Page 405 - Characterization and Properties of Petroleum Fractions - M.R. Riazi

P2: IML/FFX
QC: IML/FFX
P1: IML/FFX
AT029-Manual
AT029-09
June 22, 2007
14:25
16 AT029-Manual-v7.cls T1: IML 9. APPLICATIONS: PHASE EQUILIBRIUM CALCULATIONS 385
14 Data
Model
12
Wax Weight%_ 10 8 6
4
2
0
220 240 260 280 300 320
Temperature, K
(a) Oil 1

10
Data
8 Model FIG. 9.20—Effect of pressure on cloud-point temperature and
wax formation in a synthetic crude oil at low pressures. Taken
Wax Weight%_ 6 4 322
with permission from Ref. [17].

2 __ 320
Cloud Point Temperature, K 318

0
220 240 260 280 300 320
Temperature, K Original Oil
(b) Oil 6 30% CO 2
FIG. 9.18—Prediction of wax precipitation 316 30% C1
and cloud-point temperature for oils 1 and 6 30% C2
30% C5
given in Table 9.10. Taken with permission from
Ref. [43]. 314
0 100 200 300 400 500 600
Pressure, bar
0.01 temperature at high pressures for a crude oil di-
FIG. 9.21—Effect of pressure on cloud-point
Solute Mole-Fraction in Liquid Phase 0.001 9.4 ASPHALTENE PRECIPITATION:
luted by various light hydrocarbons. Taken with
permission from Ref. [17].

SOLID–LIQUID EQUILIBRIUM

Prediction of asphaltene precipitation is more difficult and
Data
complex than prediction of wax precipitation. The reason for
Calculated with Cp term
this complexity is the complex nature of asphaltenes and the
Calculated without Cp term
mechanism of their precipitation. The presence of resins fur-
0.0001
ther complicates modeling of asphaltene precipitation. In ad-
3.35 3.4 3.45 3.5 dition asphaltene molecules are polar and when aggregated
1000/T, 1/K
they behave similar to polymer molecules. Asphaltenes are
FIG. 9.19—Effect of ΔC P term on calculation of heavier than wax and they precipitate at a higher tempera-
solute solubilities at 1 bar [43]. Drawn based on ture than WAP. Asphaltenes usually exist in heavier oils and
data from Ref. [43]. for the case of crude oils at atmospheric pressures the amount

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