CV based flows along with supplementary metrics

This calculation method uses the Cv curve of a valve to estimate the flow rate through it. Valve Flow Coefficient (Cv) is the flow capability of a control valve at open conditions relative to the pressure drop across the valve.

Flow Control Valves have a table of open % vs Cv value. XV’s or SV’s have a single CV value for when they are fully open. In addition to the Cv value, numerous physical properties for the respective gas flowing through the valve are used to compute the flow rate.

It’s method of estimating the flow based on interpolation of the flow chart. In following gdoc gdoc you can find set of examples and CV tables for each CV based metric.

Second part flow recovery rate interpolated based on FL table.

formula

Each set of metrics based on following formula inputs: psig_in, psig_out, valve, temp, gas

valve is between 0 and 100 and it’s %

Intermediate variables are computed:

psia_in         = psig_in + 14.696        #absolute pressure
psia_out        = psig_out + 14.696       #absolute pressure
pressure_change = psia_out / psia_in
rankine_temp    = temp + 460
cv              = cv_interpolation(valve)
fl_recovery     = fl_interpolation(valve)

Following constant are in use:

• gas_density_vs_air it’s physical constant dependant on gas type
• 1360 is a unit version factor for variables and output in imperial units
• 834 is a unit version factor for variables and output in imperial units
• gas_std_density it’s physical constant dependant on gas type
• 1.25 is a ratio applied to argon gas streams to estimate the N2 flow rate to condense the stream

Main formula returns lb/h:

• 0 if valve < 0 or 100 < valve or pressure_change >= 1
• (gas_std_density * cv) / (sqrt(gas_density_vs_air * rankine_temp) / (fl_recovery * 834 * psia_in)) if pressure_change < 0.53
• (gas_std_density * cv) / (sqrt(gas_density_vs_air * rankine_temp) / (sqrt((psia_in - psia_out) * psia_out) * 1360)) if pressure_change >= 0.53

At the end scfm = to_scfm(gas_type, lbh)

fcv_202_lbh, fcv_202_scfm

Inputs: psig_in=PT201, psig_out=0, valve=FCV202, temp=75°F if ARS14002 or ARS16006 else 150°F, gas=Ar

Formula special case for fcv_202_scfm

0 if FCV202 <= 1 or FCV204 >= 15 or ft_202_scfm <= 100

based on FCV204: gdoc

fcv_204_lbh, fcv_204_scfm, coldbox_lbh, coldbox_scfm

Inputs: psig_in=PT201, psig_out=0, valve=FCV204, temp=75°F if ARS14002 or ARS16006 else 150°F, gas=Ar

Formula special case for fcv_204_scfm

• 0 if FCV202 > fcv202MinFlowThreshold and (FCV204 < fcv204NoFlowThreshold or FCV204ZT < fcv204NoFlowThreshold)
  • where fcv202MinFlowThreshold = 15 if ARS13007 else 20
  • where fcv204NoFlowThreshold = 6 if ARS15008 or ARS13007 or (ARS16006 and before(2020-06-03) else 5
• ft_202_scfm if FCV202 <= 1 or FCV204 >= 15 or ft_202_scfm <= 100
• HRS18006: fcv_204_scfm = FT100 - FT_101A (coldbox metrics are empty)

Extra formula values:

• coldbox_scfm = ft_202_scfm - fcv_204_scfm
• coldbox_lbh = lbh(coldbox_scfm)

gdoc

fcv_204b_lbh, fcv_204b_scfm (only for ARS19004, ARS20009, ARS15002)

Inputs: psig_in=PT201, psig_out=0, valve=FCV204B, temp=75°F, gas=Ar

Extra formula values:

• if FCV204 = 0:
  • fcv_204_scfm = fcv_204b_scfm
  • fcv_204_lbh = fcv_204b_lbh
  • coldbox_scfm = ft_202_scfm - fcv_204b_scfm
  • coldbox_lbh = lbh(coldbox_scfm)

gdoc

fcv_605_scfm, fcv_605_lbh, fcv_605_n2_use_lbh, fcv_605_n2_use_scfm

Inputs: psig_in=PT701, psig_out=PT601, valve=FCV605, temp=-300°F, gas=Ar

There are times where HXR_600 becomes full of argon such that the flow of argon through FCV_605 into the heat exchanger becomes obstructed and flow stops. In this situation FCV_605 cannot relieve pressure in TK_700 like it is supposed to do and it get stuck fully open (100%).

During this time period we log a high fcv_605_scfm value, even though there is realistically 0 flow. Because of this fcv_605_scfm performs a check on the level of argon in HXR_600 according PDT_601_ALT and if it exceeds a threshold, the output flow rate fcv_605_scfm is set to 0.

For ARS20009 after 2024-07-10 use FCV605_ZT instead of normal FCV_605.

Site	threshold
ARS14002	130
ARS15002	90
ARS15008	90
ARS16005	130

Extra formula values:

• fcv_605_n2_use_scfm = fcv_605_scfm * 1.25
• fcv_605_n2_use_lbh = lbh(fcv_605_n2_use_scfm)

gdoc

sv_205_out_lbh, sv_205_out_scfm, sv_205_out_scfm_cb, sv_205_out_scfm_atm

Inputs: psig_in=PT222, psig_out=PT201, valve=100 if ARS19004 and SV205A/B/C = 1 or SV205 = 1 else 0, temp=50°F, gas=Ar

Extra formula values:

• sv_205_out_scfm_atm = sv_205_out_scfm * fcv_204_scfm / ft_202_scfm
• sv_205_out_scfm_cb = sv_205_out_scfm - sv_205_out_scfm_atm

Additionaly for ARS19004 and ARA20009:

sv_205a_out_scfm_atm + sv_205b_out_scfm_atm + sv_205c_out_scfm_atm = sv_205_out_scfm_atm (evenly distributed among open valves)

sv_205a_out_scfm_cb + sv_205b_out_scfm_cb + sv_205c_out_scfm_cb = sv_205_out_scfm_cb (evenly distributed among open valves)

gdoc

xv_1005_scfm, xv_1005_lbh

Inputs: psig_in=PT1003, psig_out=0, valve=100 if XV1005OUT = 1 else 0, temp=50°F, gas=Ar

gdoc

fcv_207_scfm, fcv_207_lbh, fcv_207_n2_use_lbh, fcv_207_n2_use_scfm

Inputs: psig_in=PT1002, psig_out=PT601, valve=FCV207_REFINED, temp=50°F, gas=Ar

Extra formula values:

• for ARS19004 and ARS20009: FCV207_REFINED = 0 if XV_207_OUT = 0 and XV_208_OUT = 0 else FCV207
• Other: FCV207_REFINED = FCV207
• fcv_207_n2_use_scfm = fcv_207_scfm * 1.25
• fcv_207_n2_use_lbh = lbh(fcv_207_n2_use_scfm)

gdoc

xv_623_scfm, xv_623_lbh

Inputs: psig_in=PT601, psig_out=0, valve=100 if XV623 = 1 else 0, temp=TE601, gas=Ar

CV is flat:

• ARS16005 = 4.3
• other = 32

fcv_405_scfm, fcv_405_lbh, fcv_405_n2_use_lbh, fcv_405_n2_use_scfm (ARS19004, ARS20009)

Inputs: psig_in=PT701, psig_out=PT601, valve=FCV405, temp=-300°F, gas=Ar

For ARS20009 after 2024-07-10 use FCV405_ZT instead of normal FCV_405.

Extra formula values:

• fcv_405_n2_use_scfm = fcv_405_scfm * 1.25
• fcv_405_n2_use_lbh = lbh(fcv_405_n2_use_scfm)

gdoc

fcv_755_scfm, fcv_755_lbh, fcv_755_n2_use_lbh, fcv_755_n2_use_scfm

Inputs: psig_in=PT751, psig_out=PT701, valve=FCV755, temp=-300°F, gas=Ar

Extra formula values:

• fcv_755_n2_use_scfm = fcv_755_scfm * 1.25
• fcv_755_n2_use_lbh = lbh(fcv_755_n2_use_scfm)

gdoc

fcv_504_scfm, fcv_504_lbh

Inputs: psig_in=PT603, psig_out=1, valve=FCV504, temp=TE504, gas=N2

Extra formula condition: <empty> if PDT603 < 5

gdoc

fcv_754_scfm, fcv_754_lbh

Inputs: psig_in=PT753, psig_out=1, valve=FCV754, temp=-302°F, gas=N2

gdoc

sv_1207_scfm, sv_1207_lbh

Inputs: psig_in=PT1201, psig_out=0, valve=SV1207, temp=50°F, gas=Ar

gdoc

xv_523_out_scfm, xv_523_out_lbh (ARS16006, ARS19004, ARS20009)

Inputs: psig_in=PT601, psig_out=0, valve=XV523OUT, temp=TE501, gas=Ar

gdoc

xv_1109a/b_scfm, xv_1109a/b_lbh, xv_1109a/b_scfm_recond, xv_1109a/b_scfm_atm

Inputs: psig_in=PT1101A/B, psig_out=PT701 if PDT603 < 10 else PT601, valve=0 if PDT601ALT > 410 or XV1109A/B_OUT_AVG_5M > 0.9 else SV1109A/B_OUT, temp=boil(PT1101A/B), gas=Ar

Caveats are to set flow to 0 if the HXR_600 is full of argon and therefore gas cannot flow through XV_1109. HXR_600 being full is assessed according to PDT_601 level. Valve should never be open for extended time periods, so after 5 minutes of being open it is assumed there is 0 flow also.

Extra formula values:

xv623sph = 40 if ARS13007 else XV623SPH

• xv_1109a/b_scfm_recond = xv_1109a/b_scfm if PDT603ALT > 10
• xv_1109a/b_scfm_atm = xv_1109a/b_scfm if PDT603ALT <= 10

gdoc

xv_1309a/b_scfm, xv_1309a/b_lbh

Inputs: psig_in=PT1301A/B, psig_out=0.5, valve=100 if XV1309A/B_OUT = 1 else 0, temp=boil(PT1301A/B), gas=N2

gdoc

xv_806_scfm, xv_806_lbh

PT_802D = 0 if ARS13007

Inputs: psig_in=sum(PT_802A/B/C/D), psig_out=0, valve=100 if XV806 = 1 else 0, temp=50, gas=Ar

Extra formula values:

• xv_806_scfm = min(xv_806_scfm, p_800_scfm) (upper bound)

gdoc

sv_725_scfm, sv_725_lbh for ARS13007

Inputs: psig_in=PT721, psig_out=0, valve=100 if SV725 = 1 else 0, temp=-290°F, gas=Ar

gdoc

fcv_102_scfm, fcv_102_lbh

Final result is a sum of flows for each active tower. Following input has set of separate sensors variants for each active tower, i.e. PT_101_PP or FCV_102_T1.

Inputs: psig_in=PT101, psig_out=0, valve=FCV_102, temp=TE101, gas=Ar

Upper bound for flow for each active tower is defined as follows:

• FT1002/n where n is number of active towers
• for ARS14002, FT1002 is divided among active towers as follows:
  • if FT1002 > 3000: PP=44%, T1=27%, T2=29%
  • if FT1002 > 3000: PP=61%, T1 or T2=39%
  • PP=29%, T1=36%, T2=35%
  • PP=45%, T1 or T2=55%
  • T1=50%, T2=50%
• for ARS19004
  • For Tower B the cap on the FCV_102 flow rate is smc_atb_supply_flow
  • For Tower C the cap on the FCV_102 flow rate is smc_atc_supply_flow

gdoc

For HRS18006 formula is defined as:

Inputs: psig_in=PT100, psig_out=0, valve=FCV102VENT, temp=TT100, gas=He

gdoc