Spirit flow-x, Справочник по функциям

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4-90
Flow-X─ Function Reference
Flow-X General functions - fxAPI_Dens20C_NGL_LPG
1. When API 11.2.4 rounding is enabled, the input density and temperature values
are rounded in accordance with the standard
2. At the start of the iteration the density at [20

C, equilibrium pressure] is set
equal to the observed density and the CPL value is set to 1.
3. First the density corrected for pressure is calculated by dividing the observed
density by the CPL value.
4. The relative density corrected for pressure is calculated from the density
corrected for pressure
5. The relative density at [60

F, equilibrium pressure] is calculated from the relative
density corrected for pressure and the observed temperature according to Table
23E
6. The relative density at [20

C, equilibrium pressure] is calculated from the
relative density at [60

F, equilibrium pressure] converted to 20

C according to
Table 24E
7. The density at [20

C, equilibrium pressure] is calculated from the relative density
at [20

C, equilibrium pressure]
8. The CTL value is calculated by dividing the density corrected for pressure by the
density at [20

C, equilibrium pressure]
9. Depending on the value of input 'Equilibrium pressure mode', either value of
input 'Equilibrium pressure value' is used or the equilibrium pressure (vapor
pressure) is calculated according to GPA TP-15. Whether the GPA TP-15 rounding
and truncation rules are applied is dictated by input ‘GPA-TP15 rounding’
10. API 11.2.2M requires the density at [15

C, equilibrium pressure]. For this
purpose the relative density at [15

C, equilibrium pressure] is calculated
according to Table 24E from the relative density at [60

F, equilibrium pressure]
and at 15

C. This relative density value is then converted to the density at [15

C,
equilibrium pressure].
11. The compressibility factor F is calculated according to API MPMS 11.2.2M from
the density at [15

C, equilibrium pressure] and the 'Observed temperature',
with, depending on input API 11.2.2M, rounding and truncation according to the
standard.
12. The CPL value is calculated from the compressibility factor, the equilibrium
pressure and the 'Observed pressure' input value.
13. The new value for density at [20

C, equilibrium pressure] is calculated by dividing
the observed density by the CTL and CPL values.
14. Steps 2 though 6 are repeated taking the density value from step 6 as the staring
value until the absolute difference between two consecutive density values is
less than the convergence limit.
To avoid convergence problems different convergence limits are applied,
depending on the whether API 11.2.2M and/or GPA TP-15 rounding is applied:
If API 11.2.2M rounding is enabled
-> Limit = 0.05 kg/m3
else if GPA TP-15 rounding is enabled -> Limit = 0.005 kg/m3
else
-> Limit = 0.00001 kg/m3
15. If API 11.2.4 rounding is enabled, then the density at [20

C, equilibrium pressure]
is rounded to 0.1
Conversion method 2: from standard to observed conditions.
The function performs straightforward calculations to determine the density at observed conditions:
1. When API 11.2.4 rounding is enabled, the input density and temperature values
are rounded in accordance with the standard