Task 2

Thermochemical Energy Storage CaCO₃-based Materials Reactivity, Stability and Attrition Resistance for Ca-Looping Process

🕒 30 months

Objectives | Assess the up-scale effect on the reactivity of selected TCES materials in a laboratorial fixed bed reactor (FxBR) under different experimental conditions (including reactivation techniques) and characterize the material after the carbonation-calcination cycles. Evaluate the materials attrition resistance in a fluidized bed reactor (FBR).

Task Description | The TCES materials identified in task 1 will be tested in a fixed bed reactor (FxBR) and fluidized bed reactor (FBR). The most favourable experimental conditions achieved in task 1will be used, namely, carbonation and calcination temperatures and respective atmospheres (e.g. N₂, CO₂, Air). Reactivationtechniques, specifically, the use of steam hydration and the use of different atmospheres during the first calcination (or pre-calcination) will be applied; the idea is evaluate its effect on the increasing of TCES material lifetime and CO₂ carrying capacity.
The great advantage of the FxBR and FBR, comparatively with the TGA and insitu-XRD techniques used in task 1 is the production of enough used/spent TCES material to be analysed by N₂ sorption, that provide relevant information about textural properties. Besides, the higher volume of sample allow obtain a more representative SEM analysis.
The tests to perform in the FBR will be especially relevant to evaluate the attrition resistance of TCES materials. Attrition resistance will be determined in terms of sorbent loss from bed (fines elutriation) and changes in particle size distribution (abrasion and fragmentation) during the calcination-carbonation cycles in the FBR.
The attrition rate of a sorbent particle along the cycles will be estimated through the median particle size at initial (D50, 0) and after N cycles (D50, N). Since the attrition is less significant for partides greater than 75 µm, the attrition resistance will be also evaluated considering the mass of particles in the bed ? 75µm at initial and after N cycles. After the cycles, the sorbents particles higher and lower 75μm will be characterized separately by N₂ sorption, XRD and SEM analysis. Depending of experimental particle size distribution, a different size could be selected.

Results | Achieve optimal experimental conditions, taking into account the stability and carrying capacity of CO₂ during the Ca-looping: (i) carbonation and calcination temperature and atmosphere, (ii) reactivation techniques, (iii) attrition resistance. The data obtained will be used for parameters estimation and models validation in task 4 and 5.