Process Analytics in Alkaline Water Electrolysis (AEC): Ensuring Safety and Purity in Harsh Environments
Alkaline Water Electrolysis (AEC) is the most mature and cost-effective technology for utility-scale green hydrogen production. However, operating with highly corrosive liquid electrolytes (typically 20–30% KOH) at elevated temperatures creates a demanding environment for process instrumentation.
To maintain plant safety, optimize gas purity, and extend the lifespan of the electrolyzer stack, precise online measurement at critical process points is non-negotiable.
Technical Challenges in AEC Plants
KOH Aerosol Carryover: Saturated gas leaving the separator carries corrosive KOH mist, which can easily poison traditional sensors.
Saturated Wet Gas Streams: The raw hydrogen gas at the electrolyzer outlet is 100% saturated with water vapor. Standard gas sensors suffer from severe drift under these conditions.
Hazardous Gas Crossover: Diaphragm degradation or pressure imbalances can cause hydrogen to leak into the oxygen stream (or vice versa), risking explosive mixtures.
Critical Analytical Measurement Points (MPs)
MP 1 & MP 2: Gas Crossover Safety & Raw Purity
The Process Goal: Continuously monitor the H2 concentration in the O2 stream (and O2 in the H2 stream) to ensure the mixture stays well below the Lower Explosive Limit (LEL). Simultaneously, monitor raw H2 purity.
The Analytical Challenge: Raw gases are extremely wet and contaminated with KOH trace aerosols. Standard thermal conductivity (TCD) sensors will misread water vapor as hydrogen, leading to measurement errors of 1–5 vol% H2.
MZD Solution Link: At these wet gas checkpoints, we integrate our MZD Active Water-Vapor Compensated Hydrogen TCD Analyzer, paired with our Optical Fluorescence Quenching Oxygen Analyzer which is completely immune to high-humidity drift.
MP 3: Gas Drying & Purification Control
The Process Goal: Verify that the gas dehydration and purification units (deoxis) are performing efficiently before the hydrogen is compressed or stored.
The Analytical Challenge: Detecting trace moisture (H2O) down to low ppm levels under fluctuating pressure conditions.
MZD Solution Link: Post-purifier moisture verification is handled by our absolute P2O5 Electrolytic Trace Moisture Analyzer, providing drift-free performance.
MP 4: KOH Electrolyte Concentration Control
The Process Goal: Maintain the optimal electrical conductivity and concentration of the circulating KOH solution to maximize hydrogen generation efficiency.
The Analytical Challenge: Strong alkaline environments cause standard glass electrodes or 2-electrode sensors to scale and drift rapidly.
MZD Solution Link: We recommend our 4-Electrode Conductivity Analyzer, designed specifically to withstand high-salinity industrial fluids.
Contact
For detailed technical documentation, including process instrumentation layouts and application-specific measurement recommendations, please contact: sales@mzdd.de .