KEP SUPERtrol II, Manual

Page: 99 / 127

SUPERtrol II Flow Computer
95
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
P T 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 (-20T
b
)] – 1.317 T
b
4
p (1.69 – p
2
)
E
3
= 1 – 0.00075 p
2.3
[2 – exp (-20T
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 (-20T
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
– X E
6
= E
3
– X E
7
= E
1
– X E
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