Hydrocarbon Processing - July 2021 - 53

Process
Optimization
J. E. ECHENAGUCIA, Heatoil Solutions LLC,
Venezuela
Reverse refining: A novel approach to
the refining process
The crude oil refining processing
sequence is based on the separation of
distillate products from heavier ones
and concentrating the heavy molecules
of the barrel for processing at the end of
the refining run. Processes developed to
convert the concentrated bottom of the
barrel into valuable distillates include hydrocracking
or coking (hydrogenation or
carbon rejection methods). In essence,
the processes to convert the long-chain
hydrocarbons-which are heavily concentrated
in the bottom of the barrel-
are complex, costly and limited to largersized
units (e.g., 30,000-bpd minimum
crude throughput).
Reverse refining. This article will detail
several benefits of first converting the
heavy molecules of the barrel at the beginning
of the refining run before the separation
and treatment of the end products are
performed. In this alternative, converting
asphaltenes into aromatics and saturates
(i.e., aromatic, cyclic and paraffins) is accomplished
at the beginning of the refining
process sequence.
It is a better alternative to use a lowercost
thermal cracking process (i.e., visbreaking)
to reduce the asphaltenes to
a minimum before the crude enters the
atmospheric distillation process. Using a
thermal cracking process, converting the
asphaltenes at the beginning of the refining
process has the following advantages:
* It allows the refiner to purchase
less-expensive crude (such as
heavy or extra-heavy crude) and to
convert it to its appropriate quality
prior to the refining process. By
adjusting the heavy ends conversion
and the production of distillates
before entering the refining
process, this minimizes the tedious
To gas plant
Steam
SE-3
Separator
SE-2
Cabimas crude 21
*API
SE-1
P-1
VB
Visbreaker
P-2
HDT = Mild hydrotreater
HDS = Hydrotreater
VGO = Vacuum gasoil
FIG. 1. Reverse refining process flow diagram.
Hydrocarbon Processing | JULY 2021 53
FH-1
furnace
FH-2
furance
P-4
IFO-180
Water
P-3
Atmospheric
tower D-1
Gas
To gas plant
CW
Naphtha
Kerosene
Diesel
To HDT and
reformer
VGO to
To HDT
To HDS
cat cracker
Vacuum tower
V-1
CW
blending required to optimize the
crude-quality feed to the process
plants. This alternative could
save refiners $10/bbl-$15/bbl.
* It optimizes the crude-quality
feed to the refinery. Using the
present conventional refining
process flow is complex and costly;
however, the reverse refining
method is a simpler alternative.
* This process significantly lowers
crude acidity and sulfur content by
cracking the naphthenic acids and
converting the sulfur molecules
in crude oil into hydrogen sulfide
(H2
S). Naphthenic acids are
converted into saturated molecules,
while the H2
S is separated from
the upgraded crude to be treated
in the acid gas plant. The result is a
reduction of metal corrosion of the
crude feed to the refining process.
Hydrocarbon Processing - July 2021

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