PSA or TSA for Green Hydrogen Drying
K. Khodke (TU Delft - Mechanical Engineering)
M. Ramdin – Mentor (TU Delft - Mechanical Engineering)
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Abstract
Green hydrogen produced by alkaline water electrolysis may contain residual water vapour and other impurities that must be removed before use in fuel-cell applications. This study investigated adsorption-based hydrogen drying using Pressure Swing Adsorption (PSA) and Temperature Swing Adsorption (TSA), with particular attention to process modelling in Aspen Adsorption.
Zeolite 4A was selected because of its strong affinity for water at low partial pressures. Water adsorption equilibrium was represented using a Dual-Site Langmuir 2 model, while mass transfer was described using the Linear Driving Force model. A non-isothermal packed-bed model was developed for a hydrogen feed containing 872 ppmv water at 25 bar, 298.15 K, and a flow rate of 0.0223 kmol s−1. Several PSA configurations were tested, including conventional pressure regeneration, vacuum regeneration, and temperature-assisted vacuum regeneration. Conventional regeneration at 1 bar produced only limited reduction in solid water loading, while deep-vacuum simulations showed numerical convergence problems during multi-cycle operation. Therefore, the detailed cyclic and economic assessment was continued using TSA.
For the TSA process, the simulated breakthrough time was approximately 19 250 s, and an adsorption time of 14 000 s was selected to provide a safety margin before water breakthrough. Regeneration w