چكيده به لاتين
Changes in operating pressure during the extraction and transfer of hydrocarbon products lead to a gas-liquid flow. This situation creates many difficulties for the optimal performance of rotating and stationary equipment in transmission and process lines. To reduce the damage caused by biphasic flows, mechanical separators that perform based on the difference in density of the operating fluids are considered. In this regard, axial flow cyclonic separators with involute inlet and outlet have a significant advantage over other existing separators. This dissertation aims to improve the performance of cyclonic gas-liquid axial flow separator with involute inlet and outlet. The separator has a fixed geometry and is designed for a specific and uniform inlet flow. The intermittent and non-reproducible behavior of the inlet gas-liquid flow causes unstable performance and significantly affects the optimum efficiency of this separator. The present study is carried out to make the cyclone performance function is independent of the different conditions of the inlet flow field. Therefore, the work focuses on the frequency content of the inlet flow with intermittent and non-repetitive behavior to the field with stochastics and reproducible behavior. Accordingly, experimental study and numerical simulation in four different sections in the present study have been investigated. In the first part, the frequency content is studied along with the changes governing the flow field parameters, such as the length and speed of slug transmission, with the help of pressure data and images recorded utilizing the high-speed camera. In the numerical part, two methods, volume of fluid model and hybrid model, have been used to prepare more accurate predictions of flow patterns and related parameters. What is obtained from the results is that the statistical parameters of the slug flow pattern have a non-repetitive behavior, while the mentioned parameters show a constant repetitive behavior for at least 30 seconds. In the second and third sections, the geometric modification of the separator inlet is studied on the transient behavior of the gas-liquid slug flow with the help of the frequency bandwidth. In the second part, the installation of convergent nozzle geometry, and in the third part, the installation of the 90-degree elbow with different radii (17, 34, 51, and 68cm) and all with a rectangular cross-section with length (34) mm and width (21) mm Have been studied. The results show that the predominant frequency of the slug flow remains constant after passing through the nozzle as well as the 90-degree elbow, while the power of the low-frequency spectrum of the flow field (less than 10 Hz) increases, and in this regard, the Shannon entropy parameter increases (2-5) Equal for nozzle geometry and (1.3-1.8) equal for elbow geometry emphasizes the accuracy of the results. The evaluations show that the slug flow is known as an oscillating flow with a wide distribution from bubbles size, While this flow pattern after passing through the nozzle and elbow to an oscillating flow in which the distribution of bubbles is severely limited in longitudinal scales and to a quasi-homogeneous bubble flow containing gas plugs much smaller than slugs of the inlet flow is inclined. In the fourth section, the performance of the axial flow cyclonic separator was investigated using inlets with different geometry, including short nozzle, extended nozzle, and nozzle with a 90-degree elbow in different operating conditions for gas separation from the liquid. Evaluation of the results has shown that the output performance of light phase in conditions where long nozzles are used is much more desirable than the use of short nozzles and has increased (2-7) percent separation efficiency. In comparison, applying a 90-degree elbow has reduced the gas phase separation performance from the liquid by 5% compared to the short nozzle. The results also show that increasing the volumetric passage of the gas phase reduces the efficiency parameters. While increasing the liquid phase has improved the performance and increased the separation of the lighter phase.
