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Volumetriche, Massiche, Multifase, Fiscali… come non perdersi nel Pianeta "misure di portata"

(n lingua inglese)

Le misure di portata rappresentano un aspetto molto rilevante per la corretta gestione dei processi produttivi. La disponibilità di principi di misura molto differenti può lasciare l’utente disorientato di fronte alla scelta dello strumento più adatto per le proprie applicazioni.
Il contributo fornisce una panoramica sulle principali tecnologie, identificando i benefici di ciascuna famiglia di prodotto e presentando alcune semplici linee guida per la selezione dei misuratori.

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Atti di convegni o presentazioni contenenti case history
mcT Petrolchimico Milano novembre 2017 workshop

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da Benedetta Rampini
mcT Petrolchimico Milano 2017Segui aziendaSegui




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Estratto del testo
Milano, 30 novembre 2017 Gli atti dei convegni e pi di 8.000 contenuti su www.verticale.net ' MCT PETROLCHIMICO, 30 NOVEMBRE 2017
Volumetriche, Massiche, Multifase, Fiscali'come non perdersi nel Pianeta ' misure di portata' Gregorio Ciarlo ' Introduction
Conventional flow measuring techniques
- Measuring Principle - Applicability and Limitations - How to maximize measurement effectiveness Latest improvements from ABB
- Coriolis Flowmeters FCB - Flow Computers Flow-X Conclusions December 4, 2017 Slide 2 Agenda ' The industrial measurement practice is a largely changing world due to several factors:
' Manufacturing of devices is often pushed to locations where raw materials are available economically ' Competitive environment is leading to a further specialization among the main instrumentation vendors ' Market is expecting a continuous improvement in the quality of the products as well as a complete traceability of the production itself. ' End-User requirements are often becoming more and more challenging in terms of performances of the meters as well as in terms of specific project customizations ' Among the different measurement device families, flow measurement represents probably the most articulated and varied ' This scenario poses additional challenges to the operators and technicians that have to properly face the measuring task. Industrial measurement ' an evolving ' world' Introduction December 4, 2017 Slide 3 Industrial Flow Measurement ' a traditional overview Introduction December 4, 2017 Slide 4 Flow measurement devices Volume totalizers Direct Displacement Oval Gear Oscillating Piston Rotary Piston Indirect Rotary Vane / Spiral Gear Vortex Flowmeter Flowrate meters Volume Flowrate Differential Pressure Variable Area Electromagnetic Ultrasonic Mass Flowrate Coriolis Thermal Mass ' The previous overview does not take into account the requirements for each specific applications:
' Fluid Characteristics (Liquid, Gas, Steam, Density, Viscosity') ' Operating conditions (Pressure, Temperature, ') ' Performance requirements (Accuracy, Rangeability) ' Installation requirements and specific conditions which prevent the adoption of a specific technology ' Certification requirements (Fiscal, Hazardous Areas,') ' Operators and technicians may be disoriented by the broad range of alternatives and hesitant to select the most appropriate measurement principle
' Maintenance of largely different devices requires dedicated expertise also for Service operators which must be familiar with lot of devices ' even from different manufacturers Industrial Flow Measurement ' challenges Introduction December 4, 2017 Slide 5 Industrial Flow Measurement ' a traditional overview Introduction December 4, 2017 Slide 6 Flow measurement devices Volume totalizers Direct Displacement Oval Gear Oscillating Piston Rotary Piston Indirect Rotary Vane / Spiral Gear Vortex Flowmeter Flowrate meters Volume Flowrate Differential Pressure Variable Area Electromagnetic Ultrasonic Mass Flowrate Coriolis Thermal Mass Vortex Flowmet Differential Pressure Variable Area Electromagnetic Ultrasonic Coriolis Thermal Mass ' Focus will be given to a selected group of solutions (i.e. those with highest technological content) ' Main guidelines on applicability of each one will be given ' Some hints on most advanced techniques will be also presented:
' Multiphase flowmeters ' Flow computers Application fields Conventional measuring principles December 4, 2017 Slide 7 Application & Features Variable Area Differential Pressure Electro- magnetic Vortex Ultrasonic Thermal Mass Coriolis Liquids
Conductive ' ' ' ' ' ' Non-Conductive ' ' ' ' ' Solids Content ' ' ' Pulsating ' ' ' ' Viscosity 10+ cP ' ' ' ' Custody transfer ' ' Gases
Dry/Clean ' ' ' ' ' ' Moist ' ' ' ' ' Corrosive ' ' ' Contaminated ' ' ' ' ' ' Custody transfer ' ' Steam ' ' ' ' ' ' Variable Area Flowmeters: vertical cone tube with diameters increasing in the upward direction with a float located inside the tube ' Fluid streams from bottom to top and the float lifts off
' When the forces are balanced, the float will be stable: ' FG = Gravitational Force function of the float weight ' FA = Buoyancy Force Function of the medium density ' FS = Fluid pressure force Depends on float geometry ' The position of the float is a direct indication of the flow rate. Measurement Principle Variable Area Flowmeters December 4, 2017 Slide 8 FA FG FS Two possible configurations Variable Area Flowmeters December 4, 2017 Slide 9 Glass VA Armored VA (Metal Tube) Technology characteristics at a glance Variable Area Flowmeters December 4, 2017 Slide 10 Advantages Limitations ' Reliable devices for gas, liquids and steam
' Virtually no limitations due to high pressures
' Very versatile and robust meters applicable to aggressive and opaque fluids ' Does not require any straight section upstream and downstream ' Capable of managing very low flowrates
' No power supply needed
' Ideal also as a back-up measurement ' Technology accuracy is limited (around 1.6% of reading) ' Large sizes not available (4' max)
' Limited measurement turndown (1:10)
' Not well suited for high viscosity fluids or with solid particles Reliable and flexible meters typically adopted to measure 'not-valuable' fluids also in challenging conditions ' Differential Pressure (DP) Flowmeters are based on the Bernoulli's law of energy conservation:
' A restriction in a pipe generates a pressure drop which is proportional to the flow velocity (and therefore to the volumetric flowrate) ' DP flowmeters exploit various obstruction shapes in the pipe to measure the flow. Most common technologies:
' Orifice plates ' Venturi Tubes ' Nozzles ' Wedge ' Pitot Tubes Measurement Principle Differential Pressure Flowmeters December 4, 2017 Slide 11 const v m p m h g m E = + + = 2 2 r p q v D Technology characteristics at a glance Differential Pressure Flowmeters December 4, 2017 Slide 12 Advantages Limitations ' Suitable for both gases, liquids, vapours and bi-phase fluids ' No moving parts
' Cost effective (especially in large pipes)
' Easy installation ' Meter rangeability is very limited compared to other technologies (1:4'1:10) ' Limited accuracy
' Meter performances subject to ageing effects (erosion, deposits) ' Output signal not linear with flow rate ' Quick and dirty' solution to measure liquids and gases with not demanding accuracy requirements and limited flow oscillations DC Measuring Electrodes Magnet Coils Tube Lining Measurement principle Electromagnetic Flowmeters December 4, 2017 Note ' in standard EMF solutions, excitation of coils is made through Direct Current Slide 13 ' Elecromagnetic Flowmeters are based on Faraday's Law:
' Two coils generate a consistent magnetic field across the whole pipe area ' A conductive fluid flowing across a magnetic field generates an induced voltage ' An insulating lining preserves the voltage in order to be gathered by electrodes ' Voltage is measured by two electrodes and is proportional to the fluid velocity ' From fluid velocity, volumetric flowrate can be easily derived. DC Standard Technology Limitations Electromagnetic Flowmeters December 4, 2017 Slide 14 ' Standard DC current meters can cover up to 90% of EMF installations ' They have significant limitations due to the principle itself ' Measurement is taken after the stabilization of the magnetic field ' Effective measurement time is just of the total ' DC current meters are therefore suited only for continuous flow while pulsating flows are very difficult to manage ' Accuracy drops significantly in presence of large solid content, with pulsating flow and/or high pulp stocks ' Low conductivity fluids (below 5.0 S/cm) tend to generate too weak signals and EMF struggle to perform properly Magnetic Field Stabilisation Signal Measurement Period Signal Measurement Period Magnetic Field Stabilisation Average Signal ABB FSM4000 ' Overcoming the challenges Electromagnetic Flowmeters December 4, 2017 Slide 15 ' ABB FSM4000 is the AC-based EMF tailored for managing such challenging application ' Liquids with high content of solids (mining slurries, pulps or yoghurt with fruit particles) ' Pulsating or with highly varying flow conditions ' Liquids with rapidly changing conductivity ' A pre-amplifier enables the monitoring of very low conductive fluids (0.5 S/cm) 167ms 0 167ms 5ms AC FSM4000 @ 70Hz DC Meter @ 25 Hz 0 0.7% error 0.07% error ABB AquaMaster ' State-of-the-art solution for water applications Electromagnetic Flowmeters December 4, 2017 Slide 16 ' Water distribution has typically additional requirements for EMFs:
' MID Certification for Cold Water ' Instrumentation without power supply from network ' ABB has developed AquaMaster which perfectly meets specific requirements:
' Power supply through renewables or battery ' Data-logging capability with features to transfer directly to supervisory systems ' Certified accuracy in a broad range of flowrates (even at low flow) ' Installation possible without inlet and outlet straight sections Minimal footprint Technology characteristics at a glance Electromagnetic Flowmeters December 4, 2017 Slide 17 Advantages Limitations ' Huge turndown (up to 1:100)
' No pressure drop
' Virtually no limitations due to size
' Accuracy up to 0.2%
' Several possible combination of electrodes & liner for each specific applications ' Able to manage also challenging fluids (abrasive, solids particles) ' Only liquid with sufficient conductivity (standard 5.0 S/cm, up to 0.5 S/cm with ABB FSM4000) ' Temperature of the fluid shall not exceed 150-200C ' Upstream and downstream straight pipe required ' Dry content up to 15% in sludge (30% with ABB FSM4000) ' Pulp content up to 5'7% (up to 15% with ABB FSM4000) Electromagnetic flowmeters are the typical solution for water (clean, dirty) and conductive fluids Measurement Principle Vortex Flowmeters December 4, 2017 Slide 18 Piezo sensor f V Bluff body ' Vortex Flowmeters are based on the Karman vortex street:
' A flow obstruction (bluff body) creates vortices on both side of the bluff body ' These vortices create periodic pressure and velocity variations ' Frequency of the vortex is proportional to flow velocity ' A piezo-sensor detects the pressure forces and convert them in an impulse signals ' Suited for the measurement of volumetric flowrate of both liquids and Gases ' Perfectly tailored for steam measurement Integrated temperature sensor Vortex Flowmeters December 4, 2017 Slide 19 Flow piezo sensor Internal RTD ' A temperature signal can be embedded or retrofitted in the meter
' No additional wiring requested ' Temperature device is implemented in the proper section ' Direct mass measurement in saturated steam applications ' Possibility to read also a pressure signal through HART or 4'20mA
' Completely compensated volume or mass output also for gases and saturated steam Technology Requirements Vortex Flowmeters December 4, 2017 Slide 20 ' Vortex measurement principle has some specific requirements:
' A critical Reynolds number shall be met minimum flowrate necessary ' Vortices can form properly if the velocity profile is not distorted ' Requirements turn into technology limitations: ' A cut-off at low flowrates is present ' Installation length needs to be significant: at least 15 DN upstream and 5 DN downstream shall be considered An upgrade to conventional vortex measurement ABB SwirlMaster December 4, 2017 Slide 21 Flow profile shaped f Higher flow speed Advantages compared with a Vortex flowmeter ABB SwirlMaster FSS4xx December 4, 2017 Slide 22 = SwirlMaster = Vortex Flowmeter accuracy viscosity span Pressure loss In- and outlet section typ. 15/5 x DN typ. 1:30 < 30 cP typ. 1:20 < 7,5 cP B et te r B et te r 0,5 % of rate typ. 3/1 x DN DN80- DN400 < 5 < 10 DN15-DN32 DN40-DN50 Gas liquids 0,9 % of rate 0,65% of rate Min Flowrate Technology characteristics at a glance Vortex Flowmeters December 4, 2017 Slide 23 Advantages Limitations ' Versatile measurement for liquid and gas ' Ideal for low conductivity liquids (e.g. demineralized water, condensate) ' Perfectly suited for steam measurement
' Applicable to very high temperature (up to 400C) ' Mass measurement with embedded temperature signal and an external pressure signal ' Integrated flow computer functionalities for energy and mass calculations ' Installation space affected by upstream and downstream straight sections requirements (ABB SwirlMaster reduces radically) ' Normally limited to viscosity values up to 5'7 cP (up to 30 cP with ABB SwirlMaster) ' Cut-off at low flowrate values (ABB SwirlMaster drastically reduces cut-off issues) Vortex flowmeters are the tailored solution for gas/liquid in challenging conditions (high temperature, hazardous areas). ' Most of the Ultrasonic Flowmeters are based on the Time Transit Method:
' A sound impulse (ultrasonic) is transmitted between two transducers ' Each transducer acts partially as transmitter and partially as receiver ' The time required to receive the signal is measured in both directions ' Transit time in the flow direction is smaller than in the opposite direction ' Difference between the two times is proportional to velocity of the fluid ' Volumetric flowrate of both gas and liquid can be accurately measured with this technology Measurement Principle Ultrasonic Flowmeters December 4, 2017 Slide 24 - = 2 1 1 1 cos 2 1 t t v a Technology characteristics at a glance Ultrasonic Flowmeters December 4, 2017 Slide 25 Advantages Limitations ' Technology applicable to liquids and gas
' Non invasive technology with clamp-on installation ' Minimal pressure drop induced
' Very competitive solutions for large pipes
' Typical solution for Custody transfer applications of gases ' Velocity profile shall be axisymmetric Upstream and downstream straight sections required ' Transit time method requires clean fluids (e.g. without solids) and without air bubbles Versatile technology suitable also for non-invasive measurement of both liquids and gases A quick overview Multiphase Flowmeters (MPFM) December 4, 2017 Slide 26 ' Upstream production facilities usually collect streams from a number of wells drilled to properly exploit hydrocarbon reservoirs ' Each well stream is actually a mixture of oil, hydrocarbon gas and water in highly variable proportions depending on locations and on reservoir age. This is why they are called Multiphase Streams ' Conventional measuring instruments are typically not effective in dealing with such mixture ' Therefore the typical solution is the installation of cumbersome test separators to separe the phases and then measure with traditional products ' MPFM are able to measure the individual flow rates in a single compact solution. ABB VIS ' a completely new approach Multiphase Flowmeters December 4, 2017 Slide 27 ' Most of the available solutions are based on combination of dP solutions (typically venturi) and radio-active sources ' Gamma-sources are necessary in order to provide sufficient accuracy when gas content is significant ' Radioactive sources become an headache for importation, disposal and for maintenance activities during meter lifecycle Typical Multiphase Solutions ' Based on a unique patented technology: Isokinetic Sampling Method
' Based only on conventional instrumentation (dP, P, T)
' Specifically tailored for most challenging applications (high gas content) ' With its unique design can be a valuable option also for Gas Storage applications ABB VIS Multiphase Flowmeters '-source Measurement Principle Thermal Mass Flowmeters December 4, 2017 Slide 28 ' Thermal Mass Flowmeters measure flowrates on the base of the heat transferred to a body within the fluid.
' Two sensors (platinum resistors) are actually present in the meter ' One is at the temperature of the fluid ' The other is electrically heated in order to keep constant the difference between the resistors Gas flow ' Electrically heated platinum sensor Gas temperature sensor Heating current Ih ~ Mass Gas flow Technology characteristics at a glance Thermal Mass Flowmeters December 4, 2017 Slide 29 Advantages Limitations ' Direct mass measurement
' Huge turndown (up to 1:150)
' Negligible Pressure drop
' Very quick response time
' Accuracy up to 1.0%
' Minimal maintenance requirement
' Optimal behavior also in negative pressure
' Possibility to adopt a single device to measure different gases ' Thermal Mass flowmeters can be adopted for gas measurement only ' Condensate must be avoided
' Sticky dirt can lead to deviations
' Measurement can be strongly affected if needed upstream sections are not available ' The composition of the gas has to be known Thermal Mass flowmeters are the optimal solution to have a direct mass measurement of gases Measurement Principle Coriolis Mass Flowmeter December 4, 2017 Slide 30 Temperature sensor Sensor B (outlet) Vibrating measurement tubes Actuator Sensor A (inlet) m & Transmitter Controller Signal processing Measurement Principle Coriolis Flowmeters December 4, 2017 Slide 31 Operation without flow Operation with flow ' The tube vibration is generated by an electromagnetic coil in the middle of the tubes ' Coriolis forces creates a phase shift between inlet and outlet of the meter the tubes 'twists'
' Phase shift is proportional to mass flow ' Frequency is proportional to fluid density Technology characteristics at a glance Coriolis Flowmeters December 4, 2017 Slide 32 Advantages Limitations ' Direct mass measurement for both liquid and gases ' Multivariable output (Flow, density and temperature) ' Independent from temperature, viscosity, density, etc. ' Very high accuracy ' Flowrate ' up to 0.10% ' Density ' up to 0.5 g/l ' Suitable for Custody transfer applications ' Typically limited in size (up to 6'10 inches)
' Pressure drop could be relevant depending on meter shape ' Large footprint
' Initial investment larger than other measuring techniques ' High gas content in liquid reduces measurement accuracy Coriolis are the best option for measuring valuable products with maximum accuracy Key benefits ABB CoriolisMaster FCB1xx and FCB4xx December 4, 2017 Slide 33 High precision Low pressure drop Short installation length Up to 40 % shorter Wider inner tubes to reduce 50 to 90 % pressure drops Top-class accuracy for mass flow, volume flow and density Other relevant features ABB CoriolisMaster FCB1xx and FCB4xx December 4, 2017 Slide 34 Key characteristics at a glance ' Through The Glass (TTG) operations Enabling parametrization also in Ex-Areas without other tools ' Output signals completely scalable Up to 5 different I/Os available ' Specifically designed to optimize operations as well as Services actions: ' Redundant data storage with SensorApplicationMemory (data are saved both on primary and transmitter) maintenance / replacement without information losses ' Based on ABB Common Platform (i.e. same look&feel of other devices pressure, temperature,flow, etc.) Unique electronics for all the 4-wires flow devices (EMF, Thermal Mass, Coriolis) Advanced functionalities ' ABB CoriolisMaster provides state-of-the-art optional features: ' VeriMass: fingerprint verification of measuring tubes integrity and possible erosion issues ' DensiMass: real-time concentration measurement of liquid solutions ' FillMass: fill functionality for slow filling procedures High Accuracy Option ABB CoriolisMaster FCB1xx and FCB4xx December 4, 2017 Slide 35 ' CoriolisMaster has been successfully tested and certified in accordance with OIML R117
' Both process (FCB) and hygienic (FCH) versions are covered by the certification ' The new option grants enhanced performances:
' Density accuracy: 0.5 g/l ' Improved zero point stability better accuracy at lower flowrates ' Improved accuracy on the volume flow: 0.11% of reading ' New approval allows the usage for Custody transfer of liquids other than water (MI-005) Definitions Custody Transfer Applications December 4, 2017 Slide 36 Overview ' Custody transfer, also referred as fiscal metering, is a typical practice in O&G any time liquids or gases are traded between different parties (e.g. two different operators) ' Custody transfer is characterized by a payment, which is function of the amount of the material exchanged. ' Accuracy in the measurement is of paramount importance since even very little errors can generate consistent losses for one of the parties involved ' Typically countries regulate Custody Transfer since it includes also government taxation and agreements between parties ' Specific standards have been also developed by relevant organizations (e.g. API, AGA, GERG, GOST, ISO, etc.). Components ' Custody transfer metering stations are highly engineered systems comprising: ' Flow meters ' Pressure and temperature transmitters ' Gas chromatographs and quality analyzers ' Provers for meter calibration ' Flow computers ' Metering supervisory software Flow Computers Custody Transfer Applications December 4, 2017 Slide 37 ' Flow computers main function is to provide accurate measurement, archiving and reporting functionalities for the fluid transferred between the parties
' Historical data can provide relevant information for the actual and prior quantities reported: ' To apply corrections to measurement errors ' To update calculations in case of standards changes ' To check if the measurement equipment is outside the accuracy tolerances or has incorrectly recorded some measurement parameters ' Data allows parties with to independently verify the correctness of the reported quantities. Accuracy and security with state-of-the-art technology ABB Flow-X December 4, 2017 Slide 38 Main Features ' Flow-X is designed for single stream installations 1 Flow Computer per flow meter ' Accuracy: ' Analog input accuracy is better that 0.002% ' Data processing and storage based on 64-bit resolution to avoid any loss of accuracy. ' Security (prevention of unauthorized access)
' Traceability & Auditability
' Flow-X is certified for the most accurate calculations for Oil and Gas:
' API, AGA, GERG, GPA, ISO, etc A unique spare part for different configurations Conclusions December 4, 2017 Slide 39 ' Flow metering is one of the most complex measurement practices in the process industry ' Large availability of different measuring principles ' Operating conditions and requirements may make inadequate techniques otherwise tailored for a specific measurement ' A vendor with the largest portfolio can provide un-biased support and effective suggestions for the implementation of the proper solutions ' With its complete offering and skilled network of technicians and specialists, ABB can act as an ADVISOR, helping you and your Customer in identifying the proper solution for each application. ' ABB is focused in making easier operators job also after meter installation common meter design and compatibility allow minimizing the efforts and required expertise for maintenance as well as for components to be kept at stock. ' ABB is committed in meeting end-user requirements in terms of TotEx (CapEx + OpEx) providing solutions tailored to optimize the whole lifecycle cost


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