The development of a reactor concept with a moving reaction bed for thermochemical energy storage as central topic of this thesis is subdivided into four different fields, namely reactor selection, modelling, modification of reaction material and experimental proof of concept.
First of all, basic reactor concepts for the reaction system CaO/Ca(OH)2 are discussed and according to appropriate parameters a moving bed is favoured for further investigation. For the mathematical description of the system an existing model with direct heat transfer was extended for an indirect heat transfer and the indirect heat exchange was experimentally validated by a reactor with an unmoved reaction bed. The operating method with the indirect heat transfer is preferred due to the easier reaction control and higher operational flexibility. However, due to the low thermal conductivity of the bulk a narrow reactor geometry is essential for an indirect concept. Contrary, the addiction of the material to agglomeration effects during the thermochemical cycling and the poor flowability in consequence of strong cohesive forces necessitate a modification of the fine grained powder. By means of the dry addition of nanoparticles at precisely defined mixing conditions a minimization of agglomeration effects and specific adjustment of the flowability have been achieved. This method allows an easy modification of the movement properties of the material in order to realize innovative reactor concepts with narrow geometry for improved heat exchange. The cycling stability of the modified Ca(OH)2 material was analysed after a 10 cycles treatment in a pilot scale reactor. The investigation of the particle size distribution and XRD measurements show a stable coating of the nanoparticles on the surface at the expense of storage capacity due to formation of calcium silicates.
Concluding, the flow behaviour of the modified material is investigated under ambient, hot and reaction conditions in a lab-scale reactor and a proof of concept is provided. Even though, the material throughput and reaction was achieved, the overall conversion at the reactor outlet was limited. This was caused by inadequate sealing effect of the screw conveyors in this experimental set-up leading to an insufficient gas transport. In further works the implementation of additional gas locks can solve these challenges