Air Separation Equipment Product Details

Air Separation Unit: High-Efficiency, Energy-Saving, and Intelligent Core Equipment for Industrial Gases

An Air Separation Unit (ASU) is an industrial equipment that separates oxygen, nitrogen, argon, and rare gases (such as helium, neon, krypton, and xenon) from air through physical or chemical methods. It is widely used in metallurgy, chemical engineering, energy, electronics, and other fields. The following is a detailed introduction to its core content:

I. Core Technologies and Working Principles

ASUs mainly adopt the following three technical routes:

Cryogenic Distillation Method (Deep Cooling Method)

Principle: Compress and cool air to a liquid state (approximately -196°C), then separate the components in a distillation column by utilizing the differences in their boiling points (oxygen: -183°C, nitrogen: -196°C, argon: -186°C).

Features:

Ultra-high purity (oxygen ≥ 99.5%, nitrogen ≥ 99.999%, argon ≥ 99.99%), suitable for scenarios with high-purity requirements such as iron and steel, chemical engineering industries.

Relatively high energy consumption (approximately 0.6-0.7 kWh/Nm³ of oxygen), large equipment volume, and high investment cost, but stable operation in the long term.

Process Flow:

Pretreatment: Remove dust, moisture, carbon dioxide, and hydrocarbons through air filters, pre-cooling systems, and molecular sieve adsorbers.

Refrigeration and Liquefaction: Achieve deep freezing of air using turboexpanders and heat exchangers.

Distillation Separation: Adopt a double-tower (upper tower and lower tower) or multi-tower structure, and realize component enrichment by adjusting the reflux ratio.

Pressure Swing Adsorption (PSA) Method

Principle: Utilize the selective adsorption of different gases by molecular sieves to separate oxygen or nitrogen through periodic pressure-up adsorption and pressure-down desorption.

Features:

Compact equipment and fast start-up (≤ 30 minutes), suitable for small and medium-scale production (oxygen output: 10-1000 Nm³/h).

Medium purity (oxygen: 90%-95%, nitrogen: 95%-99.9%) and relatively low energy consumption (approximately 0.4-0.6 kWh/Nm³ of oxygen).

Application Scenarios: Fields with relatively low purity requirements such as medical oxygen supply, food preservation, and chemical protective gas.

Membrane Separation Method

Principle: Realize separation by leveraging the difference in permeability of oxygen and nitrogen through polymer membranes (e.g., polyimide membranes).

Features:

Simple structure and low maintenance cost, suitable for ultra-small-scale (≤ 100 Nm³/h) and mobile applications.

Lowest purity (oxygen: 21%-40%, nitrogen: 90%-95%) and lowest energy consumption (approximately 0.3-0.5 kWh/Nm³).

Typical Applications: Scenarios with low gas purity requirements such as mine ventilation and aquaculture.

II. Core Products and Application Fields

1. Core Products

Oxygen: Purity 99.5%-99.999%, used in iron and steel smelting (oxygen-enriched combustion), chemical oxidation reactions (e.g., methanol synthesis), medical emergency rescue, etc.

Nitrogen: Purity 95%-99.999%, used in electronic chip manufacturing (protective gas), food packaging (anti-corrosion), petrochemical industry (purging), etc.

Argon: Purity 99.99%-99.999%, used in stainless steel refining (decarbonization), semiconductor lithography (protective gas), etc.

Rare Gases:

Helium: Purity 99.99%, used in aerospace, magnetic resonance imaging (MRI), and hydrogen fuel cell cooling.

Neon, Krypton, Xenon: Used in semiconductor lithography, optical fiber manufacturing, and laser technology.

2. Application Fields

Metallurgical Industry: Oxygen-enriched coal injection in blast furnaces (increasing iron output by 10%-20%), converter steelmaking (rapid decarbonization).

Chemical Industry: Coal-to-olefins, natural gas reforming (providing high-purity oxygen), and nitrogen protection (preventing explosions).

New Energy Field:

Hydrogen Energy: Purify hydrogen (purity ≥ 99.97%) through cryogenic distillation or PSA methods for fuel cell vehicles.

Photovoltaic and Semiconductor: Ultra-high-purity nitrogen (purity ≥ 99.9999%) for environmental control in wafer manufacturing.

Environmental Protection Field: Separate oxygen in carbon capture and storage (CCS) to improve combustion efficiency and reduce carbon emissions.

III. Technology Trends and Innovation Directions

High-Efficiency and Energy-Saving Technologies

Magnetic Suspension Compressors: Reduce energy consumption by 15%-20%, with commercial application realized by Hangyang Co., Ltd.

Full-Liquid Air Separation: Flexibly adjust the ratio of gaseous to liquid products to adapt to fluctuating demands.

Intelligent and Digitalization

Predictive Maintenance: Monitor equipment status through the Internet of Things (IoT) and AI algorithms to reduce unplanned downtime.

Optimized Control: Adjust distillation parameters in real time to increase argon extraction rate to over 85%.

Green and Low-Carbon Transformation

Renewable Energy Coupling: Use wind power and photovoltaic power to drive ASUs, realizing "green electricity for oxygen/nitrogen production".

Energy Efficiency Standard Upgrade: China's "Energy Efficiency Limits for Air Separation Equipment" requires a 5% reduction in unit energy consumption by 2025, promoting the popularization of technologies such as magnetic suspension and turboexpanders.

IV. Selection Suggestions and Precautions

Key Factors for Selection

Purity and Output: Choose the technical route based on requirements (e.g., cryogenic method for the electronics industry, PSA method for the medical industry).

Energy Consumption and Cost: The cryogenic method is suitable for large-scale long-term operation, while the PSA method is suitable for small and medium-scale intermittent production.

Site and Flexibility: Membrane separation equipment has a small volume, suitable for space-constrained scenarios; modular ASUs (e.g., Linde Inspire™ series) can be quickly deployed.

Safety and Maintenance

Low-Temperature Protection: Prevent frostbite for deep cooling equipment, and regularly inspect the perlite sealing of cold boxes.

Impurity Control: Replace molecular sieves regularly (service life: 8-10 years) to avoid hydrocarbon accumulation and potential explosions.

Compliance: Comply with standards such as GB 16912-2008 "Safety Technical Regulations for Oxygen and Related Gas Production by Deep Cooling Method".