Page 449 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

410 Production

Correlation constants are given in Table 6-13.
Next, correlation of critical properties and acentric factor (0) of hydrocarbons
and derivatives is developed in terms of M, Tb and S. Since molecular mass is
readily determined by experiments, it is introduced as a correlating variable to
obtain more general results. The specific gravity is the ratio of the density of
the liquid at 20°C to that of water at 4°C.
The critical properties and acentric factor of C, to C,, n-alkanes are correlated
with M by the following equation:
e, = C, + C,M + C,W + C4M3 + C,/M (6-31)

where e, represents T,, L,P,, V, or COT, of a n-alkane. The coefficients C, to C,
are reported in Table 6-14 for each property. It was additionally correlated S
and Tb of the n-alkanes by Equation 6-31 and the coefficients are included in
Table 6-14. The correlated SA and ThA of the n-alkanes will be required in the
perturbation equations to follow as independent variables.
The average absolute deviations (AAD) of the correlations from the American
Petroleum Institute project 44 table values are 0.15% for T, 1.0% for p,
(excluding methane), 0.8% for V,, 1.2% for 0, 0.11% for T, and 0.07% for S.
The specific gravity correlation applies only to C5-C16, which are the only n-alkanes
that are liquids at 20°C.
Properties of the general hydrocarbons and derivatives are correlated as
perturbations of those of n-alk&es according to the equation
e = e, + A,AS + A,AT, + 4 (AS)* + A~ (AS)(AT,) + A,(AT,),

+ %(AS)3 + A,(AS)*(ATb) + A,,(AS)(AT,), + A.$ATb)3 (6-324
with

AS = S - SA (6-323)
ATb = Tb - TbA (6-32~)

Table 6-13
Correlatlon Constants for Ec iatlon 6-30
B a b C

H (Molecular mass) 4.5673*10-' 2.1962 -1.0164
T, (Critical Temperature OR) 24.2787 0.58848 0.3296
P, (Critical Pressure, psie) 3 .12281*109 -2.3125 2.3201
Vem (Holar critical volume
fta/ lb mole) 7.0434*10-' 2.3829 -1.683
V, (Critical Volume fta/lb) 7.52l4*1OJ 0.2896 -0.7666
V (Llquid molar volume at 20%
and 1 atm (d/g mole) 7.6211*l(rc 2.1262 -1.8688
p (Liquid density g/cc) 0.982554 0.002016 1.0055
1