Publication: DESARROLLO DE MODELOS PREDICTIVOS PARA LA DETERMINACIÓN DE LOS TIPOS DE FLUJO EN SILOS Y TOLVAS
Date
2016
Authors
QUIROZ GUERRERO, ALEXANDRA TERESITA
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Abstract
Este trabajo se centra en el desarrollo de modelos predictivos que permitandeterminar el tipo de flujo que se desarrolla en silos y tolvas, ya que conocer elcomportamiento de un material sólido a granel al ser descargado es un procesofundamental para las industrias que utilizan este tipo de materiales (alimenticia,minera, forestal, entre otras).Para esto se construyó un prototipo físico a escala de un silo cilíndrico con unatolva cónica que permitió realizar mediciones experimentales y observación del tipode flujo al ser descargado. Se ensayaron cinco materiales sólidos a granel (Gritz demaíz, azúcar, fertilizante, pellet de plástico y arena), con tres distintos recubrimientosde pared interna de la tolva (acero inoxidable, papel Canson, lija de madera n°180) ycinco ángulos de inclinación de tolva (15°, 20°, 30°, 35° y 45°). Además secaracterizaron las propiedades físicas y de fluidez de los materiales. Esto permitióobtener una base de datos que identificó tres zonas de flujo (flujo másico, flujoembudo y una zona de transición entre ambos) abarcando un amplio rango desituaciones existentes.En este trabajo se desarrollaron modelos predictivos de la descarga de silos contolvas tipo cuña y cónicas, mediante un diagrama de cuerpo libre y balance de fuerzasa las que se encuentra sometido el sólido a granel dentro del silo. De los modelos seobtuvieron ecuaciones implícitas y los resultados son presentados de forma gráficapara cada caso.Los resultados experimentales y los modelos desarrollados se compararon conla literatura existen. Para tolvas tipo cuña el modelo numérico representa fielmentelos ensayos experimentales y entrega resultados similares que los modelos yaexistentes. Para tolvas cónicas los resultados experimentales concuerdan con laliteratura, pero el modelo predictivo no describe adecuadamente el fenómeno.
This work focuses on the development of predictive models to determine thetype of flow that is developed in silos and hoppers. The knowledge of bulk solidmaterials behavior when it is discharged is a fundamental issue for industries that usethose materials (e. g. mining, forest industry, food industry, etc.).For this purpose a physical scale prototype was built of a cylindrical silo withconical hopper. In this prototype were made experimental tests and observations ofdischarge flow type. Five bulk solid materials were tested (gritz, sugar, fertilizer,plastic pellets and sand), with three hopper coatings (stainless steel, Canson paper andwood sandpaper N°180) and five tilt angles of hopper (15°, 20°, 30°, 35° and 45°).Also, bulk solid materials were characterized with their physical and flow properties.It allowed to build a database to identify three flow zones (mass flow, funnel flowand transition between both of them) and cover a wide range of possible cases.In this work two numerical predictive models of discharge flow types havebeen developed (conical silos and wedge-shaped hopper silos). Those models weredeveloped through free-body diagrams and force balances of bulk solid materialinside the silo. Implicit equations were obtained and the results were presented in agraphic chart for each case.The experimental results and numerical models were compared with literatureresults. The wedge-shaped hopper model responds appropriately the experimentalresults and the graphic chart is similar with existing models. For conical hopper theexperimental results are consistent with literature, but the predictive model describespoorly the physical phenomenon.
This work focuses on the development of predictive models to determine thetype of flow that is developed in silos and hoppers. The knowledge of bulk solidmaterials behavior when it is discharged is a fundamental issue for industries that usethose materials (e. g. mining, forest industry, food industry, etc.).For this purpose a physical scale prototype was built of a cylindrical silo withconical hopper. In this prototype were made experimental tests and observations ofdischarge flow type. Five bulk solid materials were tested (gritz, sugar, fertilizer,plastic pellets and sand), with three hopper coatings (stainless steel, Canson paper andwood sandpaper N°180) and five tilt angles of hopper (15°, 20°, 30°, 35° and 45°).Also, bulk solid materials were characterized with their physical and flow properties.It allowed to build a database to identify three flow zones (mass flow, funnel flowand transition between both of them) and cover a wide range of possible cases.In this work two numerical predictive models of discharge flow types havebeen developed (conical silos and wedge-shaped hopper silos). Those models weredeveloped through free-body diagrams and force balances of bulk solid materialinside the silo. Implicit equations were obtained and the results were presented in agraphic chart for each case.The experimental results and numerical models were compared with literatureresults. The wedge-shaped hopper model responds appropriately the experimentalresults and the graphic chart is similar with existing models. For conical hopper theexperimental results are consistent with literature, but the predictive model describespoorly the physical phenomenon.
Description
Catalogado desde la version PDF de la tesis.
Keywords
MODELO PREDICTIVO , SILOS , TIPO DE FLUJO , TOLVAS