Abstract

Sand erosion is a severe problem that many oil and gas producers have to deal with. Therefore, it is desirable to have a model that can predict erosion for various operating conditions. Predicting erosion is a complex problem due to the number of parameters that are involved. The complexity of predicting erosion increases when producing or transporting multiphase fluids through pipelines. It is well known that the characteristics of multiphase flow affect sand erosion in the pipelines. This work specifically concentrates on investigating multiphase-slug characteristics using a measurement technique based on Wire Mesh Sensor. A 16 × 16 dual Wire Mesh Sensor is installed before a standard 76.2 mm (3-inch) elbow for a horizontally oriented pipe. The distance by which the dual Wire Mesh Sensors are separated is 32 mm. The local void fraction is extracted where horizontal and vertical wires of the sensor intersect, utilizing the differences in conductance between gas and liquid as they pass through the crossings of the wires. The fluids used in these multiphase experiments were air and either water or water-Carboxy Methyl Cellulose mixture to increase the liquid viscosity. Experiments were conducted, where superficial gas velocity ranged from 9.1 m/s to 35 m/s, and superficial liquid velocity was 0.76 m/s. Three different liquid viscosities (1 cP, 10 cP and 40 cP) were used for performing the experiments. The void fraction data obtained using the dual Wire Mesh Sensors is utilized to achieve the interfacial velocities of the liquid slug. Further analysis of the data is conducted to obtain other slug characteristics such as the liquid slug body length distribution and frequency of the slugs. Additionally, liquid slug fronts and slug tails were identified. The differences in the characteristics of slug flow and pseudo-slug flow are addressed. Finally, the slug characteristics were utilized in order to enhance the understanding of sand particle impact velocities with the pipe wall and the resulting erosion in the horizontal pipelines and elbow.Copyright © 2013 by ASME

Abstract

Stratified and annular gas–liquid flow patterns are commonly encountered in many industrial applications, such as oil and gas transportation pipelines, heat exchangers, and process equipment. The measurement and visualization of two-phase flow characteristics are of great importance as two-phase flows persist in many fluids engineering applications. A wire-mesh sensor (WMS) technique based on conductance measurements has been applied to investigate two-phase horizontal pipe flow. The horizontal flow test section consisting of a 76.2mm ID pipe, 18m long was employed to generate stratified and annular flow conditions. Two 16 16 wire configuration sensors, installed 17 m from the inlet of the test section, are used to determine the void fraction within the cross section of the pipe and determine interface velocities between the gas and liquid. These physical flow parameters were extracted using signal processing and cross-correlation techniques. In this work, the principle of WMS and the methodology of flow parameter extraction are described. From the obtained raw data time series of void fraction, cross-sectional mean void fraction, time averaged void fraction profiles, interfacial structures, and velocities of the periodic structures are determined for different liquid and gas superficial velocities that ranged from 0.03m/s to 0.2m/s and from 9m/s to 34m/s, respectively. The effects of liquid viscosity on the measured parameters have also been investigated using three different viscosities. [DOI: 10.1115/1.4027799]