Experimental investigations of two-phase flow measurement using ultrasonic sensors

This thesis presents the investigations conducted in the use of ultrasonic technology to measure two-phase flow in both horizontal and vertical pipe flows which is important for the petroleum industry. However, there are still key challenges to measure parameters of the multiphase flow accurately. Four methods of ultrasonic technologies were explored. The Hilbert-Huang transform (HHT) was first applied to the ultrasound signals of air-water flow on horizontal flow for measurement of the parameters of the two- phase slug flow. The use of the HHT technique is sensitive enough to detect the hydrodynamics of the slug flow. The results of the experiments are compared with correlations in the literature and are in good agreement. Next, experimental data of air-water two-phase flow under slug, elongated bubble, stratified-wavy and stratified flow regimes were used to develop an objective flow regime classification of two-phase flow using the ultrasonic Doppler sensor and artificial neural network (ANN). The classifications using the power spectral density (PSD) and discrete wavelet transform (DWT) features have accuracies of 87% and 95.6% respectively. This is considerably more promising as it uses non-invasive and non-radioactive sensors. Moreover, ultrasonic pulse wave transducers with centre frequencies of 1MHz and 7.5MHz were used to measure two-phase flow both in horizontal and vertical flow pipes. The liquid level measurement was compared with the conductivity probes technique and agreed qualitatively. However, in the vertical with a gas volume fraction (GVF) higher than 20%, the ultrasound signals were attenuated. Furthermore, gas-liquid and oil-water two-phase flow rates in a vertical upward flow were measured using a combination of an ultrasound Doppler sensor and gamma densitometer. The results showed that the flow gas and liquid flow rates measured are within ±10% for low void fraction tests, water-cut measurements are within ±10%, densities within ±5%, and void fractions within ±10%. These findings are good results for a relatively fast flowing multiphase flow

Introduction to modern instrumentation: for hydraulics and environmental sciences

Preface Natural hazards and anthropic activities threaten the quality of the environment surrounding the human being, risking life and health. Among the different actions that must be taken to control the quality of the environment, the gathering of field data is a basic one. In order to obtain the needed data for environmental research, a great variety of new instruments based on electronics is used by professionals and researchers. Sometimes, the potentials and limitations of this new instrumentation remain somewhat unknown to the possible users. In order to better utilize modern instruments it is very important to understand how they work, avoiding misinterpretation of results. All instrument operators must gain proper insight into the working principles of their tools, because this internal view permits them to judge whether the instrument is appropriately selected and adequately functioning. Frequently, manufacturers have a tendency to show the great performances of their products without advising their customers that some characteristics are mutually exclusive. Car manufacturers usually show the maximum velocity that a model can reach and also the minimum fuel consumption. It is obvious for the buyer that both performances are mutually exclusive, but it is not so clear for buyers of measuring instruments. This book attempts to make clear some performances that are not easy to understand to those uninitiated in the utilization of electronic instruments. Technological changes that have occurred in the last few decades are not yet reflected in academic literature and courses; this material is the result of a course prepared with the purpose of reducing this shortage. The content of this book is intended for students of hydrology, hydraulics, oceanography, meteorology and environmental sciences. Most of the new instruments presented in the book are based on electronics, special physics principles and signal processing; therefore, basic concepts on these subjects are introduced in the first chapters (Chapters 1 to 3) with the hope that they serve as a complete, yet easy-to-digest beginning. Because of this review of concepts it is not necessary that the reader have previous information on electronics, electricity or particular physical principles to understand the topics developed later. Those readers with a solid understanding of these subjects could skip these chapters; however they are included because some students could find them as a useful synthesis. Chapter 4 is completely dedicated to the description of transducers and sensors frequently used in environmental sciences. It is described how electrical devices are modified by external parameters in order to become sensors. Also an introduction to oscillators is presented because they are used in most instruments. In the next chapters all the information presented here is recurrently referred to as needed to explain operating principles of instruments. Unauthenticated Download Date | 10/12/14 9:29 PM VIII Preface Chapters 1 to 4 are bitter pills that could discourage readers interested in the description of specific instruments. Perhaps, those readers trying this book from the beginning could abandon it before arriving at the most interesting chapters. Therefore, they could read directly Chapters 5 to 11, going back as they feel that they need the knowledge of the previous chapters. We intended to make clear all the references to the previous subjects needed to understand each one of the issues developed in the later chapters. Chapter 5 contributes to the understanding of modern instrumentation to measure flow in industrial and field conditions. Traditional mechanical meters are avoided to focus the attention on electronic ones, such as vortex, electromagnetic, acoustic, thermal, and Coriolis flowmeters. Special attention is dedicated to acoustic Doppler current profilers and acoustic Doppler velocimeters. Chapter 6 deals with two great subjects; the first is devoted to instruments for measuring dynamic and quasi static levels in liquids, mainly water. Methods to measure waves at sea and in the laboratory are explained, as well as instruments to measure slow changes such as tides or piezometric heads for hydrologic applications. The second subject includes groundwater measurement methods with emphasis on very low velocity flowmeters which measure velocity from inside a single borehole. Most of them are relatively new methods and some are based on operating principles described in the previous chapter. Seepage meters used to measure submarine groundwater discharge are also presented. Chapter 7 presents methods and instruments for measuring rain, wind and solar radiation. Even though the attention is centered on new methods, some traditional methods are described not only because they are still in use, and it is not yet clear if the new technologies will definitely replace them, but also because describing them permits their limitations and drawbacks to be better understood. Methods to measure solar radiation are described from radiation detectors to complete instruments for total radiation and radiation spectrum measurements. Chapter 8 is a long chapter where we have tried to include most remote measuring systems useful for environmental studies. It begins with a technique called DTS (Distributed Temperature Sensing) that has the particularity of being remote, but where the electromagnetic wave propagates inside a fibre optic. The chapter follows with atmosphere wind profilers using acoustic and electromagnetic waves. Radio acoustic sounding systems used to get atmospheric temperature profiles are explained in detail as well as weather radar. Methods for ocean surface currents monitoring are also introduced. The chapter ends with ground penetrating radars. Chapter 9 is an introduction to digital transmission and storage of information. This subject has been reduced to applications where information collected by field instruments has to be conveyed to a central station where it is processed and stored. Some insight into networks of instruments is developed; we think this information will help readers to select which method to use to transport information from field to office, by means of such diverse communication media as fibre optic, digital telephony, Unauthenticated Download Date | 10/12/14 9:29 PM Preface IX GSM (Global System for Mobile communications), satellite communications and private radio frequency links. Chapter 10 is devoted to satellite-based remote sensing. Introductory concepts such as image resolution and instrument?s scanning geometry are developed before describing how passive instruments estimate some meteorological parameters. Active instruments are presented in general, but the on-board data processing is emphasized due to its importance in the quality of the measurements. Hence, concepts like Synthetic Aperture Radar (SAR) and Chirp Radar are developed in detail. Scatterometers, altimeters and Lidar are described as applications of the on-board instruments to environmental sciences. Chapter 11 attempts to transfer some experiences in field measuring to the readers. A pair of case studies is included to encourage students to perform tests on the instruments before using them. In this chapter we try to condense our ideas, most of them already expressed throughout the book, about the attitude a researcher should have with modern instruments before and after a measuring field work. As can be inferred from the foregoing description the book aims to provide students with the necessary tools to adequately select and use instruments for environmental monitoring. Several examples are introduced to advise future professionals and researchers on how to measure properly, so as to make sure that the data recorded by the instruments actually represents the parameters they intend to know. With this purpose, instruments are explained in detail so that their measuring limitations are recognized. Within the entire work it is underlined how spatial and temporal scales, inherent to the instruments, condition the collection of data. Informal language and qualitative explanations are used, but enough mathematical fundamentals are given to allow the reader to reach a good quantitative knowledge. It is clear from the title of the book that it is a basic tool to introduce students to modern instrumentation; it is not intended for formed researchers with specific interests. However, general ideas on some measuring methods and on data acquisition concepts could be useful to them before buying an instrument or selecting a measuring method. Those readers interested in applying some particular method or instrument described in this book should consider these explanations just as an introduction to the subject; they will need to dig deeper in the specific bibliography before putting hands on.Fil: Guaraglia, Dardo Oscar. Universidad Nacional de la Plata. Facultad de Ingeniería. Departamento de Hidraulica. Area Hidraulica Basica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Pousa, Jorge Lorenzo. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Laboratorio de Oceanografía Costera y Estuarios; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin

Deducing water parameters in rivers via statistical modelling

Advanced monitoring of water quality in order to perform a real-time hazard analysis prior to Water Treatment Works (WTW) is more of a necessity nowadays, both to give warning of any contamination and also to avoid downtime of the WTW. Downtimes could be a major contributor to risk. Any serious accident will cause a significant loss in customer and investor confidence. This has challenged the industry to become more efficient, integrated and attractive, with benefits for its workforce and society as a whole. The reality is that water companies are not yet prepared to invest heavily in trials, before another company announces its success in implementing a new monitoring strategy. This has slowed down the development of the water industry. This research has taken the theoretical idea that the use of advanced online monitoring technique in the water industry would be beneficial and a step further; demonstrating by means of a state-of-the-art assessment, usability trials, case studies and demonstration that the barriers to mainstream adoption can be overcome. The findings of this work have been presented in four peer-reviewed papers. The research undertaken has shown that Turbidity levels in rivers can be measured from the rivers’ mean flow rate, using either Doppler Ultrasound device for real-time readings or based on past performance history. In both cases, the Turbidity level can also help estimate both the Colour and Conductivity levels of the subject river. Recalibration of the equations used is a prerequisite as each individual river has its own unique “finger print”

Multiphase flow measurement in the slug regime using ultrasonic measurement techniques and slug closure model

Multiphase flow in the oil and gas industry covers a wide range of flows. Thus, over the last decade, the investigation, development and use of multiphase flow metering system have been a major focus for the industry worldwide. However, these meters do not perform well in slug flow conditions. The present work involves experimental investigations of multiphase flow measurement under slug flow conditions. A two-phase gas/liquid facility was designed and constructed at Cranfield University. It consisted of a 0.05 m diameter 25 m long horizontal pipeline with the necessary instrumentation. An ultrasonic multiphase metering concept has been proposed and investigated. The concept was based on the combination of non-invasive and non-intrusive ultrasonic sensors and a slug closure model. The slug closure model was based on the "slug unit" model to infer the gas and liquid phase volumetric flowrates. The slug characteristics obtained by non-invasive and non-intrusive ultrasonic techniques were inputs to slug closure model which calculates the factors KI (Liquid), K2 (Liquid), K3 (Gas) and K4 (Gas). These factors are function of the slip ratio in the slug body, flow profile (CO), drift velocity (Vd), liquid holdup and gas void fraction in slug body, slug length, film length, and the total length of the slug unit. Based on ultrasonic sensor measurements, the slug translational velocity was estimated and the slug closure model then calculates the gas and liquid phase volumetric flowrates. Air water slug flow data were gathered and processed for a range of superficial velocities VSL=0.3 to 1.03 ms'1 and VsG=0.6 to 3.01 ms'1. The overall goal of a 5% relative error metering for both phases was not achieved for the conditions tested. The liquid phase percentage errors were from -63.6% to 45.4% while the gas phase percentage errors were from 42% to -14.6%. Key words: slug flow, slug characteristics, slug closure model, non-invasive ultrasonic, non-intrusive ultrasonic, clamp-on transit time ultrasonic flowmeter

Measurement of the local properties of multiphase flows

Flows of mixed fluids in pipes are frequently encountered in several areas of engineering, such as chemical, petroleum and nuclear. Two key parameters characterising such flows are the local volume fraction distribution and the axial velocity distribution of the dispersed phase. In order to achieve a further understanding of the flow properties, vector velocities are important too. A common intrusive method that is used for acquiring these parameters is the local conductivity probe. The reason is that conductivity probes are more accurate than other measuring techniques, such as ERT (Electrical Resistance Tomography) systems, and are therefore used for the calibration and validation of ERT systems. Also the measurements from conductivity probes show a more representative distribution of volume fraction and velocity of the dispersed phase than other non intrusive methods. They are also useful for validating data produced by CFD (Computed Fluid Dynamics) simulations. In this thesis, research has been done on designing probes, and improving the related signal processing algorithms, and several experiments have been run in multiphase loops for measuring the local volume fraction and velocity of the dispersed phase in vertical and inclined pipes and in swirling flows. All these attempts have recognised an extra problem that is not negligible when using local conductance probes. This problem is the interaction between the probe and the bubble. It is known that local probes alter the true value of the bubble’s vector velocity due to the fact that bubbles are slowed down by the probe. A number of experiments were performed and a comparison between ERT and local conductivity probes was made. Both techniques gave velocity distributions of the dispersed phase which do not agree, showing that ERT is unable to accurately measure the gas velocity and volume fraction profiles. Furthermore the current thesis presents results from dual sensor and four sensor local conductivity probes in steady vertical and inclined air-water and oil-water flows and in steady swirling flows, and a proposed new design for fabricating a rotary index dual sensor probe with a new algorithm for the signal processing scheme is given. This new type of conductivity probe has a relatively small frontal area that reduces the bubble-probe interaction hence the probe’s effect on the dispersed phase is less that of other types of probe.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Enhancing filtration by electroacoustic methods

Fouling of filter media and physico-chemical properties of suspensions decrease the efficiency of filtration devices in a wide range of process industries. Environmental protection causes increasing demand to clean effluent waters to higher standards and to recycle process waters more completely. Conventional deliquoring processes are mainly based on a single driving force, usually gravity, underpressure or pressure. Today, multiforce deliquoring processes based on a combination of ultrasonic and/or other nonmechanical forces, like an electric field, are being developed. These new technological applications, namely electro-acoustic deliquoring techniques, will most probably enable higher deliquoring rates and final solid contents than conventional methods have been able to yield. Results from an experimental study of electric and/or ultrasonic field assisted filtrations are presented in this thesis. Both electric and ultrasonic fields can reduce fouling of the filtration medium and have a significant influence on filtration capacity. The extent of filtration improvement is affected mostly by particle size, surface charge, acoustic frequency, intensity and field strengths. Theoretical examinations of the use of electric and/or ultrasonic fields to enhance filtration efficiency are laid out. Some aspects regarding orthokinetic interaction in acoustic agglomeration have been considered, and energy consumptions of the filtrations of different suspensions used in experiments were also determined. Using electric field as a pre-treatment, biolfiber suspension filtration can be enhanced 4-fold and energy consumption of electric field enhancing the filtration (kWh kg1 separated water; product final dry solid content 23 % by mass) was only about 17 % of the total energy consumption of conventional vacuum filtration. Pre-treatment units can be connected to the filtration unit, for instance before the filter drum. Possible pre-treatment apparatuses could be electroflotation equipment or a pre-treatment tube technique introduced in this Ph.D. Thesis

Gas-Liquid Two-Phase Flow in the Pipe or Channel

The main goal of this Special Issue was to contribute to, highlight and discuss topics related to various aspects of two-phase gas–liquid flows, which can be used both in fundamental sciences and practical applications, and we believe that this main goal was successfully achieved. This Special Issue received studies from Russia, China, Thailand, ROC-Taiwan, Saudi Arabia, and Pakistan. We were very grateful to see that all the papers presented findings characterized as unconventional, innovative, and methodologically new. We hope that the readers of the journal Water can enjoy and learn about the experimental and numerical study of two-phase flows from the published material, and share these results with the scientific community, policymakers and stakeholders. Last but not least, we would like to thank Ms. Aroa Wang, Assistant Editor at MDPI, for her dedication and willingness to publish this Special Issue. She is a major supporter of the Special Issues, and we are indebted to her