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BACKGROUND OF THE INVENTION
In my prior U.S. Pat. No. 4,496,464, there is disclosed a filter system
that has a filter media comprised of particles of filter material
contained within a vessel. Liquid flows through the vessel and the filter
media in a particular manner in order for the filter media to remove
unwanted contaminants from liquid. The present invention is an improvement
over the filter apparatus set forth in my previous U.S. Pat. No.
4,496,464. Reference is made to the prior art cited in that previous
patent.
In my copending U.S. patent application Ser. No. 07/001,912 filed Jan. 9,
1987, there is disclosed a filter vessel within which a filter media is
supported. The media includes pecan hulls, or a mixture of pecan hulls,
walnut hulls, and apricot pits. The present invention sets forth in
greater detail the use of pecan hulls; as well as a mixture of pecan hulls
and walnut hulls; pecan hulls and apricot pits; and, pecan hulls together
with varying amounts of apricot pits and walnut hulls.
Walnut hulls have been used for many years as a filter media, as evidenced
by the U.S. Patents to Hirs, U.S. Pat. Nos. 3,992,291; 3,780,861 and to
Clark, U.S. Pat. No. 2,733,138. In the present invention, the term "walnut
hulls" is intended to include the type of hulls or shells that one would
expect to be shipped to him should he order walnut hulls from a commercial
firm that specializes in the sales of filter media. There are those who
allege that black walnut hulls are superior to other walnut hulls and such
use is included by the term "walnut hulls". Applicant prefers to use pecan
hulls admixed with ordinary walnut hulls and sometimes, apricot pits, as
his filter media.
The present invention also sets forth an improved filter system wherein the
filter media is scrubbed and cleaned within the vessel, thereby cleaning
the media from time to time without removing the media from the vessel.
SUMMARY OF THE INVENTION
This invention is to both method and apparatus for filtering contaminants
from a stream of fluid. The invention includes the employment of a screen
means, which can be of various different geometrical configurations, that
is placed within a vessel in a manner to suitably support a filter media.
The media is made of a multiplicity of discrete pieces of filter material
which substantially will not pass through the screen means, and which
includes pecan hulls or a mixture of pecan hulls and walnut hulls. Apricot
pits sometimes are included.
During the filtering operation, contaminated liquid flows into the vessel,
through the media, through the screen means that supports the media, and
away from the vessel, while the contaminants are deposited on the media.
The media is periodically subjected to a scrubbing operation wherein it is
cleaned or rejuvenated whenever the accumulated contaminants have reached
a magnitude which increases the pressure drop across the filter vessel to
an unacceptable and predetermined value. The rejuvenation steps include a
novel flow system that carries out the functions of fluidization,
discharge, settling, and normalization, all of which are carried out,
while the filter media remains within the vessel.
The fluidization step is carried out by arranging a pump inlet and outlet
within the vessel in a manner to form a toroidal flow path, with a second
screen means being included within the flow pattern such that flow must
occur thereacross. The fluidization step scrubs the contaminants from the
filter media by transferring the contaminants into the scrub water. This
enables the subsequent discharge step to efficiently remove the
contaminated water while relatively clean make-up water flows into the
vessel.
The discharge step comprehends flowing the dirty scrub water through the
second screen means and away from the vessel. This is achieved by
perforating the pump discharge so that it forms said second screen means,
extending the pump discharge through an enclosure so that an annulus is
formed therebetween, and flowing dirty scrub water from the annulus and
away from the vessel.
The vessel is then isolated a sufficient length of time for the cleaned
media to settle into a filter bed, and thereafter a normalization step is
carried out so that any contaminants in the water contained within the
filter vessel are removed from the water. Filtration is then resumed until
the pressure drop across the filter media is again elevated to an
unacceptable value. At that time, the above rejuvenation process is
repeated.
Accordingly, a primary object of the present invention is the provision of
method and apparatus for sequentially filtering with and then cleaning a
filter media which is used to filter a stream of liquid.
Another object of the invention is to provide method and apparatus by which
a contaminated stream of liquid is filtered for one interval of time to
provide separation of the contaminants and the liquid, and the filter
media is then scrubbed clean in a new and unobvious manner during another
interval of time, with the filtering step and cleaning step both occurring
within the same vessel.
A further object of this invention is to disclose and provide a method of
filtering a stream of contaminated liquid by flowing the contaminated
liquid into a vessel having a liquid space and a filter media space;
whereupon, the contaminated liquid proceeds to flow through the filter
media thereby leaving the contaminant within the media, so that clean,
filtered liquid exits from the vessel; and, thereafter, the filter media
is scrubbed without removing the media from the vessel.
A still further object of this invention is to provide an unusual and
unobvious filter system having particles of filter media contained therein
which filters contaminants from a flowing liquid, and wherein the filter
media is made of at least 50% pecan hulls, and occasionally is scrubbed
clean of contaminants, and the contaminants removed from the system, with
both the scrubbing and filtering action occurring within the same vessel.
Still another object of the present invention is the provision of a filter
device having a filter media made mostly from crushed pecan hulls
supported by a screen wherein the filtrate travels through the screen, and
wherein the filter media is subsequently scrubbed and the scrub water
exits the vessel in a novel manner.
Another object of this invention is the provision of an improved filter
apparatus that utilizes pecan hulls as the filter media, or at least part
of the media.
A further object of this invention is the provision of a filter media
comprised of pecan hulls and another media comprised of a mixture of pecan
hulls, walnut hulls, and apricot pits.
These and various other objects and advantages of the invention will become
readily apparent to those skilled in the art upon reading the following
detailed description and claims and by referring to the accompanying
drawings.
The above objects are attained in accordance with the present invention by
the provision of a method for use with apparatus fabricated in a manner
substantially as described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a part diagrammatical, part cross-sectional, side view of a
filter apparatus made in accordance with the present invention;
FIG. 2 is a part cross-sectional view of another embodiment of the present
invention;
FIG. 3 is a cross-sectional view taken along line 3--3 of FIG. 2;
FIGS. 4-6 set forth a plot showing the use of a filter media according to
the present disclosure;
FIG. 7 is an enlarged, idealized, perspective view of the filter media
disclosed herein;
FIG. 8 is a fragmentary, enlargement of some of the filter media of this
disclosure;
FIG. 9 is a fragmentary, enlarged, representation of another filter media
made in accordance with this invention; and,
FIG. 10 is a fragmentary, broken, part longitudinal, cross-sectional view
of the filter apparatus disclosed in FIGS. 1 and 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the figures of the drawings, and in particular FIG. 1, there is
disclosed a filter system 10 made in accordance with the present
invention. The system 10 includes a vessel 12 that forms an enclosure 14.
The enclosure 14 can be referred to as the lower enclosure 16 and the
upper enclosure 18. A pump means 20, which can take on several different
forms, includes a support 22 by which the pump 20 is suspended from a
manhole assembly 24 located at the upper terminal end of vessel 12.
The pump 20 is commercially available and includes a suction 26 and an
outlet 27. The outlet 27 is connected to a scrub water discharge apparatus
28. Numeral 30 indicates the end of a nozzle 70 which directs flow as
indicated by arrows 32. The outlet 30 of the nozzle is shown spaced above
and perpendicularly disposed respective to a fill-line 19 of the filter
media; however, the outlet can be located at other elevations respective
to the fill-line 19 if desired.
The arrows at numeral 32 indicate a toroidal flow pattern with the
discharge apparatus 28 being located at the center of the toroid. The
toroidal flow pattern is effected by fluid flow into suction 26 and fluid
flow from the nozzle outlet 30.
The scrub water discharge apparatus 28 includes annular discharge chamber
72 connected to discharge pipe 74 by which dirty scrub water can be
discharged from the vessel at discharge 76. Flow control valve means 78 is
connected to the discharge 76.
A screen means 34, which can take on several different forms, is located in
the lower enclosure 16. The lower circumferentially extending edge of the
screen 34 terminates in attached relationship respective to attachment
flange 36. The screen 34 includes an apex 38 which is axially aligned with
the discharge apparatus 28. The screen means 34 can be made of a plurality
of individual elements 40 which are made triangular in form and have
adjacent opposite sides 42, 44; a base 46; and, a common apex 38. The
sides 42, 44 are attached to one another while the base 46 is attached to
flange 36. The flange 36 is supported by means of the illustrated lower
flange 48 that is attached to the outer shell 12 that forms enclosure 14.
The screen 34 separates the lower chamber 16 into a filtrate chamber 50 and
leaves ample space for the filter bed as indicated by fill-line 19. This
arrangement also provides ample space at upper enclosure 18 for a dirty
water chamber. As disclosed in FIG. 1, the filter bed is in the act of
being scrubbed or rejuvenated and therefore has been fluidized and is
flowing in a toroidal flow path.
Discharge valve 52 can momentarily be connected to the inlet 54, and
thereafter can be connected to an appropriate disposal facility for
disposing of dirty water, except in those instances where the contaminant
is valuable, whereupon valve 52 would be connected to a collection and
holding facility.
Valve 51 removes compressible fluid from the uppermost end of the upper
enclosure 18.
Water inlet 54 is connected to enable the vessel to receive a supply of
contaminated liquid that must be filtered. Filtrate valve 58 is connected
to provide a flow path for the clean filtered water. Valve 60 provides a
convenient means by which all of the filter media can be removed from the
enclosure 14 when it is desired to renew the filter media. The filtrate
chamber 50 is connected to pipe 56 which in turn is connected to the tee
that accepts valves 52 and 58.
A computerized control panel 62 provides intelligence and sends appropriate
signals along conduits 63 and 64 for actuating valves 52, 54, and 58, and
for controlling the action of pump 20 in a logical, predetermined,
sequence as will be more fully appreciated after this disclosure has been
digested. Numerals 55, 57, and 59 indicate a control device for actuating
valves 54, 52, and 58. Numeral 66 indicates power input into the control
panel 62.
In the embodiment of the invention set forth in FIG. 2, the settled filter
media 80 is shown supported within the lower enclosure 16 with screen 134
separating the media from the filtrate chamber 50, and with the filter
media 80 separating the liquid contained within the upper enclosure 18
from the screen 34.
The pump 20' of FIG. 2 is located externally of the vessel and is connected
to receive flow from suctions 26, 26' which are symmetrically supported
within the upper end of the vessel and aligned with the toroidal flow path
32 of FIG. 1. The discharge apparatus 28 extends axially down through the
manhole 24 and terminates at nozzle outlet 30 and in proximity of the
fill-line 19. The filtrate exits at 56 and to valves 52, 58 (shown in FIG.
1).
The equipment for the apparatus is minimized, so as to keep costs and
complexity to a minimum. The filtration unit of FIG. 1 consists of one
fluidization pump which is submerged down into the top of the vessel with
an easily accessible manway; or, as seen in FIG. 2, an external pump with
a discharge apparatus aligned centrally of the vessel; and, one wire
screen which, in FIG. 1, is conically shaped (i.e. tee-pee) and welded or
otherwise fixed around the inside bottom of the vessel; one inlet pipe
leading to the upper end of the vessel comprising a "check" valve; only
one outlet pipe which leads from the bottom center of the vessel including
one actuated valve 58; and one scrub water discharge valve leading to a
suitable disposal facility.
The Filter 10 or 110 employs a much more efficient technique as compared to
a sand filter. Rejuvenation of the bed requires less time, 20 minutes or
less, and produces much less waste discharge volume than a comparable sand
filter. Filtration and Clean-Up Sequence:
1. Filtration . . . . . . . . . 30 hours or less
2. Fluidization . . . . . . . . . 15 seconds
3. Discharge . . . . . . . . . 12 minutes under normal conditions
4. Settling . . . . . . . . . 1 minute
5. Normalization . . . . . . . . . 1 minute
Return to Step 1.
As seen in FIG. 2, dirty water is pumped by a feed pump (not shown) from
the dirty water source, through inlet pipe 54 near the top of vessel 12.
The water flows down through the media bed 80, then out through the bottom
conical wire screen 134 where solids are trapped and remain in the media
bed, and the clean water exits down through the clean water outlet 56. The
filtration mode will be controlled by a timer which can be set to
accommodate different types and severity of water contaminants. If the
water is much more contaminated than well water, the filtration sequence
will have to be of much shorter duration, and the media bed rejuvenated
more often. If the water contains low amounts of solids, the filtration
time can be extended because rejuvenation and discharge will not be needed
quite as often.
When the time has elapsed for the filtration mode, or when the pressure
drop across bed 80 has unduly increased, valve 58 (outlet for clean water
in FIG. 1) will shut off and no more dirty water will enter the vessel
through inlet pipe 54. The fluidization pump 20 will turn on and begin
pulling the water and media up through the Lop of it by suction. The water
and media will flow down the discharge apparatus 28 and back out into the
vessel as seen at 32 in FIG. 1, for example. By flowing the water through
pump 20, pump outlet 27, nozzle 70, nozzle outlet 30 and down through the
middle of the vessel, it will be directed onto the center of the screen 34
or 134 and flow down the sides thereof and thereafter, hit the sides of
the vessel and then flow back up to the pump intake 26. This flow will
form what is known as a toroidal flow path. The fluidization mode will
last 15 seconds, for example, to assure that the entire bed has formed
into a toroid for mixing.
In FIG. 1, once the bed has been fluidized, the discharge outlet valve 78
will then be opened and pump 20 will remain turned on to continuously mix
and scrub the bed. The nozzle screen 70 which previously served solely as
a discharge tube leading to the nozzle outlet 30 will now take on the new
task of cleaning the dirty scrub water from the media. This unique method
of utilizing a discharge nozzle 70 as a dual function apparatus is an
object of this invention. The discharge screen 70 will now simultaneously
act as a separator as well as a nozzle. It will hold back the media, but
the unwanted solids, dirt, and other contaminants will be washed through
the screen openings, into the dirty scrub water annulus 72, through piping
74 where the water is transported to the discharge 76 and through valve
78. Discharge time may be only twelve minutes under normal water filtering
conditions.
In FIG. 1, once the discharge step is complete, the outlet discharge valve
78 will close and the fluidization pump 20 will turn off. This allows the
media to gravitate back onto and around the primary screen to form a
rejuvenated bed 80. The Lime allowed for settling is about one minute.
In FIGS. 1 and 2, once the bed has settled, the filter control 62 (of FIG.
1) will move the system into a prefilter or normalizing step. This is
achieved by opening the outlet discharge valve 52 (of FIG. 1) in order
that the extra water and solids can flow out through the discharge valve
and thereby prepare the bed for another filtration cycle. At the end of
this normalization step, valve 58 will open, allowing clean water to be
transported to wherever it is needed once the filtration begins again,
then valve 52 will be closed.
The control panel 62 can be a computer which is programmed to switch the
variables of the system to achieve various modes of operation in
accordance with the desired program selected for a specific filter
operation. On the other hand, the control panel 62 can be equipped with a
cam timer which will control the above filtration sequence. The timer will
control the opening and closing of the actuated valves 52, 58, 54, and 78;
and, the pump will be turned off and on by the panel.
The discharge from valve 52 can be backed into inlet 54 so that after the
scrubbing, discharge, and settling steps the normalization step can be
carried out by closed circuit flow from 56, 52, 54, through the vessel and
to 56, thereby filtering contaminants from all of the water contained in
the closed circuit.
The filter media used will be crushed pecan hulls for a tight packed, more
efficient filtration. English walnut hulls can be added for a somewhat
looser packing and to improve the life of the media and wear on the
vessel. It is also possible to use any mixture of the following materials:
crushed walnut hulls, crushed pecan hulls, and crushed apricot pits.
Reference is made to my previous U.S. Pat. No. 4,496,464 for the pump
horsepower, vessel diameter and length, and the amount of filter media a
typical filter installation may require, as well as the details of the
wedgewire screens 34, 134, and 70.
In FIG. 2, there is a small amount of filter media traveling outside the
vessel during the cleaning or scrubbing step. Such an operation
nevertheless is considered to fall within the claimed language "scrubbing
the media while the media is contained within the vessel".
This invention comprehends the use of crushed pecan hulls as the filter
media 80, FIG. 2. Where the size distribution of the contaminants is a
bell-shaped curve as seen in FIG. 4, a mixture of 80% pecan hulls and 20%
walnut hulls is the preferred media 80, FIG. 2. This provides a tightly
packed bed 80 of pecan hulls that is propped open with the walnut hulls
sufficiently to achieve a reasonable cycle time. This mixture is
diagrammatically shown in FIG. 9.
In FIGS. 7-9, the bed 80 or 180 is comprised of pecan hulls 82, walnut
hulls 84, or a mixture thereof. The use of pecan hulls alone is shown in
FIGS. 6 and 8, and should be employed where most of the contaminants are
very small and consequently the media needs to be a tightly packed bed.
The 100% pecan hull filter media maintains a long cycle time, is very
efficient, and provides advantages over other known filter media.
Walnut hulls should be added to the pecan hulls in increasing amounts as
the size of the contaminants increases. In FIG. 5, the average size of the
contaminants has further increased beyond that set forth in FIG. 4 and
therefore the percentage of walnut hulls contained within the mixture of
pecan and walnut hulls has been increased to 40%, as seen in FIG. 5.
In FIG. 7, the pecan hulls are seen to be in the form of flat, well defined
pieces of a sphere, whereas the walnut hulls are more like an irregular
ball having a much greater thickness as compared to the pecan hull
particles. As seen in FIG. 9, the walnut hull particles prop open the
layered pecan hulls and thereby provide a "looser" bed as compared to the
use of 100% pecan hulls of FIG. 8. The looser bed of FIG. 9 is
advantageously employed in filtration conditions such as set forth in FIG.
5, whereas the tight bed of FIG. 8 is preferred in conditions such as set
forth in FIG. 6.
The tight bed 180 that uses 100% pecan hulls would be employed for
filtering sea water, for example, which has an average particle size of 2
micron or greater and 50 parts per million (ppm) total suspended solids
under normal operating conditions; whereas the loose bed of FIG. 9 is
preferred for filtering plant water having an average particle size of 2
micron or greater and 50 ppm total suspended solids and 100 ppm oil. These
two extremes are illustrated in FIGS. 5 and 6, with FIG. 4 being somewhere
therebetween.
The walnut hulls can therefore be said to be a "propping agent" or a
"propant" in the sense that it props open and thereby loosens the bed of
pecan hulls, thereby modifying tile pecan hull bed for use in filtering
liquids admixed with increasing particle size contaminants.
EXAMPLE: A Filter bed comprised of 100% pecan hulls weighing 150 pounds was
placed in a vessel 1 foot in diameter and 11 feet in height.
Sea water was pumped through the Filter media at a rate of 15 gpm. The
filtrate was cleaned of most material above 2 micron particle size. The
cycle time was as follows:
Filtration . . . . . . . . . 27 hours
Fluidization . . . . . . . . . 1/2 minute
Discharge . . . . . . . . . 15 minutes at 15 gpm
Settling . . . . . . . . . 1 minute
Normalization . . . . . . . . . 1 minute.
Should the above filter system be used to Filter a contaminated stream of
plant liquid having 200 ppm oil, 200 ppm solids of 2 micron size or
greater, it is anticipated that the following cycle of operation would be
encountered:
Filtration . . . . . . . . . 4 hours
Fluidization . . . . . . . . . 1/2 minute
Discharge . . . . . . . . . 15 minutes
Settling . . . . . . . . . 1 minute
Normalization . . . . . . . . . 1 minute
This unsatisfactory cycle time is due to all of the contaminants being
removed and concentrated onto the top surface 19 of the bed 80 which
rapidly accumulates into an impermeable barrier which elevates the
pressure drop across the vessel to an unacceptable value. Consequently,
the bed must be rejuvenated often as compared to a looser bed made of a
mixture of pecan and walnut hulls, as seen in FIGS. 4, 5, and 9, for
example.
Should the above filter system be adjusted to a mixture of 60% pecan hulls
and 40% walnut hulls, the following results are anticipated:
Filtration . . . . . . . . . 18 hours
Fluidization . . . . . . . . . 1/2 minute
Discharge . . . . . . . . . 15 minutes
Settling . . . . . . . . . 1 minute
Normalization . . . . . . . . . 1 minute
This is an acceptable cycle time. Should the walnut hulls be increased to
more than 50%, for example, the filtrate at 56 may indicate that the
contaminants were not being satisfactorily removed from the contaminated
liquid and under these circumstances, it would be necessary to increase
the pecan hull ratio until the contaminants are properly removed from the
liquid. Hence, the ratio of pecan and walnut hulls used as the filter
media is adjusted to achieve the desired cycle time and degree of
filtration.
The above example of poor filter performance can be overcome by the
provision of the separator apparatus 83 seen in FIGS. 1, 2, and 10. Where
the poor performance is due to the presence of oil and other lighter than
water fluids present in the contaminated liquid entering the vessel at 54,
the separator 83 forces most of the lighter weight material to flow
upwards within the vessel and towards the vent, while the heavier
components are forced to flow in a downward direction towards the bed.
This unusual subcombination of this invention enables most of the lighter
components Lo be removed from the system by flowing the lighter material
through the vent and to suitable storage where it can be accumulated. The
lighter material, such as oil, is often of significant value.
An unexpected advantage discovered by using separator 83 is that it further
enhances the configuration of the bed, and thereby increases the overall
filter efficiency. The flow through passageway 85' formed in inlet pipe 85
is diverted at tee 86. The divided flow proceeds through passageway 87 and
is discharged at upper and lower annular discharge ports 88, 89. The
annular opposed discharge ports 88, 89 are formed by flat plate members 90
which are supported in spaced relationship respective to outlet ends 91,
92 by means of a plurality of standoffs 94. The flat plate members 90 are
about 1-1/2-2 diameters larger than the tee, and are concentrically
arranged respective to outlets 91, 92 of the tee. The plates 90 are spaced
about one pipe diameter from the outlets 91, 92. The plurality of
standoffs 94 can be any suitable length of rod, and are attached to the
opposed ends of the tee. The rods are radially spaced from the central
axis of the outlets 91, 92; and, have opposed ends welded to the tee and
plate.
Flow through passageway 85' splits at 87 and proceeds through outlets 91,
92. The flow at 88, 89 is emitted as two annular flow paths which enlarge
in diameter and decelerate as the flow proceeds radially away from the
outlets. This action causes an unexpected small amount of disturbance at
the upper surface of the bed 19. Heretofore, the surface of the bed has
assumed an irregular configuration with there being a deep dished area due
to the jet-like action of a prior art inlet. That is, the pipe inlet acts
like a nozzle and disturbs the upper surface of the bed during the
filtration cycle. The present invention reduces this disturbance and
provides a more regular bed surface.
Further, oil and other light ends are separated front the inlet liquid and
are withdrawn through the vent, rather than removed by the bed, thereby
avoiding contamination of the bed with oil and greatly extending the
filtering cycle. The separation occurs because the oil tends to rise
towards the top of passageway 85', where it is then entrained by the
upwardly flowing liquid which directs the oil phase through the outlet 89
where it continues to rise towards the top of the vessel and is discharged
through the vent.
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