GB2161941A - Mass flow meter - Google Patents

Mass flow meter Download PDF

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Publication number
GB2161941A
GB2161941A GB08418484A GB8418484A GB2161941A GB 2161941 A GB2161941 A GB 2161941A GB 08418484 A GB08418484 A GB 08418484A GB 8418484 A GB8418484 A GB 8418484A GB 2161941 A GB2161941 A GB 2161941A
Authority
GB
United Kingdom
Prior art keywords
flow meter
inlet
meter
differential pressure
velocity
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB08418484A
Other versions
GB8418484D0 (en
Inventor
Robert Cherry Mottram
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University of Surrey
Original Assignee
University of Surrey
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University of Surrey filed Critical University of Surrey
Priority to GB08418484A priority Critical patent/GB2161941A/en
Publication of GB8418484D0 publication Critical patent/GB8418484D0/en
Publication of GB2161941A publication Critical patent/GB2161941A/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
    • G01F1/20—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by detection of dynamic effects of the flow
    • G01F1/32—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by detection of dynamic effects of the flow using swirl flowmeters
    • G01F1/325—Means for detecting quantities used as proxy variables for swirl
    • G01F1/3259—Means for detecting quantities used as proxy variables for swirl for detecting fluid pressure oscillations
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
    • G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
    • G01F1/36—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure the pressure or differential pressure being created by the use of flow constriction
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/76—Devices for measuring mass flow of a fluid or a fluent solid material
    • G01F1/86—Indirect mass flowmeters, e.g. measuring volume flow and density, temperature or pressure
    • G01F1/88—Indirect mass flowmeters, e.g. measuring volume flow and density, temperature or pressure with differential-pressure measurement to determine the volume flow

Abstract

A flow meter includes a profile (8) defining a flow restricting nozzle (10) connected to a throat (12). A differential pressure transducer (18) is connected to tappings (14, 16) opening at the entrance to the nozzle and within the throat (12) to provide a signal representing the differential pressure across the nozzle entrance. A velocity meter (20) is located in the throat. Computing means (30) produce an output to meter (32) proportional to the mass flow rate from the ratio of the differential pressure and velocity signals. An output is provided to meter (34) representing the density of the fluid flowing in the meter which is derived from the ratio of the differential pressure and the square of the velocity signals. The flowmeter may comprise a vortex generator, thermistor, hot wire, turbine etc. <IMAGE>

Description

SPECIFICATION Flow meters The present invention relates to flow meters and, more specifically, to flow meters adapted to measure mass flow rate and/or the density of a fluid flowing through the meter.
Various designs of flow meter have been proposed which include sensors for measuring various parameters of a flow from which the mass flow rate can be derived. For example a turbine meter or vortex shedding flow meter may be used to measure the flow velocity of a fluid. Such meters produce an oscillating signal the frequency of which is proportional to the velocity. In order to determine the mass flow rate it is then either necessary to know or measure the density. Such density measurement can prove difficult and expensive particularly for multicomponent fluids such as gas mixtures or two-phase flows. Most density meters include vibrating parts in the path of the fluid flow and therefore have a high risk of mechanical failure.
Such meters have further proved unsuitable for multicomponent flows.
The present invention seeks to solve'the technical problem of providing a mass flow rate meter which is simple and economical to produce and can be used for measuring the mass flow rate of multicomponent flows.
The present invention accordingly provides a flow meter comprising an inlet and an outlet, flow restriction means connecting said inlet to a reduced diameter passage connected to said outlet, means for measuring the differential pressure between the inlet and said reduced diameter passage, means for measuring the flow velocity of fluid within said reduced diameter passage, and means for deriving the mass flow rate from the ratio of the measured differential pressure and velocity.
Preferably the velocity measuring means is a vortex shedding bluff body.
In a preferred embodiment, the flow meter is further provided with means for deriving the density of the fluid from the ratio of the differential pressure and the square of the measured velocity.
The above defined type of meter is particularly suitable for two-phase flows as there is no requirement for a specific device for measuring the density directly.
An embodiment of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawing which is a section through a flow meter in accordance with the invention.
The illustrated flow meter is formed in a pipe section 2 having an inlet 4 and an outlet 6.
Within the pipe section there is mounted a venturi nozzle 8 which is set back from the inlet and has a nozzle entrance 10 connecting the inlet to a reduced diameter throat 1 2. In the present embodiment the profile of the nozzle entrance is a quarter circle of radius of d/3 where d is the diameter of the throat. Two tappings 14, 1 6 for connection to respective inputs of a differential pressure transducer 1 8 are provided in the wall of the meter. The first tapping 1 4 is adjacent the nozzle entrance 10 and is connected to one input of the differential pressure transducer 1 8.
The second tapping 1 6 opens into the throat 1 2 a distance 2d/3 downstream from the front face of the nozzle and is connected to the other input of transducer 1 8. The output of the pressure transducer 1 8 connected to these tappings represents the differential pressure across the nozzle entrance 10. An independent pressure transducer may also be connected to tapping 14 if the inlet pressure is required. Alternatively a further tapping can be provided within one or two pipe-diameters of the inlet to the nozzle 8.
A third tapping 20 is provided downstream of the second tapping 16. This tapping 20 is positioned to be located behind a vortex shedding bluff body 22 such as a strut spanning the nozzle throat transverse to the section of the drawing. The strut 22 may be of rectangular, delta, T-section, or have any other appropriate contour. The tapping 20 may be used for a thermal probe for detecting the vortices shed by the strut or by a sensitive pressure transducer for detecting the pressure fluctuations generated by the vortices. In a known manner, it is possible to produce an output signal which has a frequency equal to the frequency of the vortices and is proportional to the velocity of the fluid in the throat from the output of a hot wire probe or sensitive pressure transducer connected at tapping 20.
Various types of thermal probe may be used. A hot-wire probe is suitable for clean gas flows in the laboratory whereas a thermistor would be suitable for an industrial environment. Other sensors such as ultrasonic transmitter/receivers and strain gauge elements may also be used for detecting the vortices and these or pressure sensors may be mounted in the strut itself. Other types of velocity meter can be employed to produce a velocity signal. For example an electromagnetic velocity meter or a turbine meter or any other known type can be used.
As illustrated, the throat 1 2 of the nozzle 8 is of a uniform diameter along its length but it may also be tapered or include a small step and the consequent variation in the measured velocity taken into account during calibration of the meter.
As illustrated, there is an abrupt transition between the nozzle profile and the outlet of the flow meter, however, a conical diffuser may be inserted to provide a smooth change in the diarneter of the flow passage.
The outputs of the pressure transducers and the velocity flow meter are connected to computing means 30 which produces outputs to meters 32, 34 indicative of the mass flow rate and the density of the fluid respectively. The mass flow rate output is derived from the ratio of the measured differential pressure (Ap) and velocity (V) signals.
The differential pressure Ap generated across the nozzle is proportional to the kinetic energy of the fluid, i.e.
pV2 Apoi -and Mci pV therefore Mci A p/V 2 where p = density and M is the mass flow rate. The computing means 30 also outputs a signal representing the density of the fluid flowing through the meter which is derived as the ratio of the measured differential pressure and the square of the velocity signal since
pV2 PciT V2ciAp/V2 In the case of a two-phase flow such as wet steam the measurement of density and the upstream pressure yields the dryness factor and this may also be displayed if required, where the upstream pressure is measured by a pressure transducer at tapping 14 or another suitable tapping.It will be appreciated that the meters 32, 34 can be calibrated by reference to sources of fluids of known density passing through the meter at constant rates or by other appropriate techniques.
It will be appreciated that the particular nozzle profile described is exemplary only and various other types of fluid restricting profile could be provided to connect the inlet to a constant diameter throat in which the fluid velocity can be measured. In a constructed embodiment of the flow meter, the fluid pipe was 80mm in diameter and the throat diameter d was 20mm. The bluff body or strut 22 was located 20mm behind the second pressure tapping 1 6 with the tapping 20 for the hot wire probe opening 5mm from the front face of the strut 22. The strut itself was of rectangular section with a width in the diametral plane of the throat 0.24d and a depth along the pipe axis of 0.67 times its width.

Claims (8)

1. A flow meter comprising an inlet and an outlet, flow restriction means connecting said inlet to a reduced diameter passage connected to said outlet, means for measuring the differential pressure between the inlet and said reduced diameter passage, means for measuring the flow velocity of fluid within said reduced diameter passage, and means for deriving the mass flow rate from the ratio of the measured differential pressure and velocity.
2. A flow meter as claimed in claim 1, wherein the velocity measuring means is a vortex shedding bluff body.
3. A flow meter as claimed in claim 1 or 2, further provided with means for outputting a signal representing the density of the fluid flowing through the meter derived from the ratio of the measured differential pressure and -the square of the velocity signal.
4. A flow meter as claimed in any one of claims 1 to 3, wherein the reduced diameter passage is connected to the outlet my means of a conical diffuser.
5. A flow meter as claimed in any one of the preceding claims, wherein the reduced diameter passage has a uniform diameter.
6. A flow meter comprising an inlet, a differential pressure transducer having one input connected adjacent the inlet, means defining a nozzle connecting the inlet to a throat, the second inlet of the pressure transducer being connected at the entrance to said throat, a strut traversing the throat behind the second connection to the pressure transducer, means for sensing the frequency of the vortices generated by said strut which is proportional to the velocity of fluid flowing in the throat, and means for dividing the output signal from the differential pressure transducer by a signal representing the frequency of said vortices to produce an output signal proportional to the mass flow rate of fluid within the flow meter.
7. A flow meter as claimed in claim 6, further comprising means for dividing the pressure difference signal by the square of the frequency signal to produce an output signal proportional to the density of fluid within the flow meter.
8. A flow meter substantially as herein described with reference to the accompanying drawing.
GB08418484A 1984-07-19 1984-07-19 Mass flow meter Withdrawn GB2161941A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08418484A GB2161941A (en) 1984-07-19 1984-07-19 Mass flow meter

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08418484A GB2161941A (en) 1984-07-19 1984-07-19 Mass flow meter

Publications (2)

Publication Number Publication Date
GB8418484D0 GB8418484D0 (en) 1984-08-22
GB2161941A true GB2161941A (en) 1986-01-22

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB08418484A Withdrawn GB2161941A (en) 1984-07-19 1984-07-19 Mass flow meter

Country Status (1)

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GB (1) GB2161941A (en)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2594946A1 (en) * 1986-02-21 1987-08-28 Flopetrol Etu Fabrications FLOW METER PARTICULARLY FOR WELLS OF HYDROCARBONS
GB2218519A (en) * 1988-05-11 1989-11-15 Gas Res Inst A trapped-vortex flowmeter
FR2649790A1 (en) * 1989-07-13 1991-01-18 Vallat Bernard Device for measuring the density or mass flow rate of a liquid
GB2261519A (en) * 1991-11-06 1993-05-19 Exal Reservoir Serv Ltd Hydro-carbon flow rate monitor
GB2267758A (en) * 1992-05-28 1993-12-15 Nagano Limited Airflow measuring device
US5445035A (en) * 1991-12-18 1995-08-29 Delajoud; Pierre R. Precision gas mass flow measurement apparatus and method maintaining constant fluid temperature in thin elongated flow path
WO2002034417A1 (en) * 2000-10-27 2002-05-02 Nordson Corporation Fluid dispenser with fluid weight monitor
WO2008025934A1 (en) * 2006-08-29 2008-03-06 Richard Steven Improvements in or relating to flow metering
WO2009158605A2 (en) * 2008-06-27 2009-12-30 Rosemount, Inc. Velocity-enhanced flow measurement
WO2010008866A2 (en) * 2008-06-23 2010-01-21 Schaaf Philip J Integrating media display into computer peripherals and computing systems: the media mouse, media keboard, media monitor, media mate, media screen and mediabook
CN103206989A (en) * 2012-01-13 2013-07-17 上海安钧电子科技有限公司 Under-pressure installation insertion type V cone flow rate meter
CN103674127A (en) * 2012-09-07 2014-03-26 麦克科罗米特股份有限公司 Angled port differential pressure flow meter
CZ305834B6 (en) * 2014-12-19 2016-03-30 Technická univerzita v Liberci Method of setting direction of gas or liquid flow from a nozzle and apparatus for making the same
EP3879237A1 (en) * 2020-03-12 2021-09-15 Schneider Electric Systems USA, Inc. Vortex flowmeter providing extended flow rate measurement
US11815377B2 (en) 2021-02-19 2023-11-14 Schneider Electric Systems Usa, Inc Vortex flowmeter providing extended flow rate measurement

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111664902A (en) * 2020-06-24 2020-09-15 江苏杰创流量仪表有限公司 Novel temperature compensation vortex shedding flowmeter

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1089203A (en) * 1963-08-15 1967-11-01 Int Combustion Holdings Ltd Improvements in or relating to fluid flow measuring devices
GB1126474A (en) * 1966-02-10 1968-09-05 Grigory Nikolaevich Puzanov Variable differential pressure flowmeter for liquids and/or gases

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1089203A (en) * 1963-08-15 1967-11-01 Int Combustion Holdings Ltd Improvements in or relating to fluid flow measuring devices
GB1126474A (en) * 1966-02-10 1968-09-05 Grigory Nikolaevich Puzanov Variable differential pressure flowmeter for liquids and/or gases

Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2594946A1 (en) * 1986-02-21 1987-08-28 Flopetrol Etu Fabrications FLOW METER PARTICULARLY FOR WELLS OF HYDROCARBONS
GB2218519A (en) * 1988-05-11 1989-11-15 Gas Res Inst A trapped-vortex flowmeter
GB2218519B (en) * 1988-05-11 1992-07-08 Gas Res Inst Trapped-vortex pair flowmeter
FR2649790A1 (en) * 1989-07-13 1991-01-18 Vallat Bernard Device for measuring the density or mass flow rate of a liquid
GB2261519A (en) * 1991-11-06 1993-05-19 Exal Reservoir Serv Ltd Hydro-carbon flow rate monitor
GB2261519B (en) * 1991-11-06 1994-10-26 Exal Reservoir Serv Ltd Hydro-carbon flow rate monitor
US5445035A (en) * 1991-12-18 1995-08-29 Delajoud; Pierre R. Precision gas mass flow measurement apparatus and method maintaining constant fluid temperature in thin elongated flow path
GB2267758A (en) * 1992-05-28 1993-12-15 Nagano Limited Airflow measuring device
WO2002034417A1 (en) * 2000-10-27 2002-05-02 Nordson Corporation Fluid dispenser with fluid weight monitor
GB2381321A (en) * 2000-10-27 2003-04-30 Nordson Corp Fluid dispenser with fluid weight monitor
US6579563B1 (en) 2000-10-27 2003-06-17 Nordson Corporation Fluid dispenser with fluid weight monitor
GB2381321B (en) * 2000-10-27 2004-05-19 Nordson Corp Fluid dispenser with fluid weight monitor
WO2008025934A1 (en) * 2006-08-29 2008-03-06 Richard Steven Improvements in or relating to flow metering
GB2453511A (en) * 2006-08-29 2009-04-08 Richard Steven Improvements in or relating to flow metering
GB2453511B (en) * 2006-08-29 2011-03-23 Richard Steven Improvements in or relating to flow metering
US8056409B2 (en) 2006-08-29 2011-11-15 Richard Steven Hybrid flowmeter that includes an integral vortex flowmeter and a differential flow meter
WO2010008866A2 (en) * 2008-06-23 2010-01-21 Schaaf Philip J Integrating media display into computer peripherals and computing systems: the media mouse, media keboard, media monitor, media mate, media screen and mediabook
WO2010008866A3 (en) * 2008-06-23 2010-03-04 Schaaf Philip J Integrating media display into computer peripherals and computing systems: the media mouse, media keboard, media monitor, media mate, media screen and mediabook
WO2009158605A2 (en) * 2008-06-27 2009-12-30 Rosemount, Inc. Velocity-enhanced flow measurement
WO2009158605A3 (en) * 2008-06-27 2010-03-11 Rosemount, Inc. Velocity-enhanced flow measurement
US8548753B2 (en) 2008-06-27 2013-10-01 Rosemount Inc. Velocity-enhanced flow measurement
CN102077061B (en) * 2008-06-27 2014-04-23 罗斯蒙特公司 Velocity-enhanced flow measurement
CN103206989A (en) * 2012-01-13 2013-07-17 上海安钧电子科技有限公司 Under-pressure installation insertion type V cone flow rate meter
CN103674127A (en) * 2012-09-07 2014-03-26 麦克科罗米特股份有限公司 Angled port differential pressure flow meter
CN103674127B (en) * 2012-09-07 2017-03-29 麦克科罗米特股份有限公司 Angling hole differential pressure flowmeter
CZ305834B6 (en) * 2014-12-19 2016-03-30 Technická univerzita v Liberci Method of setting direction of gas or liquid flow from a nozzle and apparatus for making the same
EP3879237A1 (en) * 2020-03-12 2021-09-15 Schneider Electric Systems USA, Inc. Vortex flowmeter providing extended flow rate measurement
US11815377B2 (en) 2021-02-19 2023-11-14 Schneider Electric Systems Usa, Inc Vortex flowmeter providing extended flow rate measurement

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