Chemical Engineering June 2010 - 14

ChementatoR
Pt-free fuel cells
Solvay S.a. (Brussels, BelH2
unit combines production, purification and compression
A
recently developed hydrogen
generation unit
combines an autothermal,
fluidized-bed methane reformer
with a metal hydride
compressor.
Aside
from combining the reforming,
H2 separation
and compression,
which
Water
Natural gas
methanol
gasoline/diesel
Reformer
processor Water
Fuel
are part of conventional H2
generation (top diagram),
the engineers behind the
system demonstrated the
use of Pd-alloy membranes
in a fluidized-bed environment.
The unit is designed
to produce H2 outputs of
15 m3/h (standard temperature
and pressure) and
has achieved H2 purities of 99.99%.
The system, originally supported under
Natural gas
alternative
fuels
Air
Water
a U.S. Dept. of Energy (DOE; Washington,
D.C., www.energy.gov) program, was developed
by Membrane Reactor Technologies
Ltd. (MRT; Vancouver, B.C., Canada; www.
membranereactor.com), along with partners
Ergenics Corp. (Ringwood, N.J.; www.
ergenics.com) and Linde North America Inc.
(Murray Hill, N.J.; www.us.lindegas.com).
MRT developed a steam methane reformer
equipped with 25 palladium-alloy membranes
that allow in-situ separation of H2 generated
by the methane reforming reaction (bottom
diagram). The Pd alloy membrane selectively
allows H2 molecules to diffuse out of
the reforming zone through the foil. " The H2
removal actually drives the thermodynamic
reaction equilibrium forward, " says MRT
CO + H2O
CO2 + H2
Shift
converter
CO2, N2
Membrane
reactor
Fuel
processor
president Tony Boyd, " so methane conversion
rates are high at relatively mild operating
conditions " (550°C reactor temperature).
The purified H2 is absorbed into cool metal
hydride beds, then desorbed at higher pressure
after heating. A series of metal hydride
beds can compress H2 from sub-atmospheric
pressure to 100 bar in a single system by
engineering the hydride composition in each
compression stage, Ergenics says.
Boyd envisions the system being used in
smaller industrial markets for onsite H2
production, to avoid transporting large numbers
of H2 cylinders. In addition, the system
could be located at future H2 filling stations
that supply fuel-cell automobiles.
The team is working to address remaining
technical issues before moving to the design
of a commercial prototype, Boyd says.
Using DME to extract 'green crude' from algae
A
Hydride
thermal
compressor
Compression
Pressure
swing
adsorption
Purification Compressor
Syngas
H2, CO, CO2, N2 H2, CO2, N2
CO2, N2
H2 (99.99%)
H2 (99.99%)
gium; www.solvay.com) has
increased its stake in aCal
energy (runcorn, u.K.) by investing
£1.5 million (€1.75 million).
aCal will use the funds
to accelerate the next stage of
development of its FlowCath
Pt-free cathode technology for
fuel-cell systems. This technology
uses a proprietary liquid
catalyst in the cathode instead
of precious metals. Solvay and
aCal are currently preparing
to install the world's first
demonstration fuel-cell system
using FlowCath at Solvay
interox's industrial site at warrington,
u.K. expected to be
operational later this year,
the £1.9-million investment
will consist of three fuel-cell
stacks with an electric power
of 5 kw per unit. The units are
manufactured by SolviCore, a
50:50 joint venture of Solvay
and umicore (Brussels; www.
umicore.com).
Water-free solar plant
Construction has begun on a
solar Brayton-cycle demonstration
plant and research facility
at CSiro's national Solar energy
Center (newcastle, new
South wales, australia; www.
csiro.com). The project is a joint
effort of the CSiro energy
Transformed Flagship and the
australian national university
(anu; Canberra; www.anu.
edu.au).
unlike conventional solarlgae
has recently become an R&D focus
for making third-generation biofuels because
these oil-containing microorganisms
reproduce so quickly and can be grown away
from arable farmland. However, getting the
oil from the cells - and the water - is energy
intensive. Traditionally, the cells are
first concentrated into a slurry by compression
or centrifugation. Then, the cell walls
are broken down by acid hydrolysis or pulverization.
Finally, liquid-liquid extraction
with an organic solvent (such as hexane or
acetone) is used to extract the oil, and the
solvent recovered by distillation.
A simpler process, which also promises to
be more efficient while consuming less energy,
is being developed by Hideki Kanda,
chief scientist of the Energy Engineering
Research Laboratory, Central Research Institute
of Electric Power Industry (CRIEPI,
Tokyo, criepi.denken.or.jp/en). The process
takes advantage of a unique property of liquefied
dimethyl ether (DME) - its miscibility
in both oil and (to a lesser extent) water.
In the process, liquified DME is continuously
circulated through a column containing
algae slurry at room temperature and
0.5 MPa pressure. After about 10 minutes,
the oil is extracted into the DME. The oilladen
DME can then be phase separated
from the water, and the DME recovered as
(Continues on p. 16)
14 ChemiCal engineering www.Che.Com June 2010
thermal plants, which concentrate
the sun's energy to
generate steam for driving a
turbine, the Brayton thermodynamic
does not use water.
instead, the concentrated
solar energy is used to heat
compressed air, which then
expands through a gas turbine
to generate power. energy to
compress the air is obtained
from batteries. The Brayton
cycle consists of four steps:
adiabatic compression, isobaric
heating, adiabatic expansion
of the heated gas, and
isobaric cooling.
The CSiro system includes
450 heliostats to reflect the sun
onto a 30-m-high solar tower,
which will power a 200-kw turbine.
The plant will be capable
of operating at temperatures
above 900°C and will be fully
operational by march 2011.
http://www.solvay.com http://www.umicore.com http://www.energy.gov http://www.membranereactor.com http://www.ergenics.com http://www.us.lindegas.com http://www.csiro.com http://www.anu http://www.edu.au http://criepi.denken.or.jp/en http://www.Che.Com
Chemical Engineering June 2010

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