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AGA7 http://www.xivix.ca/AGA_ALL/AGA/ENG/AGA7.htm 1 de 8 21/06/2008 02:02 p.m. AGA #7: Turbine Meter Gas Volume Calculation for Pulse, Frequency and Analog Input (2002) standard Function Description This function is used to calculate Turbine Meter Gas Volumes for Pulse, Frequency and Analog types of inputs. It uses the AGA Report #7 (2002) standard. The calculation block also requires a list of input constants and provides the required outputs to meet the reporting standard. Some of the input constants can be created from other function blocks, such as from AGA#8, while others can be manually entered or downloaded from a host SCADA system. See below for examples and the list of inputs and outputs: The additional parameters EN and ENO can be configured. Complementary Functions Other function blocks complement this function when used in conjunction with the AGA#7 block.: The AGA#8 can be used to calculate the Compressibility Factor of Natural Gas and Related Hydrocarbon Gases. The Totalizer function can be used to total the volume flow rate output from AGA#7. Representation in FBD Representation: This is an example of using AGA#7 Turbine Meter Gas Calculation with AGA#8 and the Totalizer function block. Representation in LD Representation: Representation in IL Representation: CAL AGA7_Instance (METER, TFLOW, PFLOW, TBASE, PBASE, PARA, ZFLOW, ZBASE, UNITS, TIMEBASE, QF, QB, PMR, TMR, ZMR) Representation in ST Cl ick to bu y N OW ! PD F-XChange w ww.docu-track .co m C lic k t o b uy N OW ! PD F-XChange w ww.docu-track .co m http://www.docu-track.com/buy/ http://www.docu-track.com/buy/ AGA7 http://www.xivix.ca/AGA_ALL/AGA/ENG/AGA7.htm 2 de 8 21/06/2008 02:02 p.m. Representation: AGA7_Instance (METER, TFLOW, PFLOW, TBASE, PBASE, PARA, ZFLOW, ZBASE, UNITS, TIMEBASE, QF, QB, PMR, TMR, ZMR) Parameter Description For a definition of each parameters units, refer to the "Unit Conversion Constants and Universal Constants" section below. Note: The defined (Default) value will be used, if the input constant is configured with a wrong value. The following table describes the AGA#7 input parameters: Parameter Type Comment Units USC Metric METER REAL Meter Input (Pulse, Freq or Analog) TFLOW REAL Flowing Temperature meter °F °C PFLOW REAL Flowing Pressure meter psig kPag TBASE REAL Base Temperature °F °C PBASE REAL Base Pressure psia kPaa PARA Para_AGA7 AGA#7 input attributes (see Para_AGA7 table below for moredetail) ZFLOW REAL Z Flow (from AGA#8) ZBASE REAL Z Base (from AGA#8) UNITS INT Units (0=SI Metric, 1=US(Default)) TIMEBASE UINT Timebase for Output (0=Hourly, 1=Daily(Default)) The following table describes the AGA#7 input attributes for [Para_AGA7]: Parameter Type Comment Units USC Metric MTRTYP REAL Meter Type (1=Pulse,2=Freq,3=Analog(Default)) MCF REAL Meter Correction Factor KFAC REAL K Factor, pulses/unit volume PATMOS REAL Atmospheric Pressure psia kPaa The following table describes the AGA#7 output parameters: Parameter Type Comment Units USC Metric QF REAL Flow Rate Instantaneous ft3/hr m3/hr QB REAL Flow Rate @ base T&P conditions ft3/hr m3/hr PMR REAL Pressure Multiplier Ratio TMR REAL Temperature Multiplier Ratio ZMR REAL Compressibility Multiplier Ratio Definition of Terms kPaa kilopascals atmospheric kPag kilopascals gauge psia pounds-force/sq.in atmospheric psig pounds-force/sq.in gauge Turbine Meter Calculation Theory for Cl ick to bu y N OW ! PD F-XChange w ww.docu-track .co m C lic k t o b uy N OW ! PD F-XChange w ww.docu-track .co m http://www.docu-track.com/buy/ http://www.docu-track.com/buy/ AGA7 http://www.xivix.ca/AGA_ALL/AGA/ENG/AGA7.htm 3 de 8 21/06/2008 02:02 p.m. AGA Report #7 - 2002 PURPOSE This document contains the proposed calculations for turbine meters or any other linear meter i.e.; (positive displacement, ultrasonic, coriolus, vortex shedding meter) used in natural gas applications. TERMS OF REFERENCE All equations are based on American Gas Association Report No. 7. This AGA 7 handles the volume and mass flow calculations for a natural gas fluid. For a gas turbine meter AGA 7 calculates the flow rate of natural gas determined at flowing and base temperature/pressure conditions. BASE CONDITIONS (Pb, Tb) The base conditions for the flow measurement of natural gases are defined in the United States in customary (USC) units is a pressure of 14.73 pounds per square inch absolute (101.560 kilopascals) at a temperature 60.0°F (15.56 °C ). According to the International Standards Organization, base conditions are defined as a pressure of 14.696 (101.325 kilopascals) at a temperature of 59°F (15.0°C) FLOW MEASUREMENT EQUATION Flow Rate at Flowing Conditions The volumetric flow rate at flowing conditions can be calculated using the following equation: Case – Meter with pulse output Case – Meter with frequency output Case – Meter with analog output Case – Meter with volume output Where: Cl ick to bu y N OW ! PD F-XChange w ww.docu-track .co m C lic k t o b uy N OW ! PD F-XChange w ww.docu-track .co m http://www.docu-track.com/buy/ http://www.docu-track.com/buy/ AGA7 http://www.xivix.ca/AGA_ALL/AGA/ENG/AGA7.htm 4 de 8 21/06/2008 02:02 p.m. Qf = flow rate at flowing conditions KF = meter K factor in pulses per unit volume Cuf = units conversion factor Cl ick to bu y N OW ! PD F-XChange w ww.docu-track .co m C lic k t o b uy N OW ! PD F-XChange w ww.docu-track .co m http://www.docu-track.com/buy/ http://www.docu-track.com/buy/ AGA7 http://www.xivix.ca/AGA_ALL/AGA/ENG/AGA7.htm 5 de 8 21/06/2008 02:02 p.m. Flow Rate at Base Conditions The volumetric flow rate at base (standard) conditions can be calculated using the following equation: Where: Qf = flow rate at flowing conditions Pf = absolute pressure at flowing conditions Pb = absolute pressure at base conditions Tb = absolute temperature at base conditions Tf = absolute temperature at flowing conditions Zf = Compressibility of gas at flowing conditions. Zb = Compressibility of gas at base conditions Pressure Multiplier The pressure multiplier can be calculated using the following equation: Where: Pf = Static gauge pressure of the fluid at flowing conditions. Pbar = Atmospheric pressure Pb = Base or reference pressure Temperature Multiplier The temperature multiplier can be calculated using the following equation: Where: Tf = Absolute temperature of the fluid at flowing conditions. Tb = Absolute base temperature Compressibility Multiplier The compressibility multiplier can be calculated using the following equation: Where: Cl ick to bu y N OW ! PD F-XChange w ww.docu-track .co m C lic k t o b uy N OW ! PD F-XChange w ww.docu-track .co m http://www.docu-track.com/buy/ http://www.docu-track.com/buy/ AGA7 http://www.xivix.ca/AGA_ALL/AGA/ENG/AGA7.htm 6 de 8 21/06/2008 02:02 p.m. Zf = Compressibility of gas at flowing conditions. Zb = Compressibility of gas at base conditions These gas compressibility values may be determined from the AGA 8 calculations. Cl ick to bu y N OW ! PD F-XChange w ww.docu-track .co m C lic k t o b uy N OW ! PD F-XChange w ww.docu-track .co m http://www.docu-track.com/buy/ http://www.docu-track.com/buy/ AGA7 http://www.xivix.ca/AGA_ALL/AGA/ENG/AGA7.htm 7 de 8 21/06/2008 02:02 p.m. Mass Flow Rate The mass flow rate at base (standard) conditions can be calculated using the following equation: The mass flow rate at flowing conditions can be calculated using the following equation: Where: Qf = flow rate at flowing conditions Qb = flow rate at base conditions b = density at base conditions t,p = density at flowing conditions Unit Conversion Constants and Universal Constants Variable(s) U.S.IP Metric SI P1, P2, Pf, Pb psia psia bar Pa t,p, b lbm/ft3 lbm/ft3 kg/m3 kg/m3 qm lbm/hr lbm/hr kg/hr kg/s qv, Qb ft3/hr ft3/hr m3/hr m3/s Tf, Tb, Tr °F °F °C °K R 10.7316 10.7316 0.0831451 8314.51 psia-ft3/lbmol-°F psia-ft3/lbmol-°F bar-m3/kmol-°C J/kmol-°K Mrair 28.9625 28.9625 28.9625 28.9625 CALCULATION BLOCK MAPPING Meter Run Configuration Inputs 1) Selected units for the calculation · USC Units · Metric Units 2) Pressure Base (Pb) 3) Temperature Base (Tb) 4) Atmospheric pressure (Pbar) 5) K Factor (KF) 6) Meter Factor (MF) Cl ick to bu y N OW ! PD F-XChange w ww.docu-track .co m C lic k t o b uy N OW ! PD F-XChange w ww.docu-track .co m http://www.docu-track.com/buy/ http://www.docu-track.com/buy/ AGA7 http://www.xivix.ca/AGA_ALL/AGA/ENG/AGA7.htm 8 de 8 21/06/2008 02:02 p.m. Variable Inputs 7) Flowing Temperature (Tf) 8) Flowing Static Pressure (Pf) 9) Compressibility Factor at base conditions (Zb) 10) Compressibility Factor at flowing conditions (Zf) 11) Density at base conditions ( b) 12) Density at flowing conditions ( t,p) Calculated Outputs 1) Volume flow rate at base conditions (Qv) 2) Mass flow rate (qm) CALCULATION APPROACH The general outline of the solution procedure for linear meters is as follows: A. Calculate the volume flow rate at flowing conditions - Qf B. Calculate absolute flowing pressure - Pf C. Calculate pressure multiplier D. Calculate temperature multiplier E. Calculate compressibility multiplier F. Calculate volume flow rate at base conditions - Qb Cl ick to bu y N OW ! PD F-XChange w ww.docu-track .co m C lic k t o b uy N OW ! PD F-XChange w ww.docu-track .co m http://www.docu-track.com/buy/ http://www.docu-track.com/buy/
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