Hydrocarbon Processing - September 2021 - 52

Refining Technology
schematic of the integrated pre-filter/coalescer
module alongside the actual, fabricated
equipment being installed at the
refinery is provided in FIG. 5.
FIG. 5. CAD rendering of the first commercial unit supplied to a South American refinery (left)
and the completed module being installed at the refinery (right).
Rental units. In addition to a permanent
installation, another option is the implementation
of rental pre-filter and cartridge
liquid-liquid coalescer skids. This allows
refineries to quickly install a filter and/or
liquid-liquid coalescer skid to solve a fouling
or quality problem. The time frame for
rental unit deployment is days to weeks vs.
months to years for purchased, customengineered,
permanent
fleet
of rental skids is available that generally
meets or exceeds refinery specifications.
These skids are large enough to
handle most process flows, while providing
acceptable filter life and liquid-liquid
coalescer performance. Examples of a proprietary
liquid-liquid coalescer rental skidd
and a proprietary pre-filter rental skide
provided in FIGS. 6 and 7, respectively.
are
FIG. 6. Proprietary high-efficiency horizontal
liquid-liquid coalescer rental unitd
.
increased water, salt and clay changeout
frequencies, and thus requiring additional
unplanned downtime and financial losses.
A final additional cost to consider is
connected to the operation of the ECP
where caustic slugs or upsets occur. These
conditions can lead to the electrical grids
shorting out, which will require premature
maintenance for replacement. Depending
on the availability of components, significant
lead times may be required, and the
limitations on jet fuel production may be
protracted, thereby deepening product
margin losses for the refinery. The associated
costs include replacement parts, maintenance
labor and margin losses due to bypassing
or curtailing jet fuel production.
Commercial options. The use of highefficiency
cartridge liquid-liquid coalescers
can be deployed in two ways. The
ECP can be completely replaced, allowing
the cartridge coalescer to process the
full kerosene flow, or the coalescer can be
used in parallel to the ECP, processing a
portion of the total kerosene flow to allow
the ECP to operate at a flowrate that
is low enough to significantly improve its
performance and the reactor protection
it is intended to provide. Schematics2
these options are depicted in FIG. 4.
FIG. 7. Proprietary duplex, horizontal pre-filter
rental unite
.
The advantage of using the full-flow
option is that it will be more flexible in
separating tougher emulsions that can be
created by a higher TAN content in the
inlet kerosene feed or by using a higher
concentration of caustic that may be desirable
to reduce waste disposal costs.
The use of the cartridge liquid-liquid
coalescer in parallel to the existing ECP
may be beneficial for cost reductions, given
that this arrangement would require
smaller cartridge coalescer equipment.
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52 SEPTEMBER 2021 | HydrocarbonProcessing.com
First commercial unit. The first commercial
unit for applying the high-efficiency
cartridge liquid-liquid coalescers
to the mercaptan oxidation kerosene
caustic pre-wash has been supplied to a
refinery in South America and is expected
to be commissioned in mid-2022. The
unit consists of dual vertical pre-filters
that contain absolute-rated particle filters
followed by a horizontal liquid-liquid
coalescer vessel that contains fluoropolymer-type
coalescer cartridges. The system
will operate with one filter online
and one in standby mode to allow continuous
protection of the coalescer cartridges
from particulate fouling. The coalescing
system is designed for a flowrate of
10,000 bpd (292 gpm). A CAD-rendered
Takeaway. The use of high-efficiency
cartridge liquid-liquid coalescers was
clearly demonstrated as an improved
alternative to ECP through successful
onsite pilot trials at five global refineries
where high-TAN (greater than 0.025
mg KOH/g feed) kerosene was present.
This cartridge coalescer technology,
which provides enhanced separation of
the caustic and naphthenic salts over the
ECP, has a significantly lower associated
capital investment and a much smaller
footprint. The process benefits related to
reduced carryover of the contaminants
contained in these caustic-washed kerosene
streams include a dramatic reduction
in fouling issues in the mercaptan
oxidation reactor bed and the ensuing reduction
in unit downtime (and in lost jet
fuel production margins) resulting from
avoidance of excessive hot-water washing
to restore reactor permeability. The onset
of increased differential pressure-and
the risk of crushing the activated carbon
bed granules in the reactor, requiring
replacement and associated costs-will
also be greatly reduced.
The first commercial high-efficiency
cartridge liquid-liquid coalescer unit has
been delivered to a South American refinery
and is slated to start up operations
by 2022. The two different approaches
for installation of the cartridge liquidliquid
coalescers are to fully replace the
equipment. A

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