Spirit flow-x, Function Reference

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Flow-X─ Function Reference
Flow-X General functions - fxGPA2172_09_M
fxGPA2172_09_M
This function calculates the heating value, specific gravity and compressibility factor at metric (imperial)
conditions from the compositional analysis of a natural gas mixture in accordance with GPA2172-09.
This function does not support the theoretical hydrocarbon liquid content calculation that has been
added to GPA-2172 2009 revision.
GPA2172 describes the calculation methods to determine the compositional properties based on the
individual component values and it refers to the GPA Standard 2145 (GPA2145) standard for these
individual component values.
The effect of water on the calculations is rather complicated and is accounted for with a simplified
equation that is considered to be adequate for custody transfer applications.
Therefore compositional properties are calculated for the following gas compositions:

Wet gas composition
the water fraction of input "Composition' is taken as the actual water fraction.

Dry gas composition
the water fraction is set to 0 and the composition is normalized to unity.

Saturated gas composition
the water fraction is set to the value when the gas is saturated with water and the
composition is normalized to unity
GPA-2172 prescribes that the most recent edition of GPA2145 used for the individual component
values. The function provides the option to use the values from edition 2009.
Compliance

GPA Standard 2172-09, Calculation of Gross Heating Value, Relative Density, Compressibility
and Theoretical Hydrocarbon Liquid Content for Natural Gas Mixtures from Compositional
Analysis - 2009

API MPMS 14.5

GPA Standard 2145-09, Table of Physical Constants
Function inputs Remark EU SW tag Range Default
Name Optional tag name, tag
description and tag group
Composition Standard composition as
defined section 'Standard
Gas Composition' mol/mol COMP 0..1 0
Edition Refers to the base
conditions and the editions
of the GPA2145 values.
Note that these base
conditions are used for both
the density and the heating
value.
3: 15°C, 1.01325 bar(a),
GPA2145-09 - EDITION 2