Pilot-scale investigation of high-temperature thermochemical energy storage based on the material system CaO/Ca(OH)₂ in a bubbling fluidized bed

Utilizing fluidized bed technology for thermochemical energy storage with CaO/Ca(OH)₂ is promising for temperatures from 400 °C to 600 °C in industrial-scale applications. Much progress has been made on laboratory scale to develop this technology in recent years. Continuously changing material properties throughout storage cycles, mainly due to particle breakage, are identified to be challenging for scale-up. Transferability to large-scale systems needs to be examined. Investigations on a pilot scale (d_i = 257 mm, h = 600 mm, steam for fluidization, 700 °C, 6 bar_g) are done. A temperature-induced (456 °C discharging and 586 °C charging) and a pressure-induced (1.5 bar_g discharging and 3.5 bar_g charging) cyclization is performed. The applicability of standard scaling rules (scaling factor of 17) is possible. Fluidization regimes and breakage rates are transferrable. A detailed experimental characterization of the storage materials fluidization properties that are crucial for scale-up is done using a fluidization test rig (d_i = 140 mm, h = 658 mm, nitrogen for fluidization, ambient temperature and pressure).