Thesis RECOMENDACIONES DE DISEÑO PARA SISTEMAS DE BOMBEO QUE ALIMENTAN DE MANERA DIRECTA PEQUEÑAS POBLACIONES EN ALTURA
Date
2018
Authors
ALVARADO VICENCIO, REGINALD ENRIQUE
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Abstract
La accidentada topografía de importantes ciudades como Viña del Mar o Valparaíso, plantea un importante reto al abastecimiento de agua potable. Siendo un caso particular, los sectores elevados de baja población en los que la presión entregada por la red no es suficiente y no puede ser instalado un nuevo estanque a mayor cota.Al no poder disponer de un estanque como solución, se generan dos grandes problemas. Primero la variabilidad del caudal de demanda deberá ser absorbida por el sistema de bombeo a emplear; y segundo, el sistema de bombeo deberá ser capaz de suplir la demanda en todo su rango de variación, que podrían ser desde una fracción de litros por segundo, hasta los 16 [L/s] exigidos en el evento de incendio como mínimo. Con base a la experiencia se ha evidenciado que en los casos en que la población es poco numerosa y además el caudal mínimo de demanda es menor que el caudal mínimo de impulsión de las bombas, se producen repetidas partidas y paradas de las bombas que podrían reducir sustancialmente la vida útil de los equipos.Se estudia la solución a esta problemática particular, evaluando tres alternativas actuales al problema de demanda variable de agua potable: bomba con variador de frecuencia, bomba con estanque hidroneumático, y bomba con variador de frecuencia y estanque hidroneumático (sistema mixto). A partir de dicha evaluación, se determina que la solución óptima es el sistema mixto.Se presenta una metodología para el diseño de la solución en función del sistema mixto y una revisión de la formulación clásica para el cálculo del volumen de los estanques hidroneumáticos denominada formulación propuesta, con base en dichas ecuaciones se han propuesto mejoras para el cálculo del estanque hidroneumático, con el objetivo de optimizar su volumen, asegurando así mantener la operación de las bombas (arranques máximos por hora) dentro de los límites indicados por el fabricante. El empleo de la formulación clásica o propuesta para el cálculo del volumen del estanque hidroneumático se encuentra acotada a un rango de aplicación recomendada por el autor de la presente memoria.Se realizan una serie de simulaciones computacionales de distintos modelos hidráulicos que permiten contar la cantidad de arranques por hora generados en las bombas a fin de evaluar el comportamiento de las bombas sin un estanque hidroneumático, y con un estanque hidroneumático calculado según la formulación clásica y la propuesta. De acuerdo a dichos resultados, se confirma la necesidad de un estanque hidroneumático debido al alto número de arranques por hora generados en las bombas y su sustancial disminución a un número menor al límite máximo recomendado por los fabricantes al agregarlo. Respecto al volumen calculado del estanque hidroneumático, los resultados muestran que siempre se obtiene un volumen menor al emplear ya sea la formulación clásica o la propuesta dentro del rango de aplicación recomendado.Finalmente, debido a que no se pudo conseguir datos de medición que permitiesen confirmar la hipótesis del planteamiento base para la formulación propuesta, la que considera que se puede despreciar el tiempo de llenado del estanque hidroneumático al ser mucho menor al tiempo de vaciado (TLL<< Tva), se recomienda para validar de manera robusta lo planteado realizar mediciones reales en un sistema del tipo descrito que permitan contrastar lo planteado.
The hilly topography of important cities as Viña del Mar or Valparaíso, propose an important challenge to the supply of drinking water. A particular case is the low population that is on elevated neighborhood, in which the pressure delivered by the water supply network doesn’t meet the minimum requirements and cannot be installed an elevated water tank.Because there is not possibility of an elevated water tank as a solution, two big problems are generated. First, the high variability in the water demand by the population must be absorbed by the pumps; and second, the pumping station must be able to supply the demand in the all variation range, this could be from a fraction of liters per second to the minimum request of 16 [L/s] in a fire event. Based on experience it have been show that in low population case and the minimum demand flow is lower than the minimum pumping flow, are produced repeatedly stars in the pump that could reduce the service life.The solution of this particular problem is studied evaluating three current alternatives of solution: pumping station with variable-frequency drive, pump station with a hydropneumatic tank, and pumping station with variable-frequency drive and with a hydropneumatic tank (mixed system). From this evaluation is determined that the optimal solution is the mixed system.A methodology is presented for the design of the mixed system and an overhaul to the classic equations of the hydropneumatic tank volume calculation, based on these equations improvements have been proposed (proposed equations), with the aim of optimizing (reducing) the hydropneumatic tank volume, thus ensuring the pump operation (star per hour) within the limits recommended by the manufacturer. The use of the classic equations or the proposed equations for the hydropneumatic tank volume calculation is bounded to an application range recommended by the author of this document.A series of computer simulation of different hydraulic models are carried out to evaluate the quantity of star per hour generated in the pumps with the aim of evaluated the behavior of the pumps without a hydropneumatic tank, and with a hydropneumatic tank calculated according with classic equations and the proposed equations. In agreement with those results, the need for a hydropneumatic tank is confirmed due the high number of stars per hour generated in the pumps and their substantial decrease to number lower than the manufacturer’s limit when it’s added. Regarding the calculated volume of the hydropneumatic tank, the results show that always a smaller volume is obtained either when using the classic equations or the proposed equations within the recommended application range.Finally, due the fact that was not possible to obtain measurement data that would allow to confirm the hypothesis of the base approach for the proposed equations, which considers that the filling time of the hydropneumatic tank can be neglected owing is much shorter that the emptying time (TLL<< Tva), it is recommended to validate in a robust way what is proposed carry out real measurements in a system of the described type that allows to contrasting the proposed.
The hilly topography of important cities as Viña del Mar or Valparaíso, propose an important challenge to the supply of drinking water. A particular case is the low population that is on elevated neighborhood, in which the pressure delivered by the water supply network doesn’t meet the minimum requirements and cannot be installed an elevated water tank.Because there is not possibility of an elevated water tank as a solution, two big problems are generated. First, the high variability in the water demand by the population must be absorbed by the pumps; and second, the pumping station must be able to supply the demand in the all variation range, this could be from a fraction of liters per second to the minimum request of 16 [L/s] in a fire event. Based on experience it have been show that in low population case and the minimum demand flow is lower than the minimum pumping flow, are produced repeatedly stars in the pump that could reduce the service life.The solution of this particular problem is studied evaluating three current alternatives of solution: pumping station with variable-frequency drive, pump station with a hydropneumatic tank, and pumping station with variable-frequency drive and with a hydropneumatic tank (mixed system). From this evaluation is determined that the optimal solution is the mixed system.A methodology is presented for the design of the mixed system and an overhaul to the classic equations of the hydropneumatic tank volume calculation, based on these equations improvements have been proposed (proposed equations), with the aim of optimizing (reducing) the hydropneumatic tank volume, thus ensuring the pump operation (star per hour) within the limits recommended by the manufacturer. The use of the classic equations or the proposed equations for the hydropneumatic tank volume calculation is bounded to an application range recommended by the author of this document.A series of computer simulation of different hydraulic models are carried out to evaluate the quantity of star per hour generated in the pumps with the aim of evaluated the behavior of the pumps without a hydropneumatic tank, and with a hydropneumatic tank calculated according with classic equations and the proposed equations. In agreement with those results, the need for a hydropneumatic tank is confirmed due the high number of stars per hour generated in the pumps and their substantial decrease to number lower than the manufacturer’s limit when it’s added. Regarding the calculated volume of the hydropneumatic tank, the results show that always a smaller volume is obtained either when using the classic equations or the proposed equations within the recommended application range.Finally, due the fact that was not possible to obtain measurement data that would allow to confirm the hypothesis of the base approach for the proposed equations, which considers that the filling time of the hydropneumatic tank can be neglected owing is much shorter that the emptying time (TLL<< Tva), it is recommended to validate in a robust way what is proposed carry out real measurements in a system of the described type that allows to contrasting the proposed.
Description
Catalogado desde la version PDF de la tesis.
Keywords
BOMBA , ESTANQUE , HIDRONEUMATICO , VARIADOR DE FRECUENCIA