Experimental Analysis of Modified CNTs-Based Gas Sensor

As a significant equipment in power system, the operation condition of transformers directly determines the safety of power system. Therefore, it has been an indispensable measure to detect and analyze the dissolved gases in transformers, aiming to estimate the early potential faults in oil‐insulated transformers. In this chapter, the adsorption processes between modified carbon nanotubes (CNTs) (CNTs‐OH, Ni‐CNTs) and dissolved gases in transformers oil including C2H2, C2H4, C2H6, CH4, CO, and H2 have been simulated based on the first principle theory. Meanwhile, the density of states (DOS), adsorption energy, charge transfer amount, and adsorption distance of adsorption process between CNTs and dissolved gases were calculated. Moreover, two kinds of sensors, mixed acid‐modified CNTs and NiCl2‐modified CNTs, are prepared to conduct the dissolved gases response experiment. Then, the gas response mechanisms were investigated. Finally, the results between response experiment and theoretical calculation were compared, reflecting a good coherence with each other. The CNTs gas sensors possess a relatively high sensitivity and fine linearity, and could be employed in dissolved gas analysis equipment in transformer

Metodología de gestión ambiental para aceite dieléctrico de transformador: “Análisis del Ciclo de Vida (ACV)”

Resumen: Durante los últimos treinta años, la industria petroquímica y de lubricantes, se ha convertido en uno de los sectores más comercializados en el mundo, aunque sus actividades y productos derivados como combustibles y aceites lubricantes, presentan riesgo de contaminación al medio ambiente. En el año 2010 la demanda mundial de aceites lubricantes, de base mineral en su mayoría, alcanzó los 34,5 millones de toneladas, de las cuales un 56% fueron utilizados como lubricantes de automóviles; un 26% fue empleado como lubricantes industriales; un 8% utilizado en grasas y el 10% restante se empleó como aceites de proceso. Aproximadamente un 50% de todos los lubricantes mundiales, son liberados al medio ambiente por derrames, actividades durante su uso y en su eliminación, situación preocupante, ya que estos tipos de lubricantes tradicionales, no presentan alta biodegradabilidad en el ambiente. En este estudio se aplicó la metodología Análisis del Ciclo de Vida (ACV) a un aceite dieléctrico mineral de transformador, con el fin de determinar los impactos ambientales en el ciclo de vida del producto. La unidad funcional definida es 1 kg de aceite producido. Los datos fueron extraídos de la base de datos ECOINVENT y de visitas a las instalaciones de la empresa EPM en la ciudad de Medellín. Se utilizó el software Umberto para análisis de la información, empleando el método CML 2001 para la evaluación del impacto. Los resultados obtenidos en el estudio demuestran que los aceites dieléctricos de base mineral empleados en transformadores, son contaminantes para el medio ambiente y la salud humana en todo su ciclo de vida. Los mayores impactos ambientales dentro del ciclo de vida del aceite dieléctrico, se presentan en las categorías de impacto como cambio climático, agotamiento de ecosistemas acuáticos marinos y toxicidad humana.Abstract: During the last thirty years, the petrochemical industry and lubricants, have become one of the most marketed items in the world, but these industrial activities and products derived from them, such as fuels and lubricating oils are potential environmental pollutants. In 2010, global demand for lubricating oils, mineral base reached 34.5 million tons, which 56% were used as automobile lubricants, 26% was used as industrial lubricants, 8% was used as fat, the remaining 10% was used as process oils. Approximately 50% of all global lubricants are released into the environment from spills, activities of use and disposal, which is a lot of concern, since these types of traditional lubricants do not have high biodegradability in the environment. In this study the methodology of Life Cycle Analysis (LCA) was applied to a mineral insulating oil transformer, in order to determine the environmental impacts in the product life cycle. The functional unit is 1 kg of oil produced. The data were extracted from the database ECOINVENT and site visits to EPM company in Medellin. Umberto software was used for data analysis, using the CML 2001 method for impact assessment. The results of the study show that mineral-based insulating oils used in transformers, are environmental contaminants and human health throughout their life cycle. The major environmental impacts in the life cycle of the dielectric oil, are presented in the impact categories such as climate change, depletion of marine aquatic ecosystems and human toxicity.Maestrí