The role of advanced waste-To-energy technologies in landfill mining

Publicado en: WIT Transactions on Ecology and the Environment, Volume 224, Issue 1, 20 September 2017, Pages 403-409Recently, the European Parliament has decided to include a specific reference to "Enhanced Landfill Mining" (ELFM) in the Landfill Directive proposing a regulatory framework for ELFM so as to permit the retrieval of secondary raw materials that are present in existing landfill sites. Recent studies are supporting ELFM since they consider that landfill mining would be economically feasible only if combined with energy recovery (i.e., waste-To-energy, WtE) and if a wide range of materials are recovered (i.e., waste-To-materials, WtM). In this study, a combined material (landfill mining) and energy (advanced WtE) recovery is proposed where the excavated waste (MSW refuse) can be directly recycled or pretreated and used in the production of refuse-derived fuel (RDF) for an advanced (gasification-based) WtE plant producing power and heat. Both material and energy recovery are challenging in the circular economy since contributes to a loop-closing objective in human activities. An exhaustive assessment of each particular landfill site must be carried out in order to determine the profitability of the ELFM.Ministerio de Economía y Competitividad ENE2012-31598Ministerio de Ciencia, Innovación y Universidades CTM2016-78089-RUniversidad de Sevilla Contrato de Acceso al Sistema Español de Ciencia, Tecnología e Innovación (VPPI-US

Change of existing circulating fluidized bed boilers to oxy-firing conditions for CO2 capture

This work investigates a circulating fluidized bed boiler, originally designed for air-firing, retrofitted to oxy-firing with the purpose of removing the CO2 emission from coal combustion. Previous studies have shown that the heat balance on the gas-particle side can be satisfied without changes in the boiler, but then the volume flow of gas is reduced. To retain the operation like that during air-firing, the volume flow, that is the fluidization velocity, in oxy-firing should be equal to that in air-firing. It is the main purpose of this work to determine the conditions for the transition from air to oxy-firing, while the heat transfer conditions are maintained at a constant fluidization velocity. Measures to achieve this, such as adjusting the supply of additional gas and the heat transfer surface, are analysed. The fulfilment of the furnace\u27s heat balance requires extra fuel or reduction of the heat-transfer surface in the furnace. These changes affect the performance of the back pass, which must be modified to accommodate the change in gas composition and the higher sensible heat content of the flue gas. Strategies to deal with these circumstances in CFB boilers are discussed

Approximate Prediction of Gas-Solid Conversion in Fluidized Bed Reactors

A simple method is proposed to evaluate the performance of fluidized bed reactors where an nth-order gas-solid reaction occurs. The method takes into account the fluid dynamics of the fluidized bed by a two-phase flow model and the rates of diffusion in the solid reactant particles (internal and external) by a simple particle model. Approximate analytical expressions are derived in terms of three effectiveness factors: interphasic, external and intraparticle. These account for the contribution of fluid-dynamic and diffusional resistances to the overall mass-transfer resistance. Gas conversion is expressed in terms of four dimensionless governing quantities and the reaction order, in this way facilitating computations. Limiting cases of the general solution are discussed by comparison with analytical solutions found in literature. The methodology can be applied to catalytic or non-catalytic systems under isothermal conditions, where one heterogeneous reaction is involved

Plan de intervención fisioterápico para la enfermedad de Parkinson en estadío temprano: a propósito de un caso

Introducción: La Enfermedad de Parkinson es el segundo trastorno neurodegenerativo más prevalente cuyas manifestaciones son principalmente motoras y cursan con un deterioro progresivo de la calidad de vida. Además del tratamiento farmacológico, existen diferentes abordajes desde la fisioterapia, sobre todo basados en ejercicio terapéutico. Objetivos: Describir el caso de un paciente de Parkinson, plantear una intervención y analizar los resultados obtenidos. Metodología: Tras una evaluación inicial, se llevó a cabo una intervención fisioterápica de 6 semanas enfocada al tratamiento de síntomas existentes y a la mejora de la fuerza, movilidad, equilibrio, marcha y capacidad funcional. Una vez finalizada, se reevaluó el estado del paciente. Resultados: Hubo aumentos de la fuerza, movilidad y estabilidad postural, así como una reducción del riesgo de caídas. También se mejoraron aspectos relacionados con el desarrollo de las actividades de la vida diaria. No se produjeron cambios significativos en los aspectos no motores ni en la marcha. Discusión: Los resultados parecen indicar que este abordaje es efectivo y económico a la hora de mejorar las habilidades motrices de los enfermos de Parkinson, tal y como muestra la evidencia actual. No obstante, no existe consenso científico sobre el enfoque más adecuado. La duración del plan podría ser insuficiente como para extrapolar los efectos a largo plazo, pero en este sentido es importante lograr que los pacientes adopten el hábito del ejercicio físico para mejorar el pronóstico de la enfermedad. La falta de material y recursos para la evaluación de los resultados fue un aspecto limitante. Conclusiones: Este plan de intervención fisioterápico en un paciente con Parkinson podría ser efectivo para la mejora de varios aspectos motores. <br /

Fluid dynamic analysis of dual fluidized bed gasifier for solar applications

A hydrodynamic model of a dual fluidized bed gasifier (DFBG) is developed and its predictions are compared with measurements of solids flux and pressure profiles from a cold flow model (CFM). Then, the performance of a DFBG gasifier is theoretically analyzed in terms of solids circulation and solids distribution under changes in riser and loop seal aeration, solids inventory and particle size, and a sensitivity analysis is made to delimit the model prediction capability. Furthermore, the model is applied to analyze the effects of key design aspects of DFBG, such as the relative size of riser and gasifier, the connection between both units, the circulation rate of solids and their distribution around the system. The model is further used to extend the DFBG operation with external solar energy carried by heated solid particles, i.e. to design solar DFBG (SDFBG). The analysis is focused on the performance with high solids inventory in the gasifier to increase the char conversion (operation with a large solar share) and the control of solids circulation to meet the heat demand of the gasifier with the availability of solar energy. The operation with large solids inventory in the gasifier requires the size of the gasifier to increase considerably compared to that of the conventional DFBG. The substitution of the connection pipe between the riser and the bubbling bed (current design in commercial DFBG) by a lower loop seal enables better control of the solids circulation, thus, benefiting the solar design

Data for the modelling of the future power system with a high share of variable renewable energy

Energy and power system models have become necessary tools that provide challenges and technical and economic solutions for integrating high shares of Variable Renewable Energy. Models are focused on analysing strategies of power systems to achieve their decarbonisation targets. The data presented in this paper includes the model algorithm, inputs, equations, modelling assumptions, supplementary materials, and results of the simulations supporting the research article titled “Facing the high share of variable renewable energy in the power system: flexibility and stability requirements”. The analysis is based on data from the system operator of one of the European Union member states (Spain). The developed model allows making projections and calculations to obtain the power generation of each technology, the international interconnections, inertia, emissions, system costs and flexibility requirements of new technologies. These data can be used for energy policy development or decision making on power capacity and the balancing needs of the future power system.Ministerio de Ciencia e Innovación PID2020-114725RA-I00Universidad de Sevilla VI PPIT-USPlan nacional I+D+I CTM2016-78089-RJunta de Andalucía P18-RT-451

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