Decarbonisation Technology August 2025 Issue

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Process stage

Figure 5 Hydrogen concentration in oxygen stream (left) and oxygen concentration in hydrogen stream (right) in AEL systems

hazards, and decreased fuel cell or industrial performance. Recommended mitigation • Proper system design with backflow preventers and safe shutdown sequences. • Use robust separation membranes and pressure balancing controls. • Installation of MOD 1040 and MOD 1060 analysers inline for real-time detection. • Monitoring for vacuum and pressure events, which often precede contamination. Measurement challenges and Modcon solutions Modcon MOD 1040 and MOD 1060 analysers are designed with low sensitivity to relative humidity to operate reliably in 0-100% RH without the need for dryers. Both analysers are designed for inline installation in both low- and high-velocity application and real-time pressure, and temperature compensation is built in to maintain accuracy. Modcon analysers are proven in the field, with successful installations by major OEMs confirming the robustness and safety of these ATEX, IECEx and SIL2 certified analysers. The anatomy of the AEL process reveals a complex interplay of environmental and operational variables. Reliable online hydrogen and oxygen analysis depends on technology capable of adapting to these dynamic conditions. MOD 1040 and 1060 deliver industry-leading performance and resilience, ensuring safe and

accurate gas monitoring throughout the full lifecycle of the electrolyser process. KOH traces in gas streams In AELs, potassium hydroxide (KOH) is commonly used as the electrolyte. During electrolysis, small amounts of KOH can be entrained into the gas streams due to bubble formation, spray entrainment, or incomplete phase separation. These traces of KOH, though typically present in ppm levels, can pose significant challenges to online analysers. Potential challenges include: • Corrosion or degradation of sensitive analyser components. • Conductive contamination, leading to false readings or signal noise. • Clogging or residue build-up in sample lines or sensors. Robust sensor design and material compatibility are critical. MOD 1040 and 1060 analysers are engineered to handle these environments, with proven resistance to KOH exposure and minimal maintenance requirements. Their performance remains stable even with fluctuating levels of KOH present in the gas streams. Nitrogen presence in the AEL process While hydrogen and oxygen are the primary gases generated in an AEL, nitrogen (N₂) is often detected in the process. Although inert, nitrogen impacts gas purity and measurement accuracy.