Publication: ANÁLISIS DE OPERACIÓN DE CICLO DE VAPOR EN PLANTA DE CONCENTRACIÓN SOLAR DE POTENCIA TIPO TORRE EN CONDICIONES FUERA DE DISEÑO
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Date
2021-07
Authors
MACHUCA LAZO, NICOLÁS IGNACIO
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Abstract
Debido a la creciente inestabilidad climática mundial producto del aumento de emisiones de gases de efecto invernadero generados por el uso de fuentes energéticas y la actividad antropógeno es que varios países del mundo han comenzado a realizar acuerdos y marcar objetivos para reducir sus emisiones. Esto ha incentivado el desarrollo de tecnologías que utilizan fuentes energéticas renovables como solar, eólica e hidráulica. La tecnología fotovoltaica tiene uno de los mayores crecimientos de instalación y generación en la actualidad dentro de las tecnologías con fuentes renovables, sin embargo, poseen factores de planta entre los 20-30% y alternativas de almacenamiento de energía costosas. Una de las alternativas en tecnología renovables que permite producir energía con factores de planta más altos es la concentración solar de potencia (CSP) debido a la posibilidad de integrar un sistema de almacenamiento térmico relativamente económico, permitiéndole generar electricidad en la noche.
En este estudio se modela y analiza el bloque de potencia de una planta de Concentración Solar de tipo torre en condiciones fuera de diseño. A pesar de que el bloque de potencia es altamente conocido en centrales termoeléctricas, existen pocos modelos que detallen su comportamiento en condiciones fuera de diseño, debido a que no han sido diseñados para operar en condiciones variables y en ambientes desérticos. Por esta razón se analiza el rendimiento del bloque de potencia en condiciones de carga parcial producto de la variación del recurso solar y la variación de la temperatura ambiental. Para esto se utiliza las herramientas EBSILON y SAM para diseñar el bloque de potencia y la planta CSP con torre respectivamente.
Se determinó que la eficiencia del bloque de potencia de una planta CSP con torre se ve afectada por los periodos de carga parcial de operación del ciclo reduciendo su eficiencia hasta en un 5% para cargas de potencia de 30% respecto a la carga nominal. Por otra parte, la temperatura ambiental de diseño del ciclo térmico influye directamente en el tamaño del condensador y en la eficiencia del ciclo tanto en su condición de diseño como en su condición fuera de diseño, marcando una diferencia de 2% entre un ciclo configurado para una temperatura ambiental de 30°C, respecto a uno de 20°C en el caso de diseño. Además, se comprobó que la caída de eficiencia producto del aumento de temperatura en un día de operación afecta en mayor medida al ciclo térmico diseñado con 20 °C en comparación con el ciclo diseñado con 30°C lo que influye directamente en el rendimiento anual del ciclo. Esto permite generar alrededor de un 2,3% más energía anual representando 2,7 Millones de dólares anuales con un acuerdo de compra de electricidad (PPA) de 100 USD/MWh.
Finalmente se considera que el paso de tiempo del típico año metereológico (TMY) utilizado para el cálculo del rendimiento influyen de manera significativa en los periodos en que el ciclo térmico experimenta algún cambio abrupto en su carga o en la temperatura ambiental, recomendando utilizar un paso de tiempo de 10 minutos. Este parámetro junto con la consideración de efectos transientes de los flujos másicos y flujos de calor presentan una buena alternativa para producir rendimientos diarios y anuales más precis
Due to the present problems on global ecosystems produced by the greenhouse gas emission generated by burning fossil fuel is that many countries around the world are starting to make agreement and established objectives to reduce these emissions. These have permitted to take measures that have allowed the development of renewable energy technologies such as solar, wind and hydropower. The photovoltaic technology is the one with the highest number of installed plants and generation of electricity nowadays within the renewable technologies, however it has plant capacity factor around 20-30% and the alternatives to store energy very costly currently. An alternative within renewable energy technologies with better capacity factor is Concentrated Solar Power (CSP) due to the possibility of integrated an energy store system with relative lower prices, allowing this technology to dispatch energy during night hours. In this study a Power Block of a CSP plant with tower is modeled and analyzed in its off-design conditions. The power Block is a mature technology in thermoelectric plants, but there are few models that consider off-design conditions because these systems are no design to work in variable conditions such as the conditions CSP plant usually have by location and power load. Because of this, performance of the power block in partial load conditions due to variations in solar source and variations in ambient temperature are analyzed in this study. The software EBSILON and SAM are used to design and configure the power block and the CSP plant with tower, respectively. As results, the efficiency of the power block of CSP plant with tower is affected by partial load operation periods, decreasing 5% at 30% of nominal load. Besides, design ambient temperature of thermal cycle affected directly on the size and performance of the air-cooled condenser selected, producing a difference of 2% between thermal cycle designed with 30°C and a one with 20°C in design conditions. Regarding off-design conditions, the condenser with higher design ambient temperature is less affected due to the variations in ambient temperature throughout the day in comparison with a lower design ambient temperature. This difference in performance allows to generate 2,3% more annual energy and an increase in annual income of 2,7 MUSD/year with a PPA of 100 USD/MWh. Finally, the time lapse of the Typically meteorological year (TMY) used to calculate the annual performance affected significantly in the periods of load changes or big ambient temperatures changes, a good recommendation is use 10 minutes as time lapse to simulate annual performance. This parameter and a consideration of transient effects in mass flow and heat flows of thermal cycles present alternatives to improve daily and annual calculations of Power block and CSP plant with tower
Due to the present problems on global ecosystems produced by the greenhouse gas emission generated by burning fossil fuel is that many countries around the world are starting to make agreement and established objectives to reduce these emissions. These have permitted to take measures that have allowed the development of renewable energy technologies such as solar, wind and hydropower. The photovoltaic technology is the one with the highest number of installed plants and generation of electricity nowadays within the renewable technologies, however it has plant capacity factor around 20-30% and the alternatives to store energy very costly currently. An alternative within renewable energy technologies with better capacity factor is Concentrated Solar Power (CSP) due to the possibility of integrated an energy store system with relative lower prices, allowing this technology to dispatch energy during night hours. In this study a Power Block of a CSP plant with tower is modeled and analyzed in its off-design conditions. The power Block is a mature technology in thermoelectric plants, but there are few models that consider off-design conditions because these systems are no design to work in variable conditions such as the conditions CSP plant usually have by location and power load. Because of this, performance of the power block in partial load conditions due to variations in solar source and variations in ambient temperature are analyzed in this study. The software EBSILON and SAM are used to design and configure the power block and the CSP plant with tower, respectively. As results, the efficiency of the power block of CSP plant with tower is affected by partial load operation periods, decreasing 5% at 30% of nominal load. Besides, design ambient temperature of thermal cycle affected directly on the size and performance of the air-cooled condenser selected, producing a difference of 2% between thermal cycle designed with 30°C and a one with 20°C in design conditions. Regarding off-design conditions, the condenser with higher design ambient temperature is less affected due to the variations in ambient temperature throughout the day in comparison with a lower design ambient temperature. This difference in performance allows to generate 2,3% more annual energy and an increase in annual income of 2,7 MUSD/year with a PPA of 100 USD/MWh. Finally, the time lapse of the Typically meteorological year (TMY) used to calculate the annual performance affected significantly in the periods of load changes or big ambient temperatures changes, a good recommendation is use 10 minutes as time lapse to simulate annual performance. This parameter and a consideration of transient effects in mass flow and heat flows of thermal cycles present alternatives to improve daily and annual calculations of Power block and CSP plant with tower
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Keywords
INTERCAMBIADORES DE CALOR , ENERGÍA RENOVABLE , CALOR - TRANSMISIÓN , PLANTAS DE ENERGÍA SOLAR
