Chemical Engineering July 2021 - 6

promoted by applying
electric potentials to the
catalyst. While these
methods have already
improved the selectivity
and activity of heterogeneous
catalysts
under static conditions,
the use of dynamic external
stimuli has been
underexplored.
Now, a team of scientists,
led by associate
professor Yan
Ning from the Dept. of
Chemical and Biomolecular
Engineering at
the National University
of Singapore (NUS;
www.nus.edu.sg) ,
has demonstrated a
method to increase the
rate of ethylene hydrogenation
by a factor of
five, compared to typical
industrial rates. The
technique developed
by NUS researchers
applies oscillating
electric potentials to a
commercial hydrogenation
catalyst, which
then dramatically increased
the hydrogenation
rate of ethylene
to ethane.
" Such enhancements
in the rates or selectivity
of chemical reactions
are instrumental in making
a chemical process
more efficient, " says
Yan. " Our work demonstrates
a more direct
and cost-effective way
of optimizing catalyst
performance that is
beyond conventional
methods, " he says.
The study was published
in a recent issue of
the Journal of the American
Chemical Society.
NAPHTHA
Axens (Rueil-Malmaison,
France; www.
axens.net) and Sulzer
Chemtech's (Winterthur,
Switzerland; www.
sulzer.com) GTC Technology
business have
formed an alliance to
license an advanced
process for FCC (fluid
catalytic cracking)
naphtha processing.
The combined offering
(Continues on p. 7)
6
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
JULY 2021
Combine three steps in one unit with this wastewatertreatment
process
A
cyclic activated-sludge (AS) process,
trademarked te-cyc, combines biological
treatment and solids settlement
in a single treatment step, thereby significantly
reducing the footprint compared to
a conventional AS plant, which requires three
separate processes - primary settlement
tanks, aeration tanks and final settlement, says
Ben Hazard, a process engineer at Te-Tech
Process Solutions, Ltd. (Totton, Southampton,
U.K.; www.te-tech.co.uk). " This ultimately results
in a lower capital cost due to less infrastructure
being required. "
The first plant of this kind was completed
in 1999 at Neubrandenburg, Germany, with a
nominal capacity of 140,000 PE (population
equivalent). Now, Te-Tech Process Solutions
has developed a modular unit that has been
specifically designed for small- to mediumsized
treatment works, which offers the same
benefits of the larger plants, but at a smaller
scale and with a design for manufacture and
assembly approach in mind.
The te-cyc process is fundamentally based
on a traditional sequencing batch reactor (SBR)
whereby a sequence of tank filling, wastewater
aeration, solids settlement and treated effluent
decanting is repeated on a continuous cycle, explains
Hazard. In the te-cyc process (diagram),
there is typically 2 h of simultaneous filling and
aerating, 1 h of settlement and 1 h of decanting.
In the standard design, there will always be
two or more tanks in parallel with their operating
cycles out of phase with each other. This allows
for a continuous
inflow
into
the process
as
a whole,
therefore
eliminating
the need
for an upstr
eam
buf fer
Start fi ll
Fill/Aerate
Decant
Settle
Te-Tech
tank, which would require energy-consuming
mechanical mixing, says Hazard.
" Unique to the te-cyc process is the inclusion
and design of an anaerobic selector zone,
internal return activated sludge pump and bespoke
mechanically driven decanter, " Hazard
continues. The combination of the anaerobic
selector zone and internal recycle suppresses
the growth of poorly settling filamentous bacteria
and promotes the growth of floc-forming
bacteria that aggregate and form a large macrofloc.
These macroflocs are larger than the
typical flocs formed in conventional AS or SBR
processes, and as such provide two key benefits:
1) the increased size leads to a quicker
and more effective settlement of solids; and 2)
the macroflocs are large enough to consist of
an external aerobic zone and an internal anaerobic/anoxic
zone, explains Hazard. " This
means that nitrification and denitrification can
occur simultaneously in the aeration phase of
the te-cyc operation cycle, " he says.
This carbon-fiber composite material is good at
dissipating heat
CFRP materials
A
technology that increases the heatdissipating
properties of carbon-fiberreinforced
plastic (CFRP) to that of
metals has been developed by Toray
Industries, Inc. (Tokyo, Japan; www.toray.
com). Applying this technology to CFRP dissipates
heat effectively from their sources
through thermal conduction paths inside that
material. This can help suppress battery degradation
in mobility applications while boosting
performance in electronic device applications,
says the company.
CFRP is less thermally conductive than aluminum
alloys and other metals. This has prompted
efforts to enhance heat dissipation by employing
external or internal graphite sheets offering
excellent thermal conductivity and heat dissipation
and diffusion. However, these sheets are
easy to fracture, scatter and damage, which
compromises the performance of CFRP.
Toray has created a heat-conductive layer
CFRP prepreg
Graphite
sheets
Porous CFRP support
Thermal
conductive layer
Toray
employing a porous CFRP support that safeguards
the graphite sheets (diagram). Laminating
CFRP prepreg on this thermally conductive
layer enabled Toray to attain a thermal conductivity
above that of metals, which would be
impossible with regular CFRP, without compromising
the mechanical properties and quality of
that material. Prepreg is a sheet-like intermediate
material made by impregnating fibers with
resin to reinforce them. The company was able
to determine the thickness and lamination positions
of graphite sheets that form thermal conduction
paths. This enabled a flexible thermal
management design, which controls the paths
to release or use heat, for CFRP cooling efficiency
and heat-diffusion paths.
http://www.te-tech.co.uk http://www.nus.edu.sg http://www.toray http://www.axens.net http://www.sulzer.com http://WWW.CHEMENGONLINE.COM
Chemical Engineering July 2021

Table of Contents for the Digital Edition of Chemical Engineering July 2021
