ENGINEER TO ENGINEER
In brief
Netherlands bio-power scheme
relies on mixing tech
The newly-expanded Sleeuwijk wastewater
plant serves around 64,000 people and has
been designed to optimise the performance
as well as e ciency of sewage treatment in
western Rivierenland. It features a more e cient
sludge digestion facility where methane gas
is upgraded to natural gas quality and then is
introduced into the Dutch natural gas network.
The ‘Energy Factory’ at Sleeuwijk, in the
province of North Brabant, is one of the rst
facilities of its type to use Ephyra technology,
an innovative approach to sludge digestion
that o ers greater capacity in a smaller space.
Developed by Royal HaskoningDHV, this process
is said to break down sludge more e ectively
than conventional reactors, increasing gas
production by 20-30%.
The Ephyra system uses the plug- ow
digestion concept. The reactor vessel at
the Energy Factory is divided into three
compartments, with sludge moving between
the compartments under computer control.
The concept
allows the
di erent stages
of digestion to
be optimised
separately,
maximizing the e ciency of the process while
reducing dwell time in the tanks to as little as
seven and a half days in the Ephyra reactor and
the same time in the after-digester.
In order to work e ectively, the Ephyra
system relies on e cient mixing of the material
in each tank compartment. Flow through the
system is highly complex, impacted both by the
performance of the mixers and the e ect of the
pumps that move material between the tank
compartments.
The Sulzer solution uses a combination of
ve SCABA agitators, ranging in size from 2.2
kW to 11 kW. Since the reactor tanks produce
potentially explosive gases, each unit is built to
Zone 1 ATEX speci cations.
Radio interference at Rotterdam
airport solved by TenneT
In January 2021,
the Dutch Radio
Communications
Agency informed
electricity
transmission
system operator
TenneT that
interference coming from one of the substations
it managed and maintained was causing a
communication problem between air tra c
control and pilots on all incoming ights from
the UK at Rotterdam The Hague Airport.
When TenneT investigated, initial audible and
visual inspections showed nothing unusual, a
partial discharge inspection conducted using the
Fluke ii910 Precision Acoustic Imager identi ed
that corona discharge was responsible for a
10-20 second communication blackout between
ground sta and pilots.
“The Fluke ii910 precision acoustic imager
proved invaluable in helping to quickly and easily
identify the partial discharge issue,” says Roel
Van Hees, operational maintenance engineer at
TenneT. “In the past, we would have had to listen
and/or use an ultraviolet (UV) camera, which are
slow and ine cient methods compared to the
Fluke ii910. With its wide view, the Fluke ii910
enabled us to quickly scan an entire substation
and identify the places of concern.”
Following identi cation of the issue,
maintenance work at the substation was
undertaken to x the areas su ering from
corona discharge. As a result, all communication
has been restored between the airport control
tower and pilots.
In fact, TenneT's Van Hees was involved in
early testing of the device, reports Tako Feron,
product manager, acoustic imaging, at Fluke
Corporation.
A global mining operator has
upgraded the backstop on its
incline conveyors to non-rollover
cam technology to prevent
material pile up on stops and stalls.
Tsubaki’s Cam Clutch design also
incorporates rollers, contributing
to longer life operation, enhanced
by a labyrinth seal for signifi cantly
reduced ingress.
Instrumentation specialist
Baumer develops sensors together
with customers to meet specifi c
requirements, such as fl ow and
temperature sensors for fi lter
monitoring applications in the
dairy industry. For example,
Homann, part of the Müller Group,
manufactures a range of dairy
products including yogurts, milk
drinks, mayonnaise and salad
dressings. Baumer has helped
Homann achieve its goal of
maximising process optimisation
in the production processes with
monitoring sensors. Thermal
fl ow sensors, such as Baumer
FlexFlow, are an effective, viable
and cost-effective solution for fi lter
monitoring, as they measure not
only the temperature, but also the
fl ow rate, based on the calorimetric
measurement principle
El Temsah Lake, west of the
Suez Canal, had become heavily
polluted by decades of run-off
from the region’s farms. The Al
Mahsama plant has been designed
to reverse the lake’s declining
ecology, catching and treating
up to 1 million cubic meters (35
million cubic feet) of agricultural
wastewater per day. Each of the
plant’s 28 disk fi lter installations,
for example, uses a Sulzer vertical
multistage (VMS) pump to
recirculate backwash water. This
design provides a continuous
process, even during a backwash.
Elsewhere in the plant, 10 Sulzer
Scaba agitators are used to prepare
and mix aluminium sulphide
and activated carbon used in the
treatment process, while 27 Sulzer
XFP submersible pumps, ranging
in size from 14 kW to 30 kW, are
installed across the plant fulfi lling
various roles.
90 www.operationsengineer.org.uk Winter 2021
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