Note: Descriptions are shown in the official language in which they were submitted.
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FLUIDIZED BED APPARATUS AND METHOD FOR REMOVING SOLUBLE AND
PARTICULATE MATTER FROM A LIQUID
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] None.
BACKGROUND OF THE INVENTION
[0002] In the treatment of water, it is known in the industry to use conical
sludge blanket
clarifiers (CSBC) for clarification and cold lime softening applications.
CSBCs
incorporate a cylindrical inlet flow device located at the bottom of an
inverted conical
vessel. Liquid enters the cylindrical inlet flow device at multiple tangential
inlet ports
which creates an upward helical liquid flow pattern. In its typical operation,
a CSBC
contains a sludge blanket of suspended solids within the inverted conical
vessel.
[0003] It is also known in the industry to use fluidized bed biological
reactors (FBBR)
containing sand media to treat wastewater. FBBRs containing sand media having
a high
specific surface area per unit volume of media (M2/M3) which provides for high
biomass
concentrations, hence high biological loadings. FBBRs have influent
distribution
systems which must achieve uniform distribution of influent liquid flow across
the entire
reactor area, prevent plugging and media escape, minimize abrasive wear, and
minimize
shearing of biomass above the influent distribution manifold. Typical influent
distribution systems include a header manifold, lateral pipes branching from
the header
manifold, and nozzles attached to the lateral pipes pointing down towards the
bottom of
the reactor. The liquid flow pattern within FBBRs is primarily vertical from
the influent
distribution systems to the overflow collectors.
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[0004] It is also known in the industry to use fluidized bed chemical reactors
(FBCR) to
remove calcium compounds, such as calcium carbonate, from low magnesium raw
waters.. FBCRs typically have inverted conical configurations with very steep
sidewalls.
The fluidized bed media used in FBCRs often consists of fine sand. FBCRs have
tangential inlet ports which creates an upward helical liquid flow pattern.
[0005] CSBCs do not provide an ion exchange process, which can further purify
and
decontaminate liquids. With fluidized bed reactors, any suspended solids
contained in
the inlet liquid and any suspended solids generated within the reactor will be
contained in
the outlet liquid. Typically, the suspended solids must be removed in a
separate process
that follows the fluidized bed reactor. In fluidized bed reactors utilizing
ion exchange,
high concentrations of non-target ions will often be discharged in the outlet
liquid as the
fluidized bed becomes saturated with the target ions.
[0006] Accordingly, a need exists for an apparatus and method that can remove
suspended solids as well as effecting a fluidized bed media. A need also
exists for a
fluidized bed reactor that allows for the reduction of non-target ion
concentration spikes.
A further need exists for a fluidized bed reactor that has enhanced reaction
kinetics,
which leads to shorter detention times, smaller vessels, and lower costs.
SUMMARY OF THE INVENTION
[0007] The present invention is directed to a fluidized bed apparatus that
provides
removal of various contaminants using fluidized bed media in addition to the
removal of
suspended solids. In accordance with one embodiment of the invention, a
fluidized bed
reactor includes a lower section effecting a rotational flow component, a
generally
conical middle section, an upper section containing fluidized bed media, and
optionally a
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means for removing particular matter. A tangential inlet port preferably
feeds, liquid into
the lower section to assist in developing an upward helical liquid flow
pattern in the
middle section. The Fluidized bed media may be used to perform an ion exchange
process or a variety of other processes for removing contaminants.
[0008] The present invention is also directed to a method of removing soluble
and
particulate matter from a liquid including the steps of introducing a liquid
into a first
vessel in a manner creating an upward helical flow of the liquid, discharging
the liquid
from the first vessel in a generally conical second vessel that overlies the
first vessel
therefore causing a decrease in the vertical velocity component of the
generally helical
flow as the liquid moves up through the second vessel, and passing the liquid
generally
upward through a fluidized bed media that is located above the second vessel
and
formulated to remove selected contaminants from the liquid.
DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0009] In the accompanying drawings:
[0010] Fig. 1 is a cross-sectional elevational view of the fluid bed apparatus
containing a
vertical velocity component means for removing particulate matter and a flow
collection
system in accordance with one embodiment of the present invention;
[0011] Fig. 2 is a cross-sectional elevational view of the fluid bed apparatus
containing a
flow collection system in accordance with one embodiment of the present
invention;
[0012] Fig. 3 is a cross-sectional elevational view of the fluid bed apparatus
containing a
means for removing particulate matter utilizing a gravity sedimentation device
and a flow
collection system in accordance with one embodiment of the present invention;
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[0013] Fig. 4 is a cross-sectional elevational view of the fluid bed apparatus
containing a
means for removing particulate matter utilizing a buoyant granular media
filter and a
flow collection system in accordance with one embodiment of the present
invention; and
[0014] Fig. 5 is a cross-sectional elevational view of the fluid bed apparatus
containing a
means for removing particulate matter utilizing a submerged membrane
filtration device
in accordance with one embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] The present invention is directed toward a fluidized bed reactor 10 and
method for
removing soluble and particulate matter from a liquid. As shown in. Fig. 1, a
fluidized
bed reactor 10 constructed according to one embodiment of the invention
includes a
lower section 12, a middle section 14, and an upper section 16.
[0016] The lower section 12 includes a wall 18, an upper end 20, and a lower
end 22. In
one embodiment, the lower section wall 18 is generally cylindrical. However,
it will be
appreciated by those skilled in the art that the lower section wall 18 can
alternatively be
constructed in other geometries, including a generally conical configuration.
Tangential
inlet ports 24, 26 allow untreated liquid to be fed into the lower section 12.
As illustrated
in Figs. 1-5, one inlet port 24 may be larger than another inlet port 26.
However, it will
be appreciated by those skilled in the art that the inlet ports 24, 26 may
also be the same
size. While two tangential inlet ports 24, 26 are shown in Figs. 1-5, the
present invention
could include a single inlet port 24 or more than two inlet ports 24, 26.
[0017] The inlet ports 24, 26 are positioned tangential to the inner surface
of the lower
section wall 18. A tangential positioning of the inlet ports 24, 26 in the
lower section 12,
along with the removal of liquid from the upper section 16, serves to develop
an upward
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helical flow of the liquid in the lower section 12 and the middle section 14.
The helical
flow may also continue into the upper section 16. The helical flow results in
the liquid
traveling in an elongated flow path.
[0018] Flow directing vanes 28 may be provided to be in communication with the
inlet
ports 24, 26. The flow directing vanes 28 can be adjusted to vary the inlet
velocity of
liquid into the lower section 12. As illustrated in Figs. 2-5, the lower
section 12 may also
include an inlet service nozzle 30. The inlet service nozzle 30, which is
capable of
producing a high velocity liquid flow, can be used to assist the inlet ports
24, 26 in re-
suspending the fluidized bed media 48 should the fluidized bed media 48 settle
into the
lower section 12. Also, as illustrated in Figs. 2-5, the lower section 12 may
include an
outlet port 32 proximate its lower end 22 that can be used to remove heavy
grit.
[0019] The middle section 14 includes a wall 34, an upper end 36, and a lower
end 38.
In one embodiment, the middle section wall 34 is generally conical and extends
upwardly
and outwardly from the lower section upper end 20 to the upper section lower
end 46.
The primary function of the middle section 14 is to reduce the vertical
velocity vector of
the upward helical liquid flow. As the liquid rises in its upward helical path
through the
generally conical middle section 14, it spreads to fill the increasing cross-
sectional area of
the middle section 14. This results in a corresponding decrease in the
vertical velocity
vector of the liquid traveling through the middle section 14, while the net
flow rate of the
liquid through the middle section 14, as well as the net flow rate of the
liquid through the
entire reactor 10, remains constant.
[0020] The vertical velocity of the liquid continues to decrease until it
reaches a portion
of the reactor 10 having a constant cross-sectional area. Proximate the upper
section
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lower end 46, the vertical velocity of the liquid is generally equal to the
velocity required
to keep the fluidized bed media 48 in section 16 suspended. In other words,
the lifting
force of the liquid and the counteracting gravitational force on the fluidized
bed media 48
are in equilibrium. The vertical velocity that is required to keep the
fluidized bed media
48 suspended is a function of multiple factors, including the density, shape,
and size of
the fluidized bed media 48, as well as the temperature, density, and viscosity
of the liquid
being treated.
[0021] In one embodiment, the middle section wall 34 is inclined at an angle
of 40 to 60
degrees from the horizontal to provide for the proper rate of decrease in the
vertical
velocity of the liquid and to prevent the fluidized bed media from settling
and
accumulating on the wall 34. Depending upon the vertical velocity of the
liquid, there
can be fluidized bed media 48 contained in the middle section 14, as well as
the upper
section 16. As shown in Figs. 2-5, the middle section 14 may also include an
access plate
40 through which the reactor 10 can be inspected, maintained, and cleaned.
[0022] The upper section 16 includes a wall 42, an upper end 44, and a lower
end 46. In
one embodiment, the upper section wall 42 is generally cylindrical. However,
it will be
appreciated by those skilled in the art that the upper section wall 42 can
alternatively be
constructed in other geometries, including square, rectangular, or generally
conical
configurations. When the upper section wall 42 is generally conical, or
configured in any
other geometry having an increasing cross-sectional area, the vertical
velocity of the
liquid traveling through the upper section 16 will continue to decrease until
it reaches a
point where the cross-sectional area of the of the upper section 16 is no
longer increasing
and becomes constant.
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[0023] As illustrated in Figs. 2-5, the upper section contains fluidized bed
media 48. The
fluidized bed media 48 may be used to perform an ion exchange process. The
fluidized
bed media 48 may remove soluble ions, molecules, and/or other compounds from
the
liquid through biological, physical, or chemical processes. The material of
the fluidized
bed media 48 may be selected from a group consisting of granular activated
carbon, ion
exchange resin, sand, combinations thereof, or any other material suitable for
use in the
present invention now known or hereafter developed. As previously discussed,
the
fluidized bed media 48 is suspended in the upper section 16 (and in some cases
the
middle section 14 as well) by the lifting force of the liquid, which
counteracts the
gravitational force on the fluidized bed media 48.
[0024] It is desirable to have the ability to replace, regenerate, and/or
rejuvenate the
fluidized bed media 48 while the reactor 10 is in use. In order to replace,
regenerate,
and/or rejuvenate the fluidized bed media 48, the reactor must include a means
for
removing fluidized bed media and a means for adding fluidized bed media. As
shown in
Figs. 2-5, the upper section 16 may contain a fluidized bed media outlet port
66 and 68
and a fluidized bed media inlet port 68 and 66. These ports 66, 68 may be
located
between the upper section upper and lower ends 44, 46. The upper section 16
may also
contain a submerged hopper 70 having an upper end 72, a lower end 74, an
overflow dam
76 proximate the upper end 72, and a fluidized bed media outlet port 78
proximate the
lower end 74. The submerged hopper 70 provides a location where the fluidized
bed
media 48 can consolidate prior to removal from the reactor 10. The overflow
dam 76 is
located at a height equal to the maximum desirable upper level of the
fluidized bed media
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48. The level of the fluidized bed media 48 can be continuously monitored by a
level
sensor 86.
[0025] One of the events triggering removal of fluidized bed media 48 from the
reactor
occurs when the fluidized bed media 48 reaches a level above its maximum
desirable
upper level. Again, the overflow dam 76 is located at a height equal to the
maximum
desirable upper level of the fluidized bed media 48. Once the fluidized bed
media 48
reaches a level above the overflow dam 76, the fluidized bed media 48 can
enter the
region directly above the hopper 70. In this region directly above the hopper
70, the
vertical velocity of the liquid is decreased due to the hopper 70 deflecting
the upward
flow of the liquid. This decrease in vertical velocity results in the liquid
having a vertical
velocity less than that required to keep the fluidized bed media 48 suspended.
In other
words, in the region directly above the hopper 70, the lifting force of the
liquid is less
than the counteracting gravitational force on the fluidized bed media 48.
Therefore, the
fluidized bed media 48 descends into the hopper 70. Once the fluidized bed
media 48 is
in the hopper 70, it can be removed through the hopper's outlet port 78.
[0026] As illustrated in Figs. 2-5, the reactor 10 can also contain sample
lines 80. The
sample lines 80 have inlet ports 82 and outlet ports 84. The sample lines 80
are used to
obtain samples of fluidized bed media 48. While two sample lines 80 are shown
in Figs.
2-5, the present invention could include a single sample line 80 or more than
two sample
lines 80. If the reactor 10 contains two or more sample lines 80, the sample
line inlet
ports 82 can be located at multiple elevations within the fluidized bed media
48, as shown
in Figs 2-5. The sample line outlet ports 84 are located outside of the middle
section 14
near ground level for access by a user.
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[0027] The upper section 16 can also include a means 50 for removing
particulate matter,
such as suspended solids, from the liquid. As shown in Fig. 3, the means 50
for
removing particulate matter 50 can be a gravity sedimentation device 52. The
gravity
sedimentation device 52 can include tube settlers. The tube settlers can be
positioned
parallel to each other and at an incline between 30 and 60 degrees from
horizontal. For
applications requiring the use of expensive fluidized bed media 48, tube
settlers can be
used to minimize the loss of the fluidized bed media 48. In an alternative
embodiment,
the gravity sedimentation device 52 can make use of multiple flat sheets that
are
positioned parallel to each other at an incline between zero and 60 degrees
from
horizontal.
[0028] As shown in Fig. 4, the means for removing particulate matter 50 can
include a
buoyant granular media filter 54. The buoyant granular media has a specific
gravity less
than the specific gravity of the liquid in the reactor 10. The material of the
buoyant
granular media may be selected from a group consisting of polyethylene,
polystyrene,
polypropylene, pumice, combinations thereof, or any other material suitable
for use in the
present invention now known or hereafter developed. When a buoyant granular
media
filter 54 is used, the buoyant granular media is retained by an overlying
retaining screen
56. The retaining screen 56 should have openings smaller than the nominal size
of the
buoyant granular media.
[0029] The buoyant granular media 54 may require occasional backwashing. The
backwashing is accomplished by diverting outlet flow from the primary outlet
64 to a
secondary outlet 65 and adding air uniformly through an air distribution grid
58 located
beneath the granular media filter 54.
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[0030] As shown in Fig. 5, the means for removing particulate matter 50 can
include a
submerged membrane filtration device 60. The submerged membrane filtration
device 60
allows liquid to pass through it but retains particulate matter from passing.
The
submerged membranes may include hollow fibers having diameters less than 1/4
inch.
Both ends of the hollow fibers may be connected to the filtration device 60
such that the
treated liquid can be collected and passed from the filtration device 60
through the outlet
64. The submerged membrane filtration device 60 can also include a submerged
membrane that is configured in a flat sheet arrangement with a void between
two sheets
where the clarified liquid can be collected and passed from the filtration
device 60
through the outlet 64.
[0031] The reactor 10 can also-include a flow collection system 62 (Figs. 1-4)
proximate
the upper section upper end 44. The flow collection system 62 may collect the
liquid
passing through the reactor and direct it to a common collection point outside
of the
reactor 10. The flow collection system 62 can include a plurality of radial
troughs, a
plurality of parallel troughs, or a manifold header with a plurality of
lateral troughs.
[0032] Several treatment processes can be achieved within the fluidized bed
reactor 10 of
the present invention, including biological processes, ion exchange processes,
physical
adsorption processes, and chemical precipitation processes. The biological
processes can
include the anoxic de-nitrification of waters containing nitrates. The ion
exchange
processes can include the ion exchange of soluble ions, molecules, or
compounds on
synthetic or natural ion exchange media. For example, one ion exchange process
involves the removal of disinfection by-product precursors from waters. The
physical
adsorption processes can include the physical adsorption of soluble ions,
molecules, or
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compounds on the surface of adsorbents. For example, one physical adsorption
process
involves the removal of soluble organic contaminates upon activated carbons.
The
chemical precipitation processes can include the chemical precipitation upon
inert media.
For example, one chemical precipitation process involves cold lime softening
for the
removal of calcium such as calcium carbonate.
[0033] From the foregoing, it will be seen that this invention is one well
adapted to attain
all the ends and objects hereinabove set forth together with other advantages
which are
obvious and which are inherent to the structure. It will be understood that
certain features
and sub combinations are of utility and may be employed without reference to
other
features and sub combinations. This is contemplated by and is within the scope
of the
claims. Since many possible embodiments of the invention may be made without
departing from the scope thereof, it is also to be understood that all matters
herein set
forth or shown in the accompanying drawings are to be interpreted as
illustrative and not
limiting.
[0034] The constructions described above and illustrated in the drawings are
presented
by way of example only and are not intended to limit the concepts and
principles of the
present invention. Thus, there has been shown and described several
embodiments of a
novel invention. As is evident from the foregoing description, certain aspects
of the
present invention are not limited by the particular details of the examples
illustrated
herein, and it is therefore contemplated that other modifications and
applications, or
equivalents thereof, will occur to those skilled in the art. The terms
"having" and
"including" and similar terms as used in the foregoing specification are used
in the sense
of "optional" or "may include" and not as "required". Many changes,
modifications,
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variations and other uses and applications of the present construction will,
however,
become apparent to those skilled in the art after considering the
specification and the
accompanying drawings. All such changes, modifications, variations and other
uses and
applications which do not depart from the spirit and scope of the invention
are deemed to
be covered by the invention which is limited only by the claims which follow.
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