Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION
CENTRIFUGAL SEPARATOR
BACKGROUND OF THE INVENTION
The present invention relates to centrifugal separa-
tors, for example, for use in treating sludge sedimentedin rivers, lakes and marshes, soiled waters discharged
from iron mills and containing iron particles, coal,
etc., and muddy water or effluent resulting from civil
engineering work to separate the sludge, muddy water or
the like into water and semi- hydrated solids, or for
use in separating air containing a powder such as cement
into the powder and air.
Various apparatus such as filter presses and dehy-
drators incorporating a centrifugal drum are convention-
ally employed for these uses.
The conventional apparatus of any type use a filter,
which is liable to clog, therefore requires cleaning or
replacement in a short period of time and is cumbersome
to use.
Further when the filter is used, for example, the
water and the semihydrated solid matter as separated
from each other must be further treated individually so
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as not to become mixed again, whereas the semihydrated
solid matter, which is no longer fluid, is not easy to
treat.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a
centrifugal separator for separating a fluid containing
solid matter into a liquid or gas, and solids reliably
without necessitating a cumbersome procedure or
treatment.
The present invention provides a centrifugal
separator comprising a separating drum having an opening
at at least one end thereof and a vertical axis,
revolving means for revolving the separating drum around
a vertical line spaced apart by a predetermined distance
from the axis of the separating drum, rotating means for
rotating the separating drum about its own axis, and
feeder means for supplying the fluid to be treated for
separation to the separating drum.
When the fluid to be treated is supplied to the
separating drum of the separator of the invention, the
fluid is separated by the centrifugal force of
revolution into solid matter contained in the fluid and
a liquid or gas owing to a difference in specific
gravity therebetween, and the solid matter adheres to
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the inner surface of the separating drum, while the
liquid or gas forms a layer over the surface of the
solid matter and is discharged from the drum through the
opening thereof. In the meantime; the separating drum
rotates about its own axis, permitting the solid matter
adhering to the drum inner surface to face toward
different directions against the centrifugal force. The
solid matter is released from the drum inner surface
upon the centrifugal force overcoming the adhesion of
the solid matter.
According to the present invention, therefore, the
fluid containing solids can be reliably separated into
the solid matter and a liquid or gas without
necessitating a cumbersome procedure or treatment.
Preferably, the separating drum has a peripheral
wall formed with an aperture for passing therethrough
the fluid to be treated, the rotating means being
intermittently controllable so as to stop the separating
drum with the aperture facing inward, the feeder means
being intermittently controllable so as to supply the
fluid to be treated to the separating drum as stopped
with the aperture facing inward.
While the aperture is facing inward, the fluid is
efficiently separated into the solid matter and the
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liquid or gas. When the aperture is directed outward,
the solid matter is released from the drum inner surface
and centrifugally discharged through the aperture.
The feeder means may have a hollow supply member
disposed inwardly of the separating drum and revolvable
along with the separating drum, the supply member having
an outlet positionable as opposed to the inwardly facing
aperture.
The fluid to be delivered from the outlet for
treatment is forced outward by the centrifugal force of
revolution, and the fluid thus forced outward is led
into the separating drum without stagnation through the
aperture as directed inward. For example, if the feeder
means has a bent fluid supply channel, the fluid will be
inadvertently separated at the bent portion. It is then
likely that the solids separated off will adhere to the
channel wall to clog up the channel, whereas such
trouble is avoidable when the fluid is forced out
straight.
When the separating drum is provided inside thereof
with a plurality of baffle plates arranged one above
another, an elongated fluid channel can be provided
inside the separating drum.
The fluid channel can be further elongated to
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achieve an improved separation efficiency if the baffle
plates are each in the form of a horizontal plate and
are so arranged that each of the baffle plates partially
laps over another one of the baffle plates immediately
adjacent thereto when viewed axially of the separating
drum.
When the separating drum is provided with a
discharge opening at an upper end thereof and an outflow
preventing wall at a lower end thereof, the revolution
of the separating drum causes the fluid to flow upward
inside the drum.
The separating drum may be provided inside thereof
with a partition plate positioned at a higher level than
a fluid outlet of the feeder means so as to partially
occupy the cross section of the separating drum, so that
the fluid supplied to the separating drum by one cycle
of operation of the feeder means can be prevented by the
partition plate from flowing upward owing to the
centrifugal force of revolution of the fluid, with the
aperture facing inward. This assures reliable
separation of the fluid in the separating drum as held
out of rotation about its own axis, with the aperture
facing inward.
If the separating drum is temporarily held out of
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rotation about its own axis in the course of movement of
the aperture from the inwardly facing position to an
outwardly facing position, the fluid can be separated
more effectively before discharge through the aperture.
When the separating drum has its opening covered
with a filter, the water to be discharged from the drum
through its opening is filtered to ensure more effective
separation. The filter will not be clogged since the
solids acting to adhere to the filter are moved
centrifugally.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view partly broken away
along a vertical plane and showing a centrifugal
separator embodying the invention;
FIG. 2 is a view in vertical section of the same;
FIG. 3 is a perspective view of a separating drum of
the same;
FIG. 4 is a view in horizontal cross section of the
same;
FIG. 5 is a time chart showing the operation of the
separator;
FIGS. 6 (a) and 6 (b) are diagrams for illustrating
the operation of the separator;
FIG. 7 is a view in vertical section corresponding
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to FIG. 2 and showing a separating drum of a
modification of the separator;
FIG. 8 is a perspective view of the separating drum;
FIGS. 9 (a) to 9 (d) are diagrams for illustrating
the operation of the separating drum;
FIG. 10 is a time chart showing the operation of the
separating drum;
FIG. 11 is a view in vertical section corresponding
to FIG. 7 and showing a separating drum of another
modification of the separator;
FIG. 12 is a perspective view of the separating
drum;
FIGS. 13 (a) to 13 (d) are diagrams for illustrating
the operation of the separating drum;
FIG. 14 is a diagram for illustrating an operation
for preventing a filter of the drum from clogging;
FIG. 15 is an enlarged view in section of the
filter;
FIG. 16 is a sectional view corresponding to FIG. 11
and showing two filters as used in the separating drum;
and
FIG. 17 is a time chart showing the operation of the
separating drum.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
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Embodiments of the invention will be described below
with reference to the drawings.
Referring to FIG. 1 showing a centrifugal separator,
the separator comprises a hollow body lOl, a rotary
assembly 102 accommodated in the body 101 and four
separating drums 103 each in the form of a vertical
hollow cylinder and mounted on the rotary assembly 102.
The body 101 comprises a vertical tubular trunk wall
111 and a top wall 112 in the form of a flat plate and
covering an upper-end opening thereof.
The trunk wall 111 is provided with a trough 113
positioned inside thereof slightly above the midportion
of its height and a discharge pipe 114 in communication
with the trough 113. A support bar 145 in the form of a
horizontal strip extends across a lower-end opening of
the trunk wall 111 through the trunk wall axis and is
attached to the lower end of the trunk wall 111. A
lower main bearing 144 is mounted on the upper side of
the support bar 145 centrally thereof and coaxially with
the trunk wall.
A main motor 171 facing vertically upward is mounted
on the trunk wall outside thereof close to its upper
end. A main drive sprocket 172 is fixed to the output
shaft of the main motor 171.
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The top wall 112 is formed in its central portion
with a shaft hole 115 having an upper main bearing 116
fitted therein.
The rotary assembly 101 comprises a rotary shaft 121
inserted through the bearing 116, a top wall 122 secured
directly to the lower end of the shaft 121, and a bottom
wall 123 disposed below the top wall 122 at a distance
therefrom and connected to the top wall 122 by the
separating drums 103. A skirt 124 extending into the
trough 113 is integral with the outer periphery of the
top wall 122.
The rotary shaft 121 comprises an upper solid shaft
portion 131 having a small diameter and a lower hollow
shaft portion 132 having a large diameter. The solid
shaft portion 131 projects upward beyond the upper main
bearing 116 and has a main driven sprocket 173 fixed to
the projection. The sprocket 173 is coupled to the main
drive sprocket 172 by a belt 174. The hollow shaft
portion 132 is supported by the bearing 116.
Housed in the hollow shaft portion 132 is a
secondary motor 181 fixed to the top wall 122 of the
rotary assembly. The rotary shaft of the motor 181
extends through the top wall 122 to project downward
and is supported by a secondary bearing 143. A
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secondary drive sprocket 182 is fixed to the rotary
shaft of the secondary motor 181.
A distribution chamber 141 is fixedly provided on
the upper side of the bottom wall 123 centrally thereof.
The secondary bearing 143 is attached to the upper side
of top wall of the chamber 141 with a support member 142
interposed therebetween. The bottom plate 123 is
supported at the center of its lower side by the lower
main bearing 144.
A bottom wall of the distribution chamber 141 and
the bottom wall of the rotary assembly 101 are formed
respectively with upper and lower pipe holes 151, 152 in
register, and a feed pipe 153 for the water to be
treated is inserted through these holes. The bottom
wall inner periphery defining the upper pipe hole 151 is
provided with a vertical sleeve 154. The feed pipe 153
is provided at its upper end with a seal ring 155
inverted L-shaped in cross section and covering the
sleeve 154. The chamber 141 has a peripheral wall
formed with four supply pipes 156 arranged radially at
equal spacings. The four supply pipes 156 extend toward
the axes of the respective four separating drums 103 and
each have an outlet 157 at the outer end.
As shown in greater detail in FIG. 2, the separating
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drum 103 comprises an upwardly flaring portion 161 and
a lower straight portion 162. The flaring portion 161
is supported by a bearing 163 on the rotary assembly top
wall 122, and the straight portion 162 by a bearing 164
on the rotary assembly bottom wall 123. The straight
portion 132 is formed with a vertically elongated
aperture 165 for passing therethrough the fluid to be
treated. When facing inward, the aperture 165 is
opposed to the outlet 157 of the supply pipe 156.
The straight portion 162 has a plurality of baffle
plates 166 arranged one above another. As shown in
greater detail in FIG. 3, the baffle plates 166 are each
in the form of a horizontal semicircle. Each baffle
plate 166 overlaps another adjacent plate 166
;mm~; ately therebelow by a 2/3 portion of the entire
area.
A secondary driven sprocket 183 is secured to the
lower end of the flaring portion 161 on the outer side
thereof. As seen in FIG. 4, a chain 184 is reeved
around the secondary drive sprocket 182 and the
secondary driven sprocket 183.
When the main motor 171 is operated, the rotary
assembly 101 rotates about its shaft 121, revolving the
separating drums 103 around the axis of the shaft 121.
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On the other hand, the secondary motor 181, when
operated, moves the chain 184, whereby the four
separating drums 103 are rotated at the same time each
about its own axis.
The speed of revolution of the separating drums 103
is suitably determined according to the properties of
the water to be separated. The drums 103 are revolved,
for example, at a peripheral speed of 500 to 1000 m/min.
When the radius of gyration of the revolution is about
10 400 mm, the speed of revolution is 600 rpm.
As shown in FIG. 5, the separating drums 103 are
revolved continuously. In the meantime, a pump is
operated intermittently to supply the water to be
separated intermittently, for example, in such manner
that the water is supplied for 1 minute, followed by a
cessation of supply for 1 minute. During the supply of
water, the separating drums 103 are stopped from
rotating about their axes, with the apertures 165 facing
inward with respect to the radius of gyration of the
revolution. During the cessation of supply of the
water, the separating drums 103 are rotated once about
their axes, whereby the apertures 165 facing inward are
turned outward and thereafter directed inward again.
The separating drums 103 may be initiated into rotation
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about their axes simultaneously with the discontinuation
of supply of the water or upon lapse of a predetermined
period of time thereafter. The separating drums 103 may
be rotated about their axes continuously through 360
degrees, or may be rotated through 180 degrees, then
stopped for a predetermined period of time and
thereafter rotated in the opposite direction through 180
degrees.
When the water B to be treated is supplied to the
distribution chamber 141 through the feed pipe 153 with
the aperture 165 of each separating drum 103 opposed to
the outlet 157 of the corresponding supply pipe 156 as
seen in FIG. 6 (a), the water B supplied is
centrifugally forced toward the peripheral wall of the
chamber 141 by virtue of rotation of the rotary assembly
102 and discharged through the pipe 156 from the outlet
157 thereof. The water B discharged from the outlet 157
is further centrifugally accelerated, forced outward
straight and flows into the separating drum 103 through
the aperture 165. Being forced outward straight, the
water B is unlikely to spill through a small clearance
which may be formed between the edge of the drum 103
defining the aperture 165 and the edge of outlet 157 of
the supply pipe 156.
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When a predetermined period of time elapses after
the water B has been introduced into the separating drum
103, the water B is separated into solid matter D and
water W, and the water W is discharged from the upper-
end opening of the drum 103. When the drum 103 isrotated through 180 degrees as shown in FIG. 6 (b), the
solid matter D separated off is discharged from the drum
103 through the aperture 165.
A modification of the centrifugal separator will be
further described with reference to FIGS. 7 to 10. The
modification basically has the same construction as the
centrifugal separator shown in FIGS. 1 to 6.
FIGS. 7 and 8 show a separating drum 103 having a
plurality of partition plates 201 arranged one above
another inside the drum. The partition plates 201 have
the same shape as the baffle plates 166 and are each in
the form of a horizontal semicircle. All the partition
plates 201 are arranged wholly in register. When an
aperture 165 for passing therethrough the water to be
treated is positioned as directed inward and when the
drum 103 is seen in cross section, the partition plate
201 occupies the semicircular portion of the drum 103
opposite to the aperture 165, and the straight end of
the partition plate 201 opposed to the aperture 165 is
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orthogonal to the aperture 165.
The operation of the separator will be described
next with reference to FIGS. 9 and 10.
As shown in FIG. 9 (a), the water B to be treated is
supplied to the separating drum 103 as held out of
rotation about its own axis, with the aperture 165
facing inward. The water B is supplied approximately at
the level of the lowermost partition plate 201. The
water B supplied is caused to flow upward over the
lowermost partition plate 201 toward another plate 201
thereabove within the drum 103 by the centrifugal force
of revolution of the drum, thus passing over the
partition plates 201 one after another. However, the
amount of the water B to be supplied during one cycle of
operation is so determined that the water will not pass
over the uppermost partition plate 201 (see FIG. 7).
Thus, the quantity of water supplied by one cycle of
operation is collected below the uppermost partition
plate 201.
The water B collected below the uppermost partition
plate 201 is completely separated into solid matter D
and water W while the separating drum 103 is held at
rest before the start of rotation about its own axis as
seen in FIG. 7.
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16
With the start of rotation of the drum 103, the
partition plates 201 are also rotated with the drum 103.
When the straight ends of partition plates 201 become
submerged in the separated water W at an angle with
respect to the inward or outward direction as indicated
in a phantom line in FIG. 9 (b), the separated water W
starts to flow upward at a point P indicated by a solid
spot mark in the drawing, passing over the partition
plates 201 one after another, and is discharged from the
upper end of the drum 103.
The drum 103 is rotated through 90 degrees as shown
in FIG. 9 (c) and then temporarily held out of rotation.
Although the rotation takes a relatively short period of
time, the solid matter D and the water W separated from
each other differ in adhesion or fluidity and therefore
behave differently. The water W separated off moves
with the rotation of the drum 103 owing to the
centrifugal force acting thereon, shifting every moment,
and is discharged from the drum 103, whereas the solid
matter D tends to remain in position, and therefore
remains inside the drum 103, adhering to the inner
surface of the drum 103.
With the separating drum 103 held out of rotation
after rotating through 90 degrees, the solid matter D is
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subjected to the centrifugal force, whereby the solid
matter D is further separated, and the water W separated
off is discharged from the upper end of the drum 103.
Upon lapse of a predetermined period of time after
the drum 103 has been rotated through 90 degrees, the
drum 103 resumes rotation about its own axis. When the
drum 103 is rotated further through 90 degrees through
the resumed rotation as shown in FIG. 9 (d), the
aperture 165 faces outward, and the solid matter D
centrifugally acted on is discharged through the
aperture 165 thus facing outward.
The rotation of the separating drum 103 may be
discontinued when the aperture 165 is brought to the
outwardly facing position, but the drum need not be so
stopped since the solid matter D is discharged rapidly.
When the drum 103 is continuously further rotated about
its own axis, moving the aperture 165 from the outwardly
facing position to the inwardly facing position through
180 degrees, the drum 103 finishes one cycle of
operation. The separating drum 103 may be rotated
reversely every time it has been rotated through 180
degrees instead of being rotated through 360 degrees
every cycle.
The present embodiment is so adapted that the water
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18
to be treated in the drum is separated as it is wholly
collected therein and held at rest. In this respect,
the embodiment distinctly differs from the first
embodiment. With the first embodiment, the water
supplied to the separating drum is subjected to a
separating treatment while allowing the water separated
off to gradually flow out from the drum upper end at the
same time. When the water to be treated is thus moved
while being centrifugally acted on, solids are likely to
be entrained in the moving water to result in a lower
separation efficiency. Further if an increased
centrifugal force is used to increase the separation
capacity, the water separated off is more likely to
entrain solids therein, such that an increased
centrifugal force fails to improve the separation
capacity greatly as expected. Since the water to be
treated is held at rest within the separating drum
during separation according to the present embodiment,
an increased separation capacity is expectable.
Another modification of the centrifugal separator
will be described with reference to FIGS. 11 to 17.
Referring to FIG. 11, a filter 211 is used in place
of the partition plates 201 provided inside the
separating drum 103 of FIG. 7. The filter 211 is
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19
positioned immediately above an aperture 165 for passing
the fluid to be treated, and is in the form of a
horizontal disk covering the entire upper-end opening of
a separating drum 103.
As shown in FIG. 12, the filter is made of a so-
called wedge wire and has parallel passageways 221.
With the aperture 165 facing toward the center of
revolution, the lengthwise direction of the passageways
221 is positioned radially of the path of revolution.
As shown in greater detail in FIG. 15, the passageways
221 are wedge-shaped in cross section and are about 30
micrometers in minimum width C at the lower ends
thereof.
When the water to be treated is supplied to the
separating drum 103 through the outlet 157 of the supply
pipe 156 with the aperture 165 facing inward while the
drum 103 is being revolved tFIG. 13 (a)], the water
supplied is collected under the filter 211. The water
collected under the filter 211 is then separated into
water and solid matter by the centrifugal force of the
revolution, and the water separated off passes through
the filter 211 and is discharged from the drum 103
through its upper-end opening [FIG. 13 (b)]. On the
other hand, the solid matter remains collected under the
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filter 211 without passing therethrough [FIG. 13 (c)].
After the water separated off has been discharged from
the drum 103, the drum 103 is rotated about its own
axis, whereby the aperture 165 is brought from the
inwardly facing position to an outwardly facing
position. Whereas the separating drum 103 is halted
during rotation about its own axis in the case of the
embodiment shown in FIGS. 7 to 10, the drum 103 of the
present embodiment need not be so stopped. When the
aperture 165 is brought to the outwardly facing
position, the solid matter is released from the drum
inner surface by the centrifugal force of the revolution
and delivered from the separating drum 103 through the
aperture 165 [FIG. 13 (d)]. The water to be treated is
thereafter supplied to the drum 103 when the aperture
165 is brought to the inwardly facing position again.
FIG. 17 is a time chart showing the separating operation
described above.
Initially when the separating operation is started,
solids adhere to the entire area of the portion of the
filter 211 in contact with the water to be treated and
also to the portion of the filter 211 serving to pass
the separated water therethrough as shown in detail in
FIG. 14, whereas the adhering solids are forced
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outwardly of the water passing portion and unlikely to
close the water passing portion, with the result that
the water separated off smoothly flows through this
portion.
FIG. 16 shows a modification wherein two filers are
used as positioned one above the other. The openings or
passageways of the two filters 231, 232 are so
determined that the lower filter 231 serves for rough
filtration, and the upper filter 232 for finishing
filtration.
Instead of providing two filters in one separating
drum, two centrifugal separators may alternatively used.
In this case, a filter for rough filtration may be used
in each separating drum of the upstream separator, with
a filter for finishing filtration used in the downstream
separator.
To be effective, the filter is about 5 to about 50
micrometer in opening size. Besides the wedge wire
mentioned above, metal netting, fabric, nylon fiber,
ceramics, etc. are useful for making the filter.
The present modification may also have baffle plates
or partition plates used in the foregoing modification.
While liquid separating operations have been
described above, the basic principle of the present
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invention is applicable also to the separation of gases.
In this case, some alternations will be necessary in the
design of the centrifugal separator described in
accordance with the differences between the liquid and
the gas in properties. Such alterations include, for
example, gas transport means, seal means for the gas,
etc.
