Air Liquide Project: High-Purity Hydrogen Purification and Precision Filtration System

Project Background:

Air Liquide is a global leader in gases for industry and health. With the advancement of the global hydrogen strategy, their hydrogen production (SMR/Electrolysis) and refueling station projects demand near-stringent cleanliness levels. Any trace of particulates, moisture, or oil mist entering downstream proton exchange membrane fuel cells (PEMFC) or high-pressure hydrogen storage tanks could cause catalyst poisoning or safety hazards. Consequently, Air Liquide introduced Unite’s deeply customized high-pressure hydrogen fine filtration systems to ensure a supply purity of "Five-Nines" (99.999%+) or higher.

Core Challenges:

• Anti-Hydrogen Embrittlement: Hydrogen is highly permeable, and under high pressure, it can easily cause "hydrogen embrittlement" in metallic materials, leading to vessel failure.
• Ultra-High Cleanliness Standards: The system must stably intercept particles and aerosolized oil mists larger than 0.1 microns, ensuring compliance with ISO 14687 hydrogen quality standards.
• Extreme High-Pressure Operation: Systems must satisfy operating pressures of 20MPa, 35MPa, or higher, demanding exceptional weld quality and sealing reliability.
• Oil-Free Treatment: Hydrogen systems are specialty applications; all equipment must undergo rigorous degreasing and oil-free treatment to prevent fire hazards.

Our Solution:

Tailored to Air Liquide’s specific working conditions, we provided modular high-pressure hydrogen purification filtration units:

• Specialty Material Selection: Utilizing heat-treated low-carbon SS316L stainless steel or specific grades of high-nickel alloys to effectively resist hydrogen embrittlement, ensuring structural safety during long-term operation.
• Multi-Stage Composite Filtration: The first stage uses high-precision sintered metal powder elements for solid particle interception; the second stage employs imported ultra-fine fiber coalescing elements to remove trace oil mist and liquid moisture via advanced coalescing principles.
• Rigorous Manufacturing Process: Vessels undergo 100% radiographic testing and professional degreasing, pickling, and passivation. Assembly is conducted in a Class 10,000 cleanroom to ensure the equipment internals meet "dust-free and oil-free" standards.
• Intelligent Online Monitoring: Equipped with intrinsically safe explosion-proof differential pressure transmitters to monitor filter status in real-time. Connected via explosion-proof control boxes to Air Liquide’s central control system for digital safety management.

Customer Value & Results:

Since the hydrogen purification system commenced operation at Air Liquide's hydrogen stations, gas quality has consistently remained stable online, with purity fully meeting the requirements of the downstream electronics industry and hydrogen fuel cell vehicles. The high reliability of the system has significantly extended the lifespan of downstream precision valves and compressors, effectively avoiding costly unplanned maintenance. Air Liquide highly commended Unite’s expertise in anti-hydrogen embrittlement material application and oil-free clean production. The successful commissioning of this project further consolidates our leading position in the new energy gas sector.