Gas 1

aga92dc - Instructions for use

Revision: March 19, 2005

E-mail: info@felib.com

aga92dc is the C source code implementation of the International standard

ISO 12213-2:1997(E): Natural gas - Calculation of compression factor -

Part 2: Calculation using molar-composition analysis

The software is written in a C-language and embeds all the restrictions implied by ISO-12213-2.

1. Function prototype

The following is the definition of the function prototype:

void aga92dc(

/* output parameters */

unsigned long int *error_status, /* Error status */

float *sup_cal_value, /* Superior calorific value */

float *relative_density, /* Relative density */

float *compression, /* Compression (compressibility factor) */

float *density, /* Density [kg/m3] */

float *molar_density, /* Molar density [kg-mole/m3] */

float *mole_average, /* Mole average */

/* input parameters */

float tepmerature_K, /* Temperature [K] */

float pressure_MPa, /* Pressure in [MPa] */

float x20, /* molar fraction of Argon */

float x19, /* molar fraction of Helium */

float x18, /* molar fraction of n-Decane */

float x17, /* molar fraction of n-Nonane */

float x16, /* molar fraction of n-Octane */

float x15, /* molar fraction of n-Heptane */

float x14, /* molar fraction of n-Hexane */

float x13, /* molar fraction of n-Pentane */

float x12, /* molar fraction of i-Pentane */

float x11, /* molar fraction of n-Butane */

float x10, /* molar fraction of i-Butane */

float x9, /* molar fraction of Oxygen */

float x8, /* molar fraction of Carbon Monoxide */

float x7, /* molar fraction of Hydrogen */

float x6, /* molar fraction of Hydrogen Sulfide */

float x5, /* molar fraction of Water */

float x4, /* molar fraction of Propane */

float x3, /* molar fraction of Ethane */

float x2, /* molar fraction of Carbon Dioxide */

float x1, /* molar fraction of Nitrogen */

float x0 /* molar fraction of Methane */

)

2. Input and output parameters

The following Table shows the description of input and output parameters:

Table 2.1

Input parameters
Data type	Parameter name	Parameter description	Unit of measure
float	x0	molar fraction of Methane	dimensionless
float	x1	molar fraction of Nitrogen	"
float	x2	molar fraction of Carbon dioxide	"
float	x3	molar fraction of Ethane	"
float	x4	molar fraction of Propane	"
float	x5	molar fraction of Water	"
float	x6	molar fraction of Hydrogen sulfide	"
float	x7	molar fraction of Hydrogen	"
float	x8	molar fraction of Carbon monoxide	"
float	x9	molar fraction of Oxygen	"
float	x10	molar fraction of iso-Butane	"
float	x11	molar fraction of n-Butane	"
float	x12	molar fraction of i-Pentane	"
float	x13	molar fraction of n-Pentane	"
float	x14	molar fraction of n-Hexane	"
float	x15	molar fraction of n-Heptane	"
float	x16	molar fraction of n-Octane	"
float	x17	molar fraction of n-Nonane	"
float	x18	molar fraction of n-Decane	"
float	x19	molar fraction of Helium	"
float	x20	molar fraction of Argon	"
float	pressure_MPa	operating pressure	[MPa]
float	temperature_K	operating temperature	[K]
Output parameters
float	mole_average	gas mixture molar mass	dimensionless
float	molar_density	gas mixture molar density	[kg×mol/m³]
float	density	gas mixture density	[kg/m³]
float	compression	gas mixture compression factor	dimensionless
float	relative density	gas mixture relative density	"
float	sup_cal_value	gas mixture superior calorific value	[MJ/m³]
unsigned long int	error_status	error status	dimensionless

3. Parameter ranges

The following Table shows the ranges for input parameters and intermediate results, as defined by ISO 12213-2.

Table 3.1

Component	Unit of measure	A*	B**
methane	dimensionless	0.70 to 1.00	0.50 to 1.00
nitrogen	"	0 to 0.20	0 to 0.50
carbon dioxide	"	0 to 0.20	0 to 0.30
ethane	"	0 to 0.10	0 to 0.20
propane	"	0 to 0.035	0 to 0.05
butanes (n-Butane + i-Butane)	"	0 to 0.015	0 to 0.0015
pentanes (n-pentane + i-Pentane)	"	0 to 0.005	0 to 0.005
hexanes (n-Hexane)	"	0 to 0.001	0 to 0.001
heptanes (n-Heptane)	"	0 to 0.0005	0 to 0.0005
octanes plus higher hydrocarbons (n-Octane, n-Nonane, n-Decane)	"	0 to 0.0005	0 to 0.0005
hydrogen	"	0 to 0.10	0 to 0.10
carbon monoxide	"	0 to 0.03	0 to 0.003
helium	"	0 to 0.005	0 to 0.005
water	"	0 to 0.015	0 to 0.00015
argon	"	0 to 0.0002	0 to 0.0002
absolute pressure	[MPa]	0 to 12	0 to 65
temperature	[K]	263 to 338	225 to 350
relative density	dimensionless	0.55 to 0.80	0.55 to 0.90
superior calorific value	[MJ/m³]	30 to 45	20 to 48

* A: pipeline quality natural gas

** B: wider ranges of application

The wider ranges of application (B) are implemented in aga92dc routine

4. Error status

After completion of the routine the error_status (unsigned long integer) will be cleared if there were no errors during the calculation, or the corresponding bits will be set if certain errors were encountered. The error_status is represented in the following way:

Bit 0 =1 (000001H) If there exist at least one molar fraction < 0, else =0.

Bit 1 =1 (000002H) If the total sum of molar fractions <0.98 or >1.02, else =0.

Bit 2 =1 (000004H) If the total sum of molar fractions is <0.999999 or >1.000001, else =0. This bit denotes only a warning that the fractions have been normalized to give the total sum of molar fractions equal to 1. If only bit 2 was set during the calculation the results are valid.

Bit 3 =1 (000008H) If mole fraction of Methane <0.5 or >1.0, else =0.

Bit 4 =1 (000010H) If mole fraction of Nitrogen >0.5, else =0.

Bit 5 =1 (000020H) If mole fraction of Carbon Dioxide >0.3, else =0.

Bit 6 =1 (000040H) If mole fraction of Ethane >0.2, else =0.

Bit 7 =1 (000080H) If mole fraction of Propane >0.05, else =0.

Bit 8 =1 (000100H) If mole fraction of Water >0.00015, else =0.

Bit 9 =1 (000200H) If mole fraction of Hydrogen sulfide > 0.0002, else =0.

Bit 10 =1 (000400H) If mole fraction of Hydrogen >0.10, else =0.

Bit 11 =1 (000800H) If mole fraction of Carbon monoxide > 0.03, else =0.

Bit 12 =1 (001000H) If mole fraction of Oxygen >0.0002, else =0.

Bit 13 =1 (002000H) If mole fraction of Butanes (n-Butane + i-Butane) >0.015, else =0.

Bit 14 =1 (004000H) If mole fraction of Pentanes (n-pentane + i-Pentane) >0.005, else =0.

Bit 15 =1 (008000H) If mole fraction of Hexanes (n-Hexane) >0.001, else =0.

Bit 16 =1 (010000H) If mole fraction of Heptanes (n-Heptane) >0.0005, else =0.

Bit 17 =1 (020000H) If mole fraction of octanes plus higher hydrocarbons (n-Octane + n-Nonane, n-Decane) >0.01, else =0.

Bit 18 =1 (040000H) If mole fraction of Helium >0.005, else =0.

Bit 19 =1 (080000H) If mole fraction of Argon >0.0002, else =0.

Bit 20 =1 (100000H) If pressure <0.1 Pa or >65 MPa, else =0.

Bit 21 =1 (200000H) If temperature <225 K or >350 K, else =0.

Bit 22 =1 (400000H) If relative density <0.55 or >0.90, else =0.

Bit 23 =1 (800000H) If superior calorific value <20 MJ/m³ or >48 MJ/m³, else =0.

Bit 24 =1 (1000000H) If OFF-LINE calculation failed, else=0.

Bit 25,... All higer bits are unused

The error_status is returned as unsigned long integer representing all the errors encountered in the calculation. If bits 0,...,24 are all cleared, or if only bit 2 was set during the calculation, the returned output results are valid, otherwise the results are invalid, i.e. cleared.

5. Example of a main program calling the function aga92dc

The following example illustrates the call to aga92dc function from a main program. Input parameters yy[igas][0], ..., yy[igas][20] represent natural gas mixture molar fractions where igas = 0 denotes Gas 1, ..., igas =5 denotes Gas 6 (See table 6.1 in chapter 6), yy[21] represents operating pressure (6 MPa) and yy[22] represents temperature 310 K. The output results are saved in yy[23], ..., yy[28] and an error status in error, after the completion of the routine. The program prompts for the selection of the gas mixture, for the operating pressure and temperature and prints the results on the screen.

/* **************************************** */

/* THE BEGINNING OF THE MAIN PROGRAM C-CODE */