Sponge iron powder as possible future energy
carrier
Draft roadmap
Y. Shoshin
Multiphase and Reactive Flows
Eindhoven University of Technology, The Netherlands
Iron as a clean energy carrier: problems to be solved
• Iron fuel morphology: granules, pellets, powders?
• How to burn iron?
o Combustion technology may depend on application
(large, small scale combustors).
o Can exiting technologies be used to burn iron?
• How to recycle iron oxide?
o Reduction technology may depend on iron morphology.
o Which renewable energy sources can be used?
o Which existing reduction technologies can be used as a
start point?
• What do we need to know about iron combustion/iron oxide
reduction?
Presentation content
1. Motivation – global warming.
2. Combustion technologies which may be
modified to burn iron.
3. Iron oxide reduction technologies and their
possible application for zero-emission iron
oxide recycling.
4. Fundamental studies required for clean
burning/recycling of iron fuel.
5. Conclusions.
6. Metals indeed can burn – demonstration
experiment.
Global warming: do they cheat us?
…scientists, to get funded?
(https://luis40pr.wordpress.com/2013/11/30/the-greatglobal-warming-fraud/)
…governments, to collect CO2 taxes?
(http://www.hangthebankers.com/carbon-tax-proven-uselessagainst-global-warming/)
But let’s first take a look at some recent facts…
99 Percent chance 2016 will be the hottest year on record
(https://www.scientificamerican.com/article/99-percent-chance-2016-will-be-the-hottest-year-on-record/)
Arctic ice melting
(http://nsidc.org/arcticseaicenews/)
8,000 strange blue lakes appear in Antarctic
(http://anonhq.com/8000-strange-blue-lakes-appear-antarctic-threaten-existence/)
Enormous crack in Antarctic ice shelf discovered
The Larsen A ice shelf disintegrated
in January 1995, and now Larsen C
looks like it’s on its way out too.
(https://twitter.com/MIDASOnIce)
If Larsen C did end up losing all its
ice, this could raise global sea levels
by around 10 cm.
Is global warming fraud?
We may wait for another …ty years to give a
solid answer.
But, after that, it may become too late.
Better to act now.
Iron reactions energy balance
Iron combustion
3Fe + 2O2 → Fe3O4 (+373 KJ released per mole of Fe).
Iron reduction with H2 / oxidation with water
Fe3O4 + 4H2 ↔ 4H20 + 3Fe +8 kJ per mole of Fe for liquid H20 as a product.
- 50.7 per mole of Fe, or -38 kJ mole of H2 for steam as a product.
Storage material
Coal
Coal, anthracite
Coal powder
Sponge iron powder
Coal powder
26-33
Energy
density
(MJ/L)
34-43
14-18
55
Iron
Sponge iron
powder
https://en.wikipedia.org/wiki/Energy_density
Specific
energy
(MJ/kg)
7
18-21
Iron “no carbon” cycles
Dry cycle
Small energy
H2O
Fe
Fe3O4
T~1000°C H2
H2O
Wet cycle
Fe3O4
Air
Small energy
Energy
H2O
Fe3O4 H2
Energy
Air
• H2: by electrolysis of H2O using renewable energy.
• Hot electrolysis is most efficient.
• Hot H2 can directly be used for iron reduction.
How iron can be burnt for energetic applications?
Small scale devices
(tracks, ships, locomotives,
CHP systems)
• Small laminar/turbulent
burners.
• Fine powders, 5-10 μm.
• Some hydrocarbon fuel
may have to be added.
• Preheating?
Large scale devices
(power plants)
• Large turbulent flames.
• Preheating/mixing with hot
air is possible.
• Coarse powders (30 ~100
μm)?
Large scale applications: coal dust burners
(https://www.youtube.com/watch?v=74ah3GEhQbw)
•
Has newer been tried for iron, but maybe it works.
•
If it does not work, still can possibly be modified.
Power station operating on coal powder
Pulverized coal provides the thermal energy which
produces about
50% of the world's electric supply
99.9 % of dust emissions is capturer here
Iron powder supply
(https://corporate.vattenfall.com/about-energy/non-renewable-energy-sources/coal/how-it-works/)
Burning iron in medium- or small-scale devices
(from few to hundreds kW)
NJIT, USA; TU/e. Netherlands
Alternative Fuels Laboratory, McGill, Canada
•
•
•
•
Small combustion chambers – short combustion times.
Micron sized powders needed.
Small dust burners, perhaps, are available only in research labs.
Laboratory dust burners may be used as a start point to design
small burners for practical applications.
Modern iron oxide reduction technologies: CO2 emissions from iron making
industry
• Currently – the most
polluting industry.
• About 7% of world CO2
emissions.
• Currently, iron is a dirty
fuel.
• Can modern iron oxide
reduction technologies
be adopted for using
renewable energy?
Renewable energy: solar against wind power
Wind
Solar
Indexed cost of wind and solar PV power
(https://www.iea.org/publications/freepublications/publication/NextGenerationWindandSolarPower.pdf)
•
Windmills are vertical and 3D. Large volume of materials is necessary.
•
Optimization is limited – only size and shape.
•
Solar PV power is produced within a ~100 μm layer.
•
The layer becomes thinner, cheaper and more efficient with science progress.
•
Solar power seem to become main source of renewable energy in near future.
Technologies that may become a basis for recycling of iron oxide powders
Blast furnace
• Uses coal.
• Large CO2
emissions.
• Makes liquid iron,
but we need
powder.
Chemical
looping
Direct Reduced
(sponge) Iron
• Fluidized bed.
• ~1 mm ceramic
particles with thin
layer of iron (oxide)
• Incomplete
reduction.
• Uses natural or
syngas.
• Can use hydrogen.
• Low or zero CO2.
• No melting – solid.
iron produced.
?
!
Sponge iron industry
• Emerged in 70s and has
been growing very fast
since then.
• No liquid phase.
• Reduction gas: CO + H2.
• Reduction in gas flow at
high temperatures.
DRI producing plant in Iran
(http://www.tasnimnews.com)
MIDREX process
(http://www.midrex.com/process-technologies/the-midrex-process/range-of-feed-materials)
•
About 60% of the direct reduced iron is
made by the MIDREX process.
•
Ore pellets (~15) or chunk ore is used.
•
Derives reducing gas from natural gas,
coal, coke or syngas.
•
Produces pellets or briquettes of
sponge iron.
•
Sponge iron pellets are highly reactive,
can even self-ignite.
•
Pellets can be burnt, but ignition and
combustion is slow, energy flux is low.
•
Can disintegrate after few cycles.
•
Using pellets for wet cycles was
considered in literature.
Sponge iron for the storage and transmission of remotely
generated marine energy (D. Mignard, C. Pritchard, 2007)
• Potentially higher energy efficiency
for chemical storage than:
− liquid H2,
− synthetic liquid fuels made
from CO2 and H2,
− MgH2 slurry,
− methylcyclohexane–toluene–
hydrogen (MTH) system.
• Iron/oxide pellets are proposed to
use. But they disintegrate after
several cycles.
• Why not using powder? Small
particle is less likely to disintegrate.
Circored: “fine” ore direct reduction technology without pelleting
(Dirk Nuber, Heinz Eichberger, Bernt Rollinger, 2006)
Gas outlet
(H2, CO, H20, CO2)
•
Two-stage process:
Circulating fluidized
bed (CFB)
↓
Fixed bed
Circored Plant in Point Lisas, Trinidad
• Particles ~30-1000 μm.
• Possibly, can be used
without modifications to
recycle iron for power
plants.
• Fine particles
CFB.
escape
• Not good for micronsized powders.
Reducing gas
(H2, CO)
(https://www.youtube.com
/watch?v=SRfkGSd9Oq8)
Suspension reduction technology has been considered for iron making
(M. E. Choi, H. Y. Sohn, G. Han, 2008)
•
•
•
•
Original ore concentrate: ~20-30 µm particles.
Suspension reduction proposed to avoid pelleting.
No recirculation – particles reduced in one pass.
Looks as a promising technological principle for iron oxide recycling.
Kinetics of iron oxide particles reduction by H2
(M. E. Choi, H. Y. Sohn, G. Han, 2008)
Reduction at 1100 C.
100% metallization after 10 sec
Reduction at 1350 C.
100% metallization after 2.7 sec.
Sponge iron particles morphology
(http://www.jfe-steel.co.jp/en/products/ironpowders/about.html)
Particles shapes of iron powders
• Particles with larger
surface:
− Ignite more easily
− Burn faster
Atomized
Reduced
Cross-sectional microstructures of iron powders
− Can be burnt at
lower initial
temperature
− Can be burnt in a
smaller chamber
Atomized
Reduced
Sponge iron powder on market
This product is made by direct reduction of iron oxide by coal powder. The purity is controlled by the
selection of the purity of the iron oxide. Iron powder purity ranging from 95%-98% at the choice of buyers.
(https://www.alibaba.com/product-detail/Sponge-Iron-Powder_107990110.html?spm=a2700.7724857.0.0.RbCeGQ)
•
•
•
•
•
Made of still making by-products: dust, (ground) mill scale.
Particle size down to ~30-40 μm.
Produced in fixed bed by reduction by coal
May be too coarse for burning in vehicles, but can be good for power plants.
Finer sponge iron powders are not available on market.
How expensive can be iron oxide recycling?
Cost comparison of optimized solar-hydrogen
generators incorporating a16% efficient PV component
• DRI production: ~30 $/tone + (ore cost)
How production cost will change if natural gas is
replaced with H2?
• 1 kg of methane: ~ 0.3 $
• Optimized systems can produce hydrogen as low as
$0.90 per kg (C. A. Rodriguez et. all., 2014)
Production cost development of
direct reduction routes
• With 1 kg of H2, 3 times more Fe can be produced
than with 1 Kg of NG
→ Per tone of Fe; solar H2 cost can be close to NG
Iron/iron oxide transportation
Rotterdam
Netherlands
World sunlight map
Marine freight rate
for iron ore in 2016
From:
Hay Point, Australia
To:
Rotterdam,
Netherlands
Hay Point
Australia To
http://www.midrex.com/
World awerage temperature map
6.5 Euro/tone
Fundamentals of iron suspension combustion: need for knowledge
•
Individual particle combustion:
ignition
temperatures,
combustion times, regimes of
combustion
•
Iron dust flame: laminar
burning velocities in different
environments and at different
initial temperatures. Effects of
particle size and morphology.
•
Completeness of combustion,
combustion
products
composition and morphology.
•
Burning recycled powders:
completeness of combustion
products composition and
morphology.
(Dongsheng Wen, 2010)
(Metal Flames Lab McGill University)
Burner with electrodynamic fluidized bed
(Y. Shoshin, E. Dreizin, 2002)
•
Upper
layer
of
particles
becomes
charged
•
Coulomb
force
attract particles to
upper electrode.
•
Upon contact both
upper
electrode
particle recharge and
move down.
•
Process repeats and
powder
becomes
“fluidised”.
•
Air
carries
dust
though a small hole
in the top electrode
forming a thin jet
Lifted dust flames produces with ectrodynamic
fluidized bed burner (Y. Shoshin, E. Dreizin, 2002)
Flame of aerosol of 10–14-μm
aluminum powder
A short exposure (1/8000
s) image of the aluminum
aerosol 
flame showing
individual particle 
flames
•
Only small scale
dust flames can be
produced.
•
A very convenient
for studding detail
structure of dust
flames
•
A six month MSc
project began in
September 2016.
•
Improved
modular
design.
flexible
burner
Another concept burner with electrical powder
dispersion
• Upper layer of particles
becomes charged.
• Particles lifted by Coulomb
force.
• Next layer becomes charged
and process continues.
• Particles number density
controlled
by
voltage,
independently on air flow
rate.
Air flow
One of first tests of the concept design burner
•
Iron powder, ~ 10 µm
•
Gas: 50% O2 + 50% N2
•
Flow: 0.35 m/s
Conclusions
• Direct Redused Iron (sponge iron) seem to be most appropriate base
technology for iron oxide powder recycling
• Coarse oxide powders can be reduced by existing technology (Circored)
• Technology for reducing micron size oxide is yet to be developed (flow
reactor)
• Perhaps, pulverised coal burners/power staytions can be adapted for iron
powder fuel
• Iron combustion technologies for small scale devices are yet to be
developed
• Fundamental knowledge on iron dust combustion/iron oxide dust
reduction is still very limited.
o The whole cycle “combustio-reduction” needs to be studied (laboratory
reactors, laboratory burners)
o Possiblity of multiple recycling of sponge iron powders needs to be studied