Ronald E. Vieira

Experimental Investigation of Horizontal Gas–Liquid Stratified and Annular Flow Using Wire-Mesh Sensor

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]

Characterizing Slug/Churn Flow Using Wire Mesh Sensor

A wire mesh sensor (WMS) is a device used to investigate multi-phase flows. The WMS measures the instantaneous local electrical conductivity of multiphase flows at different measuring points. There is a significant difference in the electrical conductivity of the employed fluids (in this work air and water, conductivity of water is much higher than that of air). Using the difference in the electrical conductivity, the WMS provides the local void fraction. The WMS utilized in this work includes two identical planes of parallel 16×16 grid of wires. The separation distance between these two planes is 32 mm. The WMS was installed in a 76.2 mm (3-inch) diameter vertical pipe to extract information such as void fraction distribution, structure velocity, and slug/churn flow structure. The superficial gas (air) velocity (VSG) ranged from 10 to 38.4 m/s. Liquid (water) superficial velocities (VSL) of 0.30, 0.46, 0.61 and 0.76 m/s were employed. To study the effects of viscosity on the slug/churn flow structure, Carboxyl Methyl Cellulose (CMC) was added to water to increase the liquid viscosity without altering its density. Each experiment was performed for 60 seconds. An operation frequency for the WMS of 10 kHz (totaling 600,000 frames of void fraction measurement per experiment) was used for all experiments.Copyright

Experimental Study of Vertical Gas-Liquid Pipe Flow for Annular and Liquid Loading Conditions Using Dual Wire-Mesh Sensors

In gas well production, liquid is produced in two forms, droplets entrained in the gas core and liquid film flowing on the tubing wall. For most of the gas well life cycle, the predominant flow pattern is annular flow. As gas wells mature, the produced gas flow rate reduces decreasing the liquid carrying capability initiating the condition where the liquid film is unstable and flow pattern changes from fully co-current annular flow to partially co-current annular flow. The measurement and visualization of annular flow and liquid loading characteristics is of great importance from a technical point of view for process control or from a theoretical point of view for the improvement and validation of current modeling approaches. In this experimental investigation, a Wire-Mesh technique based on conductance measurements was applied to enhance the understanding of the air-water flow in vertical pipes. The flow test section consisting of a 76 mm ID pipe, 18 m long, was employed to generate annular flow and liquid loading at low pressure conditions. A 16×16 wire configuration sensor is used to determine the void fraction within the cross-section of the pipe. Data sets were collected with a sampling frequency of 10,000 Hz. Physical flow parameters were extracted based on processed raw measured data obtained by the sensors using signal processing. In this work, the principle of Wire-Mesh Sensors and the methodology of flow parameter extraction are described. From the obtained raw data, time series of void fraction, mean local void fraction distribution, characteristic frequencies and structure velocities are determined for different liquid and gas superficial velocities that ranged from 0.005 to 0.1 m/s and from 10 to 40 m/s, respectively. In order to investigate dependence of liquid loading phenomenon on viscosity, three different liquid viscosities were used. Results from the Wire-Mesh Sensors are compared with results obtained from previous experimental work using Quick Closing Valves and existing modeling approaches available in the literature.Copyright

Sand Erosion in Multiphase Flow for Low-Liquid Loading and Annular Conditions

Low-liquid loading (LLL) and annular gas-liquid flow patterns are commonly encountered in gas transportation pipelines. They may also occur in other off-shore production facilities such as gas/condensate production systems. Experience gained from production of hydrocarbons has shown that severe degradation of production equipment will occur due to sand entrained in gas-dominant multiphase flows.Sand erosion in multiphase flows is a complex phenomenon since several factors influence the particle impact velocity with the wall. In order to give a more comprehensive understanding of the particle erosion process in this particular scenario and to improve the current semi-mechanistic models, erosion and sand distribution measurements were conducted on 76.2 mm (3 inch) and 101.6 mm (4 inch) diameter pipes in a large scale multiphase flow loop with varying gas (air) and liquid (water) velocities generating low-liquid loading and annular conditions. Particle sizes used in the experiments were 150 and 300 microns with the latter being sharper than the former. Erosion measurements were made at sixteen different locations on a 76.2 mm (3 inch) standard elbow using ultrasonic technology, whereas Electrical Resistance (ER) probes were used for the measurements in a 101.6 mm (4 inch) diameter pipe. The experiments were primarily performed in the upward vertical orientation but a few measurements were performed in the horizontal orientation. Results suggest that the erosion is an order of magnitude higher when the pipe is oriented vertically compared to horizontal orientation. Also, the location of maximum erosion is identified for these flow patterns and it is not dependent on the pipe inclination.© 2012 ASME

Experimental Investigation of Slug Characteristics Through a Standard Pipe Bend

Slug flow is a very common flow pattern encountered during the production of petroleum fluids. Likewise, pipe bends are often used to change the direction of the fluids during transportation. This work focuses on comparing various slug characteristics before and after a pipe bend. For this investigation, a dual Wire Mesh Sensor (WMS) is utilized. Measurements are made by placing the sensor before and after the bend. In order to obtain higher spatial and temporal resolution of the signals, a sampling frequency of 10,000 Hz is used. Experiments were conducted in a 76.2 mm (3-inch) diameter pipe utilizing air and water as fluids. Effect of fluid viscosity is also studied by conducting the experiments using three different liquid viscosities: 1, 10 and 40 cP. The experiments were conducted with superficial gas velocity ranging from 9.1 m/s to 35 m/s, and superficial liquid velocity ranged from 0.45 to 0.76 m/s. The three-dimensional time series void data from the Wire-Mesh sensor before and after the bend are analyzed to obtain averaged void fractions, structure of the slugs, void in liquid slugs, bubble size distributions, and radial profiles of gas velocity. Also, this study presents the differences in the void fraction distributions in slugs and pseudo slugs. Since pseudo slugs occur between slug and annular regimes, this information can further the understanding of the effect of flow characteristics on erosion occurring from solid particles for this flow pattern. Finally, from this comprehensive analysis the influence of the bend on the gas and liquid distributions over the cross-section has been discussed.Copyright

Experimental Study of Slug Characteristics: Implications to Sand Erosion

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

Experimental Investigation of Horizontal Gas-Liquid Stratified and Annular Flow Using Wire Mesh Sensor

Stratified and annular gas-liquid flow patterns are commonly encountered in oil and gas transportation pipelines. The measurement and visualization of two-phase flow characteristics is of great importance as two-phase flows persist in many fluids engineering applications. A Wire Mesh Sensor technique based on conductance measurements was applied to investigate two-phase horizontal pipe flow. The horizontal flow test section consisting of a 76 mm ID pipe, 18 m long was employed to generate stratified and annular flow conditions. A 16×16 wire configuration sensor, installed at 17 m from the inlet test section, is used to determine the void fraction within the cross-section of the pipe. Physical flow parameters were extracted based on processed raw measured data obtained by the sensors using signal processing techniques. In this work, the principle of wire mesh sensors and the methodology of flow parameter extraction are described. From the obtained raw data time series of void fraction, mean void fraction and characteristic liquid film velocities are determined for different liquid and gas superficial velocities that ranged from 0.03 m/s to 0.2 m/s and from 9 m/s to 34 m/s, respectively. The effects of liquid viscosity on the measured parameters are also investigated using three different viscosities.Copyright