Tesis
Impacto técnico - económico del flujo bifásico en sistemas de desfogues de plantas criogénicas
Fecha
2017-12-08Registro en:
Hernández Guillén Liliana del Carmen. (2017). Impacto técnico - económico del flujo bifásico en sistemas de desfogues de plantas criogénicas. (Maestría en Geociencias y Administración de los Recursos Naturales). Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Ingeniería y Arquitectura, Unidad Ticomán. México.
Autor
Hernández Guillén, Liliana del Carmen
Institución
Resumen
En las plantas criogénicas se tienen mezclas de hidrocarburos con bajo peso
molecular, lo que ocasiona que en el proceso como una operación normal se tenga
flujo a dos fases (líquido-vapor), es decir, si consideramos una mezcla de etano y
propano a bajas temperaturas y presión moderada su estado será líquido (una sola
fase), esta mezcla hidrocarburos se ve afectada por los cambios de presión, como
parte del proceso se tienen pérdidas de presión y por tanto de temperatura durante el
flujo a través de las tuberías y accesorios, lo que origina que una parte del fluido pase
a fase vapor, ocasionando que se tenga una mezcla a dos fases (líquido-vapor) a
través de algunas secciones del proceso. ABSTRACT
The purpose of this thesis is determine the type of flow pattern and pressure drop of a case of study, which was developed during the relief event of a cryogenic plant.
In cryogenic process there are mixtures of hydrocarbons with low molecular weight, which causes that the process presents as a normal operation two-phase flow condition, for example if we consider a mixture of ethane-propane at low temperature and moderate pressure, the mixture phase will be liquid (single phase), this hydrocarbon mixture is affected by the pressure drop, there are losses of pressure and temperature as a result of the flow through pipes and fittings, which causes that a part of the mixture to vaporize, causing two-phase flow in some sections of the process. When a two-phase flow condition is detected, the type of flow pattern must be determined to consider an adequate pipes and supports arrangement as a part of the design.
In the case of the study the pipes arrangement were designed for two-phase flow condition with a stable flow pattern, however during the relief event the pipes, supports and concrete frames were damaged, all these damages an estimated cost of approximately more than one million of pesos according to the economic evaluation performed.
The hypothesis that the cause of the displacement of pipes, was due to an intermittent pattern of a two-phase flow, so the relief conditions were evaluated using two simulation software packages. The first simulation software uses the Dukler flow correlation to evaluate the flow pattern and pressure drops, the result obtained in this simulation was a stable flow pattern (stratified-wavy flow), while in the second simulator uses the Beggs and Brill flow correlation, it was found that flow pattern is intermittent type (slug flow), which is a support to the initial hypothesis.
Over this case of study a set of recommendations. The main suggestion is the use of Beggs & Brill flow correlation for mixtures with low molecular weight in horizontal tubes with diameters of 10 to 30 inches.