Esta tesis desarrolla un modelo sencillo pero riguroso de plantas de trigeneración con gasificación de biomasa para su simulación, diseño y evaluación preliminar. Incluye una revisión y estudio de diferentes modelos propuestos para el proceso de gasificación de biomasa.Desarrolla un modelo modificado de equilibrio termodinámico para su aplicación a procesos reales que no alcanzan el equilibrio así comodos modelos de redes neuronales basados en datos experimentales publicados: uno para gasificadores BFB y otro para gasificadores CFB. Ambos modelos, ofrecen la oportunidad de evaluar la influencia de las variaciones de la biomasa y las condiciones de operación en la calidad del gas producido. Estos modelos se integran en el modelo de la planta de trigeneración con gasificación de biomasa de pequeña-mediana escala y se proponen tres configuraciones para la generación de electricidad, frío y calor. Estas configuraciones se aplican a la planta de poligeneración ST-2 prevista en Cerdanyola del Vallés. / This thesis develops a simple but rigorous model for simulation, design and preliminary evaluation of trigeneration plants based on biomass gasification. It includes a review and study of various models proposed for the biomass gasification process and different plant configurations. A modified thermodynamic equilibrium model is developed for application to real processes that do not reach equilibrium. In addition, two artificial neural network models, based on experimental published data, are also developed: one for BFB gasifiers and one for CFB gasifiers. Both models offer the opportunity to evaluate the influence of variations of biomass and operating conditions on the quality of gas produced. The different models are integrated into the global model of a small-medium scale biomass gasification trigeneration plant proposing three different configurations for the generation of electricity, heat and cold. These configurations are applied to a case study of the ST-2 polygeneration plant foreseen inCerdanyola del Valles.

This diploma work deals with the topic application of cogeneration and trigeneration for outlying buildings supplying. The first part this work containes description of technology and methods of realization. In this part there is also described absorption circulation. The second part this work targets concepts energy independedce the building, that has concrete energy consumption, including economic analysis.

The escalating energy prices and the increasing environmental impact posed by the industrial usage of energy have spurred industry to adopt various approaches to conserving energy and mitigating negative environmental impact. This work aims at developing a systematic approach to integrate solar energy into industrial processes to drive thermal energy transfer systems producing power, cool, and heat. Solar energy is needed to be integrated with other different energy sources (biofuels, fossil fuels, process waste heat) to guarantee providing a stable energy supply, as industrial process energy sources must be a stable and reliable system. The thermal energy transform systems (turbines, refrigerators, heat exchangers) must be selected and designed carefully to provide the energy demand at the different forms (heat, cool, power). This dissertation introduces optimization-based approaches to address the following problems: • Design of cogeneration systems with solar and fossil systems • Design and integration of solar-biofuel-fossil cogeneration systems • Design of solar-assisted absorption refrigeration systems and integration with the processing facility • Development of thermally-coupled dual absorption refrigeration systems, and • Design of solar-assisted trigeneration systems Several optimization formulations are introduced to provide methodical and systematic techniques to solve the aforementioned problems. The approach is also sequenced into interacting steps. First, heat integration is carried out to minimize industrial heating and cooling utilities. Different forms of external-energy sources (e.g., solar, biofuel, fossil fuel) are screened and selected. To optimize the cost and to overcome the dynamic fluctuation of the solar energy and biofuel production systems, fossil fuel is used to supplement the renewable forms of energy. An optimization approach is adopted to determine the optimal mix of energy forms (fossil, bio fuels, and solar) to be supplied to the process, the system specifications, and the scheduling of the system operation. Several case studies are solved to demonstrate the effectiveness and applicability of the devised procedure. The results show that solar trigeneration systems have higher overall performance than the solar thermal power plants. Integrating the absorption refrigerators improves the energy usage and it provides the process by its cooling demand. Thermal coupling of the dual absorption refrigerators increases the coefficient of performance up to 33 percent. Moreover, the process is provided by two cooling levels.

Resumo: Neste trabalho é analisada a possibilidade de utilização do gás natural como combustível em indústrias frigoríficas em substituição aos combustíveis tradicionalmente utilizados, como a lenha e o óleo. Os estudos são feitos com base numa planta de um frigorífico bovino bastante representativo do setor, que utiliza equipamentos e combustíveis tradicionais para a produção de vapor para processos e compra energia elétrica de uma concessionária. São consideradas algumas opções para a ampliação da capacidade de produção, incluindo a implantação de plantas de cogeração e trigeração a gás natural que são capazes de produzir simultaneamente eletricidade, vapor para os processos e refrigeração para as câmaras frigoríficas. Para fins de avaliação do desempenho são feitas análises energéticas e exergéticas para cada uma das configurações propostas. Por fim, é realizada uma análise termoeconômica, através da Teoria do Custo Exergético, que possibilita determinar os custos exergéticos e monetários e depois avaliar os reflexos dos custos de investimento de capital e do combustível na composição dos custos dos produtos (energia elétrica, vapor e refrigeração). / Abstract: In this work, the possibility of the use of natural gas as fuel in slaughterhouses, substituting the traditional fuels used (firewood and oil), is analyzed. The studies are based on a plant of a quite representative bovine slaughterhouse, which uses equipment and fuels traditional for production of steam for processes and buys electricity of a dealership. Some options for the enlargement of the production capacity are considered, including the implantation of natural gas cogeneration and trigeneration plants, which are capable to produce, simultaneously, electricity, steam for the processes and cooling for the refrigerating chambers. For effect of performance evaluation, energetic and exergetic analyses for each one of the proposed configurations are performed. Finally, a thermoeconomic analysis is accomplished, by means of the Theory of Exergetic Cost, which makes possible to determine the exergetic and monetary costs and to evaluate the reflexes of the costs of capital investment and of the fuel in the composition of the costs of the products (electric power, steam and cooling). / Orientador: Ricardo Alan Verdú Ramos / Coorientador: Cassio Roberto Macedo Maia / Banca: Emanuel Rocha Woiski / Banca: Sílvio de Oliveira Júnior / Mestre

This thesis encompasses CO2 mitigation using three different processes: i) natural gas-fired combined cycle with chemical looping combustion (CLC), ii) trigeneration of electrical power, hydrogen and district heating with extended CLC, iii) steam-based gasification of biomass integrated in an advanced power cycle. In CLC, a solid oxygen carrier circulates between two fluidised-bed reactors and transports oxygen from the combustion air to the fuel; thus, the fuel is not mixed with air and an inherent CO2 separation occurs. In this thesis, CLC has been studied as an alternative process for CO2 capture in a natural gas-fired combined cycle (NGCC). The potential efficiency of such a process using a turbine inlet temperature of 1200 °C and a pressure ratio of 13 is between 52 and 53 % when including the penalty for CO2 compression to 110 bar. It is shown that this efficiency cannot be further improved by including an additional CO2 turbine. Two conceivable reactor designs for CLC in an NGCC are presented. Top-firing has been studied as an option to overcome a temperature limitation in the CLC reactor system. The degree of CO2 capture is shown versus the temperature in the CLC reactor and its combustion efficiency. CLC has the potential to reach both a higher efficiency and a higher degree of CO2 capture than conventional post combustion CO2 capture technique. However, further research is needed to solve technical problems as, for example, temperature limitations in the reactor to reach this potential. Extended CLC (exCLC) is introduced, in which hydrogen is not only produced but also inherently purified. The potential efficiency of a novel tri-generation process for hydrogen, electricity and district heating using exCLC for CO2 capture is investigated. The results show that a thermal efficiency of about 54% might be achieved. A novel power process named evaporative biomass air turbine (EvGT-BAT) for biomass feedstock is presented. This process contains a steam-based gasification of biomass, which is integrated in an externally fired gas turbine cycle with top-firing. In the EvGT-BAT process, the steam-based gasification is conducted in an entrained-flow tubular reactor that is installed in the SFC as a heat exchanger. The EvGT-BAT process has the potential to generate electrical power from biomass with an efficiency of 41 %.

<p>The energy consumption is continuous to increase around the world and with that follows the demand for sustainable solutions for future energy systems. With growing energy consumption from fossil based fuels the threat of global warming through release of CO₂ to the atmosphere increases. The demand for cooling is also growing which would result in an increased consumption of electricity if the cooling demand was to be fulfilled by electrically driven cooling technology. A more sustainable solution can be to use heat-driven absorption cooling where waste heat may be used as driving energy instead of electricity.</p><p>This thesis focuses on the role and potential of absorption cooling in future energy systems. Two types of energy systems are investigated: a district energy system based on waste incineration and a distributed energy system with natural gas as fuel. In both cases, low temperature waste heat is used as driving energy for the absorption cooling. The main focus is to evaluate the absorption technology in an environmental perspective, in terms of reduced CO₂ emissions. Economic evaluations are also performed. The reduced electricity when using absorption cooling instead of compression cooling is quantified and expressed as an increased net electrical yield.</p><p>The results show that absorption cooling is an environmentally friendly way to produce cooling as it reduces the use of electrically driven cooling in the energy system and therefore also reduces global CO₂ emissions. In the small-scale trigeneration system the electricity use is lowered with 84 % as compared to cooling production with compression chillers only. The CO₂ emissions can be lowered to 45 CO₂/MWhc by using recoverable waste heat as driving heat for absorption chillers. However, the most cost effective cooling solution in a district energy system is a combination between absorption and compression cooling technologies according to the study.</p><p>Absorption chillers have the potential to be suitable bottoming cycles for power production in distributed systems. Net electrical yields over 55 % may be reached in some cases with gas motors and absorption chillers. This small-scale system for cogeneration of power and cooling shows electrical efficiencies comparable to large-scale power plants and may contribute to reducing peak electricity demand associated with the cooling demand.</p>

<p>This thesis encompasses CO₂ mitigation using three different processes: i) natural gas-fired combined cycle with chemical looping combustion (CLC), ii) trigeneration of electrical power, hydrogen and district heating with extended CLC, iii) steam-based gasification of biomass integrated in an advanced power cycle. </p><p>In CLC, a solid oxygen carrier circulates between two fluidised-bed reactors and transports oxygen from the combustion air to the fuel; thus, the fuel is not mixed with air and an inherent CO₂ separation occurs. In this thesis, CLC has been studied as an alternative process for CO₂ capture in a natural gas-fired combined cycle (NGCC). The potential efficiency of such a process using a turbine inlet temperature of 1200 °C and a pressure ratio of 13 is between 52 and 53 % when including the penalty for CO₂compression to 110 bar. It is shown that this efficiency cannot be further improved by including an additional CO₂ turbine. Two conceivable reactor designs for CLC in an NGCC are presented. Top-firing has been studied as an option to overcome a temperature limitation in the CLC reactor system. The degree of CO₂ capture is shown versus the temperature in the CLC reactor and its combustion efficiency. CLC has the potential to reach both a higher efficiency and a higher degree of CO₂capture than conventional post combustion CO₂ capture technique. However, further research is needed to solve technical problems as, for example, temperature limitations in the reactor to reach this potential. </p><p>Extended CLC (exCLC) is introduced, in which hydrogen is not only produced but also inherently purified. The potential efficiency of a novel tri-generation process for hydrogen, electricity and district heating using exCLC for CO₂capture is investigated. The results show that a thermal efficiency of about 54% might be achieved. </p><p>A novel power process named evaporative biomass air turbine (EvGT-BAT) for biomass feedstock is presented. This process contains a steam-based gasification of biomass, which is integrated in an externally fired gas turbine cycle with top-firing. In the EvGT-BAT process, the steam-based gasification is conducted in an entrained-flow tubular reactor that is installed in the SFC as a heat exchanger. The EvGT-BAT process has the potential to generate electrical power from biomass with an efficiency of 41 %.</p>

L’objectiu d’aquesta tesi és estudiar la viabilitat de la integració de la tecnologia dels cicles de refrigeració per absorció ja existent comercialment, en plantes d’energia industrials, comparant els resultants amb l’alternativa convencional formada per cicles de compressió. La metodologia proposada en aquesta tesi es basa en cinc grans apartats: recopilació de dades de la planta d’energia i de la demanda de fred que es pretén cobir, seleccionar els cicles de refrigeració candidats que podrien satisfer l’esmentada demanda de fred, és a dir, establir les alternatives de disseny existents per a subministrar el fred necessari a la planta de procés utilitzant el programa XV, el qual permet la simulació i optimització de plantes d’energia. El tercer pas de la metodologia, es construir un fitxer de dades estàndard on s’introdueixen la topologia de la planta d’energia i les seves característiques específiques, incloent els paràmetres d’operació dels cicles de refrigeració. Al quart pas, es realitza l’optimització de la planta global d’energia utilitzant com a funció objectiu els costos d’operació i les prestacions de la planta i finalment es calculen els costos d’operació i els indicadors econòmics adients per a la selecció de la millor configuració. En aquesta tesi es presenten dues aplicacions pràctiques en una indústria pretroquímica de Tarragona per tal d’avaluar la metodologia proposada utilitzant equips d’amoníac/aigua i d’aigua/LiBr.

Le développement scientifique actuel contribue à assurer le confort dans les bâtiments grâce à une grande variété de technologies. Une utilisation rationnelle des ressources énergétiques a un effet bénéfique sur l'économie et la protection de l'environnement. En ce qui concerne l'utilisation de la trigénération, elle devient de plus en plus répandue. La thèse porte sur l'analyse et l'optimisation de schemas hybrides d'alimentation des espaces habitables avec de l’énergie thermique. Pour une analyse cohérente il est nécessaire d'utiliser un outil qui peut égaliser les différents types d'énergie dans le système: chimique, électrique, thermique. L'étude basée sur l'analyse exergétique met en évidence les pertes d'énergie utilisable et les opportunitées de recuperation de l'energie, tout en offrant la possibilité de prendre des décisions fonctionnelles et structurelles pour accroître l'efficacité du système. Les objectifs de cette thèse sont : l'élaboration de différents schémas pour produire simultanément de l’électricité, du froid et de l’eau chaude sanitaire; l’étude et l’optimisation des machines frigorifiques à absorption et à éjection en utilisant l’approche exergétique; l’étude d'un moteur turbo diesel suralimenté; l’étude et l’optimisation du système moteur – machine à froid en utilisant l’analyse exergétique. Deux études de cas ont été développées : bilan thermique d'un bâtiment à rafraîchir, qui a permis d’estimer la puissance frigorifique à installer et bilan global d’un système de cogénération – électricité plus chauffage urbain. / The current scientific development help ensure the comfort in buildings with a large variety of technologies. Rational use of energy resources has a positive effect on the economy and protecting the environment. Concerning the trigeneration, it is becoming more and more widespread. This PhD focuses on the analysis and optimization of hybrid schemes of production and distribution of heat for buildings. For a coherent analysis it is necessary to use a tool that can equalize the different types of energy in the system: chemical, electrical, thermal. The study based on exergy analysis highlights the energy losses and opportunities for the recovery of energy, and provide ability to take functional and structural decisions to increase efficiency.In this thesis, several aspects were examined: the development of a scheme to supply several utilities: electricity, cold and hot water; the study and optimization of absorption and ejection refrigerating machines using exergy analysis; the study of a supercharged turbo diesel engine, the study and optimization of the engine – refrigerating machine system, using exergy analysis.Two case studies were performed: the energy balance of a building, which was used to estimate the cooling capacity to install and the overall performance of a cogeneration - district heating system.

Made available in DSpace on 2014-06-11T19:23:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-05-30Bitstream added on 2014-06-13T18:48:30Z : No. of bitstreams: 1 takaki_at_me_ilha.pdf: 1453305 bytes, checksum: 0ba83e01600d7f0ddfb6ab048c8af3be (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho é analisada a possibilidade de utilização do gás natural como combustível em indústrias frigoríficas em substituição aos combustíveis tradicionalmente utilizados, como a lenha e o óleo. Os estudos são feitos com base numa planta de um frigorífico bovino bastante representativo do setor, que utiliza equipamentos e combustíveis tradicionais para a produção de vapor para processos e compra energia elétrica de uma concessionária. São consideradas algumas opções para a ampliação da capacidade de produção, incluindo a implantação de plantas de cogeração e trigeração a gás natural que são capazes de produzir simultaneamente eletricidade, vapor para os processos e refrigeração para as câmaras frigoríficas. Para fins de avaliação do desempenho são feitas análises energéticas e exergéticas para cada uma das configurações propostas. Por fim, é realizada uma análise termoeconômica, através da Teoria do Custo Exergético, que possibilita determinar os custos exergéticos e monetários e depois avaliar os reflexos dos custos de investimento de capital e do combustível na composição dos custos dos produtos (energia elétrica, vapor e refrigeração). / In this work, the possibility of the use of natural gas as fuel in slaughterhouses, substituting the traditional fuels used (firewood and oil), is analyzed. The studies are based on a plant of a quite representative bovine slaughterhouse, which uses equipment and fuels traditional for production of steam for processes and buys electricity of a dealership. Some options for the enlargement of the production capacity are considered, including the implantation of natural gas cogeneration and trigeneration plants, which are capable to produce, simultaneously, electricity, steam for the processes and cooling for the refrigerating chambers. For effect of performance evaluation, energetic and exergetic analyses for each one of the proposed configurations are performed. Finally, a thermoeconomic analysis is accomplished, by means of the Theory of Exergetic Cost, which makes possible to determine the exergetic and monetary costs and to evaluate the reflexes of the costs of capital investment and of the fuel in the composition of the costs of the products (electric power, steam and cooling).