U.S. patent application number 15/335601 was filed with the patent office on 2017-02-16 for system having foam busting nozzle and sub-surface mixing nozzle.
The applicant listed for this patent is VAUGHAN COMPANY, INC.. Invention is credited to Glenn R. Dorsch, Kent H. Keeran.
Application Number | 20170043279 15/335601 |
Document ID | / |
Family ID | 44308232 |
Filed Date | 2017-02-16 |
United States Patent
Application |
20170043279 |
Kind Code |
A1 |
Dorsch; Glenn R. ; et
al. |
February 16, 2017 |
SYSTEM HAVING FOAM BUSTING NOZZLE AND SUB-SURFACE MIXING NOZZLE
Abstract
A surface foam diffuser and digester tank system prevents and/or
suppresses the formation of foam during digestion. The system
includes a first nozzle disposed above a top surface of the at
least partially liquid contents, a splash plate positioned adjacent
to the first nozzle outlet, and a second nozzle disposed below the
top surface of the at least partially liquid contents for
suppressing foaming in the large processing tanks. The system
nozzles each have an inlet for receiving pressurized liquid and an
outlet for ejecting a liquid stream into the tank, the depth of the
second nozzle and the direction of the liquid stream there from
being such that rotation of the top surface is facilitated. The
spray of the first nozzle, as dispersed by the splash plate,
reduces foam on at least a portion of the top surface, with the
rotation of the top surface bringing each portion of the top
surface to eventually fall within the reducing spray.
Inventors: |
Dorsch; Glenn R.; (Aberdeen,
WA) ; Keeran; Kent H.; (Elma, WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VAUGHAN COMPANY, INC. |
Montesano |
WA |
US |
|
|
Family ID: |
44308232 |
Appl. No.: |
15/335601 |
Filed: |
October 27, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12694396 |
Jan 27, 2010 |
9486819 |
|
|
15335601 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D 19/02 20130101;
C02F 3/1236 20130101; C02F 2303/12 20130101; C02F 3/28 20130101;
C02F 2301/02 20130101; B05B 7/0018 20130101; B05B 13/0627 20130101;
B01D 19/0047 20130101; B05B 1/267 20130101 |
International
Class: |
B01D 19/02 20060101
B01D019/02; B01D 19/00 20060101 B01D019/00; C02F 3/28 20060101
C02F003/28; C02F 3/12 20060101 C02F003/12; B05B 1/26 20060101
B05B001/26; B05B 13/06 20060101 B05B013/06 |
Claims
1. A tiered nozzle system for suppressing foam on a top surface of
fluid material substantially filling a large digester tank, the
system comprising: a first nozzle positioned to remain above the
top surface of the fluid material when the digester tank is
substantially filled, the nozzle having an inlet for receiving
pressurized liquid and an outlet for discharging a liquid stream
into the digester tank; a splash plate positioned below the outlet
of the first nozzle such that the splash plate contacts a
discharging liquid stream at an angle of inclination relative to
the stream direction to thereby deflect at least a portion of the
stream upward and disperse the liquid stream over a greater portion
of the top surface than the liquid stream would otherwise cover
without a splash plate; and a second nozzle disposed below the top
surface of the at least partially liquid contents, the second
nozzle having an inlet for receiving pressurized liquid and an
outlet for discharging a liquid stream directly into the fluid
material, the position of the second nozzle and the direction of
the discharged liquid stream being such that rotation of the top
surface is facilitated.
2. The system of claim 1, wherein the first and second nozzle are
connected at their respective inlets.
3. The system of claim 1, wherein the first nozzle and the second
nozzle are secured to and positioned proximate an inner periphery
of the digester tank.
4. The system of claim 3, wherein the outlet of the first nozzle is
directed toward the center of the digester tank.
5. The system of claim 1, wherein the splash plate disperses the
liquid stream over at least 20% of the top surface.
6. The system of claim 1, wherein the second nozzle is disposed at
a depth of no more than 30% of the digester tank contents below the
top surface.
7. The system of claim 6, wherein the second nozzle is disposed at
a depth of no more than 20% of the digester tank contents below the
top surface.
8. The system of claim 6, wherein the second nozzle is disposed at
a depth of no more than 10% of the digester tank contents below the
top surface.
9. The system of claim 2, wherein the first and second nozzles are
positioned such that the direction of the liquid stream from the
first nozzle is offset from the direction of the liquid stream from
the second nozzle.
10. A digester tank system comprising: a digester tank containing
material having at least a partially liquid composition prone to
foaming as a result of gas byproducts from biological digestion; a
discharge line connected to the bottom of the digester tank; a pump
having an inlet connected to the discharge line; a feed line
connected to a outlet of the pump; a first nozzle disposed above a
top surface of the at least partially liquid material, the nozzle
having an inlet for receiving pressurized liquid from the feed line
and an outlet for ejecting a liquid stream in a direction toward
one of either a center or a side of the digester tank; a splash
plate positioned adjacent to the first nozzle outlet contacting the
liquid stream at an angle of inclination relative to the stream
direction to thereby disperse the liquid stream over a greater
portion of the top surface; and a second nozzle disposed below the
top surface of the at least partially liquid contents, the nozzle
having an inlet for receiving pressurized liquid from the feed line
and an outlet for ejecting a liquid stream into the digester tank,
the depth of the nozzle and the direction of the liquid stream
being such that rotation of the top surface is facilitated.
11. The system of claim 10, wherein the digester tank is a
waste-water treatment tank comprising one of either an aerobic
digester or an anaerobic digester.
12. The system of claim 10, wherein the inlet of the first nozzle
and inlet of the second nozzle are aligned and connected.
13. The system of claim 10, wherein the first nozzle and the second
nozzle are positioned proximate an inner periphery of the digester
tank.
14. The system of claim 10, wherein the outlet of the first nozzle
is directed toward the center of the digester tank.
15. The system of claim 10, wherein the second nozzle is disposed
no more than one foot below the top surface.
16. The system of claim 10, further comprising a plurality of
mixing nozzles positioned proximate a bottom surface of the
tank.
17. The system of claim 16, wherein outlets of the mixing nozzles
are aimed such that a discharging stream creates a liquid flow
pattern in the digester tank contents.
18. The system of claim 10, wherein the first and second nozzles
are positioned such that the direction of the liquid stream from
the outlet of the first nozzle is offset from the direction of the
liquid stream from the outlet of the second nozzle.
19. The system of claim 10, wherein the second nozzle is disposed
at a depth of no more than 30% of the tank contents below the top
surface.
20. The system of claim 19, wherein the second nozzle is disposed
at a depth of no more than 20% of the tank contents below the top
surface.
21. The system of claim 19, wherein the second nozzle is disposed
at a depth of no more than 10% of the tank contents below the top
surface.
Description
RELATED APPLICATIONS
[0001] The present application is a continuation of U.S. patent
application Ser. No. 12/694,396, filed on Jan. 27, 2010, titled
"System Having Foam Busting Nozzle and Sub-Surface Mixing Nozzle,"
and now U.S. Pat. No. 9,486,819. The '819 patent is hereby
incorporated by reference.
TECHNICAL FIELD OF THE INVENTION
[0002] The present system relates to a foam busting and sub-surface
mixing configuration for use in processing tanks such as, for
example, waste-water digesters. Particularly, the present system
relates to a unique nozzle arrangement which provides greater foam
suppression in sludge-type compositions.
BACKGROUND OF THE INVENTION
[0003] Surface foaming and sediment deposition can both create
problems in storage and treatment tanks where large volumes of
liquid/slurry are stored and stirred, mixed, or agitated. In many
cases the two problems are inversely related. That is, solving one
of the problems may directly worsen the other. This relationship
can make it very difficult for those skilled in the art to design
and implement a system which addresses and solves both
problems.
[0004] For example, in activated sludge secondary treatment plants,
slurries in large tanks are typically stirred, mixed, or agitated
in order to suspend solids in the liquid prior to emptying the
tank. Without such mixing, the solids would settle to the bottom of
the tank. The settling of solids over even a short period of time
can develop into a huge problem, as the build-up of mixing of
digester tank contents are: reduction of thermal stratification;
dispersing substrate for better contact with active biomass;
reduction in scum buildup; dilution of inhibitory substances or
adverse pH and temperature feed characteristics; increased
effective volume of the reactor; and, separation of reaction
product gases is improved. However, stirring, agitation and mixing
can also result in increased surface foam due to the abundance of
surfactants which can be found in such liquids.
[0005] Similarly, surface foaming can be a problem in anaerobic
digesters, where gases are the natural product of the digestion
process. The gases create foam in the form of bubbles and/or scum
on the surface of the liquid/slurry in the tank. If the foaming
problem is not addressed, the foam uses up volume in the tank, or
the tank can overflow. Further, agitation of the tank contents to
assist the digestion process may exacerbate the foaming as noted
above.
[0006] In both cases, anti-foaming agents may be added to the tanks
to suppress foaming. However, these agents are expensive and, in
some instances, are either too limited in their ability to suppress
foaming or may have negating effects on other favored processes
(e.g., digestion).
[0007] Another common problem for many activated sludge plant
digesters is the creation of a thick (viscous) upper surface. This
happens because thickened sludges from the aerobic digestion side
of the plant get fed back into the anaerobic digesters to further
break down the sludge. This makes the anaerobic digester sludge
much more viscous and harder to mix, sometimes resulting in lower
level tank mixing but not in upper surface mixing. Floor-mounted
mixing nozzles do not necessarily assure upper surface
rotation.
[0008] Mechanical anti-foaming devices, such as the nozzle system
disclosed in U.S. Pat. No. 7,628,183 to Dorsch et al. and assigned
to the Assignee of the present technology, are very effective at
suppressing foaming. The complete disclosure of U.S. Pat. No.
7,628,183 is hereby incorporated by reference. However, without
surface rotation, and due to the extensive size of digester tanks,
expensive plumbing for a plurality of anti-foaming nozzles would be
required to adequately suppress foaming.
[0009] The present invention overcomes these and many other
disadvantages of previous devices and processes. Disclosed is a
system which is effective at suppressing foaming, even during
mixing, stirring and agitation, without the use of expensive
anti-foaming agents and the system is easy and relatively
inexpensive to manufacture and install.
SUMMARY OF THE INVENTION
[0010] There is disclosed herein an improved nozzle configuration
for suppressing foaming in a treatment tank filled to a level with
at least partially liquid contents which avoids the disadvantages
of prior devices while affording additional structural and
operating advantages.
[0011] Generally speaking, the surface foam diffuser system
comprises a first nozzle disposed above a top surface of the at
least partially liquid contents, a splash plate positioned adjacent
to the first nozzle outlet, and a second nozzle disposed below the
top surface of the at least partially liquid contents. The system
nozzles each have an inlet for receiving pressurized liquid and an
outlet for ejecting a liquid stream into the tank, the depth of the
second nozzle and the direction of the liquid stream there from
being such that rotation of the top surface is facilitated.
[0012] In a particular embodiment, the system further comprises a
plurality of mixing nozzles positioned proximate a bottom surface
of the tank to keep solids entrained within the liquid medium by
creating a liquid flow pattern in the tank. The liquid stream from
the second nozzle is preferably supportive of the established flow
pattern.
[0013] These and other aspects of the invention may be understood
more readily from the following description and the appended
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] For the purpose of facilitating an understanding of the
subject matter sought to be protected, there are illustrated in the
accompanying drawings embodiments thereof, from an inspection of
which, when considered in connection with the following
description, the subject matter sought to be protected, its
construction and operation, and many of its advantages should be
readily understood and appreciated.
[0015] FIG. 1 is a plan view of one embodiment of the present
system;
[0016] FIG. 2 is a side view of the system illustrated in FIG.
1;
[0017] FIG. 3 is a close up view of an embodiment of a sub-surface
nozzle and surface defoaming spray nozzle combination;
[0018] FIGS. 4-6 are various views of one embodiment of a mixing
nozzle used in embodiments of the present system;
[0019] FIGS. 7-9 are various views of one embodiment of another
mixing nozzle used in embodiments of the present system; and
[0020] FIGS. 10 and 11 are views of one embodiment of an
anti-foaming nozzle used in embodiments of the present system.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0021] While this invention is susceptible of embodiments in many
different forms, there is shown in the drawings and will herein be
described in detail a preferred embodiment of the invention with
the understanding that the present disclosure is to be considered
as an exemplification of the principles of the invention and is not
intended to limit the broad aspect of the invention to embodiments
illustrated.
[0022] Referring to FIGS. 1-11, there is illustrated an
anti-foaming tank and nozzle system, generally designated by the
numeral 10. The described system 10 is discussed with respect to
mixing tank contents, which is typically a combination of liquids
and solids. More specifically, however, the system 10 is described
for use on very large tanks, where mixing at the surface is
somewhat diminished, and for use in digesters and the like, wherein
a viscous top surface, due to the formation of scum and foam,
reduces surface mixing. These particular foaming and scum problems
may be found anywhere large processing tanks are used, such as, but
not limited to, bio-waste plants, chemical plants, water treatment
plants, waste-water treatment plants and where the tank contents
include a 1-6% total solids concentration.
[0023] Accordingly, the system 10 is described herein with
reference to three distinct zones: tank bottom (A), content upper
surface (B), and above the content surface (C). The drawings
illustrate a specific embodiment of the system as used in a
specific tank construction, but principles of the invention can be
used for virtually any storage tank in which surface foam
(including scum) may cause a problem.
[0024] In the embodiment illustrated in FIGS. 1 and 2, a tank 11 is
shown to include a lid 12, a sidewall 13 and a conical base 14. The
representative embodiment is used for a cylindrical digester tank
having a radius of 108 feet (about 32.9 meters), a bottom cone of
4.25 feet (129.5 cm) depth, an overall depth from the bottom
sidewall of 30 to 50 feet, and a mixing system including a chopper
pump 16 and nozzle assemblies 18 such as those available from
Vaughan Co., Inc., of Montesano, Wash., and sold under the
trademark ROTAMIX.TM..
[0025] The present system 10 can be installed to achieve its
defoaming effect wherever it is needed. Appropriate valves are
provided at the pump 16 for directing liquid from the tank 11 to
the pipe 22 and then to supply pipes 28 for the mixing system
nozzle assemblies 18, and pipes 30 for the diffuser 24 and
sub-surface mixing nozzle 26. By "sub-surface" it is meant that the
nozzles are positioned within the tank contents below the surface
within the top 30% of the content depth (e.g., not more than 3 feet
deep in 10 feet of tank contents), preferably within the top 20% of
the content depth, and most preferably within the top 10% of the
content depth. Liquid from the tank 11 is supplied to the pump 16
by inlet piping, which can withdraw liquid from the lower center
portion of the tank 11 (via a sump), and extends to the pump
16.
[0026] As illustrated in FIG. 1, the mixing nozzle assemblies 18
can include an inner ring of nozzles and an outer ring of nozzles
positioned at the tank bottom (A), with each nozzle oriented in the
same general rotational direction to induce rotation of the
contents of the tank about a vertical axis 20. The outer ring
preferably comprises four dual nozzle assemblies 40, while the
inner ring comprises at least two single nozzle assemblies 50. The
pump outlet is connected to a supply pipe 22 feeding pipes 28 to
the mixing nozzle assemblies 18. The purpose of the lower mixing
nozzle assemblies 18 is to create a rotational, stirring flow
pattern in the tank contents. A suitable system is described in
U.S. Pat. No. 7,025,492 to Dorsch et al., and assigned to Vaughan
Co., Inc. or Montesano, Wash. The '492 patent is hereby
incorporated by reference
[0027] FIGS. 4-6 illustrate the preferred single nozzle 52 as a
glass-lined ductile iron nozzle having an 8-inch inlet reduced to
6-inch at the bend before reaching a tapered outlet. Although the
nozzle outlet 44 is of substantially lesser diameter than the pipes
22 and 28, nevertheless, the diameter at the outlet 44 still is
much larger than conventional spray nozzles or apertures so that
the nozzle will not become clogged with rags, hair, fiber, or other
thick, tough, stringy, or solid material from the tank.
[0028] The dual nozzle assemblies 40 are created using the same
single nozzle of FIG. 5 coupled to the intermediate nozzle 27 of
FIG. 9. Similarly, the sub-surface nozzle 26 also utilizes the
configuration illustrated in the drawings of FIGS. 7-9. The
configuration of the intermediate nozzle 27 (as nozzle 26 or nozzle
52) is well-known in the field, allowing a second nozzle (e.g.,
diffuser nozzle 24) to be connected adjacent using the same feed
pipe. The nozzles 27 and 52 should be 360.degree. fully adjustable
to allow directional positioning to create the desired stirring
flow pattern within the tank 11, be it for lower tank mixing or
sub-surface mixing.
[0029] As shown and described in U.S. Pat. No. 7,628,183, a
diffuser can be conveniently mounted in a manhole of the type
commonly used in tanks of this type. However, for the presently
illustrated embodiment, the supply pipe 22 which feeds pipe 30 to
the surface foam diffuser 24 and sub-surface mixing nozzle 26 is
preferably located within the tank 11, running from the bottom
center of the tank 11 toward the sidewall 13. The location of the
diffuser 24 along the sidewall 13, of course, varies depending on
the tank.
[0030] Referring to FIG. 2, supply pipe 22 (8-inch diameter in a
representative embodiment) connects to the upright diffuser inlet
pipe 30. Pipe 30 extends upward to an 8-inch to 6-inch reducer 32
to allow attachment of the 6-inch flange 34 and piping 36 of mixing
nozzle 26 (FIG. 3). A diffuser nozzle 24 is then attached
approximately one foot or more above the mixing nozzle 26. The
mixing nozzle 26 and the diffuser nozzle 24 are identical to the
nozzles described above, with the added features described
below.
[0031] The outlet of the diffuser nozzle 24 is sized for a desired
concentration of the liquid ejected from the nozzle, and can be
11/2 inches (3.8 cm) to 23/4 inches (7.0 cm) in diameter for a
representative installation. The horizontally directed stream of
liquid impinges on a splash plate or deflector 38 to break the
liquid stream into a reasonably uniform dispersion of droplets over
a substantial area of the surface of the liquid in the tank 11
without a great upward arc which would contact the lid 12 of the
tank or require that liquid be maintained at a lower level, thereby
wasting room in the tank 11. For most installations, an additional
four feet (1.2 meters) of "head room" is required above the
diffuser nozzle 24 to allow the stream to be dispersed without
contacting the tank lid 12.
[0032] As shown in FIGS. 10 and 11, the diffuser nozzle 24 includes
a standard coupling 41 to attach to the pipe 36 leading from mixing
nozzle 26 (FIG. 3). The splash plate or deflector 38, described in
detail below is carried by a support arm 46 pivoted to the
underside of the nozzle coupling 48 by a pivot pin or bolt 51.
Upright clamps 52 are attached to the support arm 46 and secure the
deflector 38 to the nozzle at the desired angle.
[0033] The deflector 38 is a key component of the surface foam
diffuser system 10. As noted above, it is desired that the nozzle
outlet be of substantial diameter to prevent clogging. It also is
desired that the exit velocity of the stream be quite high in order
to reach a sizeable area. The purpose of the deflector is to break
up the stream from the nozzle into droplets and disburse the
droplets over a long and wide area, while minimizing the height of
the spray to minimize the headroom required inside the tank 11.
Many different shapes and contours have been tested, with the
illustrated device constituting the current preferred
embodiment.
[0034] The deflector plate 38 is angled upward from below the
nozzle outlet at a small acute angle so that the horizontally
directed stream of liquid from the nozzle is deflected upward
without excessive loss of energy or a resulting high arc. A
10.degree. to 20.degree. angle of inclination, preferably about
15.degree., has been found to achieve the desired deflection.
[0035] The outer peripheral edge of the deflector 38 is a circular
arc centered at about the nozzle outlet, and of at least 90.degree.
angular extent, preferably at least about 120.degree.. If the shape
is too narrow, the spray and droplets fall off the sides of the
plate in an uncontrolled manner. In this embodiment, the radius of
the arc is about 14 inches (35.6 cm), resulting in the maximum
width of the "fan" being just over 21 inches (over 53.3 cm).
[0036] The outer arcuate edge is preferably formed with "saw tooth"
fingers 62 bent up relative to the inner portion of the plate,
preferably at an angle of about 45.degree.. The fingers or teeth
are of a sharp "V" shape having a tip radius no greater than 0.06
inch (1.5 mm), and a base radius between teeth no greater than 0.06
inch (1.5 mm). The teeth are small and closely spaced which has
been found to break up the stream and spread apart the spray of
droplets. A simple deflector with no teeth tends to concentrate the
spray pattern at a constant radius, whereas large teeth at mixed
angles and sizes break up the spray pattern, but not much water
falls within a 10-foot radius of the nozzle and the pattern is not
evenly distributed. The small, sharp teeth achieve a more uniform
pattern. In this embodiment, the teeth are about 0.625 inch (1.59
cm) long with a pitch (tip-to-tip) of about 0.575 inch (1.46 cm),
resulting in an included angle between adjustment tooth edges of
about 50.degree..
[0037] The plate portion of the deflector 38 is not planar, but
rather is curved about its center line at a radius of approximately
36 inches so that the outer corners droop downward about 2 inches
(5.1 cm) with respect to the center of the deflector 38. The convex
upper surface has been found to assist in disbursing the spray more
evenly from side to side.
[0038] The resulting spray from the diffuser 24 may cover as much
as about 50% of the top surface area of the tank contents. The
sub-surface mixing nozzle 26 facilitates rotation of the top
surface along with the lower mixing nozzles 18 to allow for the
eventual coverage of the entire top surface by the de-foaming
spray.
[0039] The following TABLE illustrates the effectiveness of the
present system compared to the use of chemical defoamants.
TABLE-US-00001 TABLE Spray vs. Chemical Increasing High Level
Diffuser Nozzle Concentration of Concentration of with Sub-Surface
Foam Height Chemical Defoamant Chemical Defoamant Mixing Nozzle
Maximum 17 to 19+ feet 11 to 12 feet 4+ feet Foam above liquid
level Minimum 5.5 to 6.5 feet 8 to 9 feet 2 feet Foam above liquid
level Approx. Avg. 12 to 13 feet 10 feet 3 feet Foam above liquid
level
[0040] The matter set forth in the foregoing description and
accompanying drawings is offered by way of illustration only and
not as a limitation. While particular embodiments have been shown
and described, it will be apparent to those skilled in the art that
changes and modifications may be made without departing from the
broader aspects of applicants' contribution. The actual scope of
the protection sought is intended to be defined in the following
claims when viewed in their proper perspective based on the prior
art.
* * * * *