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operating facility, there might only be a very limited number of “custody transfer” meters that are equipped for testing and calibration under real operating conditions. As an example, Table 3-3 provides a listing of different meter types, their applicable fluid medium, and a brief description of their operating principles. The table also lists manufacturers’ specified instrument errors, as provided in a survey conducted by the EU-ETS Support Group (ETSG, 2007). The information provided is an indication of potential error ranges and not the expected uncertainty ranges obtained in practice. Appendix B provides additional details about the manufacturers’ recommendations for the installation, calibration, and maintenance of these flow meters. The error levels cited refer primarily to random errors that are observed under ‘ideal’ laboratory conditions and that decrease with repeated measurements. They do not properly account for systematic errors (or bias) where the errors are due to improper installations, inadequate calibrations, or devices drift, as discussed above. However, these manufacturers’ specified measurement errors might not be attainable due to the practical operational limitations of the facility. In most O&G industry facilities, detailed inspections, maintenance, and recalibration of process control flowmeters are possible only once every few years when process units are shut down for scheduled turnaround. Table 3-3. Compilation of Specifications for Common Flow Meters a METER TYPE Rotary meter (Expected life span: 25 years) Turbine flow meter (Expected life span: 25 years) Bellows meter (Expected life span: 25 years) MEDIUM TECHNICAL DESCRIPTION MANUFACTURERS’ REPORTED ERRORS B Gas The rotary flow meter is a type of positive 0-20% of the measurement displacement (PD) flow meter that is widely used for range: 3% utility measurements of gas flow. Rotary flow meters have one or more rotors that are 20-100% of the used to trap the fluid. With each rotation of the rotors, measurement range: 1.5% a specific amount of fluid is captured. Flow rate is proportional to the rotational velocity of the rotors. Rotary meters are used for industrial applications. Gas Gas Turbine flow meters have a rotor that spins in proportion to flow rate. Many of those used for gas flow are called axial meters. Axial turbine meters have a rotor that revolves around the axis of flow. Axial meters differ according to the number of blades and the shape of the rotors. Turbine meters are used as billing meters to measure the amount of gas used at commercial buildings and industrial plants. The bellow gas meter performs volumetric measurement via its bellows. The measurements are based on the principle that the flexible bellows is periodically filled and emptied. A major problem with the bellows system is the residue in the pipe. The internal mechanisms fail to perform their tasks due to such residue, causing the meter to dysfunction and failing to perform a sound measurement. 0-20% of the measurement range: 3% 20-100% of the measurement range: 1.5% 0-20% of the measurement range: 6% 20-100% of the range: 4% Pilot Version, September 2009 3-10
Table 3-3. Compilation of Specifications for Common Flow Meters, a continued METER TYPE Venturi meter (Expected life span: 30 years) Orifice meter (Expected life span: 30 years) Ultrasonic meter (Expected life span: 15 years) Coriolis meter (Expected life span: 10 years) MEDIUM TECHNICAL DESCRIPTION MANUFACTURERS’ REPORTED ERRORS B Gas and Venturi meters are another example of differential 20-100% of the Liquid pressure flow meters, as described under orifice measurement range: 1.5% meters above. In this case, the primary element is a Venturi flow nozzle. Venturis are especially suited to highspeed flows. They are also used for custody Gas and Liquid Gas and Liquid Gas and Liquid transfer of natural gas. Orifice meters belong to the category of differential pressure flow meters that consist of a differential pressure transmitter, together with a primary element, such as the orifice plates. The orifice plates place a constriction in the flow stream, and the differential pressure transmitter measures the difference in pressure upstream and downstream of the constriction. The transmitter or a flow computer then computes flow using Bernoulli’s theorem. Orifice plates are the most widely used type of primary elements. Their disadvantages are the amount of pressure drop caused, and the fact that they can be knocked out of position by impurities in the flow stream. Orifice plates are also subject to wear over time. There are two main types of ultrasonic flow meters: transit time and Doppler. The transit time meter has both a sender and a receiver. It sends two ultrasonic signals across a pipe at an angle: one with the flow, and one against the flow. The meter then measures the “transit time” of each signal. The difference between the transit times with and against the flow is proportional to flow rate. Doppler flow meters rely on having the signal deflected by particles in the flow stream and the frequency shift in proportion to the mean fluid velocity. Coriolis flow meters contain one or more vibrating tubes. These tubes are usually bent, although straight-tube meters are also available. The fluid to be measured passes through the vibrating tubes. It accelerates as it flows toward the maximum vibration point, and slows down as it leaves that point. This causes the tubes to twist. The amount of twisting is directly proportional to mass flow. Position sensors detect tube positions. 30-100% of the measurement range: 1.5% 1-100% of the measurement range: 0.5% 1-100% of the maximum measurement range: 1% Pilot Version, September 2009 3-11
Page 1 and 2: Prepared by the LEVON Group, LLC an
Page 3 and 4: Table of Contents SECTION Page FORE
Page 5 and 6: List of Tables SECTION Page 2-1 Ove
Page 7 and 8: FOREWORD The global oil and natural
Page 9 and 10: DOCUMENT AT A GLANCE This document
Page 11 and 12: 1.0 INTRODUCTION Policymakers use e
Page 13 and 14: The Intergovernmental Panel on Clim
Page 15 and 16: 2.0 SOURCES OF UNCERTAINTY There ar
Page 17 and 18: Table 2-1. Overview of Methods Used
Page 19 and 20: the uncertainty associated with cur
Page 21 and 22: d. Data processing uncertainty Typi
Page 23 and 24: d. Material Balance For some emissi
Page 25 and 26: 3.0 OVERVIEW OF MEASUREMENT PRACTIC
Page 27 and 28: 3.1 Flow Measurement Practices Cont
Page 29 and 30: All these factors should be assesse
Page 31 and 32: Table 3-1. Example of FFMS Combined
Page 33: 3.2 Uncertainties of Flow Measureme
Page 37 and 38: EXHIBIT 3-3: FACTORS TO CONSIDER WH
Page 39 and 40: 3.3.2 Quantifying Sampling Precisio
Page 41 and 42: Table 3-4. Summary of Selected Carb
Page 43 and 44: 3.5 Heat Content Determination The
Page 45 and 46: 3.5.2 Computational Methods Heating
Page 47 and 48: using standard methods, non-standar
Page 49 and 50: 0.6 0.4 0.2 Error 0 -0.2 -0.4 -0.6
Page 51 and 52: s ± t × (Equation 4-1) n where s
Page 53 and 54: 4.2.1 Propagation Equations There a
Page 55 and 56: For two terms that might be correla
Page 57 and 58: EXHIBIT 4-1: Uncertainty Example fo
Page 61 and 62: Further guidance for assigning unce
Page 63 and 64: 4.4 Quantifying Measurement Uncerta
Page 69 and 70: Are the data based on a single poin
Page 71 and 72: Two methods are compared. The first
Page 73 and 74: . EXHIBIT 4-6: Uncertainty Example
Page 77 and 78: Table 4-13 shows the uncertainty in
Page 79 and 80: Table 4-13. Comparison of Annual Em
Page 81 and 82: • The evolution of activity and e
Page 83 and 84: These guidelines concentrate solely
Page 85 and 86:
(Reprinted from the API Compendium)
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Table 5-2. Onshore Oil Field (High
Page 89 and 90:
associated with them are assigned b
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Table 5-4. Onshore Oil Field (High
Page 93 and 94:
5.2.4 Propagating Assymetric Uncert
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U( rel) = U( rel) + U( rel) + U( re
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Coke burn rate approach (Equation 5
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Wt% C ∑ lbmole x lbmole C 12 lb C
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The CO 2 emissions are calculated u
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GHG Emissions, tonnes/yr 60,000 50,
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vast majority of the uncertainty fo
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6.0 REFERENCES AGA, 2008, Greenhous
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The Alberta Energy and Utilities Bo
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Appendix A GLOSSARY OF STATISTICAL
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Page 115 and 116:
Page 117 and 118:
APPENDIX B LIST OF INDUSTRY MEASURE
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Chapter 2.8B Establishment of the L
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Chapter 11.5.3 Chapter 12.1.1 Chapt
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Chapter 19.4 Chapter 20.1 RP 85 RP
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ISO 8222:2002 ISO 8697:1999 ISO 902
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ISO 7194:2008 Measurement of fluid
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ASTM D4292 ASTM D4892 ASTM D5002 AS
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APPENDIX C OPERATING CONDITIONS, IN
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Appendix C OPERATING CONDITIONS, IN
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Appendix D SELECT MEASUREMENT METHO
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c. ASTM UOP539-97, Refinery Gas Ana
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interference between known componen
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maintained over the room temperatur
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APPENDIX E UNITS CONVERSION
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− Gasoline density (average) = 0.
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Appendix F UNCERTAINTY ESTIMATION D
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The uncertainty for the heaters/reb
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∑ 2 U ( abs) = U( abs) ∑(Wt%C)
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Combining the fuel usage for the tw
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Uncertainty Estimate of CO 2 e Emis
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U ( abs) = ( U ( abs) + U ( abs) +
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E E CO2e 219 tonne CO ⎛ 2 0.0108
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E CO 2 6 500× 10 scf gas lbmole ga
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• Fuel Economy (miles per gallon)
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Upper: U ( abs) = (U( abs) +U( abs)
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default CH 4 content is 5.53% from
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Uncertainty Estimate of CO 2 e Emis
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( ) Urel ( ) = Urel ( ) = Urel ( )
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Uncertainty Estimate for CH 4 and C
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specific mole % for CH 4 and CO 2 i
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E CO2 0.07239 tonne CH 4 tonne mole
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U ( rel) = U( rel) +U( rel) +U( rel
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Table F-14. Fugitive Emission and U
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U ( abs) = (U( abs) +U( abs) +U( ab
Page 185 and 186:
Table F-15. Onshore Oil Field (High
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