Note: Descriptions are shown in the official language in which they were submitted.
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MAGNETIC SEPARATION APPARATUS
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a magnetic separation apparatus which in
particular
is capable of separating and removing magnetic flocs from raw water by letting
the magnetic
flocs be adsorbed onto magnetic disks.
Description of the Related Art
As a kind of a device that functions to remove pollutant substances in raw
water of
sewage, industry sewage, etc. there is one known as a magnetic separation
apparatus. This
magnetic separation apparatus adopts a method so called a magnetic seed method
in which
pollutant substances in raw water are turned into forms of magnetized magnetic
flocs by
adding flocculating agent and magnetic powder into the raw water, and by
letting the
magnetic flocs F be adsorbed onto magnetic disks having magnets being arranged
thereto,
the magnetic flocs F can be separated and removed from the raw water.
Japanese Patent Application Laid-Open No. 10-244424 discloses a solid-liquid
separation apparatus which incorporates a magnetic separation apparatus.
According to
Japanese Patent Application Laid-Open No. 10-244424, in the magnetic
separation
apparatus, a plurality of magnetic disks with a number of magnets being
attached thereto
are arranged on a rotation axis at certain intervals inside a separation tank.
In this
structure, magnetic flocs are removed and retrieved from raw water by letting
the magnetic
flocs be adsorbed onto the magnetic disks.
SUMMARY OF THE INVENTION
However, in the conventional magnetic separation apparatuses, the ability to
remove magnetic flocs from raw water is still not sufficient in terms of the
following points.
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(1) In the magnetic separation apparatus, it is important that the raw water
supplied to the
separation tank contacts equally with each of the plurality of the magnetic
disks in order to
efficiently remove the magnetic flocs inside the raw water. In this respect,
however, in the
conventional magnetic separation apparatuses, water flow inside the separating
tank can easily be
biased.
(2) In a case of adopting a structure in which the magnetic disks are
substantially half sunk
in the raw water inside the separation tank, the magnetic flocs adsorbed onto
the magnetic disks
can easily come off the surfaces of the magnetic disks while they are inside
the raw water,
whereas the magnetic flocs can become hard to come off when they are dried and
fixed to the
surfaces of the magnetic disks at the time when they are carried into the air
out from the raw water
due to rotation of the magnetic disks. In this respect, the conventional
magnetic separation
apparatuses are not taking adequate measures with respect to the problem of
the magnetic flocs
once adsorbed onto the magnetic disks coming off while inside the raw water,
and the problem as
to how the magnetic flocs adsorbed onto the magnetic disks should be
effectively removed once
they are out in the air.
The present invention is provided in view of such circumstances, and the
object of the
present invention is to resolve the problems the conventional magnetic
separation apparatuses
have concerning adsorption separation efficiency and retrieval efficiency of
magnetic flocs, and to
provide a magnetic separation apparatus which is capable of removing magnetic
flocs contained in
raw water with high efficiency.
For the purpose of achieving the above-mentioned object, there is provided a
magnetic
separation apparatus, comprising:
a separation tank to which raw water containing magnetic flocs is to flow
into, the
separation tank having a feed-water inlet provided in the lower end of the
separation tank for
supplying the raw water to the separation tank as an upward flow;
a plurality of magnetic disks which adsorb the magnetic flocs by use of
magnetic force, the
plurality of magnetic disks being arranged at predetermined intervals on a
rotation axis provided
in the separation tank and being substantially half sunk in the raw water in
the separation tank;
a retrieving device which retrieves the magnetic flocs adsorbed onto the
magnetic disks;
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flow dividing members, provided directly underneath the respective magnetic
disks, which
divide the flow of the raw water supplied from the feed-water inlet in right
and left directions with
respect to surfaces of the magnetic disks and in a thickness direction of the
magnetic disks; and
a pair of troughs, provided on opposing sides of the separation tank parallel
to the rotation
axis, where treated water after removing the magnetic flocs from the raw water
by the magnetic
disks overflows,
wherein each of the flow dividing members divides the raw water into different
raw water
flows and guides each of the different raw water flows to flow into a space
between adjacent
magnetic disks.
Therefore, preferably according to the first aspect, raw water supplied from a
feed-water
inlet provided in a lower end of a separation tank hits flow dividing members
and is divided its
flow in the radial right and left directions of magnetic disks and in the
thickness direction of the
magnetic disks. In this way, by letting the raw water supplied from the feed-
water inlet hit the
flow dividing members and being divided its flow in the right and left
directions of the magnetic
disks and in the thickness direction of the magnetic disks, a flow rate of the
raw water flowing
among the magnetic disks is reduced, whereby the raw water becomes a slow
upward flow that
moves upwardly passing among the magnetic disks. Thereby, it becomes possible
to have the
magnetic flocs in the raw water efficiently adsorbed onto the magnetic disks.
Moreover, by providing a pair of troughs on opposing sides of the separation
tank parallel
to a rotation axis, where treated water after removing magnetic flocs from raw
water by the
magnetic disks overflows, divided flows are not retained inside the separation
tank, and thus, it
becomes possible to promptly discharge the treated water out from the
separation tank.
In addition, by arranging flow dividing members directly underneath the
respective
magnetic disks, it is possible to prevent the raw water from becoming a fast
upward flow when
flowing through the vicinity of the surfaces of the magnetic disks. Therefore,
the magnetic flocs
once adsorbed onto the magnetic disks will not come off and fall inside the
raw water.
Preferably, in accordance with a second aspect of the present invention, in
the magnetic
separation apparatus according to the first aspect, the flow dividing member
is formed so that the
flow dividing member has a thickness at the upper end being the same as a
thickness of the
magnetic disk, and has a wedge shape at cross section in which the thickness
becomes thinner
towards the lower end.
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By forming flow dividing members in such shapes according to the second
aspect,
it is possible to have the flow of the raw water supplied through the feed-
water inlet divided
in the radial right and left directions of the magnetic disks and in the
thickness direction of
the magnetic disks with good accuracy.
Preferably, in accordance with a third aspect of the present invention, in the
magnetic
separation apparatus according to one of the first and second aspects, the
feed-water inlet is
formed in a square tube shape which is longer in the direction of the rotation
axis.
By having a water inlet formed in a square tube shape according to the third
aspect,
water can be easily supplied equally inside the separation tank, whereby the
removing efficiency
of the magnetic flocs can be further improved.
Preferably, in accordance with a fourth aspect of the present invention, the
magnetic separation apparatus according to one of the first to third aspects,
further includes
sealing plates provided between peripheral surfaces of the respective magnetic
disks and an
inner surface of the separation tank in a way such that base ends of the
sealing plates are fixed
to the inner surface of the separation tank and apical ends of the sealing
plates as being free
ends contact the peripheral surfaces of the magnetic disks.
By providing sealing plates between peripheral surfaces of the respective
magnetic
disks and the inner surface of the separation tank, according to the fourth
aspect, it is
possible to block a flow that takes a shorter route through the peripheral
surfaces of the magnetic
disks and overflows into the troughs without contacting the surfaces of the
magnetic disks.
Thereby, it is possible to further improve the removing efficiency of the
magnetic flocs.
Preferably, in accordance with a fifth aspect of the present invention, in the
magnetic separation apparatus according to one of the first to fourth aspects,
the retrieving
device includes: gutter-shaped scrapers, each of which being provided, in a
form of a gutter
extending from the vicinity of the rotation axis to the outside of the
separation tank, between two
adjacent rotating magnetic disks just before entering the raw water from the
air, each of the
gutter-shaped scrapers having edge parts in the upper ends of both sides
contact the surfaces of
the magnetic disks with predetermined urging force to scrape off the magnetic
flocs adsorbed
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onto the surfaces of the magnetic disks; and conveying devices provided inside
respective gutter-
shaped scrapers, each of which conveys the magnetic flocs being scraped off,
dropped and
accumulated inside the gutter-shaped scraper to the outside of the separation
tank.
Preferably, according to the fifth aspect, gutter-shaped scrapers are
provided, each of
which is in a form of a gutter extending from the vicinity of the rotation
axis to the outside of the
separation tank, between two adjacent rotating magnetic disks just before
entering the raw water
from the air, and which has edge parts in the upper ends of both sides contact
the surfaces of
the magnetic disks with predetermined urging force to scrape off the magnetic
flocs
adsorbed onto the surfaces of the magnetic disks. Thereby, it is possible to
unfailingly scrape
off the magnetic flocs even when the magnetic flocs are the ones that are
being fixed to the
surfaces of the magnetic disks due to being dried in the air, and it is
possible to unfailingly
retrieve the magnetic flocs being scraped off into the gutter-shaped scrapers.
As described above, the magnetic separation apparatus according to any of the
aspects of the present invention is capable of resolving the problems
concerning adsorption
separation efficiency and retrieval efficiency of the magnetic flocs, which
are problems
conventional magnetic separation apparatuses have, and removing the magnetic
flocs
contained in the raw water with high efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a block diagram illustrating a flow of operation in a polluted water
clarification system which incorporates a magnetic separation apparatus
according to the present
invention;
Fig. 2 is a schematic view of devices that construct the polluted water
clarification
system;
Fig. 3 is a perspective view illustrating a cross section of a part of the
magnetic
separation apparatus according to the present invention;
Fig. 4 is a sectional side view of the magnetic separation apparatus according
to the
present invention;
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Fig. 5 is a sectional front view of the magnetic separation apparatus
according to the
present invention;
Fig. 6 is an explanatory diagram illustrating operation of a flow dividing
member
arranged in the magnetic separation apparatus according to the present
invention;
Fig. 7 is a perspective view illustrating sealing plates arranged in the
magnetic
separation apparatus according to the present invention;
Figs. 8A and 8B are explanatory diagrams illustrating differences between
outmost
magnetic disks according to the conventional art and the present invention;
Fig. 9 is an explanatory diagram illustrating a relation between a magnetic
disk and a
gutter-shaped scraper in the magnetic separation apparatus according to the
present invention;
Fig. 10 is an explanatory diagram illustrating a retrieving device adopting a
screw
conveyer system;
Fig. 11 is an explanatory diagram illustrating a relation between a screw
conveyer and
a gutter-shaped scraper;
Fig. 12 is an explanatory diagram illustrating a retrieving device adopting a
finned belt
conveyer system; and
Fig. 13 is an explanatory diagram illustrating a relation between a fin in the
finned belt
conveyer system and a gutter-shaped scraper.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the following, a preferred embodiment of a magnetic separation apparatus
according to the present invention will be described with reference to the
drawings.
Fig. 1 is a block diagram illustrating a flow of operation in a polluted water
clarification system 10 which incorporates a magnetic separation apparatus 20
according to
the present invention. Fig. 2 is a schematic diagram of a flocculation device
14, the magnetic
separation apparatus 20 and a filter separation device 24.
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As shown in Fig. 1, in the polluted water clarification system 10, first, raw
water is
to be conveyed to a rapid stirring tank 14A in the flocculation device 14 by a
raw water pump
12. In certain places along a pipe arrangement connecting the raw water pump
12 and the rapid
stirring tank 14A, a magnetic powder adding device 16 for adding magnetic
powder, and a
flocculating agent adding device 18 for adding a flocculating agent are
provided so as to add the
magnetic powder and the flocculating agent to the raw water flowing inside the
pipe
arrangement. As for the magnetic powder, ferrosoferric oxide can be used
preferably. As
for the flocculating agent, a soluble inorganic flocculating agent such as
polyaluminum
chloride, ferric chloride, ferric sulfate, etc. can be used preferably.
Meanwhile, although it
is not shown in the diagram, it is preferable that a strainer is provided in
the system such
that the raw water can be filtered by having comparatively large size dirt of
several millimeter
size removed before having the magnetic powder and the flocculating agent
added.
In the rapid stirring tank 14A, by rapidly stirring the raw water, the added
magnetic powder and the flocculating agent using stirring fins 19 which rotate
in high
speed, tiny magnetic flocs F (also known as magnetic micro-flocs) each of
which with a
size of around several tens of micrometers (gm) are to be formed. It is
preferable that a
rotating speed at the edges of the stirring fins 19 is about 1 to 2 m/second.
The magnetic
powder, and solid floating particles, bacteria, plankton, etc. in the raw
water are to be taken up
by the magnetic micro-flocs.
Next, the raw water containing the magnetic micro-flocs is to be conveyed to a
slow-
speed stirring tank 14B in the flocculation device 14. In the vicinity of a
communicating room
14C that connects the rapid stirring tank 14A and the slow-speed stirring tank
14B, a high
polymer flocculating agent adding device 21 is provided so as to add a high
polymer
flocculating agent to the raw water flowing through the communicating room
14C. Here,
as for the high polymer flocculating agent, one of an anionic system and a
nonionic
system can be used preferably.
In the slow-speed stirring tank 14B, by slowly stirring the magnetic micro-
flocs and
the high polymer flocculating agent using stirring fins 19 which rotate in low
speed, large size
magnetic flocs F each of which with a size of around several hundreds
micrometers (gm) to
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several millimeters (mm) are to be formed. As shown in Fig. 2, it is
preferable that the slow-
speed stirring tank 14B is structured as a multistage stirring tank including
continuous multiple
stages with stirring tanks (A, B and C). In this case, a rotating speed of the
stirring fins 19
should decrease as it goes further down the stream from the slow-speed
stirring tank A in the
upstream side to the slow-speed stirring tank C in the downstream side.
Thereby, the magnetic
flocs F can grow bigger as they go further down the stream from the slow-speed
stirring tank A
in the upstream side to the slow-speed stirring tank C in the downstream side,
by which it will
be possible to prevent the grown magnetic flocs from breaking up. As for a
rotating speed at
the edges of the stirring fins 19, it is preferable, for instance, that the
rotating speed is about
0.5 to 1 m/second in the slow-speed stirring tank A, about 0.3 to 0.7 m/second
in the slow-
speed stirring tank B, and about 0.1 to 0.3 m/second in the slow-speed
stirring tank C.
As shown in Fig. 2, it is preferable that the flocculation device 14 has an
integral
structure that includes the rapid stirring tank 14A, the communicating room
14C and the slow-
speed stirring tank 14B. However, it is also possible to have a structure in
which these
components are connected by a pipe arrangement.
The raw water containing the magnetic flocs F of which sizes have grown
bigger,
are to be conveyed to the magnetic separation apparatus 20 according to the
present
invention. The magnetic separation apparatus 20 is intended to adsorb and
separate the magnetic
flocs F from the raw water using magnetic force. By the magnetic separation
apparatus 20, about
90% of the magnetic flocs F in the raw water are to be separated and removed.
As for a device
structure of the magnetic separation apparatus 20, details will be described
after the entire
operation flow of the polluted water clarification system 10 is explained.
The magnetic flocs F having been removed from the raw water by the magnetic
separation apparatus 20 are to be dehydrated by a dehydration device 25, which
could be a
centrifuge machine, a belt press machine or the like, so that their moisture
content will be
reduced down to about 80%. After that, the magnetic flocs F are to be loaded
on a truck, etc. to
be carried to a landfill site, an incineration plant, a compost manufacturing
factory, etc.
On the other hand, the treated water having gone through the processes in the
magnetic
separation apparatus 20 is to be next conveyed to the filter separation device
24. In the filter
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separation device 24, the treated water is to go into a rotating drum filter
26 where the treated
water will be filtered from the inside to the outside of the rotating drum
filter 26 to have the
magnetic flocs F still remaining in the treated water removed.
In this way, it is possible to purify the raw water containing pollutant
substances
such as dusts, solid floating particles, bacteria, plankton, etc. The magnetic
flocs F
attached to the rotating drum filter 26 are to be accumulated in a hopper
arranged inside
the rotating drum filter 26 by being showered with cleaning water outputted
from a showering
device 28 arranged on the upper side of the rotating drum filter 26. Then the
accumulated
magnetic flocs F are to be discharged outside the device. In this case, it is
good to have some of
the treated water being purified by the rotating drum filter 26 returned to
the showering device
28 by a circulation pump 29 so that the treated water can be reused as
cleaning water.
Discharged cleaning water which has turned dirty by containing magnetic flocs
F due to the
showering is to be brought back to a previous stage of the raw water pump by a
pump 30.
[Magnetic Separation apparatus]
Fig. 3 is a perspective view illustrating a cross section of a part of the
magnetic
separation apparatus 20 according to the present invention. Fig. 4 is a
sectional side view of
the magnetic separation apparatus 20, and Fig. 5 is a sectional front view of
the magnetic
separation apparatus 20.
As shown in Figs. 3 and 4, the magnetic separating device 20 according to the
present invention mainly includes: a separation tank 32 where raw water
containing
magnetic flocs F flow into; a plurality of magnetic disks 36 which are
arranged, at
predetermined intervals, on a rotation axis 34 provided inside the separation
tank 32 in the
horizontal direction, and which are to adsorb the magnetic flocs F by their
magnetic force;
and a retrieving device 38 which is to retrieve the magnetic flocs F adsorbed
onto the
magnetic disks 36. In this embodiment, although explanation will be given on a
case where
three to four magnetic disks 36 are used, the number of the magnetic disks 36
is not limited
to such particular numbers.
The separation tank 32 is formed in a shape of a half cylinder which is opened
in the
upper part and closed by side walls 41 in its both end faces (ref. Fig. 5). On
both sides (the
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right and the left sides in Fig. 3) of the separation tank 32, a pair of
troughs 40 are formed in
parallel with the rotation axis 34, and they have concave shapes at cross
section. Those troughs
40 are formed integrally with the separation tank 32. In the outside of the
trough 40, a floc
retrieving tank 42 is provided. The floc retrieving tank 42 is formed in
parallel with the trough
40, and has a concave shape at cross section. As shown in Fig. 3, the floc
retrieving tank 42 is
provided on the right side (the right side in Fig. 3) where the rotating
magnetic disks 36 enter in
the raw water.
As shown in Fig. 5, in the upper parts of the pair of side walls 41 of the
separation
tank 32, the rotation axis 34 is supported by axis bearings 35 in a rotatable
way, while one end
10 of the rotation axis 34 is connected with a motor 39. On the rotation
axis 34, a plurality of
magnetic disks 36 each of which having a fitting hole in the central part are
fit-supported while
having a predetermined interval between each other. Between each adjacent
magnetic disks 36,
a sleeve 31 is provided in such a way as to adjust the interval between the
adjacent magnetic
disks 36 and fix the inner periphery of the adjacent magnetic disks 36. It is
preferable that the
interval between each adjacent magnetic disks 36 is set to a value within a
range of one to three
times the thickness of the magnetic disk 36. If the interval is less than one
time the thickness
of the magnetic disk 36, it will be difficult for the raw water to flow
between the magnetic
disks 36. Whereas if the interval is over three times the thickness of the
magnetic disk 36
and becomes too wide, it will be difficult for the magnetic disks 36 to
generate strong
magnetic force between each other.
It is preferable that each of the plurality of the magnetic disks 36 being
supported
by the rotation axis 34 goes under the raw water in the separation tank 32 by
1/2 to 2/3
portion of it. In such case where the magnetic disks 36 are arranged such that
they partly
go under the water, the magnetic flocs F adsorbed onto the magnetic disks 36
in the raw
water are to be retrieved by the retrieving device 38 when the magnetic disks
36 rotate and
bring the magnetic flocs F to the air. Accordingly, it is important to set
such sinking rate
of the magnetic disks 36 that could render adsorption and retrieval
efficiencies of the
magnetic flocs F the best. Therefore, for instance, making the pair of axis
bearings 35 be
supported by a pair of elevating machines, which are not shown, so that the
magnetic disks
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36 can move up and down by a hydraulic mechanism or the like and so that the
sinking rate can
be made variable, should be a likeable method.
Moreover, in the lower end of the separation tank 32, a feed-water inlet 44
having a
square tube shape which is longer in the direction of the rotation axis 34 is
formed. This feed-
water inlet 44 and an outlet of the flocculation device 14 are connected by a
pipe arrangement 43
(ref. Fig. 4). In the feed-water inlet 44, a plurality of flow dividing
members 46 are arranged (ref.
Fig. 5). As shown in Fig. 5, these flow dividing members 46 are arranged
directly underneath the
respective magnetic disks 36, and each of them has a wedge shape, at cross
section, whose
thickness W1 in the upper end is the same as a thickness W2 of the magnetic
disk 36 and
becomes thinner towards the lower end. Furthermore, as can be seen in Fig. 4,
a width dimension
DI of each flow dividing member 46 is smaller than a width D2 of the feed-
water inlet 44,
whereby the raw water supplied through the feed-water inlet 44 can be divided
into right and left
gaps 44A and 448 each of which formed between the feed-water inlet 44 and the
flow dividing
member 46.
As shown in Fig. 4, by having these flow dividing members 46, the raw water
supplied from the feed-water inlet 44 will hit each flow dividing member 46
and divide its
flow in radial right and left directions of each magnetic disk 36. In this
way, by having
the raw water supplied through the feed-water inlet 44 divided into two flows
in the right and
left directions by letting the raw water hit each flow dividing member 46, a
flow rate of the
raw water flowing between each adjacent magnetic disks 36 can be reduced,
whereby the raw
water will become a slow upward flow that moves upwardly passing among the
magnetic
disks 36. Thereby, it is possible to have the magnetic flocs F in the raw
water efficiently
adsorbed onto the magnetic disks 36. In addition, by reducing the flow rate of
the upward
flow, the magnetic flocs F once adsorbed onto the magnetic disks 36 will
become hard to
come off.
Furthermore, as shown in Fig. 5, the raw water entering the separation tank 32
from the feed-water inlet 44 is to be also divided in a thickness direction of
the magnetic disks
36 by the flow dividing members 46. Thereby, it is possible to prevent the
magnetic flocs F
adsorbed onto the magnetic disks 36 from coming off due to the flow of the raw
water being
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supplied through the feed-water inlet 44. That is, as can be understood from
Fig. 5, without the
arrangement of the wedge-shaped flow dividing members 46, the peripheral
surfaces 36a of the
magnetic disks 36 will be exposed directly to the upward flow of the raw water
being supplied
from the feed-water inlet 44.
That is, as can be seen in Fig. 6, the flow of the raw water in a state where
there are no
flow dividing members 46 will become a fast upward flow as shown by the dotted
lines that
flows through the vicinity of the surfaces of the magnetic disks 36, and
therefore, among the
magnetic flocs F that have adsorbed onto the surfaces of the magnetic disks
36, especially the
ones near the peripheral surfaces 36a might get scraped off due to the flow of
the raw water
and thus might drop into the raw water. On the other hand, by having the
peripheral surfaces
36a of the magnetic disks 36 not exposed directly to the flow of the raw water
due to the
flow dividing members 46, the raw water entering through the feed-water inlet
44 will flow
with a slower speed as it hits the flow dividing members 46 and it will
further be divided in the
thickness direction of the magnetic disks 36, as shown by the solid arrowed
lines in Fig. 6.
Therefore, the magnetic flocs F once adsorbed onto the surfaces of the
magnetic disks 36 will
not be scraped off due to the flow of the raw water.
In addition, as shown in Fig. 4, the separation tank 32 is provided with
sealing plates
48 which seal the gaps between the peripheral surfaces 36a of the magnetic
disks 36 and the
inner surface of the separation tank 32 so that the raw water supplied from
the feed-water inlet
44 will not take a shorter route through the peripheral surfaces 36a of the
magnetic disks 36
and flow out into the troughs 40.
As shown in Fig. 7, the sealing plates 48 have their base ends fixed to a
turning
axis 50 which is supported by the separation tank 32 in a turnable way, and
have their
apical ends as being free ends touching the peripheral surfaces 36a of the
magnetic disks
36. The turning axis 50 is urged by a spring, etc., which is not shown, to
rotate in the
direction of the arrow. Thereby, since the sealing plates 48 are contacting
the peripheral
surfaces 36a of the magnetic disks 36 with predetermined contact force, they
can prevent
the raw water from taking a shorter route through the peripheral surfaces 36a
of the
magnetic disks 36 without disturbing the rotation of the magnetic disks 36. As
for the
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material of the sealing plates 48, elastic material which is softer than the
magnetic disk 36
should be used preferably, and in this respect, rubber plates, for instance,
can be suitable
for use as the sealing plates.
Now a description will be given on the magnetic disks 36.
The magnetic disk 36 is structured as including a nonmagnetic case 45 having a
torus-shape cavity inside, a number of permanent magnet pieces 37 arranged
inside the
nonmagnetic case 45 and a ferromagnetic disk substrate 33 sandwiched between
the
permanent magnet pieces 37. In the central part of the disk substrate 33,
there is a hole for
reeving the rotation axis 34. Normally, three or more magnetic disks 36 are
mounted on
the rotation axis 34.
With respect to such magnetic disks 36, the ones in the conventional art as
shown
in Fig. 8A have the permanent magnet pieces 37 on both sides of the respective
ferromagnetic disk substrates 33 with respect to the outmost magnetic disks
36A arranged
on both ends of the rotation axis 34 and with respect to the inner magnetic
disks 36B
arranged inwardly near the center from both ends of the rotation axis 34.
Therefore, in the
conventional cases, problems such as magnetic leakage from the outmost
magnetic disks
36A to the outside of the separation tank 32, deformation of the outmost
magnetic disks
36A, etc. could occur.
With respect to the inner magnetic disks 36B, because there are opposed
magnetic disks on both sides of each of them, as long as they are arranged at
equal
intervals, the magnetic force of the inner magnetic disks 36B should be kept
in a
balanced state and thus the inner magnetic disks 36B should be free of the
problems of
magnetic leakage, deformation, etc.
As a counter measure to such problems in the conventional art, Fig. 88 shows a
different arrangement of the magnetic disks 36A and 36B. As shown in Fig. 8B,
the inner
magnetic disks 36B have the same structure as the ones in the conventional
art, that is, each of
them is structured as having permanent magnet pieces 37 arranged on both sides
of the disk
substrate 33 in such a way as to sandwich the ferromagnetic disk substrate 33
therebetween.
On the other hand, with respect to the outmost magnetic disks 36A, each of
them has the
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permanent magnet pieces 37 for exerting magnetic force arranged only on the
inner side
surface of the disk substrate 33 (i.e. the surface on the side of the inner
magnetic disk 36B)
while a single iron plate 52 is arranged on the outer side surface of the disk
substrate 33 in a
way such that the magnet pieces 37 and iron plate 52 are sandwiching the disk
substrate 33
therebetween. In this case, the disk substrate 33 is essentially
ferromagnetic, although the iron
plate 52 can be either ferromagnetic or nonmagnetic. In addition, the disk
substrate 33 and the
iron plate 52 can have an integrated form by being structured as a one thick
ferromagnetic
body. Thereby, the outmost magnetic disks 36A are arranged to be able to have
more
enhanced stiffness than the inner magnetic disks 36B. In enhancing the
stiffness of the
outmost magnetic disks 36A, it is important that the stiffness is enhanced to
the extent that the
outmost magnetic disks 36A will not be deformed due to the influence of the
magnetic
force from the inner magnetic disks 368. Accordingly, it is preferable that a
thickness of
the iron plate 52 is properly determined on the basis of a distance between
the outmost
magnetic disk 36A and the inner magnetic disk 36B, magnetic force of the
permanent
magnet pieces 37, material of the disk substrate 33, and so forth.
With respect to the outmost magnetic disk 36A or with respect to the inner
magnetic
disk 36B, in the case of having the disk substrate 33 made of ferromagnetic
material, it should
be more preferable that the permanent magnet pieces 37 are glued to the disk
substrate 33 with
an adhesive agent, although it is also possible to have the permanent magnet
pieces 37 directly
attached to the disk substrate 33 using the magnetic force of the permanent
magnet pieces 37.
At this time, it is also possible to arrange such that resin is molded to the
space formed inside
the case 45.
Furthermore, in order to enhance the stiffness of the magnetic disks 36, it is
also
possible to have pockets (not shown) formed on the surfaces of the
ferromagnetic disk
substrates 33 so that the permanent magnet pieces 37 can fit in those pockets.
A method of manufacturing the magnetic disk 36 having a plurality of permanent
magnet pieces 37 fixed to the surfaces of the disk substrate 33 includes: a
disk substrate
formation process for forming the disk substrate 33 into a honeycomb structure
in which at
least one of the surfaces of the disk substrate 33 have a plurality of holes
serving as the
= CA 02640019 2013-09-11
above-mentioned pockets; a magnet fitting process for fitting the permanent
magnet pieces
37 in the pockets formed on the disk substrate 33; and a placing process for
placing the disk
substrate 33 with the permanent magnet pieces 37 being fitted therein inside
the case 45 having a
torus-shape cavity formed inside.
Thereby, it is possible to enhance the stiffness of the magnetic disk 36 since
the
sidewalls of the pockets serve as ribs (reinforcing members). In this case, it
is necessary that
the pockets are made of nonmagnetic material, and the pockets are to be glued
to the
ferromagnetic disk substrate 33 with an adhesive agent. The reason for this is
that, if the
pockets are made of magnetic material, ferromagnetic material in particular,
magnetic
10 flux will be absorbed by the sidewalls of the pockets, which results in
increasing
magnetic field only in the vicinity of the surfaces of the magnets while it
will become
difficult to form high magnetic field in places apart from the permanent
magnet pieces 37
with respect to the magnetization direction.
By structuring the outmost magnetic disks 36A in this way, it is possible to
resolve the problem of magnetic leakage with a simple measure without having
to adopt a
magnetic shield, a magnetic coil, etc., and what is more, the outmost magnetic
disks 36A
will not be deformed. Meanwhile, in forming the inner magnetic disk 368 as
having
pockets, the pockets should be formed on both sides of the disk substrate 33.
However, by not having the permanent magnet pieces 37 arranged on the outer
surfaces of the disk substrates 33 of the respective outmost magnetic disks
36A, there will be a
risk that the raw water passing between the outer surfaces of the respective
outmost magnetic
disks 36A and the inner surface of the separation tank 32 may flow out into
the troughs
without having the magnetic flocs F being adsorbed and separated. As a
countermeasure to
this problem, as shown in Fig. 5, shielding members 54 are arranged to fill in
the gaps
between the outer surfaces of the respective outmost magnetic disks 36A and
the inner
surface of the separation tank 32. These shielding members 54 are arranged in
such a way
as to not disturb the rotation of the outmost magnetic disks 36A. As for the
shielding
members 54, it is important that they will not disturb the rotation of the
outmost magnetic
disks 36A, and thus, material that has less friction and that is soft such as
resin, sponge,
etc. can be used preferably. In this way, even though the permanent magnet
pieces 37 are
CA 02640019 2013-09-11
16
not arranged on the outer surfaces of the disk substrates 33 of the respective
outmost
magnetic disks 36A, the magnetic flocs F will not flow out into the troughs 40
as they are.
As can be seen in Fig. 5, there are still concave shaped gaps formed between
the outer
surfaces of the respective outmost magnetic disks 36A and the inner surface of
the
separation tank 32 even though there are shielding members 54 to seal the
gaps. However,
this is nothing to be concerned of because the raw water will not be retained
in those
concave shaped gaps due to the influence of the centrifugal force caused by
the rotation of
the outmost magnetic disks 36A.
In addition, there is a method that forms the cases 45 of the respective
magnetic
disks 36 into honeycomb structures for the purpose of enhancing the stiffness
of the
outmost magnetic disks 36A. By adopting this method, it is also possible to
have lighter
magnetic disks 36. This method regarding the honey comb structure is not
necessary
applicable to the outmost magnetic disks 36A only, but can be applied to the
inner
magnetic disks 36B as well.
Now a description will be given on the floc retrieving device 38 that
retrieves
the magnetic flocs F adsorbed onto the magnetic disks 36.
The floc retrieving device 38 includes mainly composed of gutter-shaped
scrapers 60 and conveying devices 62.
Each of the gutter-shaped scrapers 60 is provided in a form of a gutter that
extend
from the vicinity of the rotation axis 34 to the upper side of the floc
retrieving tank 42, and it
is arranged such that it comes between two adjacent rotating magnetic disks 36
just before
entering the raw water from the air (ref Fig. 5). Each gutter-shaped scraper
60 is structured
such that its edge parts 60A in the upper ends of both sides of it are to
contact the surfaces of
the magnetic disks 36 with predetermined urging force, by which the magnetic
flocs F
adsorbed onto the surfaces of the magnetic disks 36 can be scraped off.
The conveying devices 62 are provided inside respective gutter-shaped scrapers
60,
and each of them is to convey the magnetic flocs F, which have been scraped
off, dropped
and piled up inside the gutter-shaped scraper 60, to the upper side of the
floc retrieving tank
42 where it drops the magnetic flocs F into the floc retrieving tank 42. As
for the conveying
= CA 02640019 2013-09-11
17
device 62, a screw conveyer 64 or a filmed belt conveyer 66 can be used
preferably. Figs. 9
to 11 are showing the case when the screw conveyer 64 is adopted, whereas
Figs. 12 and 13
are showing the case when the finned belt conveyer 66 is adopted. In Figs. 9,
10 and 12, only
the magnetic flocs F that are on the parts of the magnetic disks 36 exposed in
the air are
shown.
As shown in Fig. 9, the gutter-shaped scraper 60 has its edge parts 60A in the
upper ends of both sides of it contact the surfaces of the magnetic disks 36
with
predetermined pressing force, while the upper end edge parts 60A are formed in
sharp thin-
walled shapes. With this structure, the magnetic flocs F adsorbed onto the
surfaces of the
magnetic disks 36, which are rotating in the clockwise direction, are to be
scraped off by
the upper end edge parts 60A of the gutter-shaped scraper 60, and dropped into
the gutter-
shaped scraper 60.
As shown in Figs. 9 to 11, a screw part 64A of the screw conveyer 64 is
contained
inside the gutter-shaped scraper 60, and one end of the screw part 64A is
connected to a
motor 64B. In this case, as shown in Fig. 11, the inner surface of the gutter-
shaped scraper
60 from its sides to bottom should preferably have a semicircular shape so
that no dead
space will be formed for conveyance. Thereby, the magnetic flocs F which have
been
dropped and piled up inside the gutter-shaped scraper 60 will be conveyed by
the screw
conveyer 64 to the upper side of the floc retrieving tank 42 where they are to
be dropped
inside the floc retrieving tank 42.
On the other hand, in the case of adopting the finned belt conveyer 66 to
function as the conveying device 62, the structure will be as shown in Figs.
12 and 13.
The finned belt conveyer 66 is provided with a pair of pulleys 68 on both
sides of the
magnetic disk 36 in the radial direction of the magnetic disk, and an endless
belt 70
having fins 69 is wrapped around the pair of pulleys. One of the pulleys 68 in
the pair is
connected to a driving device such as a motor, etc., which is not shown. This
endless belt
70 is not supposed to contact with the surfaces of the magnetic disks 36. The
fins 69 are
provided in a large number at predetermined intervals on the outer surface of
the endless
belt 70, and they are formed as being vertical with respect to the endless
belt 70. In this
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18
case, as shown in Fig. 13, the inner surface of the gutter-shaped scraper 60
from its sides
to bottom should preferably have a shape that suits the shape of the fin 69 so
that no dead
space will be formed for conveyance. For instance, if the shape of the fin 69
is an inverted
trapezoid, then the inner surface shape of the gutter-shaped scraper 60 should
also be an
inverted trapezoid.
In Figs. 9 to 13, although supporting mechanisms for the gutter-shaped scraper
60
and the pulleys 68 of the finned belt conveyer 66 are not shown in particular,
it is possible
to have them supported by the main frame of the magnetic separation apparatus
20, for
instance. As for the slope of the gutter-shaped scraper 60, the one shown in
Fig. 10 (i.e. the
one with the screw conveyer) has a slope which is diagonally right up, whereas
the one
shown in Fig. 12 (i.e. the one with the finned belt conveyer) has a slope
which is
diagonally right down. However, it is preferable that the slope is diagonally
right up. By
having a diagonally right up slope for the gutter-shaped scraper 60, it is
possible to prevent
moisture coming out of the magnetic flocs F, while the magnetic flocs F drop
and pile up
inside the gutter-shaped scraper 60 and then be conveyed by the conveying
device, from
flowing into the floc retrieving tank 42. It is important that the magnetic
flocs F to be
retrieved by the floc retrieving tank 42 should contain moisture as low as
possible to have
reduced volume. For this purpose, it is preferable that an adjustment device
(not shown) for
adjusting a slope of the retrieving device 38 as a whole is provided so that
the diagonally
right up slope of the gutter-shaped scraper 60 can be adjusted. For instance,
with respect to
the retrieving device 38 adopting the screw conveyer system, it is possible to
have a
structure in which the gutter-shaped scraper 60 is supported by a turning axis
at its central
part in the length direction, so that the gutter-shaped scraper 60 could
become swingable
like a seesaw using an expansion device such as a cylinder device, etc.
Next, operation of the magnetic separation apparatus 20 structured in the
above-
described manner will be described.
The raw water containing the magnetic flocs F is to enter from the feed-water
inlet 44 formed in the lower end of the separation tank 32 and have its flow
divided by the
flow dividing members 46. By the flow dividing members 46, the raw water will
have its
CA 02640019 2013-09-11
19
flow dived to both right and left sides with respect to the surfaces of the
continuously
rotating magnetic disks 36, and along with that, it will also have its flow
divided so that it will
flow into a ferromagnetic space between each adjacent magnetic disks 36. While
the divided
raw water flows upwardly within the separation tank 32, the magnetic flocs F
in the raw water
will be adsorbed onto the surfaces of the magnetic disks 36. The treated water
which is being
purified by having the magnetic flocs F adsorbed onto the magnetic disks 36
will overflow into
the pair of troughs 40 provided on both right and left sides of the magnetic
disks 36.
On the other hand, the magnetic flocs F adsorbed onto the magnetic disks 36
are to be
carried into the air above the surface of the water by the continuous rotation
of the magnetic
disks 36, and thus they will be exposed to the air. As the magnetic flocs F
get exposed to
the air, moisture of the magnetic flocs F will run down the surfaces of the
magnetic disks
36 into the separation tank 32 due to gravity. Furthermore, the magnetic flocs
F adsorbed
onto the magnetic disks 36 will be consolidated due to the magnetic force of
the magnetic
disks 36. Thereby, dehydration of the magnetic flocs F will be promoted to the
extent that
they will turn into sludge forms with moisture content of about 90%.
The magnetic flocs F with their dehydration being promoted are to be conveyed
by
the continuous rotation of the magnetic disks 36 up to where the gutter-shaped
scrapers 60 are
arranged, at which point they will be scraped off by the edge parts 60A of
both sides of
respective gutter-shaped scrapers 60 and drop into the gutter-shaped scrapers
60. The magnetic
flocs F being dropped inside the gutter-shaped scrapers 60 are to be conveyed
by the conveying
devices 62, which could be the screw conveyers 64 or the finned belt conveyers
66, to the upper
side of the floc retrieving tank 42 and drop into the floc retrieving tank 42.
Since the magnetic separation apparatus 20 according to the present invention
is
provided with the flow dividing members 46 arranged directly underneath the
plurality of
magnetic disks 36, it is possible to have the magnetic flocs F in the raw
water efficiently
adsorbed onto the magnetic disks 36.
Moreover, by arranging the sealing plates 48 between the respective magnetic
disks 36 and the separation tank 32, the raw water will not short-pass through
the peripheral
surfaces of those magnetic disks 36 that are not exerting magnetic force and
overflow into
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19a
the troughs 40. Thereby, it is possible to prevent water quality of the
treated water
overflowing into the troughs 40 from deteriorating.
Furthermore, among the plurality of magnetic disks 36 arranged on the rotation
axis
34, the inner magnetic disks 368 are structured as having the same structures
as the ones in
the conventional art, that is, each of them is structured as having permanent
magnet pieces 37
arranged on both sides of the disk substrate 33, whereas with respect to the
outmost magnetic
disks 36A, each of them is structured as having the permanent magnet pieces 37
for exerting
magnetic force arranged only on the inner side surface of the disk substrate
33 (i.e. the
surface on the side of the inner magnetic disk 36B). In addition to that, the
disk substrates 33
of the respective outmost magnetic disks 36A with the permanent magnet pieces
being
arranged are made to have more enhanced stiffness than the disk substrates 33
of the
respective inner magnetic disks 36B. In this case, by adopting honey comb
structures to the
magnetic disks 36, it will be possible to have lighter magnetic disks 36 while
securing
necessary stiffness.
In addition, the shielding members 54 are arranged to fill in the gaps between
respective outer surfaces of the outmost magnetic disks 36A and the inner
surface of the
separation tank 32. Thereby, it is possible to prevent magnetic leakage from
the outmost
magnetic disks 36A and to prevent the outmost magnetic disks 36A from being
deformed.
What is more, by this arrangement, the raw water will not pass through the
outer surfaces of
the respective outmost magnetic disks 36A to flow out into the troughs 40,
whereby the water
quality of the treated water will not be deteriorated.
Moreover, by adopting gutter-shaped scrapers 60 for the retrieving device 38,
it is
possible to reliably retrieve the magnetic flocs F adsorbed onto the magnetic
disks 36.
While the magnetic separation apparatus of the present invention have been
explained
in detail, the present invention is not limited to the above examples,
needless to say, various
improvements and modifications may be added without departing from the scope
of the present
invention.
