Chemical Engineering August 2023 - 19

storage and a flexible, non-intermittent
supply of hydrogen. It will be very
exciting bringing these new renewable
technologies to life. "
Safe hydrogen handling
No matter how hydrogen is produced,
it must be handled as safely
as possible. It can be explosive when
not handled properly, especially at
the high pressures required for many
transport and end-use options. " As
it moves throughout the value chain,
hydrogen is subject to pressures
of up to 15,000 psi, and, like many
fuels, can be explosive when not
handled properly. To achieve a landscape
that can effectively and safely
meet demand, it is critical that companies
identify technologies that can
reliably and efficiently control hydrogen
fuel, from production through
end use. This requires high-pressure
solutions across the hydrogen ecosystem, "
says Akilah Doyle, global
product marketing manager at Emerson
(St. Louis, Mo.; www.emerson.com).
While the components for
hydrogen storage and transportation
have been well-demonstrated,
large-scale electrolyzers and fuel
cells require some additional safety
and control considerations. " For an
electrolyzer to work effectively and
safely, the flow of water, hydrogen
and oxygen, must be precisely controlled.
Reliable valves, backpressure
regulators and an intelligent
programmable logic controller (PLC)
can provide a high level of media
control, " explains Doyle. There are
essentially four control layers in an
electrolyzer that work in tandem to
provide the control needed to ensure
safe and efficient operation:
the valves controlling media flow (including
backpressure regulators and
pneumatic shutoff valves); the actuation
technology (including valve
islands and solenoid pilot valves);
the PLC; and the supervisory control
and data acquisition (SCADA)
system. Doyle notes that some
valves in the system will require
IP66 protection.
For fuel cells, the requirements
are similar, but because hydrogen
is the feed rather than the product,
high-pressure storage is crucial
as it helps to maximize system
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19
fuel usage. " The hydrogen storage
tanks cannot be run to empty due
to pressure constraints, so enabling
efficient fuel delivery to the fuel-cell
stack with minimal losses is critical.
The system must be able to operate
consistently across a range of
operating modes - acceleration,
deceleration, stopping and idling,
which all require varying hydrogen
flow demands. This stable system
operation is aided through a design
that employs positive, high-pressure
fuel shutoff and is achieved through
use of a reliable hydrogen regulator, "
says Paul Kondratyev, global product
marketing manager at Emerson.
Such regulators minimize the risk of
leaks and can extend the lifecycle of
fuel cells by ensuring they have an
even amount of hydrogen dispersed
across them while in use (Figure 2).
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Chemical Engineering August 2023

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