Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION:
centrifugal filtration apparatus
NAMES) OF INVENTOR(S):
Gerhard Schmidt
FIELD OF THE INVENTION
The present invention relates to a centrifugal filtration
apparatus
BACKGROUND OF THE INVENTION
Published Canadian Patent Application 2,034,918 discloses
a centrifugal filtration apparatus. The apparatus has a drum
with a plurality of perforations . Removably mounted on the
inside of the drum is a filter. In order to effect filtration,
the drum is rotated at high speed. A liquid mixture is pumped
through spray inlets into the drum. The liquids are forced
outwardly by centrifugal force. Light liquids pass through the
filter and through the perforations to the exterior of the
drum. Heavier liquids and solids are unable to pass through
the filter and, therefore, migrate along the filter until they
reach an outlet.
The centrifugal filtration apparatus, as described above,
will not operate properly if the filter becomes clogged. The
light liquids, unable to penetrate the filter will migrate
along the filter with the heavier liquids and solids until they
reach the outlet. It is, therefore, essential that the filter
be frequently inspected and, when required, changed. The
changing of the filter on a centrifugal filtration apparatus
is currently taking approximately eight hours.
SUMMARY OF THE INVENTION
What is required is an centrifugal filtration apparatus
for which the filter may be more rapidly changed.
According to the present invention there is provided a
centrifugal filtration apparatus which includes a containment
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chamber having a top closure. A perforated barrel is mounted
for high speed rotation within the containment chamber. The
barrel has sidewalls defining an interior cavity. Means are
provided for mounting a filter to the sidewalk within the
interior cavity of the barrel. Means are provided for
accessing the interior cavity of the barrel for the purpose of
changing the filter. At least one inlet is provided for
passage of liquids into the barrel. A first outlet is provided
for passage of liquids that cannot pass through the filter and
separated solids from the barrel. A second outlet is provided
for passage of liquids that have passed through the perforated
barrel from the containment chamber. Means is provided for
raising the top closure of the containment chamber, thereby
providing access to the barrel for the purpose of changing the
filter.
With the centrifugal filtration apparatus, as described
above, the top closure of the containment chamber can be raised
to provide access to the barrel for the purpose of changing the
filter. This dramatically reduces the time necessary to change
the filter. A changeover that previously took eight hours is
now taking less than one hour.
Although beneficial results may be obtained through the
use of the centrifugal filtration apparatus, as described
above, access to the filter is further improved when the barrel
has a top portion and a bottom portion that are detachably
secured together. This enables the barrel to be taken apart
to provide access to the filter.
Although beneficial results may be obtained through the
use of the centrifugal filtration apparatus, as described
above, even more beneficial results may be obtained when the
containment chamber has an access door. This enables better
access to the barrel for the purpose of detaching the top
portion of the barrel from the bottom portion.
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Although beneficial results may be obtained through the
use of the centrifugal filtration apparatus, as described
above, even more beneficial results may be obtained when the
top portion of the barrel is rotatably mounted to the top
closure and the bottom portion is rotatably mounted to a bottom
of the containment chamber. A first half of a filter is placed
in the top portion. A second half of the filter is placed in
the bottom portion. When the top closure is lifted, the top
portion of the barrel is raised thereby providing ready access
to the filter.
Although beneficial results may be obtained through the
use of the centrifugal filtration apparatus, as described
above, even a slight weight imbalance can adversely affect the
high speed rotation of the barrel. It is, therefore, preferred
that the top portion and the bottom portion are substantially
symmetrical. It is also preferred that at least one
circumferential liquid filled balancing tube is secured around
an exterior surface of the barrel.
There are various ways of detachably fastening the top
portion and the bottom portion of the barrel. One way is to
provide both the top portion and the bottom portion with
attachment flanges. These attachment flanges can be secured
together with fasteners, such as bolts.
There are various ways of lifting top closure. One way
is to provide telescopically extendible actuators, such as
hydraulic cylinders.
Although beneficial results may be obtained through the
use of the centrifugal filtration apparatus, as described
above, even more beneficial results may be obtained when the
movement of the actuators is guided by guides that guide the
movement of the top closure.
Although beneficial results may be obtained through the
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use of the centrifugal filtration apparatus, as described
above, the surface of the filter must be kept clear of solids
build up if it is to function as intended. Even more
beneficial results may, therefore, be obtained when scraper
blades are disposed within the interior cavity of the barrel.
The scraper blades are spaced closely to the sidewalls of the
barrel to prevent solids build up on the surface of the filter.
Although beneficial results may be obtained through the
use of the centrifugal filtration apparatus, as described
above, filter wear is presently only detectable by analysis of
changes in the output streams. Even more beneficial results
may, therefore, be obtained when a camera is mounted within the
barrel to monitor the condition of the filter.
Although beneficial results may be obtained through the
use of the centrifugal filtration apparatus, as described
above, in the prior art the liquid mixture was fed into the
barrel from above by a gravity feed. This works well for high
rpm applications, but is not suited for low rpm applications.
An example of a low rpm application is a liquid mixture with
a high solids content. At high rpm the filter cannot withstand
a bombardment of solid particles from a liquid mixture with a
high solids content. To preserve the filter the rpm must be
reduced. However, when the rpm is reduced the gravity feed is
no longer effective as a portion of the input will fall by
force of gravity directly from the inlet to the outlet without
the desired filtration occurring. Even more beneficial results
may, therefore, be obtained when a central column is provided
within the barrel having at least one inlet. Fluids can then
be pumped up the central column through the inlet for low rpm
applications. It is preferred that at least one pair of
opposed inlets positioned on the central column.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become more
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apparent from the following description in which reference is
made to the appended drawings, wherein:
FIGURE 1 is a side elevation view, in section of a
centrifugal filtration apparatus constructed in accordance with
5 the teachings of the present invention.
FIGURE 2 is a side elevation view, in section, of a
containment chamber of the centrifugal filtration apparatus
illustrated in FIGURE 1, with a top closure in a raised
position.
FIGURE 3 is a detailed side elevation view, in section,
of an actuator and a guide for raising the top closure as
illustrated in FIGURE 2.
FIGURE 4 is a detailed top plan view, in section, of
containment walls for the centrifugal filtration apparatus
illustrated in FIGURE 1.
FIGURE 5 is a side elevation view of containment walls for
the centrifugal filtration apparatus illustrated in FIGURE 4.
FIGURE 6 is a side elevation view, in section, of a barrel
of the centrifugal filtration apparatus illustrated in FIGURE
1.
FIGURE 7 is a detailed side elevation view, in section,
of a liquid balancing tube and attachment flange for the barrel
of the centrifugal filtration apparatus illustrated in FIGURE
6.
FIGURE 8 is a detailed side elevation view, in section,
of a gravity fed upper fluid inlet.
FIGURE 9 is a side elevation view, in section, of a
central column with a pump fed lower fluid inlet.
FIGURE 10 is a top plan view, in section, of the lower
fluid inlet in FIGURE 9.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment, a centrifugal filtration
apparatus generally identified by reference numeral 10, will
now be described with reference to FIGURES 1 through 10.
Referring to FIGURES 1 and 6, centrifugal filtration
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apparatus 10 includes a containment chamber 12 having a top
closure 14, peripheral containment walls 16 and a bottom 18.
A perforated barrel 20 is mounted for high speed rotation
within the containment chamber 12. Barrel 20 has sidewalls 22
defining an interior cavity 24. Barrel 20 has a top portion
26 and a bottom portion 28 that are detachably secured
together. Top portion 26 of barrel 20 is rotatably mounted to
top closure 14 of containment chamber 12 and bottom portion 28
of barrel 20 is rotatably mounted to bottom 18 of containment
chamber 12. The top portion 26 and the bottom portion 28 are
substantially symmetrical. Referring to FIGURE 7, top portion
26 and bottom portion 28 of barrel 20 both have attachment
flanges 30, 32 that are secured together with fasteners 34.
A circumferential liquid filled balancing tube 36 is secured
around an exterior surf ace 3 8 of the barrel 2 0 . A barrel shaped
filter 40 is provided that has a first half 40a and a second
half 40b. Hook Tape fastening strips 42 sold under the Trade
Mark VELCRO are glued to sidewalls 22 within interior cavity
24 of both top portion 26 and bottom portion 28 of barrel 20.
Filter 40 mates with hook tape fastener strips 42 to secure
filter 40 to barrel. First half 40a is secured to top portion
26 and second half 40b is secured to bottom portion 28. In
addition, both first half 40a and second half 40b have a flange
41. Flanges 41 are clamped between attachment flanges 30 and
32 of top portion 26 and bottom portion 28 when barrel 20 is
secured together. Referring again to FIGURES 1 and 6, an inlet
44 comprising an inlet chamber 46 and inlet pipe 48 is provided
for passage of liquids into barrel 20. A first outlet 50 is
provided for passage of heavy liquids and separated solids from
barrel 20. A second outlet 52 is provided for passage of light
liquids that have passed through perforated barrel 20, from
containment chamber 12 into a containment vessel 53. Referring
to FIGURES 4 and 5, containment chamber 12 has an access door
68 detachably secured to and matching the cylindrical shape of
sidewalls 14, thereby providing access to barrel 20 for the
purpose of detaching top portion 26 of barrel 20 from bottom
portion 28. Referring to FIGURES 1 through 3, a plurality of
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telescopically extendible actuators 54 are provided for raising
top closure 14 of containment chamber 12, thereby providing
access to barrel 20 for the purpose of changing filter 40. A
plurality of guides 56 are provided to guide the movement of
top closure 14. Referring again to FIGURES 1 and 6, a
plurality of side scraper blades 60 and a plurality of bottom
scraper blades 62 are disposed within interior cavity 24 of
barrel 20. Side scraper blades 60 and bottom scraper blades
62 are mounted rigidly to a lower shaft assembly 64 by means
of a plurality of brackets 66. Side scraper blades 60 are
spaced closely to sidewalls 22 of barrel 20. Bottom scraper
blades 62 are spaced closely to sloped bottom 29 of barrel 20.
Referring to FIGURE 2, A camera 39 is mounted within barrel 20
to monitor the condition of filter 40. Camera is mounted on
a swivel and can remotely controlled to pivot upon the swivel
as may be required to permit inspection of different areas of
the filter. Referring again to FIGURE 1, the ancillary and
support equipment for centrifugal filtration apparatus 10, an
hydraulic fluid supply unit 69 and an hydraulic drive 70. An
upper shaft assembly 71 and a lower shaft assembly 64 is
provided for rotation of barrel 20. A discharge pump 74 is
provided for removing accumulated liquids from containment
vessel 53. A solids discharge auger 76 is provided for
carrying discharged solids and non-filtered liquids. A
supporting structure 78 is provided for mounting and
transporting the components that comprise with apparatus 10.
At each location where components of the said assembly are
joined together, and at each location at which a component part
of said assembly rotates relative to another component part,
a connector and seal (not shown) are provided. A set of stairs
80 and a railing 82 are provided to allow an operator to access
a control box 84 and a tool box 86 mounted on supporting
structure 78. There are two inlets provided into barrel 20,
depending upon the nature of the application. For high rpm
applications it is preferred that fluids be gravity fed from
above into barrel 20. Referring to FIGURE 8, a deflector or
spreader 49 is provided to direct fluid entering barrel 20
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along a path parallel to filter 40. Once the fluid is moving
parallel to filter 40, the fluid is forced against the filter
by centrifugal force. For low rpm applications, gravity
feeding fluids from above is not workable, as the fluids fall
parallel to filter 40, but the centrifugal force is not
sufficient to force the fluid against filter 40. The result
is that a portion of the fluids fall directly to outlet 50
without engaging filter 40. For low rpm applications an
alternative feed mechanism is required. Referring to FIGURE
9, a tubular central support column 90 is provided in barrel
20. Support column 90 provides a flow channel 92 for the flow
of fluids pumped from below. Flow channel has at least one
pair of opposed outlets 94. Referring to FIGURE 10, outlets
94 are in the form of arms that extend radially outwardly
terminating in a plurality of spray jets 96. Spray jets 96 are
positioned in close proximity, within approximately 2 1/2
inches, of filter 40. Referring to FIGURE 9, scrapers 98 are
mounted to the radial arms that serve as outlets 94, so that
spray jets 96 are positioned behind scrapers 98.
The use and operation of apparatus 10 will now be
described with reference to FIGURES 1 through 10. Referring
to FIGURE l, centrifugal separation is performed by apparatus
10. Mixed liquids pass through inlet pipe 44 into inlet
chamber 46. From inlet chamber 46 mixed liquids pass along
inlet feed pipe 48 and are gravity fed into barrel 20.
Referring to FIGURE 8, deflector or spreader 49 directs liquids
entering barrel 20 along a path parallel to filter 40, these
liquids are forced outwardly against filter 40 by the
centrifugal force generated by barrel 20 which is rotated at
high rpm by hydraulic drive 70. Light liquids pass through
filter 40 and the perforations in barrel 20 into containment
chamber 12. From containment chamber 12 they drain through
second outlet 52 into containment vessel 53. Heavier liquids
or solids that will not pass through filter 40 migrate along
filter 40 until they reach first outlet 50 leading to discharge
auger 76. The effectiveness of the filtration process is
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dependent upon the condition of filter 40. The condition of
filter 40 is, therefore, monitored by camera 39. When filter
40 visually appears to be becoming clogged, water is circulated
through inlet 44 into barrel 20 to wash filter 40. After
washing, filter 40 is further inspected by camera 39. If
filter 40 is in good condition, the process of centrifugal
separation is continued. If filter 40 is seen to be showing
visual signs of wear, the process of centrifugal separation is
discontinued and steps are taken to replace filter 40.
Referring to FIGURES 4 and 5, maintenance personnel gain access
to containment chamber 12 through access door 68. Referring
to FIGURE 7, once within containment chamber 12 maintenance
personnel remove fasteners 34 that extend through attachment
flanges 30 and 32 to secure top portion 26 and bottom portion
28 of barrel 20 together. Referring to FIGURE 2, once
fasteners 34 are removed hydraulic fluid can be provided to
telescopically extend actuators 54 by hydraulic fluid supply
unit 69, thereby raising top closure 14 off of containment
chamber 12. The movement of top closure 14 is guided and made
more stable by guides 56. This provides ready access to change
filter 40. Filter 40 comes into two halves with first half 40a
secured to top portion 26 and second half 40b secured to bottom
portion 28. The means of securement is with tape fastener
strips 42, from which filter 40 can be readily detached. Once
filter 40 has been replaced, top closure 14 is lowered back
onto containment chamber 12. Maintenance personnel then secure
top portion 26 and bottom portion 28 of barrel 20 together by
inserting fasteners 34 through flanges 30 and 32, respectively.
Access door 68 is then locked into position in preparation for
the resumption of centrifugal filtration.
In low rpm applications, a gravity fed entry of liquids
through inlet 44 will not work properly. A portion of the
liquids fall parallel to filter 40, as the centrifugal force
generated by the rotation of barrel 20 is not sufficient to
force the liquids against filter 40. In order to avoid a
portion of the fluids falling directly to outlet 50 without
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engaging filter 40, for low rpm applications the alternative
feed mechanism illustrated in FIGURES 9 and 10 is used.
Referring to FIGURE 9, liquids are pumped from below up flow
channel 92 of central support column 90. The liquids are then
5 sprayed under pressure through the spray jets 96 on the
radially extending arms that serve as outlets 94.
It will be apparent to one skilled in the art that
modifications may be made to the illustrated embodiment without
10 departing from the spirit and scope of the invention as
hereinafter defined in the Claims.
