Chemical Engineering December 2010 - 14

ChementatoR
(Continued from p. 13)
ESR SpEctRomEtER
(Continued from p. 13)
The Micro-ESR sensor takes advantage of
recent advances in wireless communications
technology, and uses a samarium-cobalt permanent
magnet to generate the magnetic
field necessary to observe a signal. " We're
essentially updating an old technology with
modern microwave components borrowed
from the wireless industry, " says Active
Spectrum president James White.
The result is a device that is 100 times
smaller than conventional ESR equipment,
but that maintains sensitivity in measuring
free radicals. Also, " the dramatically lower
cost of the device is a major advantage, "
White says.
Micro-ESR can be used to evaluate the degradation
of engine oils and hydraulic fluids,
and - with the help of spin-trapping compounds
that convert transient free radicals
into stable species - oxidative breakdown of
food and concentrations of spin-labeled proteins.
Micro-ESR can also be used for realtime
monitoring of crude oil properties, such
as asphaltene and vanadium content.
A more efficient use of renewable thermal energy
A
team of engineers from the Center for Energy
Technology, University of Adelaide
(South Australia; www.adelaide.edu.au),
the University of Nantes (France) and Mie
University (Japan), have proposed a more
efficient way to generate power from low to
medium temperature (90-260°C) solar and
geothermal resources. In the new system,
called Renewable Assisted Power Generation
(RAPG), the renewable energy is used
to heat the boiler feed water (BFW), so the
efficiency is no longer limited by the renewable
resource's temperature, says team
member Eric Hu. Instead, the efficiency is
limited by the maximum temperature of the
steam cycle.
In contrast to other solar boosting or
combined power systems, in RAPG renewable-energy-generated
heat or steam does
not enter the turbine directly. Instead, the
energy is used in place of steam normally
extracted from turbine stages for BFW preheating
in regenerative Rankine cycles. The
steam that would be otherwise extracted is
create a two-dimensional version
of Teflon. Unlike its plastic
counterpart, the so-called
fluorographene is a crystalline
material, one-molecule thick,
which exhibits the high strength
of graphene and does not react
with other chemicals. The material
also can withstand high temperatures,
even in air. Potential
applications of the new material
- a wide-gap semiconductor
that is optically transparent to
visible light - include ultra-thin
tunnel barriers for light-emitting
devices and diodes.
therefore available to generate additional
power in the turbine.
For three typical temperatures of geo- and
solar-thermal resources (90, 215 and 260°C),
the team compared the performance for the
cases in which the resources were used to
generate power in a standalone capacity or
with RAPG in a typical 200-MW subcritical
power plant and in a 600-MW supercritical
steam plant. The team found that in the
RAPG system the thermal efficiency of renewable
energy generation exceeded the
Carnot efficiency, which shows that the thermal
efficiency was no longer limited by the
temperature of the renewable source, but
rather by the maximum temperature of the
Rankine cycle, that is, the maximum steam
temperature at the exit of the boiler.
In the case of a geothermal fluid at 215°C,
for example, it was found that using the
geothermal energy to heat BFW doubled
the efficiency of power generation over the
stand-alone case, and its contribution to
total power was about 16%.
Biocatalysts for biodiesel production
R
Porous plastic powder
Ticona (Florence, Ky.; www.
ticona.com), the engineering
polymers business of Celanese
Corp., has commercialized a
new porous plastic powder that
can be sintered into products
with good strength and porosity
for use in filtration applications
for gases and liquids that require
higher flowrates and lower
pressure drops. The powder,
tradenamed GUR X 192 VHMW
(very high molecular weight)
polyethylene, has a molecular
weight of 600,000 g/mol; a particle
size distribution (d50) of 451
µm; a bulk density of 0.35 g/mL;
and a 47% porosity with pore
sizes of 250 µm. The patentpending
material can be shaped
and sintered at 180-220°C into
porous objects with improved
strength and porosity.
esearchers from the Department of Environmental
and Applied Chemical Engineering,
Gangneung-Wonju National
University (Gangneung, South Korea; www.
gwnu.ac.kr) are developing a two-step enzymatic
route to biodiesel fuel that promises
to reduce production costs. The process
employs a lipase-producing bacterium and,
sequentially, a commercial enzyme. The
combination has the double advantage of reducing
the use of commercial enzyme, thus
lowering costs, and of reducing enzyme deactivation
by methanol - a problem that
has prohibited the commercialization of enzymatic
biodiesel fuel production.
The university group, led by Prof Sung Ho
Yeom, uses a lipase-producing bacterium,
Serratia marcescens, isolated from greasecontaminated
soil and chemically mutated
to increase its lipase production. The bacteria
with highest lipase activity were mutated
again to further enhance their lipase
activity. These twice mutated bacteria exhibited
2.5-times higher intracellular lipase
activity than the wild type. The enzyme combination
was used for transesterification of
soybean oil using methanol as an acyl donor.
Although the biocatalyst was less inhibited
by methanol than the commercial enzyme,
it exhibits much-lower biodiesel-conversion
activity per mass than commercial enzyme,
thus the need for both.
■
14 CHEMICAL ENGINEERING WWW.CHE.CoM DECEMbER 2010
Hydrogen separation
Inorganic membranes for
separating hydrogen in steammethane
reformers (SMRs)
have taken a step closer to
commercialization following successful
testing at a 20-Nm3/h experimental
facility of Tecnimont
KT (formerly Technip KTI S.p.A.;
Rome, Italy; www.tecnimontkt.
it). The facility, located at Chieti,
Italy, incorporated a 0.4-m2
Hysep membrane module -
developed by ECN (Petten,
the Netherlands; www.ecn.
nl) - for separating H2 during
the reforming reaction. Integrating
reforming with separation
enables the process to operate
at " well below " 650°C instead
of the 850-900°C required in
traditional SMRs, says ECN.
The membranes - thin-film Pd
on ceramic supports - demonstrated
a high flux and durability
after 500 h of operation and
more than 50 thermal cycles.
❏
http://www.ticona.com http://www.adelaide.edu.au http://www.tecnimontkt http://gwnu.ac.kr http://www.ecn http://WWW.CHE.CoM
Chemical Engineering December 2010

Table of Contents for the Digital Edition of Chemical Engineering December 2010
