Hydrocarbon Processing - January 2022 - 43

Carbon Capture/CO2
variations and areas with heavy
population density, among others.
* Corrosion: Although liquefied
CO2
does not present a
flammability hazard and dry CO2
does not present a corrosion
hazard for ordinary carbon steel,
prudent pipeline designs should
include monitoring and safeguards
against impurities such as sulfur,
mercaptans or hydrogen sulfide
(H2
cryogenic CO2 will be released
and could affect (carbonic acid
and the resulting low pH) marine
life. However, unlike hydrocarbon
spills, CO2
on the magnitude of the leak, the
CO2
vapor cloud could pose an
asphyxiation hazard for ships/
vessels in the vicinity.
S), water and others, depending
on the stack gas composition.
One key safeguard may include
upgrading to austenitic 316
stainless steel, as low-alloy carbon
steel corrosion could be a problem.
* Monitoring and specification
requirements: In addition to
monitoring for corrosion, online
instrument/control systems
should be provided to ensure
that product specifications
adhere to parameters set for
storage in caverns. For example,
instrumentation could include
online analyzers for water, sulfur
and impurities, hydrocarbons and
oxygen-and flowmeters/meter
provers and interlocks can help
halt flows to storage caverns in
the event of off-spec CO2
.
* Tank car and truck/marine
transport: These types of
transportation entail significant
handling risks of asphyxiation
and thermal shock. Tank cars or
truck transports tend to involve
considerable handling risk.
Loading/unloading racks should
include automatic programmable
logic controller (PLC) sequenced
operations or some other means
to minimize human interaction.
In addition, loading/unloading
stations should have ample
ventilation to minimize the
asphyxiation hazard.
* Transport disruptions: Risk
analyses must consider potential
disruptions and safety mishaps
(e.g., ship collision and/or fire,
truck/train accidents) and should
provide adequate warning systems
and safeguards to minimize
mishaps. The potential of
asphyxiation for workers in ships
also merits consideration. In the
event of a subsea pipeline rupture,
* Reuse and recycle: Reuse and
recycling are key pillars of a
sustainable/circular economy.
The reuse of CO2
for enhanced oil
recovery (EOR) or in the cement
industry can help improve project
economics. However, in the long
term, EOR might be impacted by
stricter government regulations.
Fortunately, considerable work is
in progress to develop new avenues
for the reuse and recycling of CO2
.
Technology
selection. Obviously, a
technology that does not meet safety,
productivity and environmental goals
would ruin an investment, as well as tarnish
a company's public image. Companies
must take a systems approach in
selecting technology that matches the organization's
existing process. The following
are several pitfalls to consider:
will escape. Depending
Mitigation
* Equipment sizes for the CO2
absorption technology: Liquid
solvent-based technologies could
entail large equipment and solvent
flowrates-hence, larger real estate.
A congested layout would make
it difficult to accommodate new
equipment additions and structural
foundation requirements. In
addition, utility requirements
(e.g., steam consumption, power
requirements, nitrogen and
instrument air) must be accounted
for. CO2
capture processes tend to
be steep in capital and operational
expenses.
* Maturity and reliability of the
technology: Nascent technologies
lack long-term reliability data.
Conversely, technology that is " too
mature " could face obsolescence
problems. For example, aminesolvent-based
processes are
relatively mature in comparison
with recent membrane processes,
which have less environmental
impact but lack operational history.
It is a delicate balancing act between
reliability and obsolescence.
* Liquid solvent or solid adsorbent
disposal issues: Even in disposal,
FIG. 1. Amine-based CO2
absorption process schematic.
FIG. 2. Adsorption-based CO2 recovery from flue gas.
Hydrocarbon Processing | JANUARY 2022 43
Hydrocarbon Processing - January 2022

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