Flow Meter Selection

transcript

FLOW METER SELECTION SEMINAR

Alan Graff

RL Stone Co I&C Sales Manager

Upstate NY & New England

RL Stone Co. New England Corporate Office: 115 Ainsley Drive, Syracuse, NY 13210 • Tel: 888-404-8882 • Fax: 315-479-5402 www.rl-stone.com

Process/ HVAC Products and Solutions

Armstrong Steam and Condensate Group: Traps, Liquid Drainers, Steam Distribution & Condensate Return Manifolds, Air Vents, Strainers, Wireless Trap Monitors, Spargers, Separators

Armstrong Humidification Group (Vermont only): Direct Steam, Ionic Bed Electric, Gas-Fired, Steam to-Steam, Evaporative Cooling Fogging, Unfired Steam Generators

Armstrong Condensate Management Group: Mechanical & Electrical Condensate Pumps and Packages, Flash Tanks, Condensate Coolers

Armstrong Heat Transfer Group: Unit Heaters, Door Heaters and Make-Up Air Heaters, Heavy-Duty Steam and Hot Water Coils, Replacement Coils, DuraMix VIFB Coils, Fumigation Heat Treat Systems

Armstrong Hot Water Group: Instantaneous Hot Water Heaters, Direct Fired Gas High Efficiency Hot Water Heaters, Thermostatic Mixing Valves, “The

Brain” & MEGAMIX Digital Electronic Mixing Center, Steam & Hot Water Hose and Mixing Valve Stations

Armstrong Pressure Temperature Control Group: PRV’s, Pneumatic and Electric Industrial Control Valves, Temperature Regulators, Radiator Control Valves

Armstrong Service Group: Steam System Optimization, Contracting: Installation Construction, Engineering Audits and Steam Surveys, Heat Treat Audits

Cataract Steel Compressed Air, Gas & Heat Transfer Products, Industrial Heat Exchangers, Pressure Vessels, Air Receivers

New and Replacement Steam, Water and DX Coils, Remote Condensers, Fluid Coolers, Evaporative Coolers

Diversified Heat Heat Transfer Equipment, Shell and Tube Heat Exchangers, Plate and Transfer Frame Heat Exchangers, Steam and Hot Water Generators

Refrigerant Leak Detection Monitoring Systems

Thermacor Pre-Insulated Above and Below Ground Piping Systems, Process Containment Piping, High Temperature Polyisocyanurate

Foam, Pressure Testable J oints, ERM Leak Detection

TMI, Inc Strip Doors, Air Doors, Screens and Curtains, Modular Enclosures, Clear and Colored Flexible PVC Film, Noise Control Products

Flow Sensors & Instrumentation, Accelabar Zero Straight Run Flow Meter, Utility Flow Metering Systems

Gauges: Pressure, Vacuum, Digital and Analog Indicators, Mini and Industrial Diaphragm Seals, Pressure Transducers, Accessories-Pressure Snubbers, Gauge Cocks, Needle Valves, Siphons, Pete’s Plugs, Bimetal Thermometers and Temperature Transmitters

R. L. Stone Services Design Build, Installation, On-Site Seminars and Training, Energy Audits, Steam Trap Surveys, Control Panels, SCADA System

A Leading Supplier of Flowmeters to A Leading Supplier of Flowmeters to HVAC & Industrial MarketplaceHVAC & Industrial Marketplace

Magmeters Vortex & Swirl Turbine Thermal & Coriolis

Mass BTU Meter Pitot, Wedge Orifice Plates, Venturi Positive Displacement Rotameter, Variable

Define Application – Basic Facts

• Flowing Media (Steam, Water, Air, Gas etc…)• Density - pressure and temperature• Flow Range, minimum to maximum (turndown

needed)• Accuracy – how stated? % of range or span• Repeatability• Straight run requirements & available• Economic Considerations – Initial cost, maintenance

cost & operating costs

Why are we here?

• There is no 1 meter that will meet every application

• Every application needs to be looked at individually

• We can make some generalizations !!!!!!

•HOW MUCH (TOTAL)

• HOW FAST (RATE)

FLOW MEASUREMENT

Flow Through A PipeFlow Through A Pipe

Real WorldIdealized

Pipe Velocity Profile

Flow Profile CorrelationFlow Profile Correlation

Velocity profile is a predictable function of Reynolds number. Fluids with the same Reynolds number will have similar velocity profiles.

SteamWaterHeavy Crude

General Flow TerminologyGeneral Flow Terminology

Reynolds Number (RE)– A single dimensionless parameter formed as the ratio of inertial to viscous forces . Magnitude indicates whether flow is laminar or turbulent

CharacteristicDimension*

Fluid Viscosity ()RE=

FluidDensity

FluidVelocity

(V)Inertia Forces

Viscous Forces

* Usually inside pipe diameter.

Characterization of Fluid FlowCharacterization of Fluid Flow

Types of Flow RE < 2100

RE >3000

*** Well documented & proven fully developed flow profiles

Transitional

Turbulent ***

Laminar

Volumetric Flowrate (Q)Volumetric Flowrate (Q)

Volume = Area x LengthVolume Flow = Area x

Velocity

Mass Flowrate (m)Mass Flowrate (m)

Where m = Mass FlowQ = Volume Flow = Fluid Density

Mass = Volume x Density

Mass Flow m = Qp

Mass vs Volume Flowmeters

• Why are we concerned?• How much does it really matter?• Flow through a 4” line measured in a Averaging Pitot

Flow Rate 1000 cfm 1000 cfm

Pressure 5 psi 5 psi

Temperature 100 F 70 F

DP in WC 12.181 11.532

There is a 6% error just by changing density / temperature slightly…can you meter cope??

General Flow TerminologyGeneral Flow Terminology

Factors affecting flowmeter performance Process media

– Liquid– Gas

Density (Specific Gravity) Viscosity Pressure

Temperature Velocity

Flowmeter PerformanceFlowmeter Performance

Accuracy Repeatability Linearity Rangeability

Types of AccuracyTypes of Accuracy

% Rate % Full

Scale % Span % Max DP

AccuracyAccuracy

% Rate The percent accuracy value is constant and applied to the actual (or indicated) flowrate

Example:

Flowrate ±1% rate100 GPM ±1 GPM50 GPM ±0.5 GPM10 GPM ±.01 GPM

% Full Scale The absolute value of error (as expressed in engineering units) Flowrate ±1% Full Scale %

Rate100 GPM ±1 GPM ±1%50 GPM ±1 GPM ±2%10 GPM ±1 GPM ±10%

Example:

AccuracyAccuracy

Percent Error Versus Flow

Poor Repeatability Means Poor Accuracy

Good Accuracy Means Good Repeatability

Good Repeatability Does Not Necessarily Mean Good Accuracy

Volumetric Flowmeters

• DP• Turbine• Vortex / Swirl• Magnetic• Target• Ultrasonic• Displacement

• Note: can be inferred mass with compensating transmitter

Differential Pressure FlowmetersDifferential Pressure Flowmeters

Flow Measurement Principles

PQ = K

ORIFICE PLATE(or FLOW TUBE) VENA

CONTRACTA

MANOMETER(or DP TRANSMITTER)h

Direction of Flow

DP Primary ElementsDP Primary Elements

VariousOrificeConfiguration

FlowNozzle

VenturiFlowmeter

FlowTube

DP Primary ElementsDP Primary Elements

Averaging Pitot

Accelabar – Combined Pitot & Venturi

Wedge Element

DP FlowmetersDP Flowmeters

DIFFERENTIAL PRESSUREADVANTAGES

• Use On Liquid, Gas, and Steam

• Suitable for Extreme Temperatures and Pressures

• No Moving Parts

• Low Cost

DISADVANTAGES

• Limited Rangeability

• Effected By Changes In Density, Pressure, and Viscosity

• Maintenance Intensive

Magnetic FlowmetersMagnetic Flowmeters

Theory of Operation

Magmeter RequirementsMagmeter Requirements

Process must be a liquid

Minimum conductivity

Meter must be full

MAGNETICADVANTAGES

• No Moving Parts

• Very Wide Rangeability

• Ideal For Slurries

• Unobstructed Flow Path

DISADVANTAGES

• Liquid Must Be Conductive

• Physical Pressure and Temperature Limits

No moving parts No pressure drop Flowrate independent of viscosity, temperature, and density Minimum upstream piping requirements Electronics interchangeable without regard to size Measure dirty liquids with solids Measure highly corrosive fluids Very large turndown Linear output

Advantages Over Other Technologies

Vortex Meter Vortex Meter

Vortex MeterVortex Meter

Principle of Operation

Q = V x A

VortexVortex

Vortex / Swirlmeter

ADVANTAGES

• No Moving Parts

• For Liquid, Gas, or Steam

• Uneffected by Pressure, Temperature, or Density Changes.

• Wide Rangeability

DISADVANTAGES

• Span Limitations Due to Viscosity

• Flow Profile Sensitive (Vortex)

VORTEX / SWIRLMETER

SwirlmeterSwirlmeter

Principle of OperationPreamplifier

Swirler Sensor Deswirler

r = local radiusVA = axial velocity of flowVT = angular velocity of flowp = static pressure

Backflow

Housing

SwirlmetersSwirlmeters

BenefitsBenefits

• High Accuracy 0.50% of Rate

• No Moving Parts

• Minimal Upstream Piping

• Measures Low Flows

• Versatile

• Electronics can be used for Diagnostics

• Works with Entrained Liquids

SwirlmeterSwirlmeter

Cut-Away ViewTechnical Data Measures liquids, gases and

steam Available integral, remote, or

flow computer electronics Accuracy ±0.50% rate Sizes 0.75" thru 16.0" Minimal upstream piping req. Flow as low as 1 GPM Excellent in light gas

applications

Installation LengthInstallation Length

Swirlmeter

15 D 5 D

25 D 5 D

50 D 5 D

Vortex 4Swirlmeter

90° elbow

Processcontrol valve

Reduction

3 D 1 D

5 D 1 D

min. 1.8 D

Turbine MeterTurbine Meter

Principle of Operation

Rotor velocity is proportional to fluid velocity

High accuracy (.5% of rate) High rangeability (up to 50:1) Compact design Fast response time Broad range of sizes Clean water applications onlyClean water applications only NIST Traceable Factory CalibrationNIST Traceable Factory Calibration Low cost, Easy to installLow cost, Easy to install In and out of line, under pressureIn and out of line, under pressure

Straight pipe run requirements Process fluid lubricity Reynolds number constraints

ViscosityDensity

Maintenance & recalibration

Performance Considerations

Turbine FlowmetersTurbine Flowmeters

TURBINEADVANTAGES

• High Accuracy

• Suitable for Extreme Temperatures and Pressures

• Can Be Used On Gas or Liquid

DISADVANTAGES

• Only For Low Viscosities

• Moving Parts

• Sensitive to Flow Profile

Positive Displacement FlowmetersPositive Displacement Flowmeters

PD FlowmetersPD Flowmeters

Helical gear Nutating disk Oscillating

piston Oval gear Rotary

Positive Displacement MeterPositive Displacement Meter

Typical Principle of Operation

Schematic of a nutating-disk meter

Schematic of a rotary-vane flowmeter Schematic of a

lobed-impeller flowmeter

PD FlowmetersPD Flowmeters

Ideal for viscous fluids Custody transfer Batching Minimal straight piping

requirements

Advantages

Ultrasonic FlowmetersUltrasonic Flowmeters

Doppler Time of

flight

DopplerFlowmeter

Ultrasonic FlowmetersUltrasonic FlowmetersPrinciple of OperationPrinciple of Operation

Transit-TimeFlowmeter

Ultrasonic FlowmetersUltrasonic Flowmeters

Reynolds number constraints Entrained gas or particles for

doppler Clean liquids for time of flight Installed without process shut

down Straight upstream piping

requirements

Performance Considerations

UltrasonicUltrasonic

ULTRASONICADVANTAGES

• No Moving Parts

• Unobstructed Flow Passage

• Wide Rangeability

DISADVANTAGES

• For Liquids Only (limited gas)

• Flow Profile Dependent

• Errors Due To Deposits

Mass Flowmeter

Direct Measurement

• Thermal Dispersion• Coriolis

Coriolis Mass FlowmeterCoriolis Mass Flowmeter

CoriolisCoriolis

CORIOLISADVANTAGES

• Direct Mass Measurement

• High Accuracy

• Additional Density Measurement

• Uneffected By Flow Profile

DISADVANTAGES

• High Purchase Price

• High Installation Cost

• Size Limitations

• Vibration Sensitive

Thermal Dispersion

Thermal Dispersion Mass Flowmeter

• Gas application only• Relatively inexpensive• Easy to install and remove under pressure• Accuracy 0.5%• Turndown, 100:1• Capable of monitoring extremely low flows• True mass flow meter (compensates for

temperature/pressure)

Piping Considerations

• Always need a full pipe

• Proper up / down diameter

BTU Monitoring

Summary – Each Application is DifferentSummary – Each Application is Different

•Flowing Media (eg Steam, Water, Air, Gas etc…)•Density - pressure and temperature•Flow Range, minimum to maximum (turndown needed)•Accuracy – how stated? % of range or span•Repeatability•Straight run requirements & available•Maintenance and reliability

General HVAC Recommendations

Steam : Accelabar or Swirl

Chilled or Hot Water: Hot Tap Insert Turbine

Natural Gas or Air: Thermal Dispersion

Fuel Oil: Coriolis or Wedge

Flow Meter Selection

Documents