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ALUMINIUM SMELTING INDUSTRY
Fig. 3: Möller Fluidflow pipe air slide from secondary alumina silo to potroom
wall; main bin and Möller Fluidflow pipe air slide along potroom (Dubal)
in the GTC system already remove most
of the coarse material (e. g. from scaling effects).
However, in brownfield aluminium
smelters the existing installation situation
may not have enough space in which to install
vibrating screens. To address this, FLSmidth
enhanced the design of the material trap in
order to include the process function of a
vibrating screen. The Möller direct pot feeding
system can generally be installed at every
brownfield smelter presently operating with a
crane feeding system.
Main bin: The main bins – normally one
main bin is used for each half of a potroom –
are located right next to the potroom wall.
The main bins are always 100% filled, and
the resulting material column ensures a continuous
mass flow of secondary alumina to all
electrolysis cells, especially to the last cell at
the end of the Möller Fluidflow pipe air slide
along the potroom.
Because of the well-defined height of the
main bin, the Möller direct pot feeding system
is independent of the filling level of the secondary
alumina silo. Whether the secondary
alumina silo is full, half full or nearly empty,
the conveying capacity of the Möller direct pot
feeding system stays
the same.
Given the sufficient height between the
outlet flange of an existing secondary alumina
silo and the superstructure of the electrolysis
cell, then the Möller Fluidflow pipe air slide
can also be installed along the potroom with
an appropriate declination (downhill slope)
without a main bin.
Distribution pieces and vent domes: From
the main Möller Fluidflow pipe air slide along
the potroom the secondary alumina is transported
via the distribution pieces into the
potroom, and then to the electrolysis cells.
According to the design requirements, a sufficient
number of vent domes will be installed
on top of the distribution pieces. All necessary
venting domes are connected to the gas duct
of the GTC.
Each of the above described distribution
pieces can be connected to one (single-feed),
two (double-feed) or even more electrolysis
cells (multi-feed), as per customer requirements
resp. installation situation.
Superstructure design requirements: Each
superstructure is specially designed as part of
the electrolysis cell’s technology. Generally,
the state-of-the-art electrolysis cell technologies
already ensure sufficient space for a direct
pot feeding system.
However, clients have
Fig. 4: Möller distribution pieces and vent dome
different requirements regarding free access
for crust breakers, dosing devices and the option
for removing the ore bunkers during operation,
and these factors influence the final
design of the Möller Fluidflow pipe air slide
to be installed on top or inside of the superstructure
of the electrolysis cell.
The self-regulating and continuous filling
process of the ore bunkers of an electrolysis
cell by the Möller direct pot feeding system
is simply ingenious. If the ore bunker is full,
then the material cone level has reached the
filling spout discharge opening of the Möller
Fluidflow pipe air slide, and the mass flow is
blocked automatically. As soon as secondary
alumina is removed from the ore bunker of
the electrolysis cell, the pneumatic transport
starts again automatically and ensures a constant
and reliable mass feed rate to the pots.
The fluidising of the secondary alumina inside
the Möller Fluidflow pipe air slide works permanently
to ensure a constant bulk density.
Fluidisation air equipment: The fluidisation
air requirements for the Möller Fluidflow
pipe air slide along the potroom and on top of
the electrolysis cells are different in regard to
the fluidisation air pressure and the specific
fluidisation air amount. Therefore, the Möller
direct pot feeding system uses two different
fluidisation air sources which can either be
frequency controlled rotary piston blowers
Fig. 5: Single-feed design …
Fig. 6: … and double-feed design of the Möller direct pot feeding system
30 ALUMINIUM · 1-2/2013