NGL supersonic separator: modeling, improvement, and validation and adjustment of k-epsilon RNG modified for swirl flow turbulence model

Abstract

ABSTRACT:The processing of natural gas requires the implementation of new technologies in a context of increasing demand around the world. The natural gas liquids (NGL) separation using supersonic devices is a novel and efficient way to reduce volume of installed equipment and operation costs using the effects of highly turbulent and circular flows. This research implemented Computational Fluid Dynamics (CFD) modeling to improve the efficiency of typical NGL recovery process using the supersonic approach. In this research, a novel turbulence modeling approach was implemented aiming to minimize the processing time, and the results obtained were validated with experimental data available. This research is based on the model called k-epsilon RNG modified for swirl flow, this model has not been used and validated previously in highly compressible, turbulent and circular flow systems. The efficiency of the process was improved by 11% in comparison to the efficiency reported in past studies, and the processing time for the modeling was reduced by 40% with the proposed and adjusted turbulence approach. During the validation of the model k-epsilon RNG modified for swirl flow the swirl factor, part of the turbulence model, was adjusted to an optimum value for compressible, turbulent and circular flow systems involved in supersonic NGL separation process, allowing accurate results to be obtained with lower processing time than with other typical and common approaches as RSM and LES.RESUMEN: El procesamiento de gas natural requiere la aplicación de nuevas tecnologías en un contexto de aumento de la demanda en todo el mundo. La separación de líquidos de gas natural (LGN) utilizando dispositivos supersónicos, es una novedosa y eficiente manera de reducir el volumen de equipos instalados y costos, utilizando los efectos de los flujos circulares altamente turbulentos. En esta investigación se implementa dinámica computacional de fluidos (CFD) para mejorar la eficiencia del proceso típico de recuperación de LGN utilizando el enfoque supersónico. También se puso en práctica un nuevo enfoque de modelado de la turbulencia con el objetivo de minimizar el tiempo de procesamiento, los resultados obtenidos fueron validados con datos experimentales disponibles. Esta investigación se basa en el modelo llamado k-épsilon RNG modificado para flujo remolino; este modelo no se ha utilizado ni validado antes en sistemas de flujo altamente compresibles, turbulentos y circulares. La eficiencia del proceso fue mejorada en un 11% en comparación con la eficiencia reportada en investigaciones previas, y el tiempo de procesamiento para el modelado redujo 40% con el enfoque turbulencia propuesto y ajustado. Durante la validación del modelo k-épsilon RNG modificado para flujo remolino el factor de remolino, parte del modelo de turbulencia, se ajustó a un valor óptimo para sistemas de flujo compresibles, turbulentos y circulares que participan en procesos de separación de NGL supersónico, lo que permite obtener resultados más precisos y con un menor ti...

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“…Tetrahedral meshes were created using advanced size function. To increase control over cells sizes, the angle between normal vectors, the number of elements used in the gaps, and the progression between minimum and maximum cell size were changed [17]. The curvature, and proximity and curvature methods were employed.…”

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