Hydrocarbon Processing - December 2021 - 64

Environment and Safety
more wasteful when the time comes to discharge the
solvent overboard after leaving port.
* The best technical approach is to add caustic to the
solution gradually, as it is consumed. This means
measuring and adjusting the pH. The scrubber system
is a small chemical plant that must be operated at sea
by operators relatively unfamiliar with process plant
operations. Using a chemically reactive solvent certainly
does not make the operation any easier to manage.
In the example given here, the SO2
The simulatorb
is strictly mass transfer-rate based, and is
therefore capable of accurately assessing the effect of the particular
packing type, its size and material, and even the brand.
The results produced are quantitatively accurate, and the effects
of changing parameters on performance can be relied
upon. The mass transfer rate-based simulation helps optimize
SO2
seawater scrubber design for sound, environmentally responsible
operation.
removal system can be
operated satisfactorily with unreacted NaOH concentrations
in the column feed above approximately 0.06 wt%, at which
concentration only 2%-3% of the CO2
is co-absorbed. However,
the bed depth is only 1.5 m, whereas the depth needed
when using seawater alone is 6 m-8 m for around 90% SO2
removal. Rather than two columns in parallel, it would make
greater economic and physical sense to have a single bed with
two feed points, one at the top for seawater only and one at the
1.5-m level (in this case) when using caustic soda. The short
bed would be on the bottom for use with caustic, and a deeper
bed would be on top, with both beds being operated together
when using seawater. Liquid distribution should be via spray
nozzles, rather than troughs, to alleviate the effect of sloshing
from vessel pitch and yaw. Such a system is not difficult to fully
automate with push-button switching from seawater to caustic
and with caustic addition under pH control to maintain the effluent
solvent above a pH of around 6.0.
NOTES
a Mellapak
b ProTreat
c Specific area is the surface area per unit volume of packing (area/volume)
PEDRO OTT joined Optimized Gas Treating Inc. in 2018 as a Senior Applications
Engineer in Business Development, providing marketing, licensing and technical
support to ProTreat and SulphurPro customers. With over 25 yr of experience,
he is an expert in acid gas treating, sulfur recovery, gasoline and distillates
hydroprocessing, sour water stripping and LNG. He holds a BS degree in chemical
engineering from Simón Bolívar University in Venezuela and a specialization in
petroleum refining and gas from IFP School in France. In addition to English, he is
fluent in Spanish and French.
RALPH WEILAND is Chairman of Optimized Gas Treating. He formed Optimized
Gas Treating more than 25 yr ago, and with Australian colleagues developed the
ProTreat mass transfer rate-based gas treating simulator, and later the sulfur
plant simulator SulphurPro. He holds BASc and MASc degrees, as well as a PhD,
in chemical engineering from the University of Toronto.
LITERATURE CITED
1
Miller, G., " Coronavirus is decimating IMO 2020 ship-scrubber savings, "
American Shipper, March 10, 2020, online: https://www.freightwaves.com/news/
coronavirus-is-decimating-imo-2020-ship-scrubber-savings
ON DEMAND WEBCAST
Moving Towards Condition-Based Maintenance for
Plantwide Automation Assets
Manoj Chandrasekharan
Offer Director - Asset Management,
Process Automation
Schneider Electric
Plant automation including fi eld devices is not only fundamental building block of any
industrial plant but also represents signifi cant capital and operational cost. Traditionally plants
have adopted preventive maintenance practices to prevent unscheduled downtime. While
this may uncover some possible problems; studies have found that not only this maintenance
approach labor-intensive, it does not eliminate the possibility of catastrophic failures.
We will discuss a Condition-Based Maintenance approach for plant automation assets which
will deliver higher plant productivity at lower risk.
* We will cover constraints of current maintenance strategy for plant automation assets
* Steps for an eff ective Condition-Based Maintenance program for plant automation assets
* A customer success story
Lee Nichols
Editor-in-Chief/Associate Publisher
Hydrocarbon Processing
64 DECEMBER 2021 | HydrocarbonProcessing.com
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Hydrocarbon Processing - December 2021

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