Page 75 - Fluid Catalytic Cracking Handbook

FCC Feed Characterization 53

Both tests produce similar results and often are interchangeable (see
Figure 2-6).
The Micro-method uses an analytical instrument to measure Conradson
carbon in a small automated set. The Micro-method (ASTM D4530)
gives test results that are equivalent to the Conradson carbon residue
test (D189). The purpose of this test is to provide some indication of
the relative coke forming tendency of such material.
The heptane insoluble (ASTM D-3279) method is commonly used
to measure the asphaltene content of the feed. Asphaltenes are clusters
of poly nuclear aromatic sheets, but no one has a clear understanding
of their molecular structure. They are insoluble in C 3 to C 7 paraffins.
The amount of asphaltenes that precipitate varies from one solvent to
another, so it is important that the reported asphaltene values be
identified with the appropriate solvent. Both normal heptane and

i \J\J q
_j

1 10 , f:
5 - ' _ . -I
c ** Jj ~ \
o / ^
•8 /
/'
$ 1
E - :\
o ? ' "1
Ht! '
-Q X ^
to _-!
••'^
| 0.1 T- =
01 U _

\
0 01
OJ31 0.1 1 10 100
Conradson Carbon, wt%
Figure 2-6. Ramsbottom Carbon Residue versus Conradson Carbon Residue,
(Copyright ASTM D-524. Reprinted with permission.)