Electrostatic precipitators.pdf
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Transcript of Electrostatic precipitators.pdf
Electrostatic Precipitators
2
lectrostatic PrecipitatorsE
Electrostatic Precipitators are filtration devices that efficiently remove fine particulate from industrial
exhaust emissions with limited influence on the gas flow.
The system “electrode - suspension - rapping” developed by Redecam optimizes the energy applied
to remove the dust and limits its re-entrainment in the gas stream.
Redecam ESP solution can be considered for new installations or to upgrade obsolete filters as well.
Cumra - Turkey
3
echanical DesignM
REER, Redecam Rigid Emission Electrodes, are
specifically designed to operate with the highest
available voltages: this allows a full distribution
of the ionisation effect over the entire length
of the electrode.
The system is designed to ensure that the
collecting plates and discharge electrodes
remain perfectly aligned during all operating
conditions.
Specific baffles are fitted inside the hoppers
and along the lateral walls of the ESP to prevent
gas bypassing the treatment zone and dust
re-entrainment phenomena.
Lucena - SpainEmitting electrodes fabrication
Collecting plates ready for shipment
4
The rapping action takes advantage of the
sound impact of the cleaning hammers on the
electrodes frames, without risk of damage for
those elements.
Their rigidity avoids any power dispersion
during the hammers hitting, which is evenly
transmitted in the same direction of the dust
particles when they are dropping from the
electrodes.
The electrodes are individually fixed at their top
and only kept aligned at the bottom to ensure
free thermal expansion and a wide flexibility
both during operation and maintenance.
Electrodes rapping: detail of motion trasmission
Rapping system of emission electrodes
5
Each electrode can expand independently (this
is not the case when electrodes are installed in
a rigid chassis) and can undertake temperature
rise during operation.
The centreline of each discharge electrode
always remains at the same distance from the
collecting plates (the lack of this condition is
one of the main causes of ESP malfunctions).
Namêche - Belgium
Alignement of electrodes
6
The rapping system of the collecting plates
Each electrode can be removed from the
suspending frame, since it is not part of a
rigid chassis, without removing the ESP roof
or creating extra openings.
The profile of Redecam collecting plates
improves the ESP efficiency during the rapping
phase by reducing the re-entrainment of dust
in the gas flow. Plates are suspended at the
top and only kept aligned by a guide frame at
the bottom to maintain their correct position
under all operating conditions.
The mechanism ensures uniform rapping
of each plate at regular intervals. Hammers
are mounted in a staggered position on the
hammer-shaft, so that only few of them impact
at the same time.
Rende - Italy
7
HV side of transformer
Supporting insulator: motion trasmission side
Cylindrical porcelain high-voltage insulators
support the discharge electrodes system of each
field. The insulators are installed on the ESP roof
and housed in weatherproof cubicles.
Step-up transformers that convert AC low
voltage (400-500 V, 3 phase) into DC high
voltage (110 kV) supply the power to the ESP.
The self-contained, weatherproof transformers
are oil insulated and include rectifying bridges.
In order to shorten the HV cable length, the
transformers are normally placed on the roof of
the ESP.
Units are supplied with a master switchboard
and a digital panel to provide the ESP’s typical
control functions:
• current and voltage regulation within the
optimal operation range according to operating
conditions of the plant
• protection against possible overload
• automatic restart of the system after any shut-off.
Electrostatic precipitator control cubicle
lectrical EquipmentE
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esign ParametersD
The definition of the ESP features (dimensions,
number of fields, surface area of the
collecting electrodes) are based on the process
parameters, i.e. temperature, capacity and
chemical composition of the gas flow.
Physical and chemical properties of the dust
(type, size, concentration) are also important
ESP design parameters. Moisture and
temperature have an important impact on the
dust resistivity, which significantly affects the
collection efficiency and the formation of the
dust layer on the collecting plates.
The specific collecting area and the gas
velocity through the ESP casing must be
carefully evaluated in order to design an
efficient dust collector. The distribution of the
gas flow across the ESP is a further critical
parameter that can affect the efficiency of the
filter. Fluid distribution inside the filter must
be homogeneous to obtain uniform velocity;
when an odd gas distribution leads to exceed
the design speed, the effect on the collection
efficiency is detrimental.
For analogue reasons inlet and outlet of the
ESP must be properly designed to provide
an even flow of the gas to prevent excessive
pressure losses.
Cuneo - Italy
9
odellingMFor several years, Redecam has been modelling
through physical simulation on 1:7 scale
models. Large scale models are needed to
respect the laws of physics and to keep the
process parameters consistent (e.g. Reynolds
number, operating pressure).
All models have been made and tested in
Redecam’s workshop, with its own equipment
and internal engineering resources.
Recently, increased modelling demand led
to extend the action field to the numerical
simulation. This approach allowed Redecam to
reach a sound control of all critical parameters
involved in the process. The same would not
have been possible with a direct approach.
Numerical simulation of inlet perforated plates
Numerical simulationof gas flow
distribution inside electrostatic precipitators
10
n-Site ActivitiesO
Redecam’s focus is on serving the industrial
sectors with a wide range of solutions and
services. Scope of work can be extended to a
turnkey solution including electrical and civil
work, or be limited to the engineering design
using local fabrication and supply of the critical
components.
Our solutions can be designed for installation
in existing plants, making “upgrades” or
“retrofits” of obsolete equipment, or designing
a complete replacement.
Each case is carefully evaluated and the resulting
solution is always custom-made.
Two sections lifting
Heavy lift during dark night
11
Tepetzingo - Mexico
Redecam GroupPiazza Montanelli, 20 – 20099 Sesto S.G. - ItalyPh. +39 02 243491 fax +39 02 24349100www.redecam.comemail: [email protected]