Manual
SP4000 Flow Computer
100
After calculating the adjusted pressure and temperature, the mixture’s pressure and tempera-
ture
correlations parameters
are calculated by
P
=
P
adj
+ 14.7
T
=
T
adj
.
1000 500
The compressibility factor is then calculated by first determining
m
= 0.0330378
T
-2
– 0.0221323
T
-3
+ 0.0161353
T
-5
n
= (0.265827
T
-2
+ 0.0457697
T
-4
– 0.133185
T
-1
)
m
-1
B
=
3 –
mn
2
9
mp
2
b
=
9
n
–
2mn
3
–
E .
54
mp
2
2
mp
2
D
= [
b
+ (
b
2
+
B
3
)
0.5
]
1/3
Where
E
is a function of the pressure
p
and temperature
T
correlation parameters. The equations for
E
are given in the following table for the designated regions. The following compressibility
Z
f
is deter-
mined by
Z
f
=
1 .
B / D
–
D
+
n /
3
p
NX-19 Natural Gas Regions and
E
Equations
Ranges
PT E
0 to 2 1.09 to 1.40
E
1
0 to 1.3 0.84 to 1.09
E
2
1.3 to 2.0 0.88 to 1.09
E
3
1.3 to 2.0 0.84 to 0.88
E
4
2.0 to 5.0 0.84 to 0.88
E
5
2.0 to 5.0 0.88 to 1.09
E
6
2.0 to 5.0 1.09 to 1.32
E
7
2.0 to 5.0 1.32 to 1.40
E
8
T
a
=
T
– 1.09
T
b
= 1.09 –
T
E
1
= 1 – 0.00075
p
2.3
exp (-20
T
a
) – 0.0011
T
a
0.5
p
2
(2.17 + 1.4
T
a
0
.5
–
p
)
2
E
2
= 1 – 0.00075
p
2.3
[2 – exp (-20
T
b
)] – 1.317
T
b
4
p
(1.69 –
p
2
)
E
3
= 1 – 0.00075
p
2.3
[2 – exp (-20
T
b
)] + 0.455(200
T
b
6
– 0.03249
T
b
+ 2.0167
T
b
2
– 18.028
T
b
3
+ 42.844
T
b
4
)(p – 1.3)[1.69(2)
1.25
–
p
2
]
E
4
= 1 – 0.00075
p
2.3
[2 – exp (-20
T
b
)] + 0.455(200
T
b
6
– 0.03249
T
b
+ 2.0167
T
b
2
– 18.028
T
b
3
+ 42.844
T
b
4
)(
p
– 1.3)[1.69(2)
1.25 + 80(0.88 – t)
2
–
p
2
]
E
5
=
E
4
–
XE
6
=
E
3
–
XE
7
=
E
1
–
XE
8
=
E
7
–
X
1
X
=
A
(
T
– 2) +
A
1
(
p
– 2)
2
+
A
2
(
p
– 2)
3
+
A
3
(
p
– 2)
4
X
1
= (
p
– 1.32)
2
(
p
–2)[3 – 1.483(
p
– 2) – 0.1(
p
–2)
2
+ 0.0833(
p
–2)
3
]
A
= 1.7172 – 2.33123
T
– 1.56796
T
2
+ 3.47644
T
3
– 1.28603
T
4
A
1
= 0.016299 – 0.028094
T
– 0.48782
T
2
– 0.78221
T
3
+ 0.27839
T
4
A
2
= –0.35978 + 0.51419
T
+ 0.165453
T
2
– 0.52216T
3
+ 0.19687T
4
A
3
= 0.075255 – 0.10573
T
– 0.058598
T
2
+ 0.14416
T
3
– 0.054533
T
4
When NX-19 is used for custody transfer applications, the base compressibility factor is calculated by:
Z
b
=
(
1 +
0.00132
)
-2
T
3.25
7.3.5
Corrected
Volume Flow
Computation
(continued)
Mass Flow Computations:
mass flow = volume flow • density
Combustion Heat Flow Computations:
combustion heat flow = mass flow • combustion heating value
7.3.6
Mass Flow
Computation
7.3.7
Comb. Heat Flow
Computation