processing, and manufacturing require quality gases.
• Operational efficiency - High purity gases are essential for optimizing reactions, reducing downtime, and extending equipment life. Impure gases may result in excessive maintenance costs and inefficiencies such as increased energy use. Purity supports a cost-effective production environment and operational efficiency.

Safety and regulatory compliance

Producing quality gas by ASUs is essential to maintain safety and meet regulatory requirements.

• Product safety and purity - Proper gas purity minimizes the chances of explosions or unexpected reactions that can compromise product safety and put workers at risk. Purity is vital in medical applications to ensure safe patient treatment.
• Operational safety - Employee safety is promoted by ensuring sufficient oxygen concentrations to prevent dangerous working conditions. Alerts are generated by the model 221R when oxygen levels are not safe for humans.
• Regulatory compliance - Gas purity is necessary to comply with national and international safety, environmental, and industry-specific regulations. Non-compliance can result in fines and damage the organization’s reputation. Emission thresholds are also easier to meet when using purified gases to meet environmental regulations. Purity standards help protect a company from legal issues with employees, consumers, or patients.