PHYSICAL PROPERTIES OF HYDROCARBON...
Transcript of PHYSICAL PROPERTIES OF HYDROCARBON...
PHYSICAL PROPERTIES OF HYDROCARBON FLUIDS
Physical Constants for Pure Components
Pitzer: ω = - log Pr – 1
where Pr = P*/Pc; P*: vapor pressure at T = 0.7 Tc
Examples, NG at 2021 psia and 595 oR:
Comp yi Pc Pc’ Tc Tc’ MW MW’
N2 0.0046 492 2.26 227 1.04 28 0.13
CO2 0.0030 1073 3.44 548 1.64 44 0.13
H2S 0.1438 1306 188 673 97.0 34 4.89
C1 0.8414 673 568 343 288 16 13.5
C2 0.0059 708 4.17 550 3.24 30 0.18
C3 0.0008 617 0.49 666 0.53 44 0.04
i-C4 0.0003 529 0.16 735 0.22 58 0.02
n-C5 0.0002 490 negl 846 negl 72 negl
Σ 1.0000 767 psi 392 oR 18.89
P/Pc’ = Pr’ = 2021/767 = 2.64, T/Tc’ = Tr’= 595/392 =1.52
Use Fig. 5.1: Z = 0.80
Correction for CO 2 and H2S:
Metric: 35560 ε.TT 'c
"c −= ( ) 55601 3 .BBT
TPP
'c
"c
'c"
c ε−+=
English: 3ε−= 'c
"c TT ( ) 31 εBBT
TPP
'c
"c
'c"
c −+=
B is mole fraction H2S in the gas
Tc” = 392 – 21 = 371 oR
Pc” = (767)(371)/[218+(0.1438)(0.8562)(21)] = 720 psia
Pr” = 2.8 and Tr” = 1.6 à Z = 0.83
EMR Approach (please read ref.: Campbell)
LIQUID PHYSICAL PROPERTIES
Physical properties of liquid mixture are rather complex.
Especially oil mixture, which has many components involve.
Watson Characterization Factor
( )ρω .lRe
TAK
/B
31
=
A = 1.22 in Metric Unit; A = 1.0 in English Unit
TB = average molal boiling point, K or oR
Rel. ρ = relative density (specific gravity)
For exp, paraffin base crudes, the values range 11.9 – 12.2
How to measure TB ? à ASTM distillation, results
what is called a true boiling point (TBP) curve.
What is relative density (specific gravity) ?
ρ (g/cm3) = (Rel. ρ) (1.0); ρ (lb/ft3) = (Rel. ρ) (62.4)
Density of water at 15 oC (60oF) = 1.00095 g/cm3
API Gravity
API..
cm/g.lReo+
==5131
51413ρ
API Barrel
The word “barell” means “API barell” = 42 US gallons
= 5.615 ft3 = 159 liters
Rel. ρ vs Molecular weight
Effect of Methane and Ethane
Density of LNG (Liquefied Natural Gas)
∑∑
−=
Cxvx
Mx
mii
iiρ
Mι = mol.wt. of component i
xι = mol fraction of component i
vι= molar volume of i
xm = mol fraction of methane
C = correction factor for volume reduction