SINGLE-POINT CONTROL BASED FEEDING METHOD FOR ALUMINUM REDUCTION CELL FEEDER

PROCEDE D'ALIMENTATION BASE SUR UN CONTROLE EN UN SEUL POINT POUR UN DISPOSITIF D'ALIMENTATION D'UNE CELLULE DE REDUCTION D'ALUMINIUM

English Abstract

Disclosed is a single-point control based feeding method for a pre-baked anode aluminum reduction cell feeder. A feeding port is divided into different regions. Equidistant voltage drop signals are sampled on anode leaders in different regions. The anode current is calculated according to the equidistant voltage drop signal. The aluminum oxide concentration in regions of the feeding port is compared according to the variation trend of the anode current. Feeding control is performed distinguishingly for states of the regions of the feeding port. Through the method, targeted controlling can be performed on the aluminum oxide concentration in each region of the electrolytic cell, thereby improving the accuracy of the feeding control, avoiding precipitation production or effect frequency, being beneficial to stable running of the electrolytic cell, and achieving the effect of saving energy, reducing consumption and improving current efficiency.

French Abstract

L'invention concerne un procédé d'alimentation basé sur un contrôle en seul point pour un dispositif d'alimentation de cellule de réduction d'aluminium à anodes précuites. Un orifice d'alimentation est divisé en différentes régions. Des signaux de chute de tension équidistants sont échantillonnés sur des conducteurs d'anode dans différentes régions. Le courant anodique est calculé selon les signaux de chute de tension équidistants. La concentration d'oxyde d'aluminium dans des régions de l'orifice d'alimentation est comparée selon la tendance de variation du courant anodique. Un contrôle d'alimentation est effectué de façon distinctive pour des états des régions de l'orifice d'alimentation. Par ce procédé, un contrôle ciblé peut être effectué sur la concentration d'oxyde d'aluminium dans chaque région de la cellule électrolytique, permettant ainsi d'améliorer la précision du contrôle d'alimentation, d'éviter la production ou la fréquence d'effet d'une précipitation, ce qui est avantageux pour un fonctionnement stable de la cellule électrolytique, et ce qui permet de parvenir à l'effet d'économiser de l'énergie, de réduire une consommation et d'améliorer le rendement en courant.

Claims

Claims
1. A single-point control based feeding method for an aluminum reduction cell
feeder,
wherein a feeding port is allocated to each different region; equidistant
voltage drop signals
are collected on anode rods in different regions; the anode current is
calculated according to
the equidistant voltage drop signals; the aluminum oxide concentration in the
feeding port
regions is compared with each other according to the variation trend of the
anode current; and
feeding control is performed regionally with respect to states of the feeding
port regions.
2. The single-point control based feeding method for an aluminum reduction
cell feeder
according to claim 1, wherein a significant decrease in the anode current in a
certain feeding
port region indicates that the aluminum oxide concentration in said region is
lower than the
average aluminum oxide concentration in the cell; and a significant increase
in the anode
current in a certain feeding port region indicates that the aluminum oxide
concentration in said
region is higher than the average aluminum oxide concentration in the cell.
3. The single-point control based feeding method for an aluminum reduction
cell feeder
according to claim 2, wherein in said region where the aluminum oxide
concentration is
higher than the average aluminum oxide concentration in the cell, feeding is
stopped for some
time until the aluminum oxide concentration therein reaches the average
aluminum oxide
concentration in the cell; and in said region where the aluminum oxide
concentration is lower
than the average aluminum oxide concentration in the cell, the feeding
interval is cut by half
until the aluminum oxide concentration therein reaches the average aluminum
oxide
concentration in the cell.

Description

CA 02840275 2013-12-23
SINGLE-POINT CONTROL BASED FEEDING METHOD FOR ALUMINUM
REDUCTION.CELL FEEDER
TECHNICAL FIELD
The present invention relates to a feeding method and, in particular, to a
single-point control based feeding method for a pre-baked anode aluminum
reduction
cell feeder.
BACKGROUND OF THE INVENTION
An aluminum reduction cell has complex feedstock balance and physical field
distribution, so the concentration of aluminum oxide is not uniform among the
different regions. The conventional method is the aluminum oxide concentration
= control method based on tracking of cell resistance, where the odd- or
even-number
feeders feed feedstock simultaneously at regular time using the slope of the
cell
resistance as the basis for control of the aluminum oxide concentration.
However, in
an reduction cell, due to changes in the technical conditions and the presence
of some
interference factors, the definite corresponding relationship between the cell

resistance and the aluminum oxide concentration changes, resulting in worse
aluminum oxide concentration control effect and even control failures, leading
to
frequent precipitate production or effect, which in turn causes the cell to be
more
unstable and creates a vicious cycle, thereby having a negative impact on the
electrolysis process.
To improve said method, researches have been done on the regional disparity in
aluminum oxide concentration, and found that by changing the conventional
simultaneous feeding at regular time by odd- or even-number feeders into
feeding
based on single-point control of the feeder, the cell would have a more
uniform
aluminum oxide concentration and a more stable performance, thereby optimizing
the
technical and economic indicators of the aluminum reduction cell.
DETAILED DESCRIPTION OF THE INVENTION
In order to solve the aforesaid technical problem, the present invention
provides
a single-point control based feeding method for an aluminum reduction cell
feeder,
which is designed for optimizing control of aluminum oxide concentration and

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enhancing the control accuracy of aluminum oxide feeding, such as to achieve a
more uniform
aluminum oxide concentration in and more stable operation of the reduction
cell, thereby
improving the current efficiency.
To said end, the present invention provides a single-point control based
feeding method
for an aluminum reduction cell feeder. A feeding port is allocated to each
different region.
Equidistance voltage drop signals are collected on anode rods in different
regions. The anode
current is calculated according to the equidistant voltage drop signals. The
aluminum oxide
concentration in the feeding port regions is compared with each other
according to the
variation trend of the anode current. Feeding control is performed regionally
with respect to
states of the feeding port regions.
A significant decrease in the anode current in a certain feeding port region
indicates that
the aluminum oxide concentration in said region is lower than the average
aluminum oxide
concentration in the cell; and a significant increase in the anode current in
a certain feeding
port region indicates that the aluminum oxide concentration in said region is
higher than the
average aluminum oxide concentration in the cell.
In said region where the aluminum oxide concentration is higher than the
average level
in the cell, feeding is stopped for some time until the aluminum oxide
concentration therein
reaches the average level in the cell; and in said region where the aluminum
oxide
concentration is lower than the average level in the cell, the feeding
interval is cut by half
until the aluminum oxide concentration therein reaches the average level in
the cell.
The advantages of the present invention: targeted controlling can be performed
on the
aluminum oxide concentration in each region of the reduction cell 7, thereby
improving the
accuracy of the feeding control, avoiding frequent precipitate production or
effect, facilitating
stable operation of the reduction cell, and achieving the effect of saving
energy, reducing
consumption and improving current efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a structural schematic diagram of the present invention.
2

CA 02840275 2013-12-23
Where 1, cell control machine; 2, aluminum oxide feeding device; 3, anode bus;

4, anode; 5, anode current collecting device; 6, anode rod; 7, reduction cell;
8, gas
control cabinet; 9, signal collecting box.
EMBODIMENTS
The present invention will be further described below with reference to the
drawings.
As shown in the drawings, the present invention provides a single-point
control
based feeding method for an aluminum reduction cell feeder. A feeding port is
allocated to each different region. Equidistant voltage drop signals are
collected on
anode rods in different regions. The anode current is calculated according to
the
equidistant voltage drop signals. The aluminum oxide concentration in the
feeding
port regions is compared with each other according to the variation trend of
the anode
current. Feeding control is performed differently with respect to states of
the feeding
port regions.
A significant decrease in the anode current in a certain feeding port region
indicates that the aluminum oxide concentration in said region is lower than
the
average aluminum oxide concentration in the cell; and a significant increase
in the
anode current in a certain feeding port region indicates that the aluminum
oxide
concentration in said region is higher than the average aluminum oxide
concentration
in the cell.
In said region where the aluminum oxide concentration is higher than the
average level in the cell, feeding is stopped for some time until the aluminum
oxide
concentration therein reaches the average level in the cell; and in said
region where
the aluminum oxide concentration is lower than the average level in the cell,
the
= feeding interval is cut by half until the aluminum oxide concentration
therein reaches
the average level in the cell.
Taking the 200KA reduction cell for an example, it has four feeding ports and
24
anodes, so the reduction cell is divided equally into four regions according
to the
positions of the feeding ports. Normally, feeding ports 1 and 3 feed
simultaneously,
and feeding ports 2 and 4 feed simultaneously. When the aluminum oxide
3

CA 02840275 2013-12-23
concentration in one of the regions, which are divided according to the
feeding ports,
is lower than the average level in the cell, feedstock should be added in a
timely
manner. The specific feeding manner is as follows: if it is determined that
feeding port
1 lacks feedstock, feeding ports 1 and 3 feed normally, and feeding port 1
also feeds at
the same time when feeding ports 2 and 4 feed simultaneously, i.e., feeding
ports 1, 2
and 4 feed simultaneously. When the aluminum oxide concentration in said
region is
higher than the average level in the cell, feeding should be controlled in a
timely
manner. The specific feeding manner is as follows: if it is determined that
feeding port
1 has fed too much feedstock, only feeding port 3 feeds when feeding ports 1
and 3
should feed normally, and feeding ports 2 and 4 feed normally.
Anode rod 6 is provided with anode current collecting device 5, the signal
collected by said device 5 transmitted to signal collecting box 9 for
preliminary
treatment before being sent to cell control machine 1 for treatment. The
relationship
between the aluminum oxide concentration state in all the feeding port regions
and the
average aluminum oxide concentration in the cell is determined by the results
of the
treatment. Anode bus 3 is connected to the anode leader 6, which is connected
at the
bottom to anode 4; and aluminum oxide feeding device 2 is connected to gas
control
cabinet 8. According to the varying results, feeding is stopped for some time
in
regions where the aluminum oxide concentration is higher than the average
level in
the cell, until the aluminum oxide concentration therein reaches the average
level in
the cell; and the feeding interval is cut by half in regions where the
aluminum oxide
concentration is lower than the average level in the cell, until the aluminum
oxide
concentration therein reaches the average level in the cell.
4

Representative Drawing