Hydrocarbon Processing - October 2022 - 15

Special Focus Plant Safety and Environment
A. GENTILUCCI and L. SPAGNUOLO, Dow Europe GmbH,
Horgen, Switzerland; and A. HUGHES, M. RUITENBEEK
and A. VANSTAEN, Dow Benelux BV, Terneuzen, Netherlands
Sustainable steel/chemicals production: Removal
of impurities for valorization of steel mill gases
Industry faces significant challenges
relating to the transition toward cleaner
energy and more sustainable feedstocks.
The key drivers of this transformation
are greenhouse gas (GHG) avoidance
and the formation of a more circular
economy to lower the waste burden on
the environment. Both transitions should
support the needs of global population
growth without affecting the planet's
ability to also supply future generations.
This is not the first transition that industry
has faced, but, where previous industrial
transitions were driven by technical
developments (technology push), the
current transitions are primarily driven
by a strong societal pull. This means that
the goals are clear, but the (technical)
path to achieve these goals is not.
A traditional petrochemical value
chain (FIG. 1) takes in carbon from fossil
origin (oil or gas) and converts it into a
broad variety of products in large assets
that have been optimized for cost efficiency
and product quality. This typically
comes with a significant energy need that
is traditionally delivered via combustion
of fossil carbon, thus resulting in significant
carbon dioxide (CO2
) emissions and
a post-consumer waste disposal problem.
Therefore, the challenge will be to develop
technologies and partnerships to
deliver circular processes that utilize renewable
energy and feedstocks.
Today, most of the global steel production
is produced using blast furnace technology
(FIG. 2). In this route, iron ore is
reduced with coke from coal in a blast furnace,
followed by the removal of residualfree
carbon in the steel by oxygen injection
in an oxygen converter. In this process,
three major gas streams are co-produced
with the target product steel: coke oven
H2, vol%
CO, vol%
CO2, vol%
N2, vol%
Oxygen (O2), vol%
Methane (CH4), vol%
C2 + C3, vol%
BFG
3-4
20-25
21-24
48-55
0.5
-
-
BOFG
4
58-65
17-20
14-18
0.5
-
-
COG
55-66
6-8
2-3
2-10
-
20-26
1-3
TABLE 1. Typical gas compositions for BFG, BOFG and COG. These gases are always
saturated with water.1
FIG. 1. Schematic representation of the carbon value chain for a petrochemical company.
gas (COG), blast furnace gas (BFG) and
basic oxygen furnace gas (BOFG).
A typical composition of these gases is
represented in TABLE 1, which shows that
COG primarily contains hydrogen (H2
)
and light hydrocarbons, whereas the
BOFG is carbon monoxide (CO) rich.1
The largest amount of gas produced in
a steel mill is BFG, which has a 1:1 ratio
of CO and CO2
trogen (N2
in a matrix of ~50% ni).
This gas is very abundant in
steel mills and is typically combusted in
a power plant to produce electricity with
a very high CO2
footprint.2
To create a
greener electricity grid, an alternate use
for CO is required. This is where industrial
symbiosis (IS) could play an important
role. Where companies traditionally
optimize their processes and products
within their own value chain, IS can take
FIG. 2. Schematic representation of a
typical blast furnace-based steel mill.
Source: ArcelorMittal.
industry to the next level, as it enables the
exploration of options to exchange water,
waste, energy and material streams in
a greater ecosystem by means of system
integration and optimization. This not
only has economic benefits, but also potentially
a positive environmental impact,
and can therefore optimize the greater
Hydrocarbon Processing | OCTOBER 2022 15
Hydrocarbon Processing - October 2022

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