Continuous CaO/Ca(OH)₂ Fluidized Bed Reactor for Energy Storage: First Experimental Results and Reactor Model Validation

Abstract

Novel thermochemical energy storage systems that employ fluidized beds of CaO/Ca(OH) 2 for hydration/dehydration reactions are under development because of the inherent advantages of the low cost of the materials and their relatively high temperature operation windows (450ºC-550ºC). We report in this work the results of the first steady state experiments conducted in a new pilot plant designed to test the concept under realistic reactor conditions. The pilot has a fluidized bed reactor with an internal diameter of 0.108 m and a height of 780 mm fed continuously with gas and solids as well as heat exchangers to supply/extract the required reaction heat. The experimental results during dynamic and steady state periods were fitted to a KL reactor bubbling bed model, using kinetic parameters from thermogravimetric studies and a single crossflow factor. The resulting continuous reactor model will serve as useful tool for the continued scaling up of this technology.

Power generation based on the Ca(OH)2/ CaO thermochemical storage system – Experimental investigation of discharge operation modes in lab scale and corresponding conceptual process design

“…Pardo et al carried out the reaction in a fluidized bed for 1.9 kg of material composed of 30 %w Ca(OH) 2 and 70 %w inert easy to fluidize particles [30]. Criado et al presented a theoretical study on a fluidized bed concept for large CSP plants [31] while recently the group proofed the concept experimentally in a newly constructed lab scale set up [32].…”

Fluidized Beds for Concentrated Solar Thermal Technologies—A Review

“…A fairly small sorbent conversion degree (20-40%) was obtained, attributed to the severe calcination conditions. Experimental tests with similar process conditions were also performed by Rougé et al (2017) in a FB reactor (Type A) equipped with hoppers and screw feeders for continuous operation. Criado et al (2014) developed a model of a TCES process based on CaO hydration/dehydration, embodying separate storage vessels for CaO and Ca(OH) 2 , and a single circulating FB reactor alternating between energy collection and retrieval.…”

Developments in calcium/chemical looping and metal oxide redox cycles for high-temperature thermochemical energy storage: A review

“…Recently, there have been remarkable improvements in attrition resistant of Ca-based materials by using sodium silicate to combine with fine CaO/Ca(OH)2 particles, which can reduce the decay in TCES over hundreds of cycles [47]. In addition to such developments, conceptual process design and experimental investigation of the process of CaO/Ca(OH)2 for thermochemical energy storage applications have been conducted, which will be useful to scale up this technology and accelerate the application of hydroxides-based systems for TCES [48][49][50].…”