Title Role of particle size on the cohesive behavior of limestone powders at high temperature
Authors Espin, M. J. , DURAN OLIVENCIA, FRANCISCO JOSÉ, Valverde, J. M.
External publication Si
Means Chem. Eng. J.
Scope Article
Nature Científica
JCR Quartile 1
SJR Quartile 1
JCR Impact 13.27300
SJR Impact 2.52800
Publication date 01/07/2020
ISI 000544679100001
DOI 10.1016/j.cej.2019.123520
Abstract Thermal Energy Storage (TES) using granular solids is gaining momentum in the last years. With no degradation up to very high temperatures and very low price the use of some granular materials such as sand or SiC would be feasible for storing sensible heat at large scale. A further step beyond TES is thermochemical energy storage (TCES) wherein the granular solids undergo a highly endothermic reaction at high temperature. Energy can be in this way more e fficiently stored in the long term and released on demand by means of the reverse exothermic reaction. The Calcium Looping process, based on the calcination/carbonation of CaCO3 , is being actively in- vestigated for this purpose. However, a caveat of using granular solids for energy storage is the possible increase of interparticle adhesive forces with temperature which would severely hamper the flowability of the solids in the process. The cohesiveness of granular materials is essentially determined by particle size. In this paper we investigate the dependence of the tensile yield strength and compressibility of CaCO3 powders on temperature and consolidation stress using samples of narrow particle size distribution in the relevant range between - 30 and - 80 mu m particle size and temperatures up to 500 degrees C. Our experimental results show that powder cohe- siveness is greatly increased with temperature especially in the case of the finest powders whose tensile yield strength can be increased by up 2 orders of magnitude. The increase of cohesiveness with temperature is further enhanced with a previously applied consolidation stress, which is particularly relevant for applications wherein large amounts of solids are to be stored at high temperature. Experimental data are consistent with the pre- dictions by a contact mechanics model assuming that the solids deform plastically at interparticle contacts. A main conclusion from our work is that some mechanical properties of the solids, specially the mechanical hardness, and how they change with temperature, play a critical role on the flowability of the solids as a ffected by an increase of temperature.
Keywords Granular materials; Energy storage; Calcium looping; Fluidization; Flowability
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