NGL GATHERING
View: Process Flow Diagram
View: Simulation Results
Four mixed-phase hydrocarbon streams are produced in a NGL field. They are transported through 4 pipelines to a common “flow gathering station” where they are mixed and though another pipeline to a process facility (PF).
Well head pressure is approximately 90 bar.
For each stream the pressure after the choke valve is to be calculated. The delivery pressure at PF is required to be 75 bar.
The hydrocarbon streams are characterized using 17 chemical components up to the C12 fraction.
The same composition is used for each stream, and is shown on the next table.
|
No |
Components |
Molar composition, % |
|
1 |
H2O |
1.421 |
|
2 |
N2 |
0.345 |
|
3 |
CO2 |
3.204 |
|
4 |
C1 |
77.348 |
|
5 |
C2 |
8.428 |
|
6 |
C3 |
3.411 |
|
7 |
IC4 |
0.651 |
|
8 |
NC4 |
1.380 |
|
9 |
IC5 |
0.601 |
|
10 |
NC5 |
0.601 |
|
11 |
NC6 |
0.739 |
|
12 |
NC7 |
0.641 |
|
13 |
NC8 |
0.562 |
|
14 |
NC9 |
0.335 |
|
15 |
NC10 |
0.158 |
|
16 |
NC11 |
0.079 |
|
17 |
NC12 |
0.099 |
The stream generated by the various well are estimated as:
|
Stream |
Est Pressure, bar |
Temperature, °C |
Flow rate, kg/h |
|
N18F |
90 |
67.5 |
37000 |
|
N19F |
90 |
67.0 |
45000 |
|
N20F |
90 |
68.2 |
33000 |
|
N21 |
90 |
67.4 |
30000 |
The calculation proceeds straightforwardly. At the first iteration the sink pressure is found to be 85.9 bar. The pressure is reset and the calculation is now perform backwards up to the production streams. Convergence is found at the second trial.
The final calculated pressure is:
|
Stream |
Pressure, bar |
|
N18F |
79.75 |
|
N19F |
79.68 |
|
N20F |
76.37 |
|
N21 |
78.78 |
Thermodynamic conditions of the sink stream PROD, which presents two liquid phases, are presented hereunder.
* STREAM 'PROD '
- Temperature 48.678 CENT - Pressure 75.0010 BAR
Phase TOTAL VAPOUR LIQUID H LIQUID W
Molar Flow Rate KMOL /HR 6270.891 5857.478 333.999 79.414
Weight Flow Rate KG /HR 145000.000 121964.518 21604.433 1431.049
Molar Fraction 0.934074 0.053262 0.012664
Weight Fraction 0.841135 0.148996 0.009869
Molecular Weight 23.1227 20.8220 64.6841 18.0200
Std Vap Vol Rate N-CUMT /HR 138499.1422
Std Liq Vol Rate CUMT /HR 36.2648 34.8352 1.4296
Act Volume Rate CUMT /HR 1804.7425 1766.7076 36.5925 1.4424
Enthalpy M-KJ /HR -13336.9018 -3821.9923 -6169.7142 -3345.1953
Spec. Enthalpy KJ/KG -91.995 -31.343 -285.628 -2338.007
KJ/KMOL -2127.182 -652.616 -18475.604 -42130.899
Spec. Heat Cap. KJ/KG-C 2.641569 2.656237 2.458020 4.162432
KJ/KML-C 61.080227 55.308226 158.994810 75.007042
Spec. Entropy KJ/KG-C 7.4276 8.0485 4.2397 2.6349
KJ/KML-C 171.7464 167.5868 274.2418 47.4807
Compressibility 0.845277
Density KG/CUMT 80.3439 69.0349 590.4061 992.1344
Gravity at 60/60 0.620174 1.001004
Viscosity CP 0.1374E-01 0.1125 0.5553
Thermal Conduct. W/MC 0.041833 0.177151 0.632675
Surface Tension DYCM 9.1121 68.1824
Reference Gas Status - Temperature 15°C - Pressure 1 atm
<XPSIM> ...generated by XpsimWin v.1.06 ...
*
RUN ID='CASE02 ' CUSTOMER=STAFF PROJECT='WINTER NGL GATHERING'
DESC WINTER 03 NGL - DESIGN CASE
DIMENSION INPUT SI PRES=BAR
*
*
System Data
*
*
CHEMCOMP H2O / N2 / CO2 / C1 / C2 / C3 / IC4 / NC4 / IC5 / NC5 / NC6 +
/ NC7 / NC8 / NC9 / NC10 / NC11 / NC12
THERMSET UID=M1
METHODS K=SRK HS=LK CP=LK D=LK TRAN=IDEAL SURT=IDEAL
*
*
Flowsheet Data
*
*
*
STREAM=S1 TEMP=50 PRES=90 RATE(W)=400000 XBASIS=M
COMP 1.421 / 0.345 / 3.204 / 77.348 / 8.428 / 3.411 / 0.651 / 1.380 / +
0.601 / 0.601 / 0.739 / 0.641 / 0.562 / 0.335 / 0.158 / 0.079 / +
0.099
*
STREAM=N18F TEMP=67.5 PRES=90 RATE(W)=37000 XBASIS=M REFSTR=S1
*
STREAM=N19F TEMP=67. PRES=90 RATE(W)=45000 XBASIS=M REFSTR=S1
*
STREAM=N20F TEMP=68.2 PRES=90 RATE(W)=33000 XBASIS=M REFSTR=S1
*
STREAM=N21F TEMP=67.4 PRES=90 RATE(W)=30000 XBASIS=M REFSTR=S1
*
PIPELINE IN N18F OUT N18P UID=N18
PARA STEP(MT)=100
CORRELAT SET=MECH2F
POINT DIST(MT)=0 ELEV(MT)=0 DIAM(M)=0.193675 ROUGH(MM)=0.04572 TEXT=9 +
K=50.,0.3,1.5,, THICK(MM)=12.7,3,1500,, HOLIM=1.5
POINT DIST=250 ELEV=3
POINT DIST=500 ELEV=-3
POINT DIST=750 ELEV=-3
POINT DIST=1000 ELEV=-3
POINT DIST=1250 ELEV=3
POINT DIST=1500 ELEV=3
POINT DIST=1750 ELEV=-3
POINT DIST=2000 ELEV=-3
POINT DIST=2250 ELEV=3
POINT DIST=2500 ELEV=3
POINT DIST=2750 ELEV=-3
POINT DIST=3000 ELEV=-3
POINT DIST=3250 ELEV=3
POINT DIST=3500 ELEV=3
POINT DIST=3750 ELEV=-3
POINT DIST=4000 ELEV=-3
POINT DIST=4250 ELEV=3
POINT DIST=4500 ELEV=3
POINT DIST=4750 ELEV=-3
POINT DIST=5000 ELEV=-3
POINT DIST=5250 ELEV=3
POINT DIST=5444 ELEV=0
*
PIPELINE IN N19F OUT N19P UID=N19
PARA STEP(MT)=100
CORRELAT SET=MECH2F
AMBIENT SOIL TEMP=9 K=1.5 UID=SOIL1
POINT DIST(MT)=0 ELEV(MT)=0 DIAM(M)=0.193675 ROUGH(MM)=0.04572 TEXT=9 +
K=50.,0.3,1.5,, THICK(MM)=12.7,3,1500,, HOLIM=1.5
POINT DIST=250 ELEV=3
POINT DIST=500 ELEV=-3
POINT DIST=750 ELEV=-3
POINT DIST=1000 ELEV=3
POINT DIST=1250 ELEV=3
POINT DIST=1500 ELEV=-3
POINT DIST=1750 ELEV=-3
POINT DIST=2000 ELEV=3
POINT DIST=2250 ELEV=3
POINT DIST=2500 ELEV=-3
POINT DIST=2750 ELEV=-3
POINT DIST=3000 ELEV=3
POINT DIST=3250 ELEV=3
POINT DIST=3500 ELEV=-3
POINT DIST=3550 ELEV=0
*
PIPELINE IN N20F OUT N20P UID=N20
PARA STEP(MT)=100
CORRELAT SET=MECH2F
AMBIENT SOIL TEMP=9 K=1.5 UID=SOIL1
POINT DIST(MT)=0 ELEV(MT)=0 DIAM(M)=0.193675 ROUGH(MM)=0.04572 TEXT=9 +
K=50.,0.3,1.5,, THICK(MM)=12.7,3,1500,, HOLIM=1.5
POINT DIST=50 ELEV=0
*
PIPELINE IN N21F OUT N21P UID=N21
PARA STEP(MT)=100
AMBIENT SOIL TEMP=9 K=1.5 UID=SOIL1
POINT DIST(MT)=0 ELEV(MT)=0 DIAM(M)=0.193675 ROUGH(MM)=0.04572 TEXT=9 +
K=50.,0.3,1.5,, THICK(MM)=12.7,3,1500,, HOLIM=1.5
POINT DIST=250 ELEV=3
POINT DIST=500 ELEV=-3
POINT DIST=750 ELEV=-3
POINT DIST=1000 ELEV=3
POINT DIST=1250 ELEV=3
POINT DIST=1500 ELEV=-3
POINT DIST=1750 ELEV=-3
POINT DIST=2000 ELEV=3
POINT DIST=2250 ELEV=3
POINT DIST=2500 ELEV=-3
POINT DIST=2701 ELEV=0
*
MIXER IN N18P N19P N20P N21P OUT TRKF UID=MX1
*
PIPELINE IN TRKF OUT PROD UID=CP
PARA STEP(MT)=100
CORRELAT SET=MECH2F
AMBIENT SOIL TEMP=9 K=1.5 UID=SOIL1
POINT DIST(MT)=0 ELEV(MT)=0 DIAM(M)=0.381 ROUGH(MM)=0.04572 TEXT=9 +
K=50.,0.3,1.5,, THICK(MM)=12.7,3,1500,, HOLIM=1.5
POINT DIST=250 ELEV=3
POINT DIST=500 ELEV=-3
POINT DIST=750 ELEV=-3
POINT DIST=1000 ELEV=3
POINT DIST=1250 ELEV=3
POINT DIST=1500 ELEV=-3
POINT DIST=1750 ELEV=-3
POINT DIST=2000 ELEV=3
POINT DIST=2250 ELEV=3
POINT DIST=2500 ELEV=-3
POINT DIST=2750 ELEV=-3
POINT DIST=3000 ELEV=3
POINT DIST=3250 ELEV=3
POINT DIST=3500 ELEV=-3
POINT DIST=3750 ELEV=-3
POINT DIST=4000 ELEV=3
POINT DIST=4250 ELEV=3
POINT DIST=4500 ELEV=-3
POINT DIST=4865 ELEV=0
*
*
Network Data
*
*
GATHERING NITER=10
SPEC PRES=75 STR=PROD
VARY STR=N18F PRES TFIX
VARY STR=N19F PRES TFIX
VARY STR=N20F PRES TFIX
VARY STR=N21F PRES TFIX
*
*
END