Understanding the Software Options

CHEMENTATOR
U.S. power plant goes dry for handling bottom ash
Practically all of the coal-fired power
plants in the U.S. collect ash from the bottoms
of their boilers using a wet system —
the ash falls into hoppers that are partially
filled with water, and once or twice per shift
the slurry is pumped to a settling pond or
solid-liquid separation tanks (dewatering
bins). In a break from that norm, Seminole
Electric Cooperative, Inc. is switching its
two 650-MW units in Palatka, Fla., from a
wet to a dry bottom ash system. The change
is expected to increase boiler efficiency and
reduce operation and maintenance costs in
comparison with wet systems.
Scheduled for startup during 2012, the
project marks the first U.S. installation of
a dry bottom ash system manufactured by
Clyde Bergemann Delta Ducon (Malvern,
Pa.; www.deltaducon.com), although in
the last four years the company has installed
over 30 systems in 16 plants and
five countries elsewhere, mostly in Asia.
Ron Grabowski, vice-president sales, says
U.S. utilities are generally slower to make
changes. However, he says the company has
A step forward for an energy-saving
desalination process
An alternative desalination process
that reduces energy consumption by
over 50% compared to “best available
technology” (BAT) has been successfully
piloted by the Industry Sector of Siemens
AG (Munich, Germany; www.siemens.
com), in collaboration with Singapore’s
national water agency, PUB, and Singapore’s
Environment and Water Industry
Program (EWI). Results of the Siemen’s
demonstration unit, which has been operating
since December 2008 and treating
50-m3 /d of seawater, were presented
last month at the Singapore International
Water Week (Singapore; July 4–8).
A new HPCA monomer
Last month, BASF SE (Ludwigshafen,
Germany; www.basf.com) launched a
new crosslinking acrylate monomer, hydroxpropl
carbamate acrylate (HPCA),
which is said to shorten the processing
time for the manufacture of carbamate-
12 CHEMICAL ENGINEERING WWW.CHE.COM AUGUST 2011
received a lot of inquiries recently because of
pending Environmental Protection Agency
(EPA; Washington, D.C.) proposals to regulate
settling ponds.
In the process, called Drycon, hot ash falls
onto a dual chain-driven line of pans that
moves continuously underneath the bottom
of the boiler. There is little or no gap between
the pans for ash to fall through, says
Grabowski. The pan line takes the ash away
from the boiler and dumps it onto a secondary
transfer conveyor that feeds a storage silo.
Compared to a wet system, Drycon saves
energy costs by emitting residual heat from
the hot ash, whereas a wet unit quenches
the ash, says Grabowski. Operation and
maintenance costs are lower because slurry
transportation tends to result in high wear,
he says. Also, pumping slurry to a pond may
take as much as 700 hp, versus 15–20 hp for
dry ash transportation. Engineering, procurement
and construction services for the
Seminole project are being provided by Roberts
& Schaefer, a subsidiary of KBR (Houston;
www.kbr.com).
Siemens, in cooperation with PUB, plans
to build a full-scale system by 2013.
Instead of using reverse osmosis
(RO), which requires high-pressure
pumps to force water through semipermeable
membranes, Siemen’s process
combines electrodialysis (ED) and
continuous electrodeionization (CEDI),
both of which draw sodium and chloride
ions across ion-exchange membranes.
Because the process runs at low pressure,
power consumption is lower than
that required for RO.
Seawater is first pretreated with a
self-cleaning disk filter, followed by
based polymers. HPCA enables crosslinkable
carbamate units to be incorporated
into the polymer in one step
instead of the usual two required by
existing processes, says BASF.
The specialty monomer is synthesized
by a biocatalytic process. From HPCA,
the carbamate-based polyacrylate can
Biopolymers
Last month, The Dow Chemical
Co. (Midland, Mich.; www.
dow.com) and Mitsui & Co.,
Ltd. (Tokyo, Japan: www.mitsui.
com/jp) announced the formation
of a joint venture (JV) and
execution of a memorandum
of understanding (MoU) to develop
sustainable products for
the high-performance �exible
packaging, hygiene and medical
markets. Under the terms
of the agreement, Mitsui would
become a 50% equity interest
partner in Dow’s sugarcane
growing operation in Santa
Vitória, Minas Gerais, Brazil.
The initial scope of the
JV includes production of
sugarcane-derived ethanol for
use as a renewable feedstock
source. When completed,
Dow and Mitsui will have the
world’s largest integrated
facility for the production
of biopolymers made from
sugarcane-derived ethanol.
Biopolymers produced at this
facility will be a “green” alternative
and drop-in replacement
for high-performance
�exible packaging.
The �rst phase of the project
includes construction of
a new sugarcane-to-ethanol
production facility in Santa
Vitória. Construction is
slated to begin in the 3rd Q
of 2011. ❐
Memcor ultrafiltration modules. The
pilot desalination plant is composed of
three ED units in series to handle the
high concentrations of salt. These are
followed by three parallel CEID units
to remove the lower salt concentration,
to produce drinking water that meets
standards of the World Health Org. (Geneva,
Switzerland). The energy demand
of the entire process, including pumping,
pretreatment, desalination and post
treatment is less than half of that used
by today’s BAT for desalination, which is
typically between 3.4 and 4.8 kWh/m 3,
says Siemens.
be produced in a single step. BASF is
using this enzymatic process in industrial
production for the first time.
In addition to proven applications in
clearcoat systems for the automobile
industry, the new monomer offers additional
benefits for potential applications
in adhesives, says the company.