Program for Sizing 2 Phase Relief Devices
InstructionsINSTRUCTION FLOWCHART FOR USING THE
2PhaseRelief0000.XLS WORKSHEET(USER MANUAL IS ALSO AVAILABLE)
USE FILE, SAVE AS OPERATIONS TO SAVE A COPY WITH THE DESIRED
NAME & LOCATIONCOMPLETE THE CALCULATION COVER SHEET, AND
CALCULATION CONTENTS SHEETUSE THE DECISION FLOWCHART TO DETERMINE
THE APPROPRIATE WORKSHEET FOR YOUR CALCULATIONENTER INPUT DATA ETC.
INTO THE RENAMED SHEETIF THE WORKSHEET HAS A SOLVE BUTTON, PRESS
ITANY MORE CALCULATIONS?YESENSURE THAT THIS IS THE SOURCE PROGRAM
FILE (2PhaseRelief0000.xls)GO TO THE APPROPRIATE WORKSHEET AND USE
THE EDIT, MOVE OR COPY SHEET COMMANDS TO CREATE A COPY OF THE
WORKSHEETRENAME THIS COPIED WORKSHEETNODELETE ALL UNUSED WORKSHEETS
(INCLUDING THIS ONE)ENSURE CALCULATION COVER AND CONTENTS
WORKSHEETS ARE COMPLETEDSAVE AND PRINT ENTIRE WORKBOOKSTARTSTOP
Calc - CoverUSER MUST INPUT THE NUMBER OF SHEETS IN CALC
>N3A.100A(10/2000)SHEET 1 OF NASTONE & WEBSTERA Shaw Group
CompanyJ.O./W.O. No:J.O./W.O. NoCLIENT:ClientCALCULATION COVER
SHEETPROJECT:ProjectLOCATION:LocationTITLE:EQUIP/DWG.No:CALCULATION
No:Calc No.OBJECTIVE:INPUTS:ASSUMPTIONS:ASSUMPTIONS REQUIRING
CONFIRMATION:BASIS OF CALCULATION, METHOD, OR SOFTWARE TO BE
USED:Two phase relief calculation software based on API RP-520, 7th
Edition, Jan 2000, Appendix DCONCLUSION:DATA CONFIRMATION
REQUIREDYNREVISION0123456PREPARER / DATECHECKER / DATEC:\Documents
and Settings\i00410\My Documents\Copy of 2PhaseRelief0000.xls
Calc - Contents3A.100B(10/2000)SHEET 2 OF NASTONE & WEBSTERA
Shaw Group CompanyJ.O./W.O. No:J.O./W.O. NoCLIENT:ClientCALCULATION
TABLE OF CONTENTSPROJECT:ProjectLOCATION:LocationCALCULATION
NUMBER:Calc No.TITLEPAGEC:\Documents and Settings\i00410\My
Documents\Copy of 2PhaseRelief0000.xls
Decision FlowchartDECISION FLOWCHART FOR SIZING TWO-PHASE RELIEF
DEVICES(Method as per API RP-520, 7th Edition, January 2000,
Appendix D)Source Program: 2PhaseRelief0000STONE &
WEBSTERSource Program Last Edited: 30/05/01, 16:33
&RDate Printed: &DSHOW / HIDE APPLICABILITY
CONDITIONS2-Phase FlowAre applicability conditions of worksheet
"Non-condensable Gas Present" satisfied?Defined as:Liquid and gas
either at inlet, outlet, or within relieving device. No
solid.NON-CONDENSABLE GAS PRESENTSHOW / HIDE APPLICABILITY
CONDITIONSAre applicabilityconditions of worksheet"2 Phase Inlet,
Close Boiling"satisfied?YESYESSIMPLE FLASHING2 PHASE INLETNOYESIs
non-condensable gas present?Does flashing occur?YESNOSHOW / HIDE
APPLICABILITY CONDITIONSVapour / gas present at inlet?YESNOAre
applicabilityconditions of worksheet"Liquid Inlet,
CloseBoiling"satisfied?NOYESSUB-COOLED LIQUID
INLETNON-FLASHINGNONOOnlysaturated water / steam present?Steam
present at inlet?YESYESNONOUse Fig. 11-2 of ASME VIII, Appendix
11Treat as dry saturated steam relief (single phase)MANDATORY ASME
CODE"2 Phase Inlet, Close Boiling""Non-condensable Gas
Present""Liquid Inlet, Wide Boiling""Liquid Inlet, Close Boiling""2
Phase Inlet,Non-flashing""2 Phase Inlet, Wide Boiling"Applicability
conditions for "Non-condensable Gas Present":
1. Two phase flashing flow with a noncondensable gas or both a
condensable vapour and noncondensable gas
AND
2. Solubility of the noncondensable gas in the liquid must not
be appreciable (else use condensable gas flashing procedure)
AND
3. EITHERFlashing multi-component systems with nominal boiling
range (highest to lowest component) < 150F (80oC)ORFlashing
single component systems where Tr < 0.9 or Pr < 0.5
AND
4. Molar fraction of the vapour phase that is non-condensable
gas, at the inlet > 0.1 AND
5. Contains less than 0.1 weight % hydrogenApplicability
conditions for "2-Phase Inlet, Close Boiling":
1. Two phase at PRV inlet, flashing through PRV.
AND
2. EITHERFlashing multi-component systems with nominal boiling
range (highest to lowest component) < 150F (80oC)ORFlashing
single component systems where Tr < 0.9 or Pr <
0.5Applicability conditions for "Liquid Inlet, Close Boiling":
1. Only subcooled or saturated liquid at PRV inlet, either
flashing or non-flashing through PRV.
AND
2. Turbulent flow
AND
3. EITHERFlashing multi-component systems with nominal boiling
range (highest to lowest component) < 150F (80C)ORFlashing
single component systems where Tr < 0.9 or Pr < 0.5
Liquid Inlet, Wide BoilingCALCULATION SHEET - TWO PHASE
RELIEFSheet No.? OF NClientClientJob No.J.O./W.O. NoProject /
PlantProjectCalc No.Calc
No.LocationLocationDateSystemByTimeApplicability"Liquid Inlet, Wide
Boiling"1. Only subcooled or saturated liquid at PRV inlet, either
flashing or non-flashing through PRV. AND2. Turbulent Flow. AND3.
EITHER Flashing multi-component systems with nominal boiling range
(highest to lowest component) > 150F (80C)OR Flashing single
component systems where Tr > 0.9 or Pr > 0.5Input DataQRelief
Ratekg/h0.00USgal/minPsetPRV set pressurebarg0.0psig%OverPPRV
allowable percentage overpressure%0%P0Relieving pressure at the PRV
inlet1.01bara14.7psiaT0Relieving temperature at the PRV
inletoC491.4Rrl0Liquid density at PRV
inletkg/m30.00lb/ft3PsSaturation (vapour) pressure (or bubble
point) corresponding to T0bara0.0psiaP990% of
Ps0.00bara0.0psiax9Mass fraction that is vapour phase at P9
(isenthalpic flash from T0, x0, Ps)-0-rv9Density of vapour phase at
P9 (isenthalpic flash from T0, x0, Ps)kg/m0.0000lb/ftrl9Density of
liquid at P9 (isenthalpic flash from T0, x0,
Ps)kg/m0.00lb/ftPaBackpressurebara0.0psiaCalculations(Method as per
API RP-520, 7th Edition, January 2000, Appendix D)r9Homogeneous
dens. at 90% of Ps (isenthalpic flash from T0, x0,
Ps)0.0kg/m30.00lb/ft3Leung omega factorws0.000transition saturation
pressure ratiohst0.000critical pressure
ratiohc0.000hs0.000ha0.000subcooling region (low subcooling if hs
> hst)00.00criticallity (critical if ha < hc)00LOW
SUBCOOLINGHIGH SUBCOOLINGwhere P = Ps if critical, P = Pa if
subcriticalGhighsub0lb/s.ftwhere h = hc if critical, h = ha if
subcriticalGlowsub0lb/s.ftRelief rate (mass
flux)G0kg/s.m0lb/s.ftValve discharge coefficient (prelim. 0.65 for
subcooled, 0.85 for sat.- TBC)Kd0.65% gauge back
pressure%gPb0.0Back pressure correction factorKb0.000Rupture disc
combination factor - use 1 for no rupture discKc1.0000Required
effective PSV discharge areaA0.00cm0.000inPSV
inlet0mm0inDesignation (Always use ballanced bellows valve for 2
phase relief)00PSVoutlet0mm0inOrifice area (per
valve)0.000cm0inNumber of operational valves00Rated flow - all
valves0kg/h0USgal/minSource Program: 2PhaseRelief0000STONE &
WEBSTERSource Program Last Edited: 30/05/01, 16:33C:\Documents and
Settings\i00410\My Documents\Copy of 2PhaseRelief0000.xlsvalve
code:0"Dummy" variables
used:nclowsub0.7543471946nlowsub0Phighsub0
Click Here to Solve for hcReturn to Decision Flowchart
Liquid Inlet, Close BoilingCALCULATION SHEET - TWO PHASE
RELIEFSheet No.? OF NClientClientJob No.J.O./W.O. NoProject /
PlantProjectCalc No.Calc
No.LocationLocationDateSystemByTimeApplicability"Liquid Inlet,
Close Boiling"1. Only subcooled or saturated liquid at PRV inlet,
either flashing or non-flashing through PRV. AND2. Turbulent Flow.
AND3. EITHER Flashing multi-component systems with nominal boiling
range (highest to lowest component) < 150F (80C)OR Flashing
single component systems where Tr < 0.9 or Pr < 0.5Input
DataQRelief Ratekg/h0.00USgal/minPsetPRV set
pressurebarg0.0psig%OverPPRV allowable percentage
overpressure%0%P0Relieving pressure at the PRV
inlet1.01bara14.7psiaT0Relieving temperature at the PRV
inletoC491.4Rrl0Liquid density at PRV inletkg/m30.00lb/ft3CpLiquid
specific heat at constant pressure at the PRV
inletkJ/kgK0.000Btu/lbRPsSaturation (vapour) pressure (or bubble
point) corresponding to T0bara0.0psiarvsDensity of vapour at
Ps,T0kg/m0.0000lb/ftrlsDensity of liquid at Ps,
T0kg/m0.00lb/fthvsSpecific enthalpy of vapour at Ps,
T0kJ/kg0.0Btu/lbhlsSpecific enthalpy of liquid at Ps,
T0kJ/kg0.0Btu/lbPaBackpressurebara0.0psiaCalculations(Method as per
API RP-520, 7th Edition, January 2000, Appendix D)vvlsDifference
between the vapour and liquid specific volumes at Ps,
T00.000m3/kg0.00ft3/lbhvlsLatent heat of vaporisation at Ps
(difference between the vapour and0kJ/kg0Btu/lbliquid specific
enthalpies at Ps, T0)Leung omega factorws0.000transition saturation
pressure ratiohst0.000critical pressure
ratiohc0.000hs0.000ha0.000subcooling region (low subcooling if hs
> hst)00.00criticallity (critical if ha < hc)00LOW
SUBCOOLINGHIGH SUBCOOLINGwhere P = Ps if critical, P = Pa if
subcriticalwhere h = hc if critical, h = ha if
subcriticalGhighsub0lb/s.ftGlowsub0lb/s.ftRelief rate (mass
flux)G0kg/s.m0lb/s.ftValve discharge coefficient (prelim. 0.65 for
subcooled, 0.85 for sat.- TBC)Kd0.65% gauge back
pressure%gPb0.0Back pressure correction factorKb0.000Rupture disc
combination factor - use 1 for no rupture discKc1.0000Required
effective PSV discharge areaA0.00cm0.000inPSV
inlet0mm0inDesignation (Always use ballanced bellows valve for 2
phase relief)0.00PSVoutlet0mm0inOrifice area (per
valve)0cm0inNumber of operational valves00Rated flow - all
valves0kg/h0USgal/minSource Program: 2PhaseRelief0000STONE &
WEBSTERSource Program Last Edited: 30/05/01, 16:33C:\Documents and
Settings\i00410\My Documents\Copy of 2PhaseRelief0000.xlsvalve
code:0"Dummy" variables used:nclowsub0.5nlowsub0Phighsub0
Click Here to Solve for hcReturn to Decision Flowchart
2 Phase Inlet, Non-flashingCALCULATION SHEET - TWO PHASE
RELIEFSheet No.? OF NClientClientJob No.J.O./W.O. NoProject /
PlantProjectCalc No.Calc
No.LocationLocationDateSystemByTimeApplicability"2 Phase Inlet,
Non-flashing"1. EITHER Two phase at PRV inlet, non-flashing through
PRV.OR Highly subcooled liquid and either a non-condensable gas,
condensable vapour, or both.Input DataWRelief ratekg/h0lb/hPsetPRV
set pressurebarg0.0psig%OverPPRV allowable percentage
overpressure%0%P0Relieving pressure at PRV
inlet1.01bara14.7psiaT0Relieving temperature at PRV
inletC491.4Rx0Mass fraction vapour at PRV inlet
(quality)-0-rvg0Density of vapour phase at PRV
inletkg/m0.0000lb/ftrl0Density of liquid at PRV
inletkg/m0.00lb/ftkCp/Cv for vapour phase at std. conditions (if
unknown, use a value of
1.0)-0-PaBackpressurebara0.0psiaCalculations(Method as per API
RP-520, 7th Edition, January 2000, Appendix D)vvg0Specific volume
of vapour phase at PRV inlet0.000m/kg0.00ft/lbv0Homogeneous
specific volume at PRV inlet0.0000m/kg0.000ft/lbvoid
fractiona00.000Leung omega factorw0.000critical pressure
ratiohc0.000critical pressurePc0.00bara0.0psiaback pressure
ratioha0.00000CRITICAL FLOWSUBCRITICAL FLOWRelief rate (mass
flux)G0kg/s.m0lb/s.ftValve discharge coefficient (preliminary value
0.85 - TBC)Kd0.85% gauge back pressure%gPb0.0Back pressure
correction factorKb0.000Rupture disc combination factor - use 1 for
no rupture discKc1.000Required effective PSV discharge
areaA0.00cm0.000inPSV inlet0mm0inDesignation (Always use ballanced
bellows valve for 2 phase relief)00PSVoutlet0mm0inOrifice area (per
valve)0.000cm0inNumber of operational valves00Rated flow - all
valves0kg/h0lb/hSource Program: 2PhaseRelief0000STONE &
WEBSTERSource Program Last Edited: 30/05/01, 16:33C:\Documents and
Settings\i00410\My Documents\Copy of 2PhaseRelief0000.xlsvalve
code0Calculation of Critical pressure ratio using curve fitMMF
Model: y=(a*b+c*x^d)/(b+x^d)Coefficient Data:w < 1Coefficient
Data: w > 1Omega (w)Coefficient to usea
=0.00115399860.262542450.000a_0b =0.746992131.1159188b_0c
=1.05949670.99341944nc calcc_0d =0.503208480.657665620d_0Data
calculated using
Tools/Solver0.010.1244780.020.1678740.050.2431710.10.3142830.20.3962250.50.5152190.990.6052310.60653120.69250450.79006100.848569200.893774500.9357961000.957029
Return to Decision Flowchart
2 Phase Inlet, Wide BoilingCALCULATION SHEET - TWO PHASE
RELIEFSheet No.? OF NClientClientJob No.J.O./W.O. NoProject /
PlantProjectCalc No.Calc
No.LocationLocationDateSystemByTimeApplicability"2 Phase Inlet,
Wide Boiling"1. Two phase at PRV inlet, flashing through PRV.
Noncondensable gas may be present. AND2. EITHER Flashing
multi-component systems with nominal boiling range (highest to
lowest component) > 150F (80oC)OR Flashing single component
systems where Tr > 0.9 or Pr > 0.5OR Pv0/P0 > 0.9 OR
Pg0/P0 < 0.1, OR contains more than 0.1 weight % hydrogenInput
DataWRelief ratekg/h0lb/hPsetPRV set pressurebarg0.0psig%OverPPRV
allowable percentage overpressure%0%P0Relieving pressure at PRV
inlet1.01bara14.7psiaT0Relieving temperature at PRV
inletC491.4Rx0Mass fraction that is vapour phase at PRV inlet
(quality)-0-rv0Density of vapour phase at PRV
inletkg/m0.0000lb/ftrl0Density of liquid at PRV
inletkg/m0.00lb/ftP990% of P00.91bara13.2psiax9Mass fraction that
is vapour phase at P9 (isenthalpic flash from T0, P0,
x0)-0-rv9Density of vapour phase at P9 (isenthalpic flash from T0,
P0, x0)kg/m0.0000lb/ftrl9Density of liquid at P9 (isenthalpic flash
from T0, P0, x0)kg/m0.00lb/ftPaBackpressurebara0.0psiaPv0Saturation
(vapour) pressure corresponding to the inlet temperature T0. For a
multi-component system, use thebubble point pressure corresponding
to T0Pg0Noncondensable gas partial pressure at the PRV
inletCalculations(Method as per API RP-520, 7th Edition, January
2000, Appendix D)vv0Specific volume of vapour phase at PRV
inlet0.000m/kg0.00ft/lbv0Homogeneous specific volume at PRV
inlet0.0000m/kg0.000ft/lbv9Homog. sp. vol. at 90% of P0
(isenthalpic flash from T0, P0, x0)0.0000m/kg0.000ft/lbvoid
fractiona00.000Leung omega factorw0.000critical pressure
ratiohc0.000critical pressurePc0.00bara0.0psiaback pressure
ratioha0.00000CRITICAL FLOWSUBCRITICAL FLOWRelief rate (mass
flux)G0kg/s.m0lb/s.ftValve discharge coefficient (preliminary value
0.85 - TBC)Kd0.85% gauge back pressure%gPb0.0Back pressure
correction factorKb0.000Rupture disc combination factor - use 1 for
no rupture discKc1.000Required effective PSV discharge
areaA0.00cm0.000inPSV inlet0mm0inDesignation (Always use ballanced
bellows valve for 2 phase relief)00PSVoutlet0mm0inOrifice area (per
valve)0.000cm0inNumber of operational valves00Rated flow - all
valves0kg/h0lb/hSource Program: 2PhaseRelief0000STONE &
WEBSTERSource Program Last Edited: 30/05/01, 16:33C:\Documents and
Settings\i00410\My Documents\Copy of 2PhaseRelief0000.xlsvalve
code0Calculation of Critical pressure ratio using curve fitMMF
Model: y=(a*b+c*x^d)/(b+x^d)Coefficient Data:w < 1Coefficient
Data: w > 1Omega (w)Coefficient to usea
=0.00115399860.262542450.000a_0b =0.746992131.1159188b_0c
=1.05949670.99341944nc calcc_0d =0.503208480.657665620d_0Data
calculated using
Tools/Solver0.010.1244780.020.1678740.050.2431710.10.3142830.20.3962250.50.5152190.990.6052310.60653120.69250450.79006100.848569200.893774500.9357961000.957029
Return to Decision Flowchart
2 Phase Inlet, Close BoilingCALCULATION SHEET - TWO PHASE
RELIEFSheet No.? OF NClientClientJob No.J.O./W.O. NoProject /
PlantProjectCalc No.Calc
No.LocationLocationDateSystemByTimeApplicability"2 Phase Inlet,
Close Boiling"1. Two phase at PRV inlet, flashing through PRV.
AND2. EITHER Flashing multi-component systems with nominal boiling
range (highest to lowest component) < 150F (80oC)OR Flashing
single component systems where Tr < 0.9 or Pr < 0.5Input
DataWRelief ratekg/h0lb/hPsetPRV set pressurebarg0.0psig%OverPPRV
allowable percentage overpressure%0%P0Relieving pressure at PRV
inlet1.01bara14.7psiaT0Relieving temperature at PRV
inletC491.4Rx0Mass fraction vapour at PRV inlet
(quality)-0-rv0Density of vapour at PRV
inletkg/m0.0000lb/ftrl0Density of liquid at PRV
inletkg/m0.00lb/fthv0Specific enthalpy of vapour at PRV
inletkJ/kg0.0Btu/lbhl0Specific enthalpy of liquid at PRV
inletkJ/kg0.0Btu/lbCpSpecific heat of liquid at PRV
inletkJ/kgK0.000Btu/lbRPaBackpressurebara0.0psiaCalculations(Method
as per API RP-520, 7th Edition, January 2000, Appendix
D)vv0Specific volume of vapour at PRV
inlet0.000m/kg0.00ft/lbvvl0Difference between the vapour and liquid
specific volumes at PRV inlet0.000m/kg0.00ft/lbv0Homogeneous
specific volume at PRV inlet0.000m/kg0.00ft/lbhvl0Latent heat of
vaporisation at P0 (difference between the vapour
and0kJ/kg0Btu/lbliquid specific enthalpies at PRV inlet)void
fractiona00.000Leung omega factorw0.000critical pressure
ratiohc0.000critical pressurePc0.00bara0.0psiaback pressure
ratioha0.00000CRITICAL FLOWSUBCRITICAL FLOWRelief rate (mass
flux)G0kg/s.m0lb/s.ftValve discharge coefficient (preliminary value
0.85 - TBC)Kd0.85% gauge back pressure%gPb0.0Back pressure
correction factorKb0.000Rupture disc combination factor - use 1 for
no rupture discKc1.000Required effective PSV discharge
areaA0.00cm0.000inPSV inlet0mm0inDesignation (Always use ballanced
bellows valve for 2 phase relief)00PSVoutlet0mm0inEffective
discharge area (per valve)0.000cm0inNumber of operational
valves00Rated flow - all valves0kg/h0lb/hSource Program:
2PhaseRelief0000STONE & WEBSTERSource Program Last Edited:
30/05/01, 16:33C:\Documents and Settings\i00410\My Documents\Copy
of 2PhaseRelief0000.xlsvalve code0Calculation of Critical pressure
ratio using curve fitMMF Model: y=(a*b+c*x^d)/(b+x^d)Coefficient
Data:w < 1Coefficient Data: w > 1Omega (w)Coefficient to usea
=0.00115399860.262542450.000a_0b =0.746992131.1159188b_0c
=1.05949670.99341944nc calcc_0d =0.503208480.657665620d_0Data
calculated using
Tools/Solver0.010.1244780.020.1678740.050.2431710.10.3142830.20.3962250.50.5152190.990.6052310.60653120.69250450.79006100.848569200.893774500.9357961000.957029
Return to Decision Flowchart
Non-condensable Gas PresentCALCULATION SHEET - TWO PHASE
RELIEFSheet No.? OF NClientClientJob No.J.O./W.O. NoProject /
PlantProjectCalc No.Calc
No.LocationLocationDateSystemByTimeApplicability"Non-condensable
Gas Present"1. Two phase flashing flow with a noncondensable gas or
both a condensable vapour and noncondensable gas. AND2. Solubility
of noncondensable gas in the liquid must not be appreciable (else
use flashing condensable gas procedure). AND3. EITHER Flashing
multi-component systems with nominal boiling range (highest to
lowest component) < 150F (80oC)OR Flashing single component
systems where Tr < 0.9 or Pr < 0.5. AND4. EITHER Pv0/P0 <
0.9 OR Pg0/P0 > 0.1, AND 5. Contains less than 0.1 weight %
hydrogenInput Data (definitions of symbols appear on separate
sheet)Wkg/hr0lb/hrrl0kg/m30.00lb/ft3Psetbarg0.0psigx0-0-%OverP%0%hv0kJ/kg0.0Btu/lbP01.01bara14.7psiahl0kJ/kg0.0Btu/lbT0oC491.4RPv0bara0.0psiaCpkJ/kgK0.000Btu/lbRPg0bara0.0psiarv0kg/m30.0000lb/ft3k1-1-rvg0kg/m30.0000lb/ft3Pabara0.0psiaCalculations(Method
as per API RP-520, 7th Edition, January 2000, Appendix
D)vvg00.000m3/kg0.00ft3/lbvvl00.000m3/kg0.00ft3/lbv00.000m3/kg0.00ft3/lbhvl00kJ/kg0Btu/lbvoid
fractiona00.000Leung omega factorw0.000critical
pressurePc0.00bara0.0psiacriticallity00SUBCRITICAL FLOWCRITICAL
FLOWhg0.544hv0.985Gg0Gv0Gsub0lb/s.ftGcrit0lb/s.ftRelief rate (mass
flux)G0kg/s.m0lb/s.ftValve discharge coefficient (preliminary value
0.85 - TBC)Kd0.85% gauge back pressure%gPb0.0Back pressure
correction factorKb0.000Rupture disc combination factor - use 1 for
no rupture discKc1.0000Required effective PSV discharge
areaA0.00cm0.000inPSV inlet0mm0inDesignation (Always use ballanced
bellows valve for 2 phase relief)00PSVoutlet0mm0inOrifice area (per
valve)0.000cm0inNumber of operational valves00Rated flow - all
valves0kg/h0lb/hSource Program: 2PhaseRelief0000STONE &
WEBSTERSource Program Last Edited: 30/05/01, 16:33C:\Documents and
Settings\i00410\My Documents\Copy of 2PhaseRelief0000.xlsvalve
code:0Variables used:ha0yg00pseudowg0hgc0pseudowv0hvc0Calculation
of Critical pressure ratio using curve fitMMF Model:
y=(a*b+c*x^d)/(b+x^d)Coefficient Data:w < 1Coefficient Data: w
> 1pseudowgpseudowvCoefficient to usea
=0.00115399860.2625424500ag0av0b =0.746992131.1159188bg0bv0c
=1.05949670.99341944hgchvccg0cv0d =0.503208480.6576656200dg0dv0Data
calculated using
Tools/Solver0.010.1244780.020.1678740.050.2431710.10.3142830.20.3962250.50.5152190.990.6052310.60653120.69250450.79006100.848569200.893774500.9357961000.957029SYMBOL
DEFINITION SHEET - TWO PHASE RELIEFSymbolDefinitionWMass flow
ratePsetPRV set pressure%OverPPRV allowable percentage
overpressureP0Relieving pressure (set pressure, plus allowable
overpressure, plus atmospheric pressure)T0Relieving temperature at
the PRV inletCpLiquid specific heat at constant pressure at the PRV
inletrv0density of the vapour* (NOT including any noncondensable
gas present) at the PRV inletrvg0density of the gas (or combined
vapour and gas) at the PRV inletrl0Liquid density at the PRV
inletvvg0Specific volume of the vapour phase at the PRV
inletvvl0Difference between the vapour* (not including any
noncondensable gas present) and liquid specificvolumes at the PRV
inletv0Homogeneous specific volume of the two-phase system at the
PRV inletx0Mass fraction that is vapour phase at the PRV inlet
(quality)hv0specific enthalpy of the vapour* (NOT including any
noncondensable gas present) at the PRV inlethl0specific enthalpy of
the liquid at the PRV inlethvl0Latent heat of vaporization at the
PRV inlet. For multi-component systems, hvl0 is the
differencebetween the vapour and liquid specific
enthalpiesPv0Saturation (vapour) pressure corresponding to the
inlet temperature T0. For a multi-componentsystem, use the bubble
point pressure corresponding to T0Pg0Noncondensable gas partial
pressure at the PRV inletkRatio of specific heats of the gas (or
combined vapour and gas) at PRV inlet. If the specific heat ratiois
unknown, a value of 1 can be usedPaBackpressure*To obtain the
vapour specific volume, or vapour specific enthalpy at the PRV
inlet,use the vapour partial pressureSource Program:
2PhaseRelief0000STONE & WEBSTERSource Program Last Edited:
30/05/01, 16:33
Click Here to Solve for Subcritical FlowReturn to Decision
Flowchart
Liquid Inlet Iterationws6.6814996415hs0.975dnc0.001Method
1(isolating
nc^2)y=mx+c0nc1nc2fn(nc1)fn(nc2)mcnc3SQRT((nc3-nc1)^2)errorsuccessful?0.8329345540.8339345540.83293454070.83379341430.85887359060.11754904960.83293445970.00000009430.0000000943YesMethod
2 (isolating
ln(nc/ns))y=mx+c0nc1nc2fn(nc1)fn(nc2)mcnc3SQRT((nc3-nc1)^2)errorsuccessful?0.83293126870.83393126870.83293150760.8338568640.92535641460.06217321510.83293446850.00000319980.0000031998YesMethod
3 (isolating
nc)y=mx+c0nc1nc2fn(nc1)fn(nc2)mcnc3SQRT((nc3-nc1)^2)errorsuccessful?0.83293535790.83393535790.83293540410.83398672041.0513162992-0.04274311380.83293445670.00000090110.0000009011Yes0.832934554Final
Answerhc0.832934554
This spreadsheet solves the above equation iteratively, to give
the critical pressure ratio, hc, for low subcooled liquid inlet to
PRV. Run macro "Solve_for_nc" to solve.
Non-condensable
Iterationw25.6649775875a00.4545454545k1ha0.875yg00.25dnc0.01First
Iterative
methody=mx+c0nv1nv2fn(nc1)fn(nc2)mcnv3SQRT((nc3-nc1)^2)errorsuccessful?0.98536953190.99536953190.9853651030.9835228225-0.18422805021.16689781060.9853657920.00000373990.0000037399Yesng10.5438914043Second
Iterative
methody=mx+c0nv1nv2fn(nc1)fn(nc2)mcnv3SQRT((nc3-nc1)^2)errorsuccessful?1.20534083411.21534083411.20534100321.2036855276-0.16554756151.4048822391.20534097920.00000014510.0000001451Yesng_-0.11602250230.98536953190.5438914043Final
Answerhv0.9853695319hg0.5438914043
This spreadsheet solves the above equations iteratively, to give
the partial pressure ratios, hv and hg, for two phase flashing flow
with noncondensable gas present. Run macro "Solve_for_nv" to
solve.
Source File Property DetailsThese Values Must Be Manually
Updated When the Source Program is RevisedDate of Last
Edit30/05/01, 16:33Filename2PhaseRelief0000(last 4 digits refer to
version (2 digits) and level (2 digits))
Sheet1
MBD000F6FBC.unknown
MBD001379AC.unknown
MBD00147DD5.unknown
MBD00189FF2.unknown
MBD001D3960.unknown
MBD00197011.unknown
MBD00151F1B.unknown
MBD00174A89.unknown
MBD0018469B.unknown
MBD0016EECF.unknown
MBD00172510.unknown
MBD00153652.unknown
MBD00150A09.unknown
MBD0013B615.unknown
MBD0013DF1C.unknown
MBD0013B409.unknown
MBD000F7466.unknown
MBD000F7468.unknown
MBD001379AA.unknown
MBD001379AB.unknown
MBD001379A9.unknown
MBD001379A7.unknown
MBD000F7467.unknown
MBD000F6FBE.unknown
MBD000F7464.unknown
MBD000F7465.unknown
MBD000F7463.unknown
MBD000F7460.unknown
MBD000F6FBD.unknown
MBD0003ACEC.unknown
MBD000A4C5E.unknown
MBD000C0D77.unknown
MBD000F6FB9.unknown
MBD000F6FBB.unknown
MBD000F6FB7.unknown
MBD000AFF88.unknown
MBD000AD977.unknown
MBD0004C417.unknown
MBD00094024.unknown
MBD0009A4EF.unknown
MBD00073E67.unknown
MBD0004C097.unknown
MBD000059C2.unknown
MBD000059C4.unknown
MBD0000CDDD.unknown
MBD000059C3.unknown
MBD000059C0.unknown
MBD000059C1.unknown
