Experimental investigation and model validation of a CaO/Ca(OH)2 fluidized bed reactor for thermochemical energy storage applications

The CaO/Ca(OH)2 hydration/dehydration chemical loop has long been recognized as a potential candidate for application in energy storage systems for concentrated solar plants. However, the technology still remains at a conceptual level because little information has been published on the performance of the key reactors in the system. In this work, we experimentally investigate the hydration and dehydration reactors in a 5.5 kWth batch fluidized bed reactor, in conditions relevant to larger systems (superficial gas velocities of up to 0.53 m/s, temperatures of up to 500°C for dehydration, input H2O(v) fractions between 0 and 0.8 etc.). Furthermore, to assist in the interpretation of the experimental results, a standard 1D bubbling reactor model has been formulated and fitted to the experimental results by including kinetic information at particle level independently measured in a thermogravimetric apparatus. The results indicate that the hydration reaction is mainly controlled by the slow kinetics of the CaO material tested while significant emulsion-bubble mass-transfer resistances were identified during dehydration due to the much faster dehydration kinetics.The financial support provided by the European Commission under the 7th Framework Program (StoRRe Project GA 282677) is acknowledged. Y.A. Criado thanks the Government of the Principality of Asturias for a Ph.D. fellowship (Severo Ochoa Program).Peer reviewe

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

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Industrial and Engineering Chemistry Research, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/acs.iecr.6b04105Novel 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 (450 °C–550 °C). 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.Financial support provided by the European Commission under the 7th Framework Program (StoRRe Project GA 282677) is acknowledged.Peer reviewe

Ca(OH)2/CaO reversible reaction in a fluidized bed reactor for thermochemical heat storage

Thermal energy storage (TES) is a key factor for increasing the efficiency of concentrated solar power plants. TES using a reversible chemical reaction appears to be a promising technology for high energy density thermal storage (100–500 kW h m-3), at high temperature(up to 1000 °C) and during a long period (24 h to several months). This paper details an experimental study to carry out the reversible reaction Ca(OH)2(s) + DHr CaO(s) + H2O(g) in a fluidized bed (FB) reactor. The 4 micron Ca(OH)2 powder fluidization has been performed with an appropriate proportion of inert easy-to-fluidize particles. Then, Ca(OH)2 dehydration and CaO hydration have been implemented in a FB reactor and 50 cycles have been reached. The mean energy density obtained is 60 kW h m-3 solid_mixture which amounts to a promising energy density of 156 kW h m-3 Ca(OH)2-bulk if the reactants and the easy-to-fluidize particles are separated. The results demonstrated the feasibility of the implementation of the Ca(OH)2/CaO thermochemical heat storage in a fluidized bed reactor

A review on high temperature thermochemical heat energy storage

Solar thermal energy represents an increasingly attractive renewable source.However,to provide continuous availability of this energy,it must be stored. This paper presents the state of the art on high temperature(573-1273K)solar thermal energy storage based on chemical reactions,which seems to be the most advantageous one for long-term storage. The paper summarizes the numerical,experimental and technological studies done so far. Each system is described and the advantages and drawbacks of each reaction couple are considered

Molecular basis of USP7 inhibition by selective small-molecule inhibitors

Ubiquitination controls the stability of most cellular proteins, and its deregulation contributes to human diseases including cancer. Deubiquitinases remove ubiquitin from proteins, and their inhibition can induce the degradation of selected proteins, potentially including otherwise 'undruggable' targets. For example, the inhibition of ubiquitin-specific protease 7 (USP7) results in the degradation of the oncogenic E3 ligase MDM2, and leads to re-activation of the tumour suppressor p53 in various cancers. Here we report that two compounds, FT671 and FT827, inhibit USP7 with high affinity and specificity in vitro and within human cells. Co-crystal structures reveal that both compounds target a dynamic pocket near the catalytic centre of the auto-inhibited apo form of USP7, which differs from other USP deubiquitinases. Consistent with USP7 target engagement in cells, FT671 destabilizes USP7 substrates including MDM2, increases levels of p53, and results in the transcription of p53 target genes, induction of the tumour suppressor p21, and inhibition of tumour growth in mice

Proof of concept of the CaO/Ca(OH)2 reaction in a continuous heat-exchanger BFB reactor for thermochemical heat storage in CSP plants

Proceedings of the 22nd SolarPACES 2016 International Conference, Abu Dhabi, UAEThe CaO/Ca(OH)2 hydration/dehydration reaction has long been identified as a attractive method for storing CSP heat. However, the technology applications are still at laboratory scale (TG or small fixed beds). The objective of this work is to investigate the hydration and dehydration reactions performance in a bubbling fluidized bed (BFB) which offers a good potential with regards to heat and mass transfers and upscaling at industrial level. The reactions are first investigated in a 5.5 kW batch BFB, the main conditions are the bed temperature (400-500°C), the molar fraction of steam in the fluidizing gas (0-0.8), the fluidizing gas velocity (0.2-0.7 m/s) and the mass of lime in the batch (1.5-3.5 kg). To assist in the interpretation of the experimental results, a standard 1D bubbling reactor model is formulated and fitted to the experimental results. The results indicate that the hydration reaction is mainly controlled by the slow kinetics of the CaO material tested while significant emulsion-bubble mass-transfer resistances are identified during dehydration due to the much faster dehydration kinetics. In the continuity of these preliminary investigations, a continuous 15.5 kW BFB set-up has been designed, manufactured and started with the objective to operate the hydration and dehydration reactions in steady state during a few hours, and to investigate conditions of faster reactivity such as higher steam molar fractions (up to 1), temperatures (up to 600°C) and velocities (up to 1.5 m/s).The financial support provided by the European Commission under the 7th Framework Program (StoRRe Project GA 282677) is acknowledged.Peer reviewe

ThermoConversion de matériaux carbonés pour produire des carburants de synthèse: cas de la biomasse

Dans le contexte énergétique actuel, la production de carburant à partir de biomasse suscite un intérêt croissant. Tandis que la première génération de biocarburants montre ses limites, une deuxième génération, basée sur la valorisation des ressources non utilisées en biomasse lignocellulosique, pourrait permettre d'augmenter sensiblement le potentiel des biocarburants en France et l'amener à couvrir jusqu'à 40 % des besoins. Parmi les filières en développement, celle basée sur le procédé Biomass to Liquid (BtL) de production de carburant de type Diesel Fischer-Trospch à partir d'un gaz de synthèse (H2, CO), obtenu par gazéification de biomasse, semble offrir des perspectives prometteuses, avec une mise en œuvre industrielle possible à relativement court terme. Néanmoins des travaux de recherche sont encore nécessaires pour lever les verrous qui subsistent. Ces études mobilisent plusieurs équipes en Europe, en particulier en Allemagne et dans les pays nordiques, et depuis récemment en France, notamment au Commissariat à l'Énergie Atomique

Dual Media Thermocline (DMT) techno-economic interest for heat storage on the range 80°C –600°C – The SMARTREC project

The economic assessment of a sensible heat storage system, the Dual Media Thermocline (DMT), is estimated for an industrial application of waste heat storage on the range of temperature 80°C to 600°C. The DMT is a main component of the standard and modular system developed in the frame of the H2020 Smartrec project (GA n° 723838). Further, the life cycle assessment (LCA) of the 1MWh Smartrec system is studied

Experimental results from a pilot scale latent heat thermal energy storage for DSG power plants – Advanced operating strategies

International audienceSince 2013, CEA has been operating a pilot scale high pressure water-steam facility called LHASSA designedto test latent thermal energy storage modules under operating conditions similar to commercial Direct Steam GenerationCSP plants. A Phase Change Material (PCM) storage module connected to this facility is composed of aluminum finnedsteel tubes immerged into sodium nitrate and surrounded by aluminum inserts for heat transfer enhancement. This paperpresents the results obtained from the third test campaign on this storage module, consisting in 25 charge-discharge cyclesunder a wide range of operating conditions (fixed of sliding pressure, complete and partial charge levels…). Thermalperformances of the storage test section show a very good repeatability, without any performance degradation comparedto the previous test campaigns. Some new operating strategies were successfully tested (charge interruption simulating acloud transient in the solar field, discharge with fixed pressure and varying mass flows, charge-discharge transitionmanagement)