Siemens 353 - AG8 - AGA 8 Compressibility Factors of Natural Gas

UM353-1B Function Blocks
April 2012
3-13
3.2.6 AG8 - AGA 8 Compressibility Factors of Natural Gas
AG8 function blocks can be used on a one per loop basis.
This block calculates the compressibility factors of natural
gas in accordance with AGA 8 Report No. 8, July 1994
(AGA Catalog No. XQ9212). It computes various
compressibility factors and the specific gravity (relative
density) using the detailed characterization method
described in the report. The mole percentage of the gas
components and the base temperature and pressure are
entered in the configuration and the flowing temperature
and pressure are provided as block inputs. Parameter
MOL% SUM provides a read only value that is the total
of all the gas compounds that have been entered. The
AGA8 computation is time consuming and is calculated
over a total of 100 scan cycles so as not to have any
significant effect on the controller cycle time.
Z
s
(compressibility at standard conditions) is calculated
after a power-up or after a configuration change is made.
Z
b
and Z
f
are calculated on a periodic basis with the
actual update time dependent on the number of gas
components and the scan cycle of the controller.
AGA 8
Zs
Output
Zs
AGA 8
AG8 ESN =
000
E
xec.
S
eq.
N
o. ...................... 000 to 250 (000)
Input
Pf
Pf
Input
Tf
Tf
P
fTU
P
N
I
TU
P
N
I
H
T
M
E
P
b
f
T
Tb
E
SEN
INPUT Tf
...............
loop tag.block tag.output (null)
INPUT Pf
...............
loop tag.block tag.output (null)
b
ase
P
ressure (psia)
................................ Real
(14.73)
b
ase
T
emperature (deg F)
..................... Real
(60.0)
A
N
Zf
Output
Zf
Zb
Output
Zb
Gr
Output
Gr
METHANE
% composition ................... Real (96.5222)
R
T
N
I
E
O
G
N
NITROGEN
% composition .................. Real (.2595)
C
O
D
I
X
C
arbon
DIOX
i
D
e
% composition ......... Real (.5956)
T
E
N
H
A
E
ETHANE
% composition ...................... Real (1.8186)
D
O
R
P
N
P
A
E
PROPANE
% composition ................... Real (.4596)
W
E
A
T
R
WATER
% composition ........................ Real (0.0)
S
Y
H
F
U
L
D
HY
drogen
SULF
i
D
e
% composition .... Real (0.0)
R
D
H
Y
E
O
G
N
HYDROGEN
% composition ................ Real (0.0)
CO
M
N
X
C
arbon
MONOX
i
D
e
% composition ..... Real (0.0)
D
O
X
O
E
Y
G
N
OXYGEN
% composition ..................... Real (0.0)
U
B
N
T
A
E
i-BUTANE
% composition ................... Real (.0977)
-i
U
B
N
T
A
E
n-BUTANE
% composition .................. Real (.1007)
-n
N
P
N
T
A
E
i-P
e
NTANE
% composition .................. Real (.0473)
-i
N
P
N
T
A
E
n-P
e
NTANE
% composition ................. Real (.0324)
-n
E
H
N
X
A
E
n-HEXANE
% composition .................. Real (.0664)
-n
P
H
N
T
A
E
n-H
e
PTANE
% composition ................. Real (0.0)
-n
C
O
N
T
A
E
n-OCTANE
% composition .................. Real (0.0)
-n
O
N
N
N
A
E
n-NONANE
% composition .................. Real (0.0)
-n
E
D
N
C
A
E
n-DECANE
% composition .................. Real (0.0)
-n
E
H
U
L
I
M
HELIUM
% composition ....................... Real (0.0)
A
O
R
G
N
ARGON
% composition ....................... Real (0.0)
SU
M
%
M
OL
MOL% SUM
(read total % composition) ..........
Real (100.0)