Hydrocarbon Processing - January 2022 - 66

Bio-Based Processing
TABLE 2. Typical process impacts for downstream treating units
Approach
Drop-in hydrotreating
Water volume
Unit size and feedstock dependent.
Increases in total facility sour water
volume in the range of 10%-25% have
been witnessed at 10% coprocessing.
HVO production
Unit size and feedstock dependent,
but large. Increases in total facility
sour water volume in the range of
40%-60% have been seen.
Drop-in FCCU
Up to 80% of the oxygen present
in the feed will convert to H2
O.
Canola oil: 85% of feed oxygen
is converted to H2
O.8
Soybean oil: 85% of oxygen is converted
to H2
O.9
Pyrolysis oil: 78% of inlet oxygen
is converted to H2
O.9
Water bulk composition
Water trace compound
composition
500 ppmw NH3
200 ppmw H2
-40,000 ppmw NH3
S-20,000 ppmw H2
S
200 ppmw CO2-2,000 ppmw CO2
Phosphate and sulfate detected.
500 ppmw NH3
200 ppmw H2
-900 ppmw NH3
S-400 ppmw H2
S
1,200 ppmw CO2
-2,000 ppmw CO2
Phosphate and other anions
expected, but data is not available.
Processing pure vegetable oils in
a lab resulted in water with acids7
:
Acetic: 900 ppmw-1,700 ppmw
Propionic: 600 ppmw-1,400 ppmw
Formic: 200 ppmw-300 ppmw
Butyric: 10 ppmw-20 ppmw
Gas bulk composition
increased from less than
50 ppmv to 4,000 ppmv to
15,000 ppmv on biofeedstock
introduction.
CO2
Dedicated hydrotreater has the
following ranges: H2
6,000 ppmv) and CO2
(2 vol%-5 vol%)
CO increased from 0 ppm to
between 1,200 ppm-4,500 ppm
for 5%-10% coprocessing.
Gas trace compound
composition
In some instances, increased
coprocessing created more than 1% CO.
While not rigorous, a rough
relationship of 400 ppmv of CO
in the recycle per 1% of biofeed
processed appears to hold.
LPG bulk composition
-
-
S (200 ppmv-
Vegetable oil: Higher C1 and C2
lower hydrogen yield vs. VGO.10
,
Pyrolysis oil: Hydrogen, methane
and ethane decreased vs. VGO.3
Vegetable oil: 12% of oxygen feed
is converted to CO2
, along with
4% to CO.8
Soybean oil: 15% of oxygen feed
is converted to CO and CO2
.9
Pyrolysis oil: Generates more CO than
CO2
Approximately 22% of the inlet
oxygen is converted to CO and CO2
.3
.9
Vegetable oil: LPG yield was the
same as from VGO.10
Pyrolysis oil: LPG yield decreased
vs. VGO.3
LPG trace composition
-
-
Ketones, aldehydes, carboxylic acids
and furans.11
On some sites, levels of
oxygenates in the LPG have increased
by an order of magnitude (e.g., from
100 ppmv to 1,000 ppmv).
Amine acid gas (AAG)
to the sulfur plant
A 0.65 mol%-0.8 mol% increase
in the CO2
in AAG per 1% of
coprocessed feed. This comes
mostly from increased generation
of CO2
from the biofeed, which
outweighs the dilution effect
from reducing the crude oil volume.
Acid gas from a dedicated
HVO amine circuit would be
predominantly CO2
H2
Increased CO2
with little
S. If there is not a pre-existing
sulfur plant in the complex, then
often a scavenger technology
will be used to remove the H2
S.
Some facilities run this through
an additional amine unit designed
to separate the H2
S and CO2
Sour water acid gas
(SWAG) to the sulfur plant
Similar to AAG; 0.65 mol%-0.8 mol%
increase in the CO2
in SWAG per 1%
of coprocessed feed.
.
A 40%-50% increase in SWAG
volume. CO2
SWAG increased to between
9%-22%, with the balance
of composition being mostly
hydrocarbons, hydrogen and
nitrogen.
66 JANUARY 2022 | HydrocarbonProcessing.com
content in combined
Increased CO2
and NH3
, decreased H2
S
vs. crude-only feed.
, decreased H2
vs. crude-only feed.
S
Increased CO2
NH3
and decreased H2
, HCN and RSH vs. crude oil.
S,
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