An ultrasonic flowmeter for gases by Donald A. Bender, Leon R. Glicksman, Carl R. Peterson.

An ultrasonic flowmeter is developed for use in natural gas mains. The characteristics of the application and the dynamic head device presently employed are described. The performance requirements, design, and prototype testing of the ultrasonic instrument are discussed. The viability of a unique metering technique using reflected acoustic pulses was experimentally demonstrated. The flowmeter developed herein requires access to one side of the gas line and is self calibrating. It was concluded that continued development will produce a unit suitable for use in commercial service

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

Two-phase slug flow measurement using ultra-sonic techniques in combination with T-Y junctions

The accurate measurement of multiphase flows of oil/water/gas is a critical element of oil exploration and production. Thus, over the last three decades; the development and deployment of in-line multiphase flow metering systems has been a major focus worldwide. Accurate measurement of multiphase flow in the oil and gas industry is difficult because there is a wide range of flow regimes and multiphase meters do not generally perform well under the intermittent slug flow conditions which commonly occur in oil production. This thesis investigates the use of Doppler and cross-correlation ultrasonic measurements made in different high gas void fraction flow, partially separated liquid and gas flows, and homogeneous flow and raw slug flow, to assess the accuracy of measurement in these regimes. This approach has been tested on water/air flows in a 50mm diameter pipe facility. The system employs a partial gas/liquid separation and homogenisation using a T-Y junction configuration. A combination of ultrasonic measurement techniques was used to measure flow velocities and conductivity rings to measure the gas fraction. In the partially separated regime, ultrasonic cross-correlation and conductivity rings are used to measure the liquid flow-rate. In the homogeneous flow, a clamp-on ultrasonic Doppler meter is used to measure the homogeneous velocity and combined with conductivity ring measurements to provide measurement of the liquid and gas flow-rates. The slug flow regime measurements employ the raw Doppler shift data from the ultrasonic Doppler flowmeter, together with the slug flow closure equation and combined with gas fraction obtained by conductivity rings, to determine the liquid and gas flow-rates. Measurements were made with liquid velocities from 1.0m/s to 2.0m/s with gas void fractions up to 60%. Using these techniques the accuracies of the liquid flow-rate measurement in the partially separated, homogeneous and slug regimes were 10%, 10% and 15% respectively. The accuracy of the gas flow-rate in both the homogeneous and raw slug regimes was 10%. The method offers the possibility of further improvement in the accuracy by combining measurement from different regimes

DEVELOPMENT OF INSTRUMENTATION AND CONTROL SYSTEMS FOR AN INTEGRAL LARGE SCALE PRESSURIZED WATER REACTOR

Small and large scale integral light water reactors are being developed to supply electrical power and to meet the needs of process heat, primarily for water desalination. This dissertation research focuses on the instrumentation and control of a large integral inherently safe light water reactor (designated as I2S-LWR) which is being designed as part of a grant by the U.S. Department of Energy Integrated Research Project (IRP). This 969 MWe integral pressurized water reactor (PWR) incorporates as many passive safety features as possible while maintaining competitive costs with current light water reactors. In support of this work, the University of Tennessee has been engaged in research to solve the instrumentation and control challenges posed by such a reactor design. This dissertation is a contribution to this effort. The objectives of this dissertation are to establish the feasibility and conceptual development of instrumentation strategies and control approaches for the I2S-LWR, with consideration to the state of the art of the field. The objectives of this work are accomplished by the completion of the following tasks: Assessment of instrumentation needs and technology gaps associated with the instrumentation of the I2S-LWR for process monitoring and control purposes. Development of dynamic models of a large integral PWR core, micro-channel heat exchangers (MCHX) that are contained within the reactor pressure vessel, and steam flashing drums located external to the containment building. Development and demonstration of control strategies for reactor power regulation, steam flashing drum pressure regulation, and flashing drum water level regulation for steady state and load-following conditions. Simulation, detection, and diagnosis of process anomalies in the I2S-LWR model. This dissertation is innovative and significant in that it reports the first instrumentation and control study of nuclear steam supply by integral pressurized water reactor coupled to an isenthalpic expansion vessel for steam generation. Further, this dissertation addresses the instrumentation and control challenges associated with integral reactors, as well as improvements to inherent safety possible in the instrumentation and control design of integral reactors. The results of analysis and simulation demonstrate the successful development of dynamic modeling, control strategies, and instrumentation for a large integral PWR

Ultrasonic Beam Propagation in Turbulent Flow

This study was conducted to examine the effect of flow turbulence on sound waves propagating across a velocity field. The resulting information can be used to determine the potential for increasing the accuracy of an ultrasonic flowmeter, and understand the data scatter typically seen when using an ultrasonic flowmeter. A modification of the Ray Trace Method was employed which enabled the use of multiple rays in a very fine grid through a flow field. This technique allowed for the computation of the statistical variation of the propagation times for sound pulses traversing a flow field. The statistical variation was studied using two flow fields: 1) a uniform flow field with a superimposed vortex street and 2) an experimentally measured channel flow. The uniform flow field with a superimposed vortex street allowed for the examination of the effects of a large-scale flow structure on sound wave propagation, and for the verification of the analysis technique. Next by using the measured turbulent channel flow, as an example, the statistical variation of sound pulse propagation time was computed for flow likely to be encountered in actual flow measurement situations. Analysis was also conducted to determine the maximum allowable repetition rate of measurements with regard to the optimal time of flight measurements. Both the propagation time of a sound pulse moving across a uniform flow field with superimposed vortex street, and the resultant computed flow were observed to vary at the same frequency of the vortex street. Further, the magnitude of the variations was proportional with the strength of the individual vortices in the vortex street. A sound pulse propagating back and forth across a measured turbulent channel flow, afforded individual time difference variation from the mean propagation time of up to 5%. It was shown that a minimum variation occurred when the sound pulses were transmitted at a 75 degree angle to the flow axis. It was also determined that the average speed of sound in a flow field affected the final flow measurements by decreasing the measured delta time difference between the upstream and downstream propagating sound waves, and therefore the measured flow. The width of the sound path also contributed to decreasing the variation of the individual measurements by integrating over a larger sound path. These findings suggest that turbulence in a flow field affects ultrasonic flowmeter measurements by creating differences in the propagation times of individual sound pulses. Thus, turbulence and large-scale flow structures can result in variations in volumetric flow rate determination made by an ultrasonic flowmeter system

Study of the influence of temperature on the measurement accuracy of transit-time ultrasonic flowmeters

Purpose: The purpose of this study is to deal largely with the influence of temperature variation on the measurement accuracy of transit-time ultrasonic flowmeter. Design/methodology/approach: The causes of measurement error due to temperature are qualitatively and quantitatively analyzed, and a mathematical model is established. The experimental data are processed and analyzed, and the temperature compensation coefficient of flow measurement is obtained. Findings: The experimental results show that the flow measurement results by temperature compensation are helpful in improving the measurement accuracy of the ultrasonic flowmeter. Practical implications: This study has certain application value, which can provide theoretical support for the design of high-precision ultrasonic flowmeters and design guidance. Originality/value: It is worth emphasizing that there are few research studies on the influence factors of temperature. This paper focuses on the influence of the temperature change on the flowmeter that is modeled, and the high precision flow parameter test system is designed based on the established model

Design and Development of a Multi-Nodal Methane Detection System for Longwall Coal Mining

Methane (CH4) explosions pose significant dangers in longwall mining that may lead to injuries and fatalities. Safety is improved through diligent monitoring of CH4 concentration. Currently, regulations require a CH4 monitor be placed on the shearer, downwind of the cutting head. Portable monitor measurements must be taken at various times and locations. If any CH4 monitor measures a concentration greater than 1%, a warning signal must be given. Based on previous research and the location of the CH4 monitor mounted on the shearer (closest monitor to the face), if 1% methane is measured, the concentration at the face may be already be at the lower explosive limit (5%). If any monitor measures a concentration greater than 2%, production is halted. However, there are spatial and temporal gaps in measurements where a dangerous CH4-air mixture may develop and go undetected. This poses a risk of shearers or other work activity igniting these dangerous mixtures. Through funding provided by The Alpha Foundation for the Improvement of Mine Safety and Health, Inc., a multi-nodal Methane Watchdog System (MWS) was developed to improve CH4 monitoring by decreasing the spatial and temporal measurement gaps. The prototype consisted of 10 sampling nodes distributed along the longwall. Each node had a sampling location near the face and gob. The nodes were connected in series and communicated with a central processing hub. Each node consisted of a sealed box which housed sensors and other components. Two CH4 sensors (metal-oxide and infrared) were mounted in a custom sampling block with climate sensors. Two tubes transported gas samples from relevant locations to the sampling block at the node. The units could sample continuously, alternating between each location. The MWS nodes were powered by low voltage DC power common among shields. In addition, a custom water powered ejector was designed to provide the motive sampling force and represented a critical system component. The ejector was designed to provide sampling for a single unit at flowrate of 2 SLPM. Pressurized water, already powering spray nozzles, would provide an inherently explosion proof motive energy source for active sampling. Ideally, water consumption should be minimized while maintaining enough suction force to draw the sample through the unit at the desired flowrate. An initial ejector design was 3D printed and tested to access its performance. During experimental testing, the ejector demonstrated two distinct operational curves (“High” and “Low” pressure), between which it was believed a flow regime transition from bubble to jet flow occurred. Based on a significant increase in performance post-transition, it was recommended that the ejector operate on the “Low” pressure curve. However, this mode did not meet the flowrate requirement. Thus, a multi-nozzle design was developed and tested, demonstrating the same flow transition. The multi-nozzle ejector was also modelled using a computational fluid dynamics (CFD) software. Experimental points were used to verify the CFD model to predict that a scaled version of the multi-nozzle design met the flowrate and suction force requirements with reduced water consumption

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.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Compact Subsea Pipe Separator- Experimental Investigation of Flow Regime in an Inclined Pipe

Master's thesis in Petroleum engineeringThe production of petroleum from well is always accompanied by water production, which causes several problems such as loss of pressure in the production line, environmental pollution, corrosion, and issues in transportation and storage facilities. The oil and water phases need to be separated after the production. However, separation of water and oil at seabed can provide the most efficient way of separating these two phases. An inclined pipe separator can do this job safely and efficiently. The design of the subsea separator and the flow regimes of oil-water are essential for the efficiency of the separator. The test facility was built at the Subsea 7 mechanical base, Dusavik. It consists of a 4 m long 3-inch acrylic horizontal PVC pipe, upward inclinable the 2.5 m long 8-inch IPIP separator, flow rate metering manifold, and high capacity pumping system. The pumping system consists of two centrifugal pumps, both equipped with control systems to have desired rates. Tap water and Exxsol D60 are the working fluids. The tests are performed in three mixture flow rate: 0.3 m/s, 0.5 m/s, and 0.8 m/s. Three pressure transducers are installed in the IPIP separator. Signals from measurement sources are collected and digitized for storage, analysis, and presentation on a personal computer (PC) by the data acquisition system. Flow regimes are determined by visual observation with video recording, and a flow pattern map is made for each condition. According to the experiments and literature study, the flow regimes of oil and water alter from stratified flow to dispersed flow pattern as pipe inclination shifts from horizontal to vertical. Besides, the oil-water flow pattern in pipe behaves as dispersed flow at high mixture velocity (more than 0.8 m/s). Based on the experiments, it is noticeable that the new design of IPIP separator separates more water at the condition of low (0.3 m/s) and medium (0.5 m/s) mixture velocity cases with 90 % water cut. This study has shown that the stratified flow regime of the oil-water mixture in the inlet of IPIP separator has a reasonable effect on the efficiency of the separation.Subsea