Hydrocarbon Processing - April 2022 - 34

Process Optimization
making it possible to add even more butane for a total of 3%-10%
additional volume increase over the CG93 volume, depending
on the properties of blending butane and naphtha available.
The cheapest and fastest way to implement the butanization
scheme is to inject butane into the tank filling line as the product
is being pumped into the tank. The disadvantage is that the
properties of the gasoline being pumped into the tank are not
well known; therefore, the butanization amount will be conservative
and not economically optimum.
The next cheapest way to implement the butanization scheme
is to sequentially inject butane into the tank filling line after the
gasoline product has been pumped into the tank. The advantage
here is that a tank sample can be taken and its properties analyzed.
This allows the determination of the maximum amount
of butane that can be injected without throwing the gasoline
product off spec. The disadvantage is that it takes much longer
to sample and analyze the tank, do the butane injection calculations,
physically add the butane, circulate the tank to ensure homogeneity,
sample the tank again, and ensure it is on spec.
TABLE 2. Downgrade CG87 to CBOB A4, with a profit of $3.7/bbl
Recipe
Component
n-Butane
Natural gasoline
Light naphtha
Medium naphtha
Heavy naphtha
Alky
Heavy reformate
Isom
MTBE
ETBE
CG87 reg
CG93
Vol%
4.56
28.2
13.02
54.23
bbl
4,200
26,000
12,000
50,000
Initial
A final option is to implement an inline blender that simultaneously
adds butane and naphtha to a stream of pipeline
gasoline. By using an online analyzer measuring RVP and potentially
other properties, operators can exploit every degree of
freedom to maximize the injection of butane and naphtha while
maintaining an on-spec blended product. Additionally, the use
of an inline static mixer ensures the homogeneity of the blend,
reducing or eliminating the time needed to circulate a tank for
homogenization. The disadvantage is the higher cost of installation
(approximately $500,000-$750,000).
BUTANE AND/OR NAPHTHA
BLENDING SCHEMES
Injection of butane and/or naphtha into the tank fill
line. Physically, butane and/or naphtha are injected via a specially
designed sparger-a pipe with holes drilled in it-that
sticks in the middle of the filling line (FIG. 1).
The butane and/or naphtha lines are each provided with
Inventory, bbl
Final
100,000
100,000
100,000
100,000
100,000
TABLE 3. Downgrade GC87 to CBOB A4 by using bio-ETBE, with a profit of $0.77/bbl
Recipe
Component
n-Butane
Natural gasoline
Light naphtha
Medium naphtha
Heavy naphtha
Alky
Heavy reformate
Isom
MTBE
ETBE
CG87 reg
CG93
Vol%
6.45
33.43
13.09
47.03
34 APRIL 2022 | HydrocarbonProcessing.com
bbl
6,452
0.01
33,425.78
13,090.03
47,031.99
Initial
Remaining
95,800
74,000
88,000
100,000
50,000
Price
$/bbl
50.51
76.38
75.12
75.78
76.44
96.75
113.05
80.74
97
107
87.03
92.15
Inventory, bbl
Final
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
Remaining
93,547.80
100,000
Price
$/bbl
99,999.99
66,574.22
100,000
100,000
100,000
100,000
86,909.97
52,968.01
50.51
76.38
75.12
75.78
76.44
96.75
113.05
80.74
97
107
87.03
92.15
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Hydrocarbon Processing - April 2022

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