PROJECT NO. PO. 4500098732 / 10 / 01.01.2018 Supply of PF Process Calculation Spreadsheet (Excel Forma) DOCUMENT TITLE Small Bore Orifice Sizing Calculation For Gas Services as per ASME-MFC-14M-2001 DATE REV. REASON FOR REVISION PREP. CHKD. APPD. APPD. DOC. NO. CEPL-PC-001-CA-009 PAGE 1 OF 7 REV. 0
DOC. NO. CEPL-PC-001-CA-009 REV. 0 PROJECT NO. PO. 4500098732 / 10 / 01.01.2018 PAGE NO. 2 of 7 BASIS Calculation Objective Calculation Basis Calculation Methodology Assumptions Software used Conclusions References Attachments
DOC. NO. PROJECT NO. CEPL-PC-001-CA-009 REV. 0 PO. 4500098732 / 10 / 01.01.2018 PAGE NO. 3 of 7 SCHEMATIC: q m P 1, T 1 P 2 The purpose of this workbook is to calculate the gas flowrate from a small-bore orifice meter using the equations defined in ASME MFC-14M-2001. The equations are only valid under the following conditions Corner Taps: 0.1 < β < 0.8 and 12 mm < D < 40 mm Flange Taps: 0.15 < β < 0.7 and 25 mm < D < 40 mm D < 40 mm d > 6 mm NRe > 1000 A β of between 0.3 and 0.7 is practical; below this, the pressure drop is too large for economical operation, and above this, the pressure drop is not large enough for an accurate reading. SCHEMATIC: ORIFICE TAG NO. LINE NO. P&ID NO. DESCRIPTION T 50 oc Operating temperature P 1 10 kg/cm2g Upstream pressure P 2 5 kg/cm2g Downstream pressure ϒ P C 1.4 350 bara Ratio of specific heat, C P /C V Critical pressure T C -10 oc Critical temperature P r 0.03 Reduced pressure T r 1.23 Reduced temperature F K 0.98 Correction factor κ 1.372 Isentropic exponent Flow is sub-critical. Q μ M Z D Tap type 1 MMSCFD Gas flow rate 0.01 cp Gas viscosity 29 kg/kmol Gas molecular weight 1 Gas compressibility factor 36 mm Pipe ID Corner
DOC. NO. PROJECT NO. CEPL-PC-001-CA-009 PO. 4500098732 / 10 / 01.01.2018 REV. 0 PAGE NO. 4 of 7 CALCULATION BASIS / EQUATIONS: Please refer attachment 1. T NTP P NTP ρ kg/m 3 NTP 1.206 Density at NTP conditions T STP P STP 0.00001 Gas viscosity, Pa.s 50.0 Temperature, o C 9.8 Upstream pressure, barg 490.3325 P, Differential pressure measured across tappings, kpa Pipe Inside diameter, mm 0 o C 0.987 atm ρ STP 1.277 kg/m 3 RESULTS: 0.418 Flow rate, kg/s 0.0358 Flow rate, m 3 /s 11.6780 Gas density, kg/m 3 4.9 71.0982125 36 Downstream pressure, barg 20 o C Temperature at NTP conditions 1 atm Pressure at NTP conditions P, Differential pressure measured across tappings, psi 0.856 ϵ, Expansibility factor 1479896 Re D, Reynolds number 35.2014 m/s, Pipe velocity Corner Tap type 0.5289 0.6039 β, Beta ratio C, Coefficient of discharge 409.7 59.4 w, Overall pressure loss caused by orifice plate, kpa w, Overall pressure loss caused by orifice plate, psi 19.040 0.75 d, mm, Orifice internal diameter d, inch, Orifice internal diameter Temperature at STP conditions Pressure at STP conditions Density at STP conditions CONCLUSIONS:
DOC. NO. CEPL-PC-001-CA-009 REV. 0 PROJECT NO. PO. 4500098732 / 10 / 01.01.2018 PAGE NO. 5 of 7 Small Bore Orifice Sizing Calculation For Gas Services as per ASME-MFC-14M-2001 ATTACHMENT 1: CALCULATION BASIS / EQUATIONS The equations implemented in the spreadsheet are sourced from ASME MFC-14M-2001 and are given below. The notation is given below. C is the discharge coefficient. D1 has to be supplied in m D1 and D2 are the diameter of the pipe and orifice respectively (m) A1 and A2 are the cross sectional areas of the pipe and orifice (m 2 ) ΔP is the pressure drop across the orifice (Pa) P1 and P std are the upstream pressure and standard pressure T and T std are the gas temperature and standard temperature is the ρ is the gas (kg/m 3 ) μ is the gas viscosity (Pa s) V1 is the liquid velocity in the pipe (m/s) R e1 is the Reynolds Number in the pipe β is the diameter ratio MW is the molecular weight of the gas (kg/mol) R is the universal gas constant (8314 J/kmol/K) γ is the specific heat ratio e is the gas expansivity Q is the volumetric flowrate (m 3 /s) Q std is the volumetric flowrate at standard conditions (m 3 /s)
DOC. NO. CEPL-PC-001-CA-009 REV. 0 PROJECT NO. PO. 4500098732 / 10 / 01.01.2018 PAGE NO. 6 of 7 ISENTROPIC EXPONENT CORRECTION FACTOR, F K (Reference: Flow Measurement Engineering Handbook, 3rd edition, Richard W. Miller)
DOC. NO. CEPL-PC-001-CA-009 REV. 0 PROJECT NO. PO. 4500098732 / 10 / 01.01.2018 PAGE NO. 7 of 7 EQUATIONS USED FOR CHOKED FLOW: