Control logic of a batch operation process using Zeolite Molecular Sieve beds

• Zeolite Molecular Sieve beds recover ppm levels of tritiated water from gas streams. • The case study is an updated four bed configuration of the DEMO coolant purification system CPS. • A MATLAB–Simulink model demonstrates continuous operation under a new control logic. • Heating phase doubles Q2O desorption to 0.1 vs 0.06 mol/mol in regeneration stream. • Radial thermal effects influence system timescales and bed performance. Tritium is a scarce and essential isotope for fusion energy, requiring efficient management and recovery even from streams with very low concentrations. A well-established technique for treating gaseous streams containing tritium at ppm levels involves oxidizing hydrogen isotopes and adsorbing the resulting tritiated water in Zeolite Molecular Sieve (ZMS) beds. Regeneration of these beds is necessary to restore their adsorption capacity. For application in a Fusion Power Plant, the process must ensure not only recovery of the desorbed tritiated water but also operate continuously, enabling efficient use of volumes and minimizing the overall tritium inventory. This work proposes a control strategy to achieve continuous operation of an inherently batch ZMS process, using the Coolant Purification System (CPS) of the Helium-Cooled DEMO fusion plant as a case study. The developed logic upgrades the baseline three-bed design to four ZMS beds operating in four sequential phases (adsorption, heating, regeneration, and cooling) while always maintaining two beds in adsorption. Individual bed behaviour was modelled in MATLAB, and all four models were integrated in Simulink. Transitions between phases occur when monitored parameters reach predefined setpoints, ensuring coordinated operation across the beds. Results demonstrate the technical feasibility of continuous ZMS operation and highlight the influence of parameters such as zeolite thermal conductivity on process timescales and efficiency. The introduction of a distinct heating phase increases the desorption peak, thereby improving the conditions for water condensation and recovery. These findings provide a foundation for optimizing CPS design, enhancing overall fusion plant performance.