experimental study of performance characteristics of turbine meter in oil medium, by onwunyili...

8/6/2019 Experimental Study of Performance Characteristics of Turbine Meter in Oil Medium, By Onwunyili Christian Chime

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FLUID CONTROL RESEARCH INSTITUTE

OIL AND GAS FLOW MEASUREMENT AND CONTROL TECHNIQUES AND STANDARDS

(AUGUST 2 to OCTOBER 30, 2010)

Project Report on

Experimental Study of Performance Characteristics of TurbineMeter in Oil Medium

Prepared by:

1. Onwunyili Christian (NIG)

2. Shungu Alfred George (TAN)3. Khadjikhanov A.A. (UZB)

4. Mustafa Falah (IRQ)

Project Guide:

Mr. P. K. Suresh, FCR, India.


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Mustafa Falah (IRQ)

Acknowledgement

Projects of this kind always receive many different kinds of assistance from many differentpeople. Ours is no exception. We wish to acknowledge a number of these contributions byname, and also give thanks to many others as well.

We owe a special debt of gratitude to FCRI, the institute that made this project possible.

Special recognition is due Mr. P. K. Suresh of FCRI who in his capacity acted as our projectguide and made great deal of contributions to us in the course of this work.

We appreciate the assistance of M. Arun, P. Sudheesh, V. R. Gineesh, Vinod and Fahad of

FCRI Oil Flow Laboratory.Finally, we appreciate the valuable contributions of all staff of FCRI and our variouscolleagues, who in the past 3 months shared knowledge with us, leading to the success of this study.

.ITEC 2010 ProjectGroup

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CONTENTS i

Abstract iiiAcknowledgement iv

List of Figures v

List of Tables v

Chapter One 1

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Introduction 1

1.1 Why Turbine Flowmeter 1

1.2 Aim of the Project 3

CHAPTER TWO 5

The Theory of Turbine Meter 5

2.1 General description of Liquid Turbine Flow Meter 5

2.2 Dynamics of Turbine Flow Meters 8

CHAPTER THREE 13

Practical Considerations 13

3.1 Meter Performance 13

3.2 Performance Indicators 14

3.3 Installation Procedure 15

3.4 Piping Consideration 16

3.5 Strainers/Filters 17

3.6 Flow Straighteners 17

3.7 Signal Conditioners/Converters 18

CHAPTER FOUR 19

Laboratory Test 19

4.1 Equipment Arrangement, Schematic & Operation Sequence 19

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4.2 Equipment Data 22

4.3 Method of Calibration 22

4.4 Results 28

4.4.1 Result for Test 1 28

4.4.2 Sample Calculations 30




4.5 Summary of Result 55

4.6 Discussion of Results and Recommendations 56

4.7 Suggestion for further studies 57

CHAPTER FIVE 58

Conclusion 58

List of FiguresFigure 1. Sectional View of Turbine Meter 5

Figure 2. Signal magnetic pickup coil 8

Figure 3. Velocity Diagram for Turbine Blade 9

Figure 4 Typical Performance Curve of Liquid Turbine Flow meter 15

Figure 5 Schematic Diagram of Oil Flow Laboratory 20

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Figure 6. Set up for Calibration of TFM under normal operating conditions 25

Figure 7. Set up for Calibration of TFM under normal operating conditions 26

Figure 8. Caliberation Curve of TFM for Test 1 29

Figure 9. Caliberation Curve of TFM for Test 3 45

Figure 10. Caliberation Curve of TFM for Test 1 48Figure 11. Caliberation Curve of TFM for Test 1: Extended to non-linear range 50

Figure 12. Caliberation Curve of TFM for Test 1: Extended to non-linear range 52

Figure 13. Caliberation Curve of TFM: Combined Curves 54

List of Tables

Table 1: Datasheet for TFM calibrated under normal operating conditions 27 Table 2: Statistical Calculations 31

Table 3: Calculation of Uncertainty 32

Table 4: Calculation of Flowrates using Best Fit Equation 37

Table 5: Calculation of Uncertainty in Best Fit Equation (F Vs Qa) 39

Table 6: Uncertainty Budget in Flowrate 40

Table 7: Datasheet for TFM calibrated under atypical pressure conditions 42

Table 8: Datasheet for TFM calibrated with a gasket protruding upstream of the meter 43

Table 9: Calculation of Uncertainty for Test 3 44

Table 10: Datasheet for TFM calibrated with upstream straight length pipe reduced to 10D. 46

Table 11: Calculation of Uncertainty in k 47

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Table 12: Test 4 Extended to Non-Linear Range 49

Table 13: Test 3 Extended To Non-Linear Range 51

Table 14: Comparison of Tests Results 53

References 58

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CHAPTER ONE

Introduction

Many factors influence the quality of turbine meter flow measurement. Recognizing these factorsallows a user to optimize the flow measurement performance of a turbine metering system. Inorder to ensure that turbine meters in the field are operating at their best, turbine meteringstations must be properly designed, calibrated, installed, and maintained. This project explains theworking principle of liquid turbine meters and the physical processes that affect the accuracy of turbine metering systems. Laboratory test was carried out using FCRI Oil Test Facilities and theresults are presented here to explain some of these phenomena.

1.1 Why Turbine Flowmeter?

Petroleum products bought and sold on the worldwide market may be transported over thousandsof miles and change ownership many times from the well head to the end user. Each time theproduct changes ownership, a custody transfer is completed and both buyer and seller expecttheir asset share to be accurately measured. The dynamic measurement provided by meters is aconvenient and accurate means to measure valuable petroleum products. Selecting the rightmeter for the job with a high level of confidence is imperative to ensure accurate measurement atthe lowest cost of ownership. Typical petroleum applications where measurement is requiredinclude: production, crude oil transportation, refined products transportation, terminal loading, fueloil tank truck loading and unloading, aviation and lube oil blending. Each of these applications isunique and a specific type of meter may be better suited for each application. Selecting thecorrect meter for a specific measurement task is dependent on the following operating conditions:

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System characteristics Pressure and temperature are typically specified but othercharacteristics such as pulsating flow from a PD pump or valve operation /location should also beconsidered as they may cause measurement errors for some types of meters.

Product characteristics The basic product characteristics of viscosity, specific or API gravity,chemical characteristics and lubricating quality must be specified. Also, any contaminates such asparticulates, air or water contained in the product must be identified and noted in an applicationanalysis.

Flow range This is the minimum and maximum flow rate over which the meter will operate. Theflow range can also be expressed as the turndown range, which is the ratio of the maximum tothe minimum flow rate (e.g., a flow range of 10 bph to 100 bph is a 10:1 turndown range).

Viscosity Range Just as the flow range can be expressed as a turndown range, the maximum to

the minimum viscosity be expressed as a turndown range.Meter Accuracy Requirements and Criteria : Accuracy requirements for the wholesale andretail trade are normally defined by the weights and measures regulations in the country or

jurisdiction in which the sale is conducted. Sales within the petroleum industry that are notnormally defined by weights & measures, but by a contract between the trading parties, areknown as Custody Transfer transactions. A typical contract may define a specific measurementstandard such as one of the American Petroleum Industry (API) Standards. Currently APIrecognizes four types of dynamic measuring devices Positive Displacement (PD) Meters, TurbineMeters, Coriolis Mass Flow Meters (CMFMs) and recently approved Liquid Ultrasonic Flow Meters(LUFMs).Contracts are also based on other recognized standards but all these standards have onething in common they all strive to minimize measurement error for a specific application. Error is defined as the difference between the measured quantity and the true value of the quantity.

The criteria associated with custody transfer and all accurate measurement includes:

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Repeatability the variation of meter factor under stable operating conditions, i.e., constantflow rate, temperature, pressure, and viscosity. The typical requirement is that a meter mustrepeat within +/- 0.05% at 95% confidence level.

Linearity the variation of meter factor over a flow range at constant temperature, pressureand viscosity.

Stability or Reproducibility the variation of meter factor over time. Unlike repeatability runswhere conditions can be kept nearly constant, operating conditions over time may have widervariations. Therefore, it is important that the meter selected have minimum sensitivity tooperational variations to achieve required accuracy.

On-site Verification or proving has always been, and remains, fundamental to custody transfermeasurement. It is the only sure method to determine and correct for both constant and variable

systemic errors.

Turbine Flowmeters (TFMs) have been used extensively for custody transfer of refined petroleumproducts for over 30 years. Significant advantages associated with the use of turbine flowmeters,in lieu of other metering principles, make increased future use inevitable. The TFMs are known fortheir excellent repeatability, higher accuracy, wide operating range, high shock capability, lowpressure loss and wide temperature and pressure limits. Probably the two main advantages of theturbine meter over conventional differential head devices are:

1. The extended and more accurate registration of flow in the low flow range of operation,which results from the registration being proportional to the velocity rather than the velocitysquared.

2. The comparatively low head loss across the meter.

The turbine meter has several advantages over the conventional positive displacement (P.D.)meters. The turbine can handle two to three times the flow of its equivalent size P.D. meter,

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resulting in a cost savings. Second, the turbine, because of its inherent design, can withstandsevere service such as sand, over-ranging, and salt water, with less maintenance and better life.In general, other advantages include a wide range of fluid applications, fast response andconvenient readout for control purposes. Each application must be considered on its own merit,

and economic consideration between the turbine and other metering is a necessity. Depending onthe type of read-out and the control required, the turbine meter system compares favorably withother metering systems. However, where maximum accuracy, wide operating range, repeatability,and convenient control is needed, the turbine meter must receive the primary consideration.

1.2 Aim of the Project

The performance characteristics of TFMs depend greatly on the upstream flow condition, the fluidproperties and the geometrical parameters of the rotor. In other words, meter performance maybe affected by conditions such as: flow rate, viscosity of the liquid, temperature of the liquid,density of the liquid, pressure of the flowing liquid, cleanliness and lubricating qualities of theliquid, foreign material lodged in the meter or flow-conditioning element, changes in mechanicalclearances or blade geometry due to wear or damage, changes in piping, valves, or valve positionsthat affect fluid profile or swirl and conditions of the prover.

It is therefore imperative to study the performance of turbine meter subjected to differentcalibration conditions in order to become familiar with fundamental characteristics and conditionssurrounding the liquid turbine flowmeter in order to better understand its usage.

In this project titled Experimental Study of Performance Characteristics of Turbine Meter in OilMedium, a liquid turbine meter was subjected to varying degrees of upstream disturbance underdifferent flow ranges to determine the effects of resulting swirls and jetting on the itsperformance. The turbine meter was also subjected to different operating pressures to studypressure effects on its performance.

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CHAPTER TWOThe Theory of Turbine Meter

2.1 General description of Liquid Turbine Flow Meter

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Figure 1. Sectional View of Turbine Meter

. It consists of multiple- bladed, free spinning, permeable blade rotor housed in a non magneticstainless steel body. In operation, the rotating blades generate a frequency signal proportional tothe liquid flow rate which is sensed by the magnetic pick up and transferred to the read outindicator

The basic construction of the turbine flowmeter incorporates a bladed turbine rotor installed in aflow tube. The rotor is suspended axially in the direction of flow through the tube. The turbine

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flowmeter is a transducer, which senses the momentum of the flowing stream. The bladed rotorrotates on its axis in proportion to the rate of the liquid flow through the tube.

Turbine Rotation

As the liquid product strikes the front edge of the rotor blades, a low-pressure area is producedbetween the upstream cone and the rotor hub. The blades of the turbine rotor will tend to traveltoward this low-pressure area as a result of this pressure differential across the blades. Thepressure differential (or pressure drop) constitutes the energy expended to produce movement of the rotor. The initial tendency of the rotor is to travel downstream in the form of axial thrust. Butsince the rotor is restrained from excessive downstream movement, the only resulting movementis rotation.Fluid flowing through the meter impacts an angular velocity to the turbine rotor blades,which is directly proportional to the linear velocity of the liquid. The degree of the angular velocityor number of revolutions per minute of the turbine rotor is determined by the angle of the rotor

blades to the flowing stream of the approach velocity.With axial thrust forcing the turbine rotor downstream, the friction resulting from contact betweenthe turbine rotor and the downstream cone would cause excessive wear if there were not somemeans of balancing the turbine rotor on its axis between the upstream and the downstream cone.Bernoulli's Principle states that when flow velocity decreases, the static pressure increases.

Therefore, a high-pressure area exists at the downstream side of the turbine rotor exerting anupstream force on the rotor. As a result, the turbine rotor is hydraulically balanced on its axis.

Signal Output Electrical output is generated using the principle of reluctance. A pickup coil, wrapped around apermanent magnet, is installed on the exterior of the flow tube or the meter body immediatelyadjacent to the perimeter of the rotor (Figure 1). The magnet is the source of the magnetic fluxfield that cuts through the coil. Each blade of the turbine rotor passing in close proximity to thepickup coil causes a deflection in the existing magnetic field. This change in the reluctance of themagnetic circuit generates a voltage pulse within the pickup coil.Each pulse generated represents a discrete amount of volumetric throughput. Dividing the totalnumber of pulses generated by the specific amount of liquid product that passed through the

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turbine flowmeter determines the K-Factor. The K-Factor, expressed in pulses per unit volume,may be used with a factoring totalizer to provide an indication of volumetric throughput directly inengineering units. The totalizer continuously divides the incoming pulses by the K-Factor (ormultiplies them with the inverse of the K-Factor) to provide factored totalization. The frequency of

the pulse output, or number of pulses per unit time, is directly proportional to the rotational rate of the turbine rotor. Therefore, this frequency of the pulse output is proportional to the rate of theflow.

By dividing the pulse rate by the K-Factor, the volumetric throughput per unit time of the rate of flow can be determined. Frequency counters or converters are commonly used to provideinstantaneous flow rate indication. Plotting the electrical signal output versus flow rate providesthe characteristics profile or calibration curves for the turbine flowmeter. Electrical output is alsogenerated using the principle of inductance. A pickup coil is installed on the exterior of the flow

tube immediately adjacent to the perimeter of the turbine rotor. The magnetic source of the fluxfield in this type of output is either the rotor itself or small magnets installed in the rotor. In thecase of the rotor, the material of construction would be nickel or some other easily magnetizedflux field. The results are identical to that of the reluctance principal.

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Figure 2. Signal magnetic pickup coil

2.2 Dynamics of Turbine Flow Meters

There are two approaches described in the current literature for analyzing axial turbineperformance. The first approach describes the fluid driving torque in terms of momentumexchange, while the second describes it in terms of aerodynamic lift via airfoil theory. The formerapproach has the advantage that it readily produces analytical results describing basic operation,some of which have not appeared via airfoil analysis. The latter approach has the advantage that

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it allows more complete descriptions using fewer approximations. However, it is mathematicallyintensive and leads rapidly into computer generated solutions. In the following, we have used themomentum exchange approach to highlight the basic concepts of the axial turbine flowmeter.

Figure 3. Velocity Diagram for TurbineBlade

In a hypothetical situation, where there are no forces acting to slow down the rotor, it will rotate ata speed which exactly maintains the fluid flow velocity vector at the blade surfaces.

When one introduces the total flow rate this becomes:

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where is the 'ideal' rotational speed, Q is the volumetric flow rate, A is the area of the annularflow cross section and is now the root-mean-square of the inner and outer blade radii, (R, a).Eliminating the time dimension from the left hand side quantity reduces it to the number of rotorrotations per unit fluid volume, which is essentially the flowmeter K factor specified by mostmanufacturers. Hence, according to Eq. (2), in the ideal situation the meter response is perfectlylinear and determined only by geometry. (In some flowmeter designs the rotor blades are helicallytwisted to improve efficiency. This is especially true of blades with large radius ratios, (R/a). If theflow velocity profile is assumed to be flat, then the blade angle in this case may be described bytan =constant X r. This is sometimes called the 'ideal' helical blade.) In practice, there areinstead a number of rotor retarding torques of varying relative magnitudes. Under steady flow therotor assumes a speed which satisfies the following equilibrium:

Fluid driving torque = rotor blade surfaces fluid drag torque + rotor hub and tip clearance fluid drag torque + rotation sensor drag torque + bearing friction retarding torque 3

Referring again to figure 3 , the difference between the actual rotor speed, r , and the ideal rotorspeed, , is the rotor slip velocity due to the combined effect of all the rotor retarding torques asdescribed in Eq. (3), and as a result of which the fluid velocity vector is deflected through an exitor swirl angle, . Denoting the radius variable by r , and equating the total rate of change of angular momentum of the fluid passing through the rotor to the retarding torque, one obtains:

which yields:

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where is the fluid density and N T is the total retarding torque. Combining Eqs. (1) and (4) andrearranging, yields:

The trends evident in Eq. (5) reflect the characteristic decline in meter response at very low flowsand why lower friction bearings and lower drag pickups tend to be used in gas versus liquidapplications and small diameter meters. In most flowmeter designs, especially for liquids, thelatter three of the four retarding torques described in Eq. (3) are small under normal operatingconditions compared with the torque due to induced drag across the blade surfaces. As shown infigure 2, the force, F , due to this effect acts in a direction along the blade surface and has amagnitude given by:

where CD is the drag coefficient and S is the blade surface area per side. Using the expression fordrag coefficient corresponding to turbulent flow , this force may be estimated by:

where Re is the flow Reynolds number based on the blade chord shown as dimension c in figure 2.Assuming is small compared with , then after integration, the magnitude of the retardingtorque due to the induced drag along the blade surfaces of a rotor with n blades is found to be:

Combining Eqs. (7) and (5), and rearranging yields:

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Eq. (8) is an approximate expression for K factor because it neglects the effects of several of therotor retarding torques, and a number of important detailed meter design and aerodynamicfactors, such as rotor solidity and flow velocity profile. Nevertheless, it reveals that linearityvariations under normal, specified operating conditions are a function of certain basic geometricfactors and Reynolds number. These results reflect general trends which influence design and

calibration. Additionally, the marked departure from an approximate (actually via Redependence of the fluid drag retarding torque on flow properties under turbulent flow, to otherrelationships under transitional and laminar flow, gives rise to major variations in the K factorversus flow rate and media properties for low flow Reynolds numbers. This is the key reason whyaxial turbine flowmeters are generally recommended for turbulent flow measurement

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CHAPTER THREEPractical Considerations

3.1 Meter Performance

Meter performance is defined by how well a metering system produces, or can be made toproduce, accurate quantity measurement. The overall performance of measurement by a meterdepends on the condition of the meter and its accessories, the temperature and pressurecorrections, the proving system, the frequency of proving, and the variations between operatingand proving conditions. The inherent accuracy of a meter is often published in the manufacturersspecification, and may be expressed as repeatability and/or linearity. In other words, accuracy isbased on how repeatable and how linear the meter can stay within the manufacturersperformance specifications. Manufacturers specifications are based on meter operation withinrecommended flow ranges, within a narrow range of pressures, temperatures, and fluid viscosities.For custody transfer applications, meters with the highest inherent accuracy should be used andshould be proved on site. The meters should operate within the manufacturers specifications. Anexcellent indicator of how well a meter performs is the development of, and history of, its meterfactor from proving the meter. A meter factor obtained for one set of conditions will not

necessarily apply to a changed set of conditions. Meter performance curves can be developedfrom a set of proving results.

The following conditions may affect the meter factor:

a. Flow rate.

b. Viscosity of the liquid.

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d. Density of the liquid.

e. Pressure of the flowing liquid.

f. Cleanliness and lubricating qualities of the liquid.

g. Foreign material lodged in the meter, strainer or flow-conditioning element.

h. Changes in mechanical clearances or internal geometry due to wear or damage.

i. Changes in piping, valves, or valve positions that affect fluid profile or swirl into a turbine meter.

j. Conditions of the prover.

3.2 Performance Indicators Accuracy The accuracy of a turbine flowmeter is derived from its output (electrical or mechanical) and is themeasure of the deviation of an indicated measurement from the referenced standard. Theaccuracy must include the error associated with the calibration standard. In the India, the NationalAccreditation Board for Testing and Calibration Laboratories represents the flow standard.

Linearity is the variation of the flowmeter K-factor from a nominal value of a point on a curve.Normally during calibration, a value is chosen which makes linearity fall in line with accuracy.Linearity may remain constant during meter life although the absolute accuracy level haschanged.

Repeatability is the ability of a turbine flowmeter to reproduce its output indefinitely underconstant operating conditions at any point over its specified operating range.

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Figure 4 Typical Perfomance Curve Of Liquid Turbine Flowmeter

3.3 Installation Procedure

Upon receipt of the turbine flowmeter a visual inspection should be performed checking for anyindications of damage which may have occurred during shipment. Inspect all packing material

carefully to prevent the loss of meter parts or auxiliary components which may have been packedwith the shipment. The meter housing is marked by a flow direction arrow and the inlet is markedIN and the outlet is marked OUT. The meter must be installed in the piping in the correctorientation to ensure the most accurate and reliable operation. Care should be taken in the properselection of the mating fittings. Size, type of material, and pressure rating should be the same asthe flowmeter supplied. The correct gaskets and bolts should be utilized. The flowmeter may beinstalled horizontally or vertically for liquid service without affecting the meter calibration. When itis expected that flow will be intermittent, the meter should not be mounted at a low point in the

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piping system. Solids which settle or congeal in the meter may affect meter performance. In orderto achieve optimum electrical signal output from the flowmeter, due consideration must be givento its isolation from ambient electrical interference such as nearby motors, transformers, andsolenoids.

3.4 Piping Consideration

As stated in the Principle of Flowmeter Operation, the fluid moving through the flowmeter engagesthe vaned rotor. Swirl present in the fluid ahead of the meter can change the effective angle of engagement and, therefore, cause a deviation from the supplied calibration (performed undercontrolled flow conditions). Turbine meters are constructed with flow straighteners to minimize theeffects of fluid swirl and non-uniform velocity profiles is adequate for most installations. However,it is good practice to maintain a minimum straight run of pipe approximately 10 pipe diameters

ahead of the inlet and 5 pipe diameters following the outlet. Proper installation of the flowmeterminimizes the negative effects of fluid swirl.

Blocking and Bypass valves should be installed if it is necessary to do preventive maintenance onthe flowmeter without shutting down the flow system. The Bypass valve can be opened before theBlocking valves allowing the flow to continue while removing the turbine flowmeter for service.

All flow lines should be purged prior to installing the meter.To prevent possible damage to themeter, install the meter ONLY in flow lines that are clean and free of debris.

Upon initial start-up of the system a spool piece should be installed in place of the flowmeter sothat purging of the system can be performed to remove all particle debris which could causedamage to the meter internals. In applications where meter flushing is required after meterservice, care should be taken as to not overspeed the meter, as severe meter damage may occur.

Avoid over-spinning the meter. Over-spinning the meter may cause damage to the meter internals and lead to needless

meter failure.

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To maintain an accurate flow measurement it is necessary to maintain a downstream pressuresufficient to prevent flashing/cavitation. Flashing of the liquid will result in an indication of flowsignificantly higher than the actual flow. In order to eliminate this condition adequate downstreampressure must be maintained. The minimum required downstream pressure may be calculated

using the following equation:

Minimum Pressure =(2 x Pressure Drop) + (1.25 x Vapor Pressure)

Downstream pressure may be maintained by a downstream valve that provides the necessarydownstream pressure to prevent flashing/cavitation in the metering run.

3.5 Strainers/Filters Turbine flowmeters are designed for use in a clean fluid service. However, the service fluid may

carry some particulate material which would need to be removed before reaching the flowmeter.Under these conditions a strainer/filter may be required to reduce the potential hazard of foulingor damage that may be caused by foreign matter.If a strainer/filter is required in the system, it should be located upstream of the flowmeter takingcare that the proper minimum distance is kept between the strainer and flowmeter.

3.6 Flow StraightenersProper application of the Turbine Flowmeter requires a suitable piping section to achieve optimumaccuracy. While an inlet straight pipe run of 10 pipe diameters and an outlet straight pipe run of 5pipe diameters provide the necessary flow conditioning in general, some applications require anupstream flow straightener. This consists of a section of piping that contains a suitablydimensioned and positioned thin walled tube cluster to eliminate fluid swirl. The term swirl is usedto describe the rotational velocity or tangential velocity component of fluid flow in a pipe or tube.Depending on its degree and direction, swirl will change the angle of attack between the fluid andthe turbine rotor blades, causing a different rotor speed at a constant flow rate to non-swirlingconditions at the same flow rate. Liquid swirl and non-uniform velocity profiles may be introducedupstream of the turbine flowmeter by variations in piping configurations or projections and

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protrusions within the piping. Swirl may be effectively reduced or eliminated through the use of sufficient lengths of straight pipe or a combination of straight pipe and straightening vanesinstalled upstream of the turbine flowmeter.

3.7 Signal Conditioners/ConvertersConsideration should be given to properly interface the turbine flowmeter output to the hostelectronics. If the system is installed in an electrically noisy area or if the distance from the turbineflowmeter to the host electronics exceeds 500 feet, a signal conditioner may be necessary. SignalConditioners for the turbine flowmeter provide amplification, filtering, and wave shaping of the lowlevel flowmeter pickup signal and generate a high level pulse output signal suitable fortransmission to a remote host system through a noisy environment. The conditioned pulse outputsignal may be transmitted several thousand feet.

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CHAPTER FOUR

Laboratory Test

4.1 Equipment Arrangement, Schematic & Operation Sequence

The tests were conducted at FCRI Oil Flow Calibration Laboratory. The layout of the laboratory isshown as figure 4. It consists of a flow source (centrifugal pumps), flow conditioners, pipe lines,test section for the Meter-Under-Test installation, valves for changing the flow, collection tanks,weigh scales, and a timer. The facility is located above an oil reservoir that has a capacity of

approximately 600 m3

. Oil flow is produced and maintained in the system by a total of four pumps:three variable velocity pumps and one constant velocity pump. One of the variable velocity pumpsis driven by 120Hp electric motor while each of the other pumps is driven by 50 Hp electricmotors. Maximum of three pumps is put in use at a time. A manifold splits the flow into threeseparate test section pipelines and a bypass of 8 diameter, with a maximum line size of 200mm.Downstream of the manifold, each pipeline has a flow conditioner that delivers a symmetric, fullydeveloped turbulent velocity profile to the flow meter in the test section.

Flow at the test section is controlled by some sets of valves. One set is located upstream near thepump, a main valve for each pipeline and a bypass throttle valve that controls the amount of oilreturned to the reservoir without passing through the meter test section. The other valves on eachpipeline (located downstream of the test section) are the fine and coarse controls for setting theoil flow rate and the pressure in the test section of the OFCF.

The facility makes use of static gravimetric calibration system for measurement and thecalibration is performed by "Standing start and stop" method. All measurements made at FCRI aretraceable to Indian National Standards.

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The medium of flow is EXXSOL D80, with a kinematic viscosity of 2.06 Centistokes at 25 0C and aspecific gravity of 0.78. It is also possible to change the medium of calibration to either Hydrol 100or Hydrol 220 for flow rates up to 100 m3/h (450 GPM). The kinematic viscosity of Hydrol 100 andHydrol 220 are 100 centistokes and 200 centistokes respectively at 40 0C. This multi viscous

facility can be used to generate "Universal viscosity curves" for turbine flow meters up to 4 " NB.

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H

H

HCP

6"

6"6"

6"

HCP

H

H

6"

6"

HCP

H

H

3"

LCP

H

H

HH

H H

4"

8"

M

M H

H

H

H H

HH

H

H

8"

8"

D R A I N

B Y

- P A S S

FILTER

8"

4"

(200mm)

(TEST LINES)

(100mm)

8"

4"

STEELYARD

2TON

WEIGHINGTANK

ON/OFFVALVE

4"

4"

8"

8"

4"

6"

VALVEON/OFF10TON

WEIGHING TANK

STEELYARD

RESERVOIR

(30 m )3

BELLMOUTHENTRY

4"

6"

8" 8"

6"

4"

TFM

TFM

8"8"8"

3"

12" 12"

8"

8"

- GATE VALVE; - CON TROL VALVE; - CHECK VALVE; H - MANUAL ACTUATOR; - PIST ON A CTUATOR; M - ROTARY MOTOR ACTUATOR;

TFM - TURBINE FLOWMETER; LCP - LOW CAPACITY PUMP (50m^3 /h,5bar);HIGH CAPACITY PUMP (200 m^3 /h, 5bar)

Schematic layout of Oil flow laboratory

8"

Densitometer

Reservoir for

200 cSt/100 cSt oil

4"

H H

H

H

H

H

Figure 5

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4.2 Equipment Data

Details of Flow Meter under Test

FLOW ELEMENT : Turbine flowmeterSIZE : 2' ' NBMODEL : HO-2X2-15-225-B-2M-F2SS

TAG NUMBER : 20307MAKE : Hoffer FlowFLOW RANGE : 10 60 m 3 /hrMEDIUM OF CALIBRATION : EXXSOL D80DATE OF CALIBRATION : 27.09.2010

Specification of Reference Instrumentsused

InstrumentRange

Uncertainty

CalibrationDue

Readability

Weighingsystem 300 kg

7.60E-03

kg 13.11.2010

0.001000

Timer 1000 sec9.61E-04 sec 05.05.2010

0.000010

DensitoMeter 1000 kg/m^3 1.00E-01 kg/m^3 07.09.2011 0.010000

Pulse counter10000 Hz

1.40E-03 Hz 18.11.2010

0.000010

Temperature20 -50 C

2.00E-01 C 20.05.2010

0.010000

Pressure gauge 10.0 bar5.80E-02 bar 07.05.2010

1.000000

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4.3 Method of Calibration

Test 1 : Caliberation of 2 Hoffer Flow Turbine Flow Meter (TFM) under normal operating conditions

Installation Conditions : 20D Length of straight pipe upstream of TFM, 10D Length of straightpipe downstream of TFM, with Flow Straightener.

Operating Pressure : 2bar (200kPa)

Test Set-up : The Turbine Flow Meter under test was installed in the standard test line of FCRI OilFlow Laboratory using suitable reducers and expanders as shown in Fig 6 . The meter was providedwith suitable straight-lengths upstream and downstream to ensure uniform flow. Standing startand stop method was employed for the calibration. A universal Counter was used to determinethe time of collection of oil. The upstream pressure of the meter was measured using a precisionpressure gauge. The density of the working fluid was determined using an Online Densitometer.

Procedure : The oil flow line was flooded and the entrapped air cleared using air bleeds. TheON/OFF valve in the system was kept open and the flow through the TFM was adjusted to therequired flow rate by controlling the electrically/manually operated control valve. As soon as theflow rate was adjusted as per the requirement, the ON/OFF valve was closed. The initial mass of the weighing tank was determined as W1.

Then the ON/OFF valve was opened to allow flow through the meter. After collecting a sufficientquantity of oil in the tank, at sufficient time, the ON/OFF valve was closed and final mass of theweighing tank recorded. The readings of the pulse counter, Online Densitometer, Online

Temperature Indicator and Universal Counter were also recorded.

This procedure was repeated for other flow rates covering the entire range of 10-60m 3/hr, andtests were carried out two times for a particular flow rate.

24


33/73

NB: As per ISO 4185-1980 section 4.1, in order to eliminate the effect of residual liquid likely tohave remained in the bottom of the weighing tank or adhering to the walls, a sufficient quantity of liquid was first discharged into the tank (or left at the end of draining after the precedingmeasurement) to reach the operational threshold of the weighing machine

The results of this test is depicted in Table 1.

Test 2 : Calibration of 2 Hoffer Flow Turbine Flow Meter (TFM) under atypical pressure conditions.

Installation Conditions : 20D Length of straight pipe upstream of TFM, 10D Length of straightpipe downstream of TFM, without Flow Straighteners.

Operating Pressure : 1.5bar (150kPa) and 3.6bar (360kPa)

Test Set-up : The test set-up is the same as that of Test 1. However, this test was carried out at

an operating pressure of 1.5 bar and then 3.6bar instead of at 2bar which is the normal operatingcondition.

Procedure : Same as Test 1

The results of Test 2 is depicted in Table 7.

Test 3 : Calibration of 2 Hoffer Flow Turbine Flow Meter (TFM) with a gasket protruding upstreamof the meter.

Installation Conditions : 20D Length of straight pipe upstream of TFM, 10D Length of straightpipe downstream of TFM, Gasket protruding upstream of TFM, without Flow Straighteners.


Test Set-up : The test set-up is the same as that of Test 1 but with a gasket made to protrude intothe liquid stream upstream of the TFM . The test was carried without a Flow straightener.

25


34/73


The result of Test 3 is depicted in Table 8.

Test 4 : Calibration of 2 Hoffer Flow Turbine Flow Meter (TFM) with upstream straight length pipereduced to 10D.

Installation Conditions : 10D Length of straight pipe upstream of TFM, 10D Length of straightpipe downstream of TFM, without Flow Straighteners.


Test Set-up : The test set-up is the same as that of Test 1. However, the length of straight pipeupstream of TFM was reduced to 10D and suitable reducers and expanders used as shown in Fig 7 .

The Flow straightener was also removed.


The result of Test 4 is depicted in Table 10.

26


35/73

WEIGHING

TANK GV GV

RTD - RESISTANCE TEMP. DETECTOR

CV - CONTROL VALVE

GV - GATE VALVE

R,E - REDUCER/EXPANDER

Turbine flow meter(Under calibration)

4"

PUMP

2TON

F R O M

R E S E R V O I R

M

M

CV

R

GOOSE NECK ASSY. M - MANIFOLD

ON/OFF

Ref TFM

ON/OFF VALVEON/OFF -

RTD RTD

6"8

4"

Ref TFM - REFERENCE TURBINE FLOW METER

30kg weighing system

Container

ON/OFF

CV

Filter

>20D>10D

Figure 6. Set up for Calibration of TFM under normal operating conditions

27


36/73

TANK

2TON

WEIGHING

Container

30kg weighing system

M

CV

CV

ON/OFF

ON/OFF

GV

RTD

4"

8

R

6"

GOOSE NECK ASSY.

F R O M

R E S E R V O I R

PUMP

>10D

(Under calibration)Turbine flow meter

>10D

GV

RTD M

4"

Ref TFM - REFERENCE TURBINE FLOW METER

R,E - REDUCER/EXPANDER

RTD - RESISTANCE TEMP. DETECTOR

Filter

Ref TFM

M - MANIFOLD

GV - GATE VALVE

ON/OFF VALVE

CV - CONTROL VALVE

ON/OFF -

4.4 Results

Figure 7. Set up for Calibration of TFM with 10D upstream straight length pipe

28


37/73

4.4.1 Result for Test 1

Table 1: Datasheet for 2 Hoffer Flow Turbine Flow Meter (TFM) calibrated under normaloperating conditions.

FLOW ELEMENT : Turbine flowmeter

SIZE :2''NB

MODEL HO-2X2-15-225-B-2M-F2SS TAG NUMBER : 20307MAKE : Hoffer Flow

FLOW RANGE :10-60

m^3/hr

MEDIUM OFCALIBRATION : EXXSOL D80DATE OF CALIBRATION : 27.09.2010

Sl.Pup W 1 W 2 t T

Density Qa Va N K F

No.

kPa kg kg sec.

deg.C kg/m 3

m^3/hr litres

pulses p/litre Hz.

1200

141.05 767.20

75.433331

28.35

786.09

38.067 797.637

30782

38.5915 408.07

2200

117.25 721.30

73.302593

28.49

785.99

37.795 769.583

29696

38.5872 405.12

3200 98.45

1049.10

73.785164

28.47

786.01

59.092 1211.133

46869

38.6985 635.21

4200

151.65

1105.05

73.955660

28.53

785.96

59.130 1214.714

47010

38.7005 635.65

29


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5200

106.00 916.00

122.372512

29.05

785.59

30.374 1032.496

40015

38.7556 326.99

6200

186.70 821.65

96.193456

29.09

785.58

30.290 809.373

31191

38.5373 324.25

7 200 113.10 607.25 161.073050 29.33 785.40 14.081 630.039 24286 38.5468 150.78

8200

105.30 603.95

163.094777

29.38

785.37

14.034 635.800

24503

38.5388 150.24

Average K-Factor =

38.6195 ppl

Linearity(%) =0.2827 %

Repeatability(%) = 0.0060 %

30


39/7365 000

70.000


40/73

T = 29.05 deg.C = 785.59 kg/m 3

N = 40015 pulses

Buoyancy Correction Factor, B =1 + = 1 + a (1/ o-1/ m )

= 1+ 1.128((1/ 785.59)-(1/ 8000))

1.001381

Flow rate: Qa = (W2-W1) X B X 3600X1000/(t X o)

= (926-106) x1.001381x3600x1000/ (122.372512x785.59)

= 30374.354 lph

Volume in liters, Va = (W2-W1) X B X 1000 / o

= (926-106) x1.001381x1000/ 785.59

=1032.496 ltrs.

Frequency, F = N / t

= 40015/122.37251

= 326.99 Hz

K Factor k = N/Va


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= 0.283%

Repeatability= n-1 x 100 / y m x n1/2

The repeatability was determined for the operating range as

= 0.086 x100/ 38.6195 x 8 1/2

= 0.1573 %

Table 2: Statistical Calculations:From Sl. No. 5 of Table1.

Pup 200 kPaW1 106.000 kg

W2 916.000 kgtime 122.372512 secTemperature 29.05 deg C

Density 785.59kg/m^3

N 40015 pulseK-factor 38.756 p/litre

Error no. of points 8erlp(x) 0.0449 p/litre


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Calculation of Uncertainty in k-factorIf we denote Qa as x and K as y then from Table 1 we have:

x y xy x^2(y-A-

Bx)^238.067 38.591 1469.048 1.449E+03 1.34E-0337.795 38.587 1458.415 1.428E+03 1.61E-0359.092 38.698 2286.752 3.492E+03 1.44E-0559.130 38.700 2288.344 3.496E+03 3.22E-0530.374 38.756 1177.176 9.226E+02 2.31E-0230.290 38.537 1167.310 9.175E+02 4.38E-0314.081 38.547 542.795 1.983E+02 2.80E-0514.034 38.539 540.856 1.970E+02 1.73E-04

282.863454 308.956071 10930.696795 12101.035521 0.03064 1


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44/73

= 38.5075

Sy= [(y-A-Bx)^2/(n-1)]^0.5= ( 0.030641 /6)^0.5

= 0.071462

Sxx = x 2 nXm 2

= 12101-(8*35.362

)= 2100

erl(x) = Sy[(1/n)+((Xi-Xm)^2/Sxx)]^0.5

= 0.0715[(1/8)+(( 30.374 -35.36)^2/2100)]^0.5

= 0.02643 p/litreStandard Uncertainty of best fit, U s = Maximum value of erl(x i) for i =1 to n

UNCERTAINTY BUDGET

In order to evaluate the Expanded Uncertainty,U E, we need to calculatethe partial derivaties of our calculated quantities Q and k (Sensitivity


45/73

Q/ Q = 1

K/ N=1/(Q*t)= 2.69*10-7

K/ K = 1

The result is tabulated as follows :


46/73

UNCERTAINTY BUDGET

Source of uncertaintyEstimates * Xi Unit

Limits

Divisor

ProbabilityDistribu

tionType A

or B

Standard

uncertainty

Partialderivat

ive

Sensitivity

Coefficient

Uncertnty

contrition

air 1.128kg/m3

4.74E-04 2.000

Type B,Normal 2.37E-04 dQ/dair

9.6721E-06

2.292

wt 8000kg/m3

4.00E-01 2.000

Type B,Normal 2.00E-01 dQ/dwt

1.4850E-10

2.970

oil 785.590kg/m3

1.57E-01 2.000

Type B,Normal 7.86E-02 dQ/doil

-1.0755E-

05-8.448

Readability 0.001kg/m3

5.00E-04 1.225

Type B,Rtglr 4.08E-04 dQ/doil

-1.0755E-

05-4.389

W(Mass) 810.00 kg.7.60E-03 1.414

Type B,Normal 5.37E-03 dQ/dW

1.0416E-05

5.598

Readability 0.0010 kg5.00E-04 1.225

Type B,Rtglr 4.08E-04 dQ/dW

1.0416E-05

4.251

time122.372

5 sec9.61E-04 2.000

Type B,Normal 4.81E-04 dQ/dt

-6.8942E-

05-3.312

Readability 1.00E-05

sec 5.00E-06

1.732 Type B,Rtglr

2.89E-06 dQ/dt -6.8942E-

-1.990


47/73


48/73

Table. 4 : Calculation of Flowrate using Best Fit Equation

Sl F Qa (lph)No. Hz y =92.922x+90.493

1 225.00 20997.9432 325.00 30290.1433 425.00 39582.3434 525.00 48874.5435 625.00 58166.7436 725.00 67458.9437 825.00 76751.1438 925.00 86043.3439 1025.00 95335.543

10 1125.00 104627.743

11 1225.00 113919.94312 1325.00 123212.14313 1425.00 132504.34314 1525.00 141796.54315 1625.00 151088.74316 1725.00 160380.94317 1825.00 169673.143


49/73

Sl F Qa erl(x)

No. Hz. lph lph

1 408.069 38066.651 22.667762 405.115 37795.351 22.609643 635.209 59091.550 39.707084 635.651 59129.626 39.753965 326.993 30374.354 23.364126 324.253 30290.429 23.468017 150.776 14081.433 36.905698 150.238 14034.059 36.96067x m y m n

379.5381 35357.932 8Sy Sxx A B

63.27244 243157.7 90.4929 92.9220 Standard Uncertainty of best fit, U s = 39.754 lphExpanded Uncertainty U E = 100.180 lph

Table. 6 : Uncertainty

41


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Budget in Flowrate

UNCERTAINTY

BUDGET

Sourceof

uncertainty

Estimates * Xi Unit Limits

Divisor

Probability

Distribution Type

A or B

Standard

uncertainty

Partialderivat

ive

Sensitivity

Coefficient

Uncertainty

contribution

Degreof

Freedm

air 1.128kg/m3

4.74E-04 2.000

Type B,Normal 2.37E-04 dQ/dair

9.6721E-06

2.2923E-09

wt 8000 kg/m3 4.00E-01 2.000 Type B,Normal 2.00E-01 dQ/dwt 1.4850E-10 2.9701E-11

oil 785.590kg/m3

1.57E-01 2.000

Type B,Normal 7.86E-02 dQ/doil

-1.0755E-

05-8.4487E-

07

Readability 0.001

kg/m3

5.00E-04 1.225

Type B,Rtglr 4.08E-04 dQ/doil

-1.0755E-

05-4.3898E-

09

W(Mass) 810.00 kg.

7.60E-

03 1.414

Type B,

Normal 5.37E-03 dQ/dW

1.0416E-

05

5.5982E-

08Readability 0.00 kg

5.00E-04 1.225

Type B,Rtglr 4.08E-04 dQ/dW

1.0416E-05

4.2514E-09

time122.3725

1 sec9.61E-

04 2.000 Type B,Normal 4.81E-04 dQ/dt

-6.8942E-

05-3.3127E-

08Readability

1.00E-05 sec 5.00E-06

1.732 Type B,Rtglr

2.89E-06 dQ/dt -6.8942E-

-1.9901E-10

42


51/73

05

Q 8.44E-03m^3/s

8.4739E-07

Flowrate

30374.35

36lph - -

Type A

3.98E+0

1

1.00E+0

0

3.9754E+

016

Combined standarduncertainty = 39.754 lph

Effective Degree of freedom = 6

(Calculated Value)From the student's distribution table, forconfidence level of 95.45and above said effective degrees of

freedom,the coverage factor, k = 2.520

Expanded uncertainty U E = 100.180 lph

43


52/73


Table 7: Datasheet for 2 Hoffer Flow Turbine Flow Meter (TFM) calibrated under atypicalpressure conditions.

Sl.Pup W 1 W 2 t T

Density Qa Va N K F

No.

kPa kg kg sec.

deg.C kg/m 3

m^3/hr litres

pulses p/litre Hz.

1

15

0

169.1

5

1046.9

5

136.5722

72

29.5

5

785.2

5

29.50

7 1119.404

4498

9

40.19

01 329.42

2150

175.25 832.85

107.366249

29.35

785.39

28.113 838.447

34652

41.3288 322.75

3150

214.50

1017.35

136.655832

29.62

785.21

26.973 1023.877

41896

40.9190 306.58

4150

187.15 877.30

81.113669

29.34

785.39

39.054 879.949

34523

39.2330 425.61

5150

171.65

1034.00

101.313537

29.40

785.36

39.071 1099.548

43110

39.2070 425.51

6 360 149.30 929.15 131.983376 29.92 785.02 27.134 994.786 40732 40.9455 308.61

7360

161.00 986.60

149.944071

30.07

784.91

25.288 1053.293

43280

41.0902 288.64

8360

170.35

1025.00

96.769632

30.23

784.80

40.569 1090.507

42929

39.3661 443.62

9 36 146.0 1032.5 99.93087 30.3 784.7 40.75 1131.219 4443 39.28 444.69


53/73

0 0 0 4 1 5 2 8 33

Average K-Factor =

40.1737 ppl

Linearity(%) = 2.6407 %

Repeatability(%) =

1.0909 %


Table 8: Datasheet for 2 Hoffer Flow Turbine Flow Meter (TFM) calibrated with a gasketprotruding upstream of the meter.

Sl.

Pu

p W 1 W 2 t T

Densi

ty Qa Va N K FNo.

kPa kg kg sec.

deg.C kg/m 3

m^3/hr litres

pulses p/litre Hz.

1200

159.30

1062.80

69.925897

29.83

784.97

59.339 1152.589

44415

38.5350 635.17

2200

126.50

1066.35

72.753034

29.84

784.97

59.328 1198.960

46203

38.5359 635.07

45


54/73

3200

101.85

1047.00

140.308421

29.86

784.96

30.937 1205.737

46393

38.4769 330.65

4200

137.85

1057.15

135.308921

29.89

784.93

31.203 1172.805

45155

38.5017 333.72

5200

152.45

1077.40

106.268950

29.93

784.91

39.975 1180.043

45478

38.5393 427.95

6200

135.80

1141.55

114.394590

29.92

784.91

40.380 1283.127

48897

38.1077 427.44

7200

140.50

1057.95

105.391263

29.93

784.90

39.982 1170.489

44906

38.3652 426.09

8200 81.70 961.45

195.117245

29.98

784.87

20.709 1122.434

43173

38.4637 221.27

9200

147.30 985.75

183.335218

29.99

784.87

21.006 1069.741

41105

38.4252 224.21

10200

194.95 793.60

161.959568

30.15

784.75

16.980 763.908

29369

38.4457 181.34

Average K-Factor =

38.4396 ppl

Linearity(%) =0.5614 %

Repeatability(%) =

0.1502 %

Table. 9 : Calculation of Uncertainty for46


55/73

Test 3

Sl Qa K erl(x)

No.

m^3/h

r p/litre p/litre1 59.339 38.535 0.082712 59.328 38.536 0.082683 30.937 38.477 0.045554 31.203 38.502 0.045295 39.975 38.539 0.044586 40.380 38.108 0.044937 39.982 38.365 0.044598 20.709 38.464 0.063099 21.006 38.425 0.06243

10 16.980 38.446 0.07178x m y m n

35.9839 38.440 10Sy Sxx A B

0.13570 2008.8 3.840E+01 1.176E-03

Standard Uncertainty of best fit, U s = 0.0827 p/litreExpanded Uncertainty U E = 0.2152 p/litre

47


56/73

65.000

70.000


48


57/73

Table 10: Datasheet for 2 Hoffer Flow Turbine Flow Meter (TFM) calibrated with upstreamstraight length pipe reduced to 10D.

Sl.Pup W 1 W 2 t T

Density Qa Va N K F

No.

kPa kg kg sec.

deg.C kg/m 3

m^3/hr litres

pulses p/litre Hz.

1200

120.95

1078.50

73.501459

28.61

785.94

59.756 1220.033

47178

38.6695 641.86

2200

128.90

1023.20

68.789303

28.63

785.91

59.634 1139.488

44101

38.7025 641.10

3200

138.80

1069.90

84.792177

28.73

785.84

50.374 1186.483

45824

38.6217 540.43

4200

119.70

1036.60

83.514346

28.78

785.80

50.368 1168.448

45115

38.6111 540.21

5200 70.20 932.80

102.845745

28.94

785.68

38.484 1099.419

42497

38.6541 413.21

6200

160.40

1026.70

103.322692

28.99

785.65

38.472 1104.177

42577

38.5600 412.08

7200

128.95

1026.55

135.560566

29.07

785.59

30.385 1144.159

44048

38.4982 324.93

8

20

0

140.1

0

1020.9

5

133.5461

94

29.1

3

785.5

5

30.26

9 1122.865

4321

3

38.48

46 323.58

9200

158.30 624.20

99.977322

29.33

785.40

21.390 594.020

22903

38.5559 229.08

10200

365.85 813.60

95.360258

29.39

785.37

21.552 570.901

21997

38.5303 230.67

13200

156.60 505.35

107.435806

29.58

785.23

14.903 444.751

17142

38.5429 159.56

49


58/73

14200

208.50 513.45

99.322439

29.62

785.20

14.096 388.909

14985

38.5309 150.87

Average K-Factor =

38.5801 ppl

Linearity(%) = 0.282 %

Repeatability(%) =

0.0329 %

50


59/73

Table. 11 : Calculation of Uncertainty in k

Sl Qa K erl(x)

No.m^3/h

r p/litre p/litre1 59.756 38.669 0.023262 59.634 38.702 0.023183 50.374 38.622 0.017404 50.368 38.611 0.017405 38.484 38.654 0.012946 38.472 38.560 0.012947 30.385 38.498 0.013498 30.269 38.485 0.013539 21.390 38.556 0.01732

10 21.552 38.530 0.0172313 14.903 38.543 0.0212414 14.096 38.531 0.02177x m y m n

35.8068 38.580 12Sy Sxx A B

0.04419 2959.2 3.846E+01 3.424E-03 Standard Uncertainty of best fit, U s = 0.0233 p/litre


60/73

Expanded Uncertainty U E = 0.1370 p/litre

52


61/73

65.000

70.000

Table 12: TEST 4 EXTENDED TO NON-LINEAR RANGE53


62/73

Sl. Pup W 1 W 2 t TDens

ity Qa Va N K FNo. kPa kg kg sec.

deg.C kg/m 3

m^3/hr litres

pulses p/litre Hz.

1 200120.9

51078.5

073.50145

928.6

1785.9

459.75

61220.0

334717

838.66

95 641.86

2 200128.9

01023.2

068.78930

328.6

3785.9

159.63

41139.4

884410

138.70

25 641.10

3 200138.8

01069.9

084.79217

728.7

3785.8

450.37

41186.4

834582

438.62

17 540.43

4 200119.7

01036.6

083.51434

628.7

8785.8

050.36

81168.4

484511

538.61

11 540.21

5 200 70.20 932.80102.8457

4528.9

4785.6

838.48

41099.4

194249

738.65

41 413.21

6 200160.4

01026.7

0103.3226

9228.9

9785.6

538.47

21104.1

774257

738.56

00 412.08

7 200128.9

51026.5

5135.5605

6629.0

7785.5

930.38

51144.1

594404

838.49

82 324.93

8 200140.1

01020.9

5133.5461

9429.1

3785.5

530.26

91122.8

654321

338.48

46 323.58

9 200158.3

0 624.2099.97732

229.3

3785.4

021.39

0594.02

02290

338.55

59 229.08

10 200365.8

5 813.6095.36025

829.3

9785.3

721.55

2570.90

12199

738.53

03 230.67

11 200119.7

5 400.40226.1572

7429.4

0785.3

6 5.696357.84

61484

941.49

56 65.66

12 200278.3

5 502.50186.5694

6229.4

7785.3

1 5.515285.82

31259

044.04

83 67.4813 200 156.6 505.35 107.4358 29.5 785.2 14.90 444.75 1714 38.54 159.56

54


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0 06 8 3 3 1 2 29

14 200208.5

0 513.4599.32243

929.6

2785.2

014.09

6388.90

91498

538.53

09 150.87

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Sl. Pup W 1 W 2 t TDens

ity Qa Va N K FNo. kPa kg kg sec.

deg.C kg/m 3

m^3/hr litres

pulses p/litre Hz.

1 200159.3

01062.8

069.92589

729.8

3784.9

759.33

91152.5

894441

538.53

50 635.17

2 200126.5

01066.3

572.75303

429.8

4784.9

759.32

81198.9

604620

338.53

59 635.07

3 200101.8

51047.0

0140.3084

2129.8

6784.9

630.93

71205.7

374639

338.47

69 330.65

4 200137.8

51057.1

5135.3089

2129.8

9784.9

331.20

31172.8

054515

538.50

17 333.72

5 200152.4

51077.4

0106.2689

5029.9

3784.9

139.97

51180.0

434547

838.53

93 427.95

6 200135.8

01141.5

5114.3945

9029.9

2784.9

140.38

01283.1

274889

738.10

77 427.44

8 200140.5

01057.9

5105.3912

6329.9

3784.9

039.98

21170.4

894490

638.36

52 426.09

9 200 81.70 961.45195.1172

4529.9

8784.8

720.70

91122.4

344317

338.46

37 221.27

10 200147.3

0 985.75183.3352

1829.9

9784.8

721.00

61069.7

414110

538.42

52 224.21

11 200 0.00 442.40416.3198

1129.9

1784.9

2 4.881564.40

37715

8136.7

07 185.33

12 200194.9

5 793.60161.9595

6830.1

5784.7

516.98

0763.90

82936

938.44

57 181.34

13 200107.9

5 405.20199.1799

7629.9

6784.8

1 6.855379.27

72341

161.72

53 117.5414 200 251.0 666.70 215.3579 29.9 784.8 8.866 530.36 2433 45.87 112.99

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0 40 8 8 7 3 96

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4.5 Summary of Result

Table 14: Comparison of Tests Results

TEST K-Average

(ppl)

K @Q nom

(ppl)

Linearity

%

Repeatability

%

StandardUncertaintyof best fit,U s

ExpandedUncertainty U E

1 38.619

5

38.62 0.282

7

0.0060 0.0449 0.1356

2.i [@1.5bar]

40.1737

40.1737

2.6406

1.0719 N/A N/A

2.i [@3.6bar]

40.1756

40.1756

2.2490

1.0909 N/A N/A

3 38.4396

38.3981

0.5614

0.1502 0.0827 0.2152

4 38.5801

38.5492

0.282 0.0329 0.0233 0.1370

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4.6 Discussion of Results and Recommendations

Careful analysis of the tests results reveals the following Within the linear range under different operating conditions, the meter factor curves werefairly linear and repeatable, especially for Test 1 which was conducted according tostandard/manufacturers recommendations

At the low end of the flow rate range the meter factor curves become less linear and lessrepeatable than they are at the medium and higher rates

If a plot of meter factor versus flow rate has been developed for a particular liquid, and othervariables are constant, a meter factor may be selected from the plot for flow rates within themeters operating/linear range

However, for greatest accuracy, the meter should be reproved at the new operating flow rate

The average k-factor, and also the k-factor at the nominal flow rate, for each of the tests(test 2, test 3 and test 4) differs from that of test 1

The deviation in k-factor values, and repeatability, (from that of test 1) was more pronouncedin test 2 (conducted under atypical pressure conditions)

The average meter factor does not change significantly for a slightly skewed velocity profilebut increases drastically for a highly skewed velocity profile

The relative volume of the liquid will change as a result of its compressibility. (The physicaldimensions of the meter will also change as a result of the expansion or contraction of itshousing under pressure.)

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Volumetric corrections for the pressure effects on liquids referenced to appropriate pressureis therefore necessary

The deviation in k-factor due to the protruding gasket upstream of the TFM, and that causedby reduction of upstream straight length pipe, were not as pronounced as would have beenexpected owing to Hoffer Flow TFM which has an in-built flow conditioner

The Hoffer Flow meter with in-built flow

conditioners

4.7 Suggestion for further studies

Extend test to larger and smaller size Turbine Flow Meters: e.g for 1 NB and 4 NB

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Repeat test at least five times for each flow rate for better assessment of repeatability

Extend all tests beyond the linear range for better understanding of TFM behaviour at thenon-linear range

Conduct with a TFM make without in-built Flow StraightenersExtend test to study the response of TFM under conditions of varying temperature, viscosity,

density, and changes in piping, valves, or valve positions that affect fluid profile or swirl.

CHAPTER FIVE

Conclusion

In view of the foregoing observation:

The overall performance of measurement by a meter depends on the condition of the meterand its accessories, the operating pressure, the calibration system and the variationsbetween operating and calibration

The potential for error increases in proportion to the difference between the calibration and

operating conditions

Calibration and usage of Turbine Flow Meter should be according to standards andmanufacturers specifications

A meter factor obtained for one set of conditions will not necessarily apply to a changed setof conditions

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For greatest accuracy, the meter should be proved at the operating conditions

Meter factors shall be determined by proving the meter under conditions of rate, viscosity,

temperature, density, and pressure similar to those that exist during intended operation.

References

API MPMS 5.3 (2005): Measurement of liquid hydrocarbons by turbine meters.

API MPMS 12.2 (2005): Calculation of liquid petroleum quantities measured by TFM orDisplacement meters.

ISO 4185-1980: Measurement of liquid flow in closed conduit-weighing methods.

ISO 5168-2005: Measurement of fluid flow-procedures for evaluation of uncertainties.

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experimental study of performance characteristics of turbine meter in oil medium, by onwunyili...

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