This calculates calorific values, density, relative density and Wobbe index from a gas composition. Results are calculated for the composition treated as both a real and an ideal gas, inferior (net) and superior (gross) calorific value and Wobbe index are displayed in each case. This version of the calculation included both the definitive and alternative methods of calculating the calorific value on a volumetric basis.
FLOCALC Calculation reference F003
Kelton calculation reference C003
Kelton calculation reference C111
International standard, Natural Gas – Calculation of calorific values, density, relative density and Wobbe index (ISO 6976: 1995/BS 7589)
International Standard, Natural gas – Standard reference conditions (ISO 13443:1996)
- No Tail
- C6 Tail
- C7 Tail
- C9 Tail
Select the appropriate hydrocarbon tail. Where a tail is selected the percentage split of each component is entered, this is generally obtained from laboratory analysis.
Reference Temperature (Combustion/Metering)
- User entered reference conditions (ISO 13443)
This option is used to select the reference temperature used for the calculation. There is a choice of various combustion/metering temperatures used around the world or to manually enter base pressure, combustion and metering temperatures which will use the equations set out in ISO 13443:1996 to correct values from ISO standard conditions to those entered by the user.
- Full Precision
This option gives the choice to use the rounded molecular weights as shown in Table 1, or calculate the molecular weights with full precision using the elemental molars masses shown beneath Table 1.
Ideal Gas Calorific Value (Mass) Method
- Definitive (Table 3)
- Alternative (Table 4)
This option is used to select whether the mass calorific value is calculated using the alternative or definitive tables.
Ideal Gas Calorific (Volumetric) Method
- Definitive (Table 3)
- Alternative (Table 5)
This option is used to select whether the volumetric calorific value is calculated using the alternative or definitive tables.
- Extended Analysis
- Refinery/Trace Gases
These boxes can be checked to include a wider range of compounds in the composition.
This performs the calculations from C111 when set for 1995