Dynamics of large-scale fluidized bed combustion plants

Fluidized bed combustion (FBC) plants are widely used in energy systems across the world for the thermochemical conversion of solid fuels, and are especially suitable for low-rank fuels (a category to which renewable solid fuels belong). FBC plants are traditionally operated for base-load electricity production and for heat production, both of which processes are characterized by steady and stable operation. As the share of variable renewable electricity (VRE) sources is expected to increase dramatically, FBC plants will have to adapt their operations to the new flexibility requirements related to the inherent variability of VRE sources. By enhancing their operational and product flexibilities, FBC plants can remain financially attractive and offer services to support the balancing of the grid. As tools for assessing the operational flexibility of thermal power plants, dynamic modeling and simulation are gaining attention from both researchers and plant operators. However, it is a common practice to assume that the dynamics of the gas side are much faster than those of the water-steam side, i.e., not accounting for the in-furnace dynamic mechanisms.This thesis aims to characterize the dynamic behaviors of commercial-scale FBC plants, accounting for both the gas and water-steam sides of bubbling and circulating fluidized bed (BFB and CFB) units. For this purpose, a dynamic semiempirical model of the gas side of FBC plants is developed and integrated into a process model of the water-steam side. The models are validated against steady-state and transient operational data measured at two commercial-scale industrial units. The model is then used to analyze the inherent dynamics of the gas and water-steam sides, to compare the transient behaviors of BFB and CFB units, and to assess the dynamic performances of FBC plants when operated under different control structures. The results of the dynamic analysis show that the stabilization times of the temperatures across the furnace differ, largely based on the local heat capacity of the region in the furnace, i.e., the amount of bulk solids. The work includes an assessment of the impact of the characteristic times of the in-furnace mechanisms (i.e., fluid dynamics, fuel conversion and heat transfer) on the computed stabilization times of key in-furnace variables at plant level, and suggests some simple mathematical relationships for predicting these times. When accounting for the water-steam side, the results show that the inherent dynamics of variables such as live steam pressure, flow and power production are in the same order of magnitude as the dynamics of the gas side, particularly for the CFB case. This highlights the importance of accounting for the gas side when attempting to model accurately the dynamics of FBC plants. Furthermore, FBC plants are found to be able to provide fast load changes when operated under control structures that manipulate the live steam valve, although this is found to trigger operational issues, such as pressure overshoots.The results of this thesis are of particular importance in terms of assessing the transient capabilities of FBC plants to operate in electricity-driven markets where fast operation is required, and they can be used to identify opportunities and challenges. Furthermore, knowledge about the transient operation of large-scale FB reactors will be crucial for the development of FB applications other than combustion, such as polygeneration or thermochemical energy storage

Fluidized bed plants for heat and power production in future energy systems

Fluidized bed (FB) plants are used for heat and power production in several energy systems around the world, with particular importance in systems using large shares of renewable solid fuel, e.g., biomass. These FB plants are traditionally operated for base-load electricity production or for heat production, and thus characterized by relatively small and slow load changes. In parallel, as the transition towards energy systems with net-zero emissions increases the share of variable renewable energy (VRE) sources, the need for implementing variation management strategies at various timescales arises – giving heat and power plants the possibility to adapt their operations to accommodate the inherent variability of VRE sources. Following this, FB technology is envisioned for a wide range of novel applications expected to play significant roles in the decarbonization of energy systems, such as thermochemical energy storage and carbon capture and storage. In this context, research efforts are needed to investigate the technical and economic features of FB plants in energy systems with high levels of VRE.The aim of this thesis is to elucidate the capabilities of FB plants for heat and power production in net-zero emissions energy systems. For this purpose, two main pathways are explored: i) transient operation as fuel-fed plants, and ii) the potential conversion into decarbonized plants, i.e., into VRE-fed layouts providing dispatchable outputs.For fuel-fed FB plants, a dynamic model of biomass-fired FB plants has been developed, considering the two types of FB boilers (BFB and CFB) and including validation against steady-state and transient operational data collected from two commercial plants. As a novelty of this work the model describes both the gas (in-furnace) and water-steam sides such that the interactions between the two can be assessed. The results of the simulations show that i) the characteristic times for the gas side are shorter in BFB furnaces than in CFBs, albeit these times are for both furnace types not longer than those for the water-steam side; ii) the computed timescales for the dynamics of FB plants fall well within those required for offering complementing services to the grid; and iii) the use of control and operational strategies for the water-steam side can confer capabilities superior to fuel-feeding control in terms of avoiding undesirable unburnt emissions and providing temporary overload operation. The retrofit of fuel-fed FB plants into poly-generation facilities cogenerating a combustible biogenic gas is also assessed, revealing that partial combustion of this gas can be used to provide faster inherent dynamics than the original configuration.For VRE-fed FB layouts, techno-economic process modeling has been carried out for large-scale deployment of solar- and electricity-charging processes based on three different chemical systems: i) carbonation/calcination (calcium); ii) thermally reduced redox (cobalt oxides); and iii) chemically reduced redox (iron oxides). One attractive aspect of these layouts is the possibility to build part of them by retrofitting current fuel-fed FB plants. While the technical assessment for solar applications indicates that cobalt-based layouts offer the highest levels of efficiency and dispatchability, calcium-based processes present better economics owing to the use of inexpensive calcium material. The results also show that electricity-charged layouts such as iron looping can play an important role in the system providing variation management strategies to the grid while avoiding costly H2 storage. Further, the economic performances of VRE-fed FB layouts are benefitted by the generation of additional services and products (e.g., carbon capture and on-demand production of H2), and by scenarios with high volatility of the electricity prices

La comunicación en salud desde el punto de vista de una Sociedad médica = Health communication from the point of view of a medical Society

Resumen: La función de las Sociedades médicas, más allá de la generación de conocimiento científico y de la actualización de habilidades y tratamientos médicos que puedan ser aplicados en la práctica clínica diaria, no tendría sentido sin una meditada planificación y estructuración que transmita correctamente dichos conocimientos a la población general. De hecho, la comunicación debería ser el vehículo sobre el que se sustenten las acciones de una Sociedad Científica. De su relación con los medios de comunicación y del uso adecuado de los numerosos canales que divulgación que permiten las nuevas tecnologías depende que la información en salud sea lo más rigurosa y didáctica posible. Con ello, se consigue potenciar la socialización del saber médico y reforzar la educación del paciente experto, estableciendo nuevas relaciones entre el médico y el paciente que cuenten con las garantías que ofrece una Sociedad científica. Palabras clave: Comunicación en salud; Sociedad Médica; Medios de comunicación; Nuevas tecnologías; redes sociales. Abstract: The function of Health Societies, further than the scientific knowledge, actualization of abilities and medical treatments that could be used in the dairy medical use, couldn’t have any sense without a meditated structure planning that could explain properly the know-how to our society. In fact, communication should be the base of all the actions of any Scientific Society. From the relationship with the social media and appropriate use by the different channels that offer us new technologies, depends that health education could be the most serious and didactic as possible only so, we can ensure accessible medical knowledge and maximize the patient education, creating new relationships between doctors and patients that only Health Societies could offer. Key words: Communication in health; Medical Society; Mass media; New technologies; Social media doi: http://dx.doi.org/10.20318/recs.2016.313

Analisis orientado a objetos de imágenes de teledetección para cartografia forestal : bases conceptuales y un metodo de segmentacion para obtener una particion inicial para la clasificacion = Object-oriented analysis of remote sensing images for land cover mapping : Conceptual foundations and a segmentation method to derive a baseline partition for classification

El enfoque comúnmente usado para analizar las imágenes de satélite con fines cartográficos da lugar a resultados insatisfactorios debido principalmente a que únicamente utiliza los patrones espectrales de los píxeles, ignorando casi por completo la estructura espacial de la imagen. Además, la equiparación de las clases de cubierta a tipos de materiales homogéneos permite que cualquier parte arbitrariamente delimitada dentro de una tesela del mapa siga siendo un referente del concepto definido por su etiqueta. Esta posibilidad es incongruente con el modelo jerárquico del paisaje cada vez más aceptado en Ecología del Paisaje, que asume que la homogeneidad depende de la escala de observación y en cualquier caso es más semántica que biofísica, y que por tanto los paisajes son intrínsecamente heterogéneos y están compuestos de unidades (patches) que funcionan simultáneamente como un todo diferente de lo que les rodea y como partes de un todo mayor. Por tanto se hace necesario un nuevo enfoque (orientado a objetos) que sea compatible con este modelo y en el que las unidades básicas del análisis sean delimitadas de acuerdo a la variación espacial del fenómeno estudiado. Esta tesis pretende contribuir a este cambio de paradigma en teledetección, y sus objetivos concretos son: 1.- Poner de relieve las deficiencias del enfoque tradicionalmente empleado en la clasificación de imágenes de satélite. 2.- Sentar las bases conceptuales de un enfoque alternativo basado en zonas básicas clasificables como objetos. 3.- Desarrollar e implementar una versión demostrativa de un método automático que convierte una imagen multiespectral en una capa vectorial formada por esas zonas. La estrategia que se propone es producir, basándose en la estructura espacial de las imágenes, una partición de estas en la que cada región puede considerarse relativamente homogénea y diferente de sus vecinas y que además supera (aunque no por mucho) el tamaño de la unidad mínima cartografiable. Cada región se asume corresponde a un rodal que tras la clasificación será agregado junto a otros rodales vecinos en una región mayor que en conjunto pueda verse como una instancia de un cierto tipo de objetos que más tarde son representados en el mapa mediante teselas de una clase particular

Implementación de geosintéticos para optimizar los espesores del pavimento flexible en la av. Micaela Bastidas, Comas, 2020

En la presente investigación se pretende determinar de qué manera influye la implementación de geosintéticos en la optimización de los espesores del pavimento flexible en la av. Micaela Bastidas del distrito de Comas, departamento de Lima. Para la recolección de datos, se realizó tres calicatas y se sacó dos muestras por cada una, una muestra de la subrasante y otra superficial. Se realizó los ensayos respectivos para conocer el tipo de suelo y proceder con el ensayo del CBR usando tres muestras. Luego de obtener los valores de los ensayos de laboratorio y constatarlos con los antecedentes, se comprobó la efectividad del geosintético, en este caso el uso de la geomalla biaxial. A través de tres muestras, el primero sin refuerzo, el segundo con un refuerzo de geomalla biaxial y el tercero con un refuerzo doble sobre la segunda y cuarta capa. En este presente estudio se analiza el comportamiento que tiene la geomalla biaxial en cuanto a la variación del CBR en un suelo tipo SM: arena limosa de baja plasticidad en la av. Micaela Bastidas

Reutilización de componentes entre cursos virtuales, presenciales y mixtos (b-learning). Un caso de estudio en Sistemas de Información Gerencial

The integration between virtual and face-to-face (ftf) classroom learning is increasing. This is leading to an increase in mixed learning or blended-learning. Due to this growing trend there is a need to reuse course components between these strategies in the interest of efficiency. Additionally, the wide availability of open source software facilitates the construction of learning activities without incurring in licences expenses; activities which can then also be included in other courses. The reuse of these learning activities between virtual, ftf and mixed education may require significant efforts to adapt them if this possibility has not been considered in advance. Adoption of certain architectures and methodologies, that facilitate flexibility and reuse, can simplify this process, as proposed in this paper. A case study is presented on reusing learning activities on Management Information Systems (MIS) developed for either ftf instruction or for an edX MOOC, that are reused in courses in various learning modes: online, blended learning and face-to-face.Cada vez es mayor la integración entre enseñanza virtual y presencial. Esto está produciendo un incremento de la enseñanza mixta o blended-learning. Dada la creciente tendencia de integración de la enseñanza virtual en la formación presencial, surge la necesidad de reutilizar componentes entre dichas estrategias en interés de la eficiencia. Adicionalmente, la gran disponibilidad de software de código abierto facilita la construcción de actividades docentes sin incurrir en costes de licencias, las cuales que pueden formar parte de distintos cursos de formación. La reutilización de estas actividades docentes en la enseñanza virtual y mixta puede requerir importantes esfuerzos de adaptación de las mismas si previamente no se ha tenido en cuenta esta posibilidad en su diseño. Estas labores pueden simplificarse mediante la adopción de arquitecturas y metodologías que favorezcan la flexibilidad y la reutilización, tal como se propone en este trabajo. Adicionalmente, se presenta un caso de reutilización de actividades docentes de un MOOC de la plataforma edX dedicado a Sistemas de Información, en el que actividades docentes son reutilizadas en otros cursos de distinta modalidad: online, híbridos y presenciales.Acción financiada por la Comunidad de Madrid en el marco del convenio plurianual con la Universidad Carlos III de Madrid en su línea de Excelencia del Profesorado

Assessment of cardiovascular safety in medium pressure hyperbaric oxygenation therapy

The “hyperbaric oxygenation therapy” (HBOT) is currently used as an adjunct therapy in many pathologies. Its therapeutic action is based on that hyperoxia at high pressure (2.4 atm) induces vasoconstriction and reduction of inflammation among others effects. Recently, a more accessible Medium Pressure Hyperbaric Oxygenation therapy” (mHBOT) at 1.4 atm is also used as therapy that resulted equally effective at a lower cost. However, up to date no studies have been carried out to support the cardiovascular safety of both treatments. For this reason, we studied the cardiovascular safety of mHBOT in rats subjected to a protocol equivalent to that applied in humans. Male Sprague Dawley rats were submitted to 30 sessions of 60 min in a hypebaric chamber at 1.44 atm. and 100% O2 . Isolated hearts were perfused through aorta at 37ºC, paced at 3 Hz, and exposed to 30 min ischemia (I) followed by 45 min reperfusion (R). Simultaneous mechanical and heat measurements and the heart damaged area (trifeniltetrazolium) were evaluated. Also aorta rings were superfused and the noradrenaline response was analyzed. Hearts from mHBOT-treated rats showed an increase in resting pressure (RP) during ischemia (p<0.05) but no changes were observed in R. An improvement (p<0.05) in post ischemic contractile recovery was observed in hearts from mHBOT-treated rats (65.4±12.9%) respect to control ones (33.5±6.1%) at 45 min R. mHBOT did not alter total heat rate (Ht), but an increase (p<0.05) in contractile economy during R (120.9±20%) respect to control (53.2±8.9%) at 45 min was observed. Also mHBOT reduced the heart damage area induced by I/R. Furthermore, arteries from mHBOT-treated rats showed similar response to noradrenaline than controls. Conclusion: the mHBOT cardioprotects hearts from I/R injury acting as a preconditioning agent. The use of this therapy is safety for the cardiovascular system.Fil: Gutierrez, Christopher. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Cardiológicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Cardiológicas; ArgentinaFil: Di Girolamo, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Cardiológicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Cardiológicas; ArgentinaFil: Castilla, Rocio Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Cardiológicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Cardiológicas; ArgentinaFil: Bonazzola, Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Cardiológicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Cardiológicas; ArgentinaLXVI Reunión Anual de la Sociedad Argentina de Investigación Clínica; LXIX Reunión Anual de la Sociedad Argentina de Inmunología; LIII Reunión Anual de la Asociación Argentina de Farmacología Experimental y XI Reunión Anual de la Asociación Argentina de NanomedicinasArgentinaSociedad Argentina de Investigacion ClinicaSociedad Argentina de InmunologíaAsociación Argentina de Farmacología ExperimentalAsociación Argentina de Nanomedicina

An integrated framework for assessing the accuracy of geobia landcover products.

Se establece un metodología para evaluar la cartografía de capas GI

Is the phase transition in the Heisenberg model described by the (2+ϵ)(2+\epsilon)-expansion of the nonlinear σ\sigma-model?

Nonlinear $\sigma$-model is an ubiquitous model. In this paper, the $O(N)$ model where the $N$-component spin is a unit vector, ${\bf S}^2=1$,is considered. The stability of this model with respect to gradient operators $(\partial_{\mu}{\bf S}\cdot \partial_{\nu}{\bf S})^s$, where the degree $s$ is arbitrary, is discussed. Explicit two-loop calculations within the scheme of $\epsilon$-expansion, where $\epsilon=(d-2)$, leads to the surprising result that these operators are relevant. In fact, the relevancy increases with the degree $s$. We argue that this phenomenon in the $O(N)$-model actually reflects the failure of the perturbative analysis, that is, the $(2+\epsilon)$-expansion. It is likely that it is necessary to take into account non-perturbative effects if one wants to describe the phase transition of the Heisenberg model within the context of the non-linear $\sigma$-model. Thus, uncritical use of the $(2+\epsilon)$-expansion may be misleading, especially for those cases for which there are not many independent checks.Comment: RevTex, 33 pages, figures embedde