Análisis computacional de factibilidad y rendimiento para la inyección de hidrógeno verde en redes de gas natural.
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Date
2025
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Universidad de Concepción
Abstract
La transición energética global posiciona al Hidrógeno Verde como un vector clave para la descarbonización. En Chile, y específicamente en la Región del Biobío, el uso de la infraestructura existente de Gas Natural mediante la técnica de Blending se presenta como una estrategia inmediata para activar la demanda de este combustible. Sin embargo, la inyección de hidrógeno en redes diseñadas para metano plantea incertidumbres críticas respecto a la integridad mecánica y la operabilidad del sistema bajo demandas energéticas reales.
El presente trabajo evalúa la factibilidad mecánica y operacional de inyectar mezclas de Hidrógeno (10% y 20%) en la red de gasoductos de la empresa Innergy, analizando tres tramos representativos (Itata, San Pedro y Laja). A diferencia de estudios previos, esta investigación aplica un enfoque isoenergético, ajustando los caudales volumétricos para mantener el suministro de energía constante ante la menor densidad energética del hidrógeno. La metodología integra simulaciones de Dinámica de Fluidos Computacional (CFD) en ANSYS Fluent utilizando el modelo de turbulencia $k-\omega$ SST, validadas posteriormente mediante cálculos analíticos de integridad estructural basados en la norma ASME B31.12 y la Ecuación de Barlow.
Los resultados de las simulaciones demuestran que, hidráulicamente, la red es robusta: el incremento de velocidad requerido para mantener la energía (hasta un 16% extra en volumen) no genera velocidades erosionales ni caídas de presión significativas que comprometan la operación. No obstante, el análisis de integridad estructural identificó al Lateral San Pedro (Caso 2) como un punto crítico. Debido a su geometría de pared delgada (4.8 mm) y alta presión de operación (38 bar), este tramo experimenta tensiones circunferenciales (Hoop Stress) cercanas a 100 MPa, operando al ~42% de su límite elástico. Se concluye que, si bien la inyección es viable hidráulicamente en todos los casos, el escenario de 20% de H2 en el tramo San Pedro presenta un riesgo moderado de fragilización por hidrógeno debido a la alta presión parcial (7.6 bar) combinada con la tensión mecánica, requiriendo protocolos de monitoreo de integridad diferenciados respecto a los tramos de menor presión como Laja.
The global energy transition positions Green Hydrogen as a key vector for decarbonization. In Chile, specifically in the Biobío Region, utilizing existing Natural Gas infrastructure through blending strategies presents an immediate opportunity to activate demand for this fuel. However, injecting hydrogen into networks designed for methane raises critical uncertainties regarding mechanical integrity and system operability under real energy demands.This work evaluates the mechanical and operational feasibility of injecting Hydrogen blends (10% and 20%) into the Innergy gas pipeline network, analyzing three representative laterals (Itata, San Pedro, and Laja). Unlike previous studies, this research applies an isoenergetic approach, adjusting volumetric flow rates to maintain constant energy supply despite hydrogen's lower energy density. The methodology integrates Computational Fluid Dynamics (CFD) simulations in ANSYS Fluent using the $k-\omega$ SST turbulence model, validated subsequently through analytical structural integrity calculations based on the ASME B31.12 standard and Barlow’s Equation.Simulation results demonstrate that the network is hydraulically robust: the required velocity increase to maintain energy (up to 16% extra volume) does not generate erosional velocities or significant pressure drops that compromise operation. However, the structural integrity analysis identified the San Pedro Lateral (Case 2) as a critical point. Due to its thin wall geometry (4.8 mm) and high operating pressure (38 bar), this section experiences Hoop Stresses near 100 MPa, operating at approximately 42% of its yield strength. It is concluded that, while injection is hydraulically viable in all cases, the 20% H2 scenario in the San Pedro section presents a moderate risk of hydrogen embrittlement due to high partial pressure (7.6 bar) combined with mechanical stress, requiring integrity monitoring protocols differentiated from lower-pressure sections like Laja.
The global energy transition positions Green Hydrogen as a key vector for decarbonization. In Chile, specifically in the Biobío Region, utilizing existing Natural Gas infrastructure through blending strategies presents an immediate opportunity to activate demand for this fuel. However, injecting hydrogen into networks designed for methane raises critical uncertainties regarding mechanical integrity and system operability under real energy demands.This work evaluates the mechanical and operational feasibility of injecting Hydrogen blends (10% and 20%) into the Innergy gas pipeline network, analyzing three representative laterals (Itata, San Pedro, and Laja). Unlike previous studies, this research applies an isoenergetic approach, adjusting volumetric flow rates to maintain constant energy supply despite hydrogen's lower energy density. The methodology integrates Computational Fluid Dynamics (CFD) simulations in ANSYS Fluent using the $k-\omega$ SST turbulence model, validated subsequently through analytical structural integrity calculations based on the ASME B31.12 standard and Barlow’s Equation.Simulation results demonstrate that the network is hydraulically robust: the required velocity increase to maintain energy (up to 16% extra volume) does not generate erosional velocities or significant pressure drops that compromise operation. However, the structural integrity analysis identified the San Pedro Lateral (Case 2) as a critical point. Due to its thin wall geometry (4.8 mm) and high operating pressure (38 bar), this section experiences Hoop Stresses near 100 MPa, operating at approximately 42% of its yield strength. It is concluded that, while injection is hydraulically viable in all cases, the 20% H2 scenario in the San Pedro section presents a moderate risk of hydrogen embrittlement due to high partial pressure (7.6 bar) combined with mechanical stress, requiring integrity monitoring protocols differentiated from lower-pressure sections like Laja.
Description
Tesis presentada para optar al título de Ingeniero/a Civil Mecánico/a.
Keywords
Hidrógeno verde, Gas natural, Blending, Combustibles, Sustentabilidad