Page 103 - Fluid Catalytic Cracking Handbook

80 Fluid Catalytic Cracking Handbook

Xp = 257.37 + 101.33(Ri) + 160.988(0.8575)

Xp = 56,7 mo.1%

Where:

Constants a = +2.5737
b = +1.0133
c - -3.573
d = +2.464
e = -3.6701
f = +1.96312
g = 4.0377
h = +2.6568
i = +1.60988

The findings from TOTAL, n-d-M, and API are summarized in Table
2-10. The comparison illustrates how sensitive the predicted feed
composition is to the refractive index @ 20°C. For instance, using the
TOTAL correlation, there is a 35% drop in the aromatic content in
using RI (20) = 1.5000 instead of RI (20) = 1.5105. When using these
correlations, every effort should be made to obtain accurate and
consistent values for the refractive index at 20°C. With the refractive

Table 2-10
Comparison of the Findings Among the 3 Correlations

API n-d-M TOTAL
Refractive Index
@ 20°C 1.5000 1.5105
Molecular Weight 413 430 446

Carbon Content: Mol% Wt% Wt%
Aromatic 11.5, (14.3)* (20.2)*,(8.8) t 19.2, (12.5)*
Naphthene 31.8, (27.9)* (20.2)*,(41.1) f
Paraffin 56.7, (57.8)* (59.6)*,(50.1) t
*Uses Rl l2i)l from n-d-M correlation to determine composition,
T
Uses RI^ 0ifrorn API correlation to determine composition.