Slug Dissipation in a Horizontal Enlarged Impacting Tee-Junction

Abstract

Abstract Enlarged Impacting Tee-junctions (EIT) are the building blocks of multiphase manifolds, which are large diameter pipe sections fed by several smaller diameter inlet pipelines. The goal of this study is to conduct an experimental and theoretical study on slug dissipation in an enlarged impacting tee-junction (EIT). Experimental data are acquired and a mechanistic model is developed for the prediction of the length required for slugs to dissipate in the EIT, namely, the "slug dissipation length". The developed model is validated with the acquired data. An EIT test section is designed and installed in a multiphase flow loop to investigate slug dissipation length at an EIT junction. The EIT inlet is a 0.05 m diameter, 4.6 m long pipe, which is connected to the center of an enlarged 0.074 m diameter 5.5 m long pipe forming the EIT section. Air and water are used as the test fluids, with superficial gas and liquid velocities in the ranges of 1-5 m/s and 0.3-1.2 m/s, respectively, to ensure slug flow at the EIT inlet. The slug dissipation process in the branches of the EIT is observed visually and recorded by a set of cameras. A slug dissipates as it enters from the reduced diameter inlet section into the EIT section. The dissipation of the slug in the EIT is due mainly to liquid drainage from the slug front and penetration of "bubble turning" into the slug body as it moves along the branches of the EIT. Thus, the length of the slug body is continuously reduced until it completely dissipates. The experimental results show that the slug dissipation length increases with increasing superficial gas velocity. The results also confirm that the dissipation length is more sensitive to the superficial gas velocity, as compared to the superficial liquid velocity. The developed mechanistic model is based on the physical slug dissipation mechanism, namely penetration of turning bubble into the slug body. The predictions of the proposed mechanistic model are in good agreement with the experimental data, showing discrepancies less than 15%. The results of this study will enable to properly design a multiphase manifold by providing a criterion for slug dissipation length in EIT.