The mOxy-CaL Process: Integration of Membrane Separation, Partial Oxy-combustion and Calcium Looping for CO2 Capture

CO2 capture and storage (CCS) is considered as a key strategy in the short to medium term to mitigate global warming. The Calcium-Looping process, based on the reversible carbonation/calcination of CaO particles, is a promising technology for post-combustion CO2 capture because of the low cost and non-toxicity of natural CaO precursors and the minor energy penalty on the power plant in comparison with amines capture based technologies (4-9 % compared to 8-12 %). Another interesting process to reduce CO2 emissions in power plants is oxy-combustion, which is based on replacing the air used for combustion by a highly concentrated (~95 % v/v) O2 stream. This work proposes a novel process (mOxy-CaL) for post-combustion CO2 capture based on the integration of membrane separation, partial oxy-combustion and the Calcium-Looping process. An oxygenenriched air stream, which is obtained from air separation by using highly permeable polymeric membranes, is used to carry out partial oxy-combustion. The flue gas exiting partial oxy-combustion shows a CO2 concentration of ~30 % v/v (higher than 15 % v/v typical in coal power plants). After that, the flue gas is passed to the CaL process where the CO2 reacts with CaO solids according to the carbonation reaction. Thermogravimetric analysis show that the multicycle CaO conversion is enhanced as the CO2 concentration in the flue gas stream is increased. Process simulations show that the mOxy-CaL process has a high CO2 capture efficiency (~95%) with lower energy consumption per kg of CO2 avoided than previously proposed post-combustion CO2 capture technologies. Moreover, the overall system size is significantly lower that state-of-the-art CaL systems, which allows for an important reduction in the capital cost of the technology

Constant rate thermal analysis for thermal stability studies of polymers

This paper explores the relationship between the shapes of temperature-time curves obtained from experimental data recorded by means of constant rate thermal analysis (CRTA) and the kinetic model followed by the thermal degradation reaction. A detailed shape analysis of CRTA curves has been performed as a function of the most common kinetic models. The analysis has been validated with simulated data, and with experimental data recorded from the thermal degradation of polytetrafluoroethylene (PTFE), poly(1,4-butylene terephthalate) (PBT), polyethylene (PE) and poly(vinyl chloride) (PVC). The resulting temperature-time profiles indicate that the studied polymers decompose through phase boundary, random scission, diffusion and nucleation mechanisms respectively. The results here presented demonstrate that the strong dependence of the temperature-time profile on the reaction mechanism would allow the real kinetic model obeyed by a reaction to be discerned from a single CRTA curve.Junta de Andalucía TEP-03002Ministerio de Ciencia e Innovación MAT 2008-06619/MA

Clay mineralogy of soils from SW Spain with high iron content

26 páginas.-- 2 graficas.-- 8 tablas.-- 26 referencias. -- Trabajo enviado para su publicación en la revista SOIL SCIENCE.-- (no se llegó a publicar).- Se convirtió en este otro artículo "Occurrence of talc in soils with high iron content from the south-west of Spain" publicado en Australian Journal of Soil Research 34: 635-651 (1996) http://hdl.handle.net/10261/65016The mineralogy of the clay fraction of four soil one alfisol and three inceptisols developed on cambian limestone, and to consider the mode of formation in terms of pedogenic processand classification has been determined. In soils I and II there is a high proportion of goethite accompanied by hematite at the bottom of the profiles, according to the data goethite is originated directly from the bedrock and hematite is produced by dehydration of goethite. The most characteristic is the presence of maghemite in the upper horizon of these profiles. Its presence is related with the weathering of hematite, that may produce goethite and later maghemite by dehydration. The non-ferrous minerals of soil are: talc, chlorite and interstratified talc-chlorite, profile II has in addition to kaolinite, vermiculite and illite. In soil IV a high proportion of goethite and hematite has been found, a high relation exist between bath iron oxides. The hematite is originated directly from the bedrock and goethite is produced from hematite. The high proportion of kaolin is characteristic, showing an external contribution or extensive pedogenic processes. Soil III is constituted by goethite and hematite and it is difficult to determine, the origen of these iron oxides. The non-ferrous minerals are kaolinite, chlorite and illite.N

The Calcium-Looping (CaCO3/CaO) Process for Thermochemical Energy Storage in Concentrating Solar Power Plants

Articulo aceptado por la revista. * No publicado aún [28-06-2019]Energy storage based on thermochemical systems is gaining momentum as potential alternative to molten salts in Concentrating Solar Power (CSP) plants. This work is a detailed review about the promising integration of a CaCO3/CaO based system, the so-called Calcium-Looping (CaL) process, in CSP plants with tower technology. The CaL process relies on low cost, widely available and non-toxic natural materials (such as limestone or dolomite), which are necessary conditions for the commercial expansion of any energy storage technology at large scale. A comprehensive analysis of the advantages and challenges to be faced for the process to reach a commercial scale is carried out. The review includes a deep overview of reaction mechanisms and process integration schemes proposed in the recent literature. Enhancing the multicycle CaO conversion is a major challenge of the CaL process. Many lab-scale analyses carried out show that residual effective CaO conversion is highly dependent on the process conditions and CaO precursors used, reaching values as different as 0.07-0.82. The selection of the optimal operating conditions must be based on materials, process integration, technology and economics aspects. Global plant efficiencies over 45% (without considering solar-side losses) show the interest of the technology. Furthermore, the technological maturity and potential of the process is assessed. The direction towards which future works should be headed is discussed.Ministerio de Economia y Competitividad CTQ2014-52763-C2, CTQ2017- 83602-C2 (-1-R and -2-R)Unión Europea Horizon 2020 Grant agreement No 727348, project SOCRATCES

Dependence of the preexponential factor on temperature

The dependence of the preexponential factor on the temperature has been examined and the errors involved in the activation energy calculated from isothermal and non-isothermal methods without considering such dependence have been estimated. It has been shown that the error in the determination of the activation energy calculated ignoring the dependence of Aon Tcan be rather large and it is dependent on x=E/RT, but independent of the experimental method used. It has been also shown that the error introduced by omitting the dependence of the preexponential factor on the temperature is considerably larger than the error due to the Arrhenius integral approach used for carrying out the kinetic analysis of TG data.Peer reviewe

Mechanisms of interaction between montmorillonite and 3-aminotriazole

The adsorption of aminotriazole, at its solution pH, with montmorillonite saturated with different cations has been studied. A pesticide-montmorillonite complex is formed through interlamellar cations which are not displaced. Aminotriazole is situated mostly as a polarized molecule around Mg2+ and Zn2+ cations, removing a great amount of water. In Na+- and Li+-montmorillonite, the pesticide remains as a non-polarized molecule, hydration water being retained in the interlamellar space; the pesticide is coordinated to interlamellar cations through water bridges. For all samples a proportion of cationic aminotriazole is also adsorbed, the amount being greater with increasing polarizing power of the interlamellar cation; consequently, in Fe3+-montmorillonite all the aminotriazole adsorbed is in the cationic form.The authors acknowledge the Direcci6n General de Investigaci6n Científica y Técnica, Spain, for financial support of this work through Project PB87-0240.Peer Reviewe

Readability of Non-text Images on the World Wide Web (WWW)

The World Wide Web associated the world in a manner that was unrealistic previously and made it a lot more straightforward for users to get data, share and impart. But, irrelevant non-text images on the web pages equally specify poor readability, disrupting the people from the emphasis of the reading. The main goal of this paper is to evaluate the impact of irrelevant or low-quality non-text images on the readability of the webpage. An automatic methodology has been proposed to compute the relevancy of the non-text images. This methodology merges different approaches to extract information from non-text images and read text from websites in order to find relevancy between them. This technique was used to analyze fifty different educational websites to automatically find the relevancy of their non-text images. A user study has been carried out to evaluate the proposed methodology with different types of questions. The results agree with the fact that the relevant non-text images enhance the readability of the web page. This research work will help web designers to improve readability by considering only the relevant content of a web page, without relying on expert judgment.This work was supported in part by the Spanish Ministry of Economy, Industry and Competitiveness under Grant CSO2017-86747-R, in part by the Andalusia Regional Projects under Grant AT17-5509-UMA ``ROSI'' and Grant UMA18-FEDERJA-074 ``ITERA,'' and in part by the European art83 under Contract 8.06/5.58.5900 DIH-HERO ``SUSTAIN.'