[ gas-liquid separation ]
Gemini Pura-Sep horizontal gas filter-coalescer( Fig. 5) to the growing hydrogen market. This technology utilises PEACH( Parker Engineered Applied Conical Helix) coalescing filters, ensuring high-efficiency separation of entrained liquid droplets down to 2 ppb of free water, with 99.99 % separation of > 0.1 micron droplets achievable. Polypropylene filter elements also offer excellent chemical resistance to KOH. 16 Gas-electrolyte separation is also required for the oxygen produced by electrolysis. This necessitates oxygen-compatible filter elements constructed from stainless steel. 17
The PEACH media utilises saturated-depth coalescing technology. A gradient is engineered through the media from tightly packed layers at the inlet face to more open layers at the outlet face. This both enhances inertial impaction and interception and facilitates the growth of larger droplets, which then separate more effectively under gravity. The lower density( higher porosity) ensures a lower pressure drop when operating wet compared to other technologies. The separation of water droplets from hydrogen can theoretically be achieved with < 5 mbar pressure drop. Handled end caps and the patented Rollout seal system ensure quicker filter change-out, minimising system downtime and ensuring the maximum return from the renewable electricity supplied to the electrolyser.
References
¹ Hall, S. M.( 2018). Rules of Thumb for Chemical
Engineers( 6th ed.). Cambridge: Elsevier. ² Svrcek, W. Y., & Monnery, W. D.( 1993). Design two-phase separators within the right limits. Chemical Engineering Progress( October), 53 – 60. ³ Towler, G., & Sinnott, R.( 2008). Chemical Engineering Design: Principles, Practice and Economics of Plant and Process Design. Elsevier.
4
American Petroleum Institute.( 2008). Specification for Oil and Gas Separators, API Specification 12J.
5
Chemical Engineering Research and Design, 201( 2024), 257 – 274.
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ICS Technology.( 2022, June). Hydrogen Degassing Management.
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Journal of the American Chemical Society,
146( 14)( 2024), 10177 – 10186.
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Renewable and Sustainable Energy Reviews,
16( 6)( 2012), 4257 – 4263
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Oil and Gas Facilities, 2( 5)( 2013), 35 – 47.
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Sutherland, K.( 2008). Filters and Filtration
Handbook. Elsevier.
¹¹ Materials Today Advances, 9( 2021), 100134.
¹² Colloids and Surfaces A: Physicochemical and Engineering Aspects, 652( 2022), 129722.
¹³ Filtration Technology Corporation. Fundamentals of Gas – Liquid Separation, with a focus on gas processing.
14
Dupuy, P. M., Fernandinho, M., Jakobsen, H. A., & Svendsen, H.( 2010). High pressure gas – liquid separation: Diffusion coefficient, the silent coalescence inhibitor. In Offshore Technology
Conference, Houston.
15
Ptak, T. J.( 2017). Gas filtration. In P. J. Brown & C. L. Cox( Eds.), Fibrous Filter Media( pp. 3 – 26). Woodhead Publishing.
16
Braskem.( 2005, December). Technical Literature: Polypropylene Chemical Resistance.
17
Gladstone, J.( 2025). White Paper: Oxygen Considerations for Electrolysers. Parker Hannifin.
About the author
Daniel Telford is a Hydrogen R & D Engineer for Parker’ s Filtration Group, based in the UK. He is part of a team focused upon improving the energy efficiency of the balance-of-plant for green hydrogen projects. Daniel has a PhD in Chemical Engineering and is a Chartered Chemist with the Royal Society of Chemistry. He has led research projects in catalysis, process development, and blue hydrogen production, and has considerable experience in experimental testing, plant commissioning, and process simulation.
Hydrogen Tech World | Issue 22 | June 2025 37