Hydrocarbon Processing - May 2022 - 34

Biofuels, Alternative Fuels and Green Petrochemicals
matches the particle average diameter. To
enhance hydrodynamics, an inert nonpowith
two different bed lengths to test two
different liquid hourly space velocities
No plugging was observed in any of the small-scale
reactors during the 23-d test. The high-throughput
16-parallel reactors system offers a reliable testing
platform to quickly screen new catalysts for the
production of renewable fuels.
rous diluent material (with a defined average
particle size distribution) is used as a
filler. Before conducting the final loading
in a steel reactor tube, a trial loading is often
performed in quartz reactors to confirm
the packing (FIG. 1). The extrudates
are not sorted for length or otherwise.
Operating conditions. A commercial
ULSD NiMo catalyst was loaded in eight
reactors (561-mm length and 2-mm ID)
1.6
0.8
dP_R1
dP_R2
dP_R3
dP_R4
dP_R5
dP_R6
dP_R7
dP_R8
(LHSVs) simultaneously. All reactors
were tested at 70 barg pressure.
Feedstock. Pressure drop is one of the
main challenges when processing vegetable
oils in hydroprocessing units. This
is even more evident when using pilot
plants with small-diameter
reactors, as
catalyst fouling can quickly lead to plugging.
For this reason, the approach of this
test was the co-feeding of the vegetable
oil (soybean oil, see properties in TABLE 1)
blended with an SRGO at different ratios,
as shown in TABLE 2.
TABLE 2 lists the different feed
blends tested over a period of 400
hr onstream (HOS) and 100% VO
over 150 hr (6 d). The feed blends
with 70% VO and 100% VO were
spiked with dimethyl disulfide
(DMDS) up to 2 wt% sulfur.
RESULTS
Mass balance. Mass balance calculations
ensure that the metered flows used
in the calculations are accurate. An accurate
mass balance is an internal control of
the data quality obtained.
When calculating mass balance, variOverall
average
0.2 ± 0.2 barg
ous accurate measurements from both
online and offline analytical equipment
are composed together to accurately measure
mass balance. Inherently, system errors
from feed distribution to analytics require
some consideration in interpreting
the reported data. The main difference is
that, compared to a single reactor, the distribution
of liquid (i.e., the LHSV) across
all the reactors has a relatively large impact
on the recorded mass balance. FIG. 2
shows the overall mass balance for all reactors
and the different feed blends.
The mass balance calculation includes
100
20% VO
80% SRGO
200
40% VO
60% SRGO
300
Time onstream, hr
70% VO
30% SRGO
FIG. 3. Pressure drop for all eight reactors for all feedstocks tested (colors varied by reactor).
TABLE 1. Product sulfur at ULSD conditions for two VO blends
Condition
40% VO
70% VO
100% VO
TABLE 2. Feedstocks tested
HOS
0-60
61-110
111-278
279-400
400-550
LHSV = 1 l/l/hr
3.3 ± 0.7 ppmw S
4.6 ± 0.7 ppmw S
1.5 ± 0.2 ppmw S
100% VO
400
500
600
the water in the gas stream measured with
the online gas chromatograph (GC). Using
the GC to measure the water content
in the effluent gas is a reliable method for
closing the mass balance. The gas-liquid
separator was operated at optimized conLHSV
= 1.5 l/l/hr
35.2 ± 3.0 ppmw S
86.4 ± 2.8 ppmw S
2.6 ± 0.5 ppmw S
Feed
SRGO
Description
Line out
20% VO + SRGO
40% VO + SRGO
70% VO + SRGO
100% VO
34 MAY 2022 | HydrocarbonProcessing.com
20% VO testing
40% VO testing
70% VO testing
100% VO testing
FIG. 4. Example SimDis for 40% VO feedstock
(above) and the liquid product (below).
Reactor pressure drop, barg

http://www.HydrocarbonProcessing.com

Hydrocarbon Processing - May 2022

Table of Contents for the Digital Edition of Hydrocarbon Processing - May 2022