H2Tech - Q1 2022 - 21

SPECIAL FOCUS: ADVANCES IN HYDROGEN TECHNOLOGY
Obtaining accurate flow measurements
is essential to electrolytic H2
The electrolysis process is used in
many different industries, including
metal extraction, zinc and copper refining,
electroplating, semiconductors and
green H2
production. This process uses
liquid in which electrodes (positively
and negatively charged materials that react
when a current is sent through them)
are suspended. At the end of the process,
a different material or set of materials is
produced. Both the electrodes and the
liquid are vital to electrolysis: the role of
measurement in this context is to ensure
that the correct amount and type of liquid
is used. The efficacy of various types
of measurement devices in achieving this
depends on both the intended end product
and the composition of the initial liquid.
The process for making chlorine gas
(Cl2
, H2
gas,
, albeit not a green H2
.
option.
age, costs, environmental impact and any
other metric the facility is required to report.
The same holds true for the salable
products at the process's end: they need
to be measured accurately to ensure the
correct amounts are flowing from the process
and are stored, sold and transported.
The following quote ought to give an
idea of how much water is used in the
creation of H2
.
" ...For every kg of hydrogen
produced, 9 kg of water must be
consumed. Therefore, 2.3 Gt of
hydrogen requires 20.5 Gt, or
20.5 billion m3
production
T. BALL, Emerson, Minneapolis, Minnesota
Vortex flowmeters. A proven, widely
used technology, the vortex flowmeter
(FIG. 1) can be used for all measurement
points. It is a relatively affordable option
and comes in dual or quad configurations
to optimize safety. The vortex flowmeter
must be of a smaller size than the pipe to
optimize the flow range, and a minimum
flow rate must be maintained for the meter
to work correctly. It is safety integrity
, per year of freshwater,
), for example, uses a water and salt
(NaCl) solution to produce Cl2
and sodium hydroxide (NaOH). It is one
path to H2
This article will focus solely on the production
of green H2
producing H2
of CO2
Green H2 production, the process of
without involving the use
-emitting fossil fuels, is achieved
O) into H2
and oxygen (O2
by using electrolysis to split ultra-pure
water (H2
).
The energy needed to provide the requisite
electrical current differs based on
what natural energy sources (solar and
wind being two examples) are available.
The importance of flow measurement
to electrolytic processes. Accurate accounting
of a material used-in the case
of green H2
production, water-requires
reliably accurate measurements. Suppose
that a device capable of delivering such
could also wirelessly transmit data on
flow, mass balance, and material coming
in and going out: this device would make
it easier for a facility to report on water usBEST
TECHNOLOGY OPTIONS
FOR MEASUREMENT POINTS
IN ELECTROLYSIS PROCESS
Four types of flowmeters can be used
at various points of the electrolysis process:
the best choice for installation will
depend on the facility's budget and where
in the process measurements are desired.
The flowmeter options are as follows:
vortex flowmeters, differential pressure
(dP) flowmeters, Coriolis flowmeters
and magnetic flowmeters. The following
are the relevant details and best practices
regarding each.
which accounts for only 1.5 ppm
of Earth's available freshwater, an
amount smaller than what is currently
consumed by fossil fuel-based energy
production and power generation1
. "
Water used, however, does not necessarily
equate to water permanently consumed.
The paper quoted above also
explains that H2
returns H2O as its waste
product when consumed as a fuel. The
water lost in the production process is
therefore returned to general circulation,
if not to the H2
production facility.
FIG. 1. Vortex flowmeter with transmittera
.
FIG. 2. A dP flowmeter with transmitterb
.
H2Tech | Q1 2022 21
H2Tech - Q1 2022

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