Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE INVENTION
Field of the invention:
The present invention relates generally to the
construction of systems for the treatment of wastewater in
an aeration basin or lagoon. More particularly, the
invention concerns a header module for use in the operation
of such systems as part of a component.
Description of the prior art:
In a system of this type, such as the one described
in Applicant's application in Canada No. 561.448 of March
15, 1988, a header spreads across the basin; the
header being a piping installation provided with means
creating aerated water jets discharging into the basin and
causing circulation of the wastewater in an endless path and
simultaneously aerating it. A dam is formed across the path
to allow sludge to settle at the bottom of the basin. A
pumping station, built into a well, allows operation of the
system to feed the header with water drawn from the top of
the body of wastewater in the basin; aerates the water as it
is discharged into the basin; draws out sludge that has
accumulated upstream of the dam and generally circulates
water to clean the piping installation.
By the term "wastewater", as used herein, should
be understood mainly waste matter from domestic, commercial
and industrial establishments carried off in sewers and
having a high water content. Other types of liquid mixtures
may also be treated by the system.
The construction of a header in such a system is a
time-consuming and therefore expensive operation and it is
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an object of this invention to propose a standardizable
aeration header module suitable to be factory made at low
cost and to which water and air pipes can easily be
connected, in situ, to thus reduce the installation costs.
The header modules can also of course be "shop connected"
prior to shipment.
SUMMARY OF THE INVENTION
The invention as broadly disclosed hereinafter is
concerned with an aeration header module of the type
comprising:
a cylindrical wastewater passage;
a cylindrical air passage adjacent to the wastewaterS passage;
a wastewater outlet conduit extending laterally from
the wastewater passage; and
air feed means which connect the air passage and the
wastewater outlet conduit, these means including an air
conduit joining the air passage and the wastewater outlet
conduit and a venturi cone located in the wastewater outlet
conduit, and being constructed to allow air to flow by
gravity entrainment, slight negative pressure or under
pressure, from the air passage and be injected into, and
mixed with the wastewater flowing in the wastewater conduit.
According to a first embodiment of the invention
which is disclosed hereinafter but not claimed and is called
"split modular jet assembly", the module includes a body
which is essentially flat and through which the air and
wastewater passages extend perpendicularly. The air conduit
extend within the body parallel to the body outer faces, as
does the wastewater outlet conduit which opens out of the
body.
For ease in manufacturing, the body is preferably
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made up of two mirror-image but otherwise identical planar
portions flatly lying one against the other with the
passages and the conduits being in half sections in the two
body portions and respectively overlapping.
According to a second embodiment of the invention
which is disclosed and claimed hereinafter and is called
"monoblock modular jet assembly", the wastewater passage is
defined by a first cylinder; the air passage is defined by a
second cylinder; the wastewater outlet conduit is defined by
a third cylinder which is connected to the first cylinder to
extend laterally therefrom; and the air conduit is defined
by a fourth cylinder joining the second and third cylinders
laterally thereof. Once again, a venturi cone is located.
This cone has a wide base solid with the third cylinder
upstream of the fourth cylinder and extending beneath the
fourth cylinder.
Thus, the invention as it is claimed hereinaifter is
directed to a jet aeration and mixing header for use in a
water or wastewater treatment system, said header
comprising:
- a first cylinder defining a water passage,
- a second cylinder extending parallel to the first
cylinder and defining an air passage;
- at least one water outlet conduit connected to said
first cylinder and laterally extending therefrom the allow
water to be expelled out of said water passage;
- at least one air-feed cylinder, each air-feed
cylinder connecting the second cylinder to one of said at
least one outlet conduit at a given point of connection
along said one outlet conduit to allow air to be delivered
from said air passage into said water flowing through said
one outlet conduit; and
- a venturi cone mounted in each outlet conduit, said
cone having a wide inlet extending across the outlet conduit
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upstream said point of connection of the air-feed cylinder,
and a narrow outlet extending centrally in said outlet
conduit downstream said point of connection to allow, in
use, air to be drawn from the air passage and mixed with the
water expelled through the narrow outlet of said cone;
characterized in that:
- each water outlet conduit is made up of a nipple
solid with an projecting from said first cylinder and of a
T-shaped coupling having a stem section and a transverse bar
section, said transverse bar section being connected at one
end to said nipple to form therewith said outlet conduit
with said stem section acting as said point of connection
for the air-feed cylinder connected to said outlet conduit.
According to a preferred embodiment, the header
further comprises a nozzle connected to each transverse bar
section forming part of one of said at least one outlet
conduit, opposite to the one end of said transve~se bar
section connected to said nipple, said nozzle having an
inlet having an internal diameter substantially identical to
the diameter of said transverse bar, and an outlet of
smaller diameter.
According to another preferred embodiment, the
header comprises sockets integral to some of its structural
elements to interconnect all of said elements by mere
fitting.
General comments regarding the invention:
There are, at the present time, three types of jet
aeration systems to be found on the market.
A first system may be said to be of the self-
suction type where the jets are designed to draw the air or
another gas at atmospheric pressure without any means of
pressurization other than the dynamic pressure of the
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flowing wastewater. The specific geometry consists in
discharging a water jet into a venturi tube (ejector
principle) entraining and shearing air bubbles at its
discharge.
In a second system, the jets are fed by air or
another gas under pressure and by water under pressure. The
specific geometry consists in discharging a water jet into
a short venturi tube shearing air bubbles at its discharge.
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There is also a self-suction and/or single jet
mixing system wherein the jets are designed to mix a liquid
tank content using the tank liquid as pressure source to
feed the jet. The entrained or secondary fluid can be in
gas or liquid form depending on the kind of mixing desired
or whether or nor a chemical reaction is also to take place
(ex. neutralization system/equalization tank, floculation tank etc.).
These types of jet systems utilize a common source
of pressurized wastewater flowing in a plenum piping system.
The above first two types of systems can also
utilize a common air piping source if the individual air
pipe cannot be connected directly from the water surface for
such reasons as ice protection, esthetics, the life
expectancy of the e~li~nt or design reasons. If there are nosuch
reasons, then the air intake piping can be simplified
especially for the self-suction type of jet aeration system.
In fact, the air piping can than be reduced to an individual
short intake pipe having quite a small diameter instead of a
main air header running parallel to the main wastewater
header. In such cases, the only pipe header necessary is
the water pipe which can be installed parallel to the water
surface in the basin and very close to the water level. The
elevation of this water header can vary indefinitely from
deeper submergence up to an above elevation over the water
surface.
The third type can consist of a single or double
nozzle mounted on the pipe header with or without any
parallel piping.
The present invention is meant to apply to all
these different applications.
The construction of a jet-type aeration header
resides basically in attaching a primary reducer cone to a
pressurized water header to produce a water jet flowing
concentrically through a secondary long or short venturi
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cone to provide a gas bubble shearing effect at its final
discharge into the water basin. A special concern is to
ensure efficient hydraulic conditions and to provide very
smooth internal surfaces to obtain a trouble-free operation.
These two major constructional requirements can be achieved
by using piping made of fiberglass-reinforced plastic
material (F.R.P.) because of its recognized properties of
smoothness, corrosion resistance but also because an
aeration jet header involves many molded pieces to be fitted
together and attached to a round pipe. Because of necessary
intensive manual work, the quality of the jet header
construction can vary a lot like standard F.R.P.
construction as well.
Gouvernment construction agencies have recognized
these difficulties with F.R.P. material of which the
structure consists in fibers glued together by resin.
Specific F.R.P. constructional codes are now available to
ensure a minimum quality level. These codes are as follows:
- Canadian standard for F.R.P. corrosion resistant
equipment CGSB 41GP22 rev./84.
- National Bureau of Standards PS15-69 for United
States.
For different reasons (mainly construction costs,
difficulties in adapting the jet construction to these codes
etc...) no aeration jet header construction on the market
today really meets those well established constructional
requirements.
The present invention is a new header construction
capable of complying with all those quality constructional
codes.
The essence of the present invention is to provide
a modular construction suitable to attach any F.R.P. type
conical jets to a F.R.P. pipe without requiring to take
exceptions of the 41GP22 or PS15-69 codes such as:
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- drilling large orifices on an existing F.R.P. pipe
to allow for jet positioning. This pipe structure
is then seriously altered as teh fibers are cut.
The pipe can no longer meet the construction
requirements even if some reinforcement fiber
layers are locally added around the nozzles;
- using the filament wound pipe construction method
and altering the angle of orientation of the
fibers when joing around the nozzles while the jet
header is being manufactured directly on the pipe
mandrel with prefabricated jets already positioned
on this mandrel. For best pipe structure, this
angle must be uniform all along the pipe, oriented
at 55 + 2 degrees maximum. The orientation
degree may varies for some construction but it
must always remain constant within +2 degrees
maximum.
The above represent two major construction deficiencies
currently not solved by North American manufacturers.
Furthermore, recognizing the importance of quality
control for this type of construction, no manufacturer can
duly internally inspect the F.R.P. jet header. Such an
inspection is impossible because the size of the pipe is
normally too small for anyone to crawl into. Yet, such an
inspection is very important to ensure that all manual work
was performed properly with no sharp edges or pretrusions on
all internal surface and particularly at the jet connections. The pos-
sibility of a complete inspection is of the utmost importance ,o be in a
position to control clogging problems associated with poor jet
connection construction. In fact, any sharp edges will
favor fibrous material to attach, accumulate and clog the
jets.
Advantages that can be derived from the present
invention are as follows:
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It permits a proper internal and external quality
control inspection of each jet aerator header module before
its assembly to top quality F.R.P. pipes.
It allows the use of standard F.R.P. pipes meeting
5all constructional requirements dictated by 41GP22 and PS15-
69. No alteration of these pipes is necessary. Pipes can
be fabricated from one of the two methods allowed, e.g.
filament-wound type or manual hand lay-up construction.
It allows the primary jets to be centered very
concentrically with the diffuser pipe (venturi) by mean of a
molded recess forming a cavity precisely designed to receive
the primary jet.
It allows to proceed with piping size reduction
for the water and air pipes. Reducer fittings can readily
be built up within the molded jet module along with the
socket connections provided in on each side of the module.
It allows to provide all necessary attachment
pieces readily molded within the jet module assemblies to
unable the anchoring of an aeration header from the bottom
of a basin/lagoon.
It provides truly concentric alignment for all
piping connection with each jet module by means of molded
end sockets.
It allows a better quality of construction of the
jet header with all components complying with the 41GP22 and
PS15-69 construction codes.
More important is that the jet header completely
comply to the same standards of construction as a finished
product.
30It allows the jet aeration header to be assembled
near thejob site and/or on the job site itself if desirable.
In fact, the aerator modules can be shipped on the
job site to be assembled locally with standard F.R.P. pipes.
To be able to provide a state of the art jet
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header construction that complies with the 4lGP22 and
PS15-69 standards as a finished product, this invention is
based on the prefabrication of each of the jet aerator in
the form of complete individual jet module.
The fabrication of most of these components is
basically done by contact molding using manual lay-up
construction method. All critical transitions can be molded
carefully and each of the pieces are finally assembled
together to form a complete jet module truly complying with
4lGP22 and PS15-69 construction codes. These jet aerators
so formed are then ready to be connected with non-altered,
standard approved F.R.P. pipes. When all joints are
performed to the same quality standard, the whole jet
aerator header also truly complies with 41GP22 and PS15-69
codes as a finished product.
As was already explained hereinabove, the
modularity of construction can be offered in tWo!majors
versions, namely
1. a split modular jet assembly, that is disclosed herein-
after but not claimed; and
2. a monoblock modular jet assembly, that is the invention
specifically claimed hereinafter.
In the split modular jet assembly, each jet module
is constructed in two identical halves boxes to be sealed
and linked together with hardware or other mean. The
primary jet, secondary jet and the air transfer pipe are to
be attached between these two halves during the assembly.
In the monoblock modular jet assembly,
prefabricated jet modules are constructed so as to be ready
to be mounted on regular non altered fiberglass pipe. This
monoblock version that is claimed hereinafter has the
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advantage of avoiding any sealing requirement within the jet
assembly as each component piece of the modular assembly is
fabricated in one piec- instead of ~
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construction.
Both constructions are of the modular type and
allow for a better quality of construction e.g. permit to
meet the established Canadian 41GP2Z and corresponding
American PS15-69 fabrication standards.
A description now follows of preferred embodiment
of this invention having reference to the appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective and exploded view of a
header module made according to the first embodiment of the
invention called "split modular jet assembly";
Figure 2 is a perspective and exploded view of a
header module section of a jet aeration system incorporating
a header module according to Figure l;
Figure 3 is an exploded view in perspective of a
header module made according to the second embodiment of the
invention called "monoblock modular jet assembly";
Figure 4 is an exploded view in perspective
similar to that of Figure 2 but with the module of Figure 3.
Description of the preferred embodiments:
The header module 1, in Figure 1, has an
essentially flat body made up of two plate-like parts 3, 5
identical in configuration but where one is a mirror-image
of the other, like two symmetrical half shells of a mold.
The parts 3, 5 have large cylindrical through bores 7, 9
normal to the parts outer faces 15, 17 and small cylindrical
through bores 11, 13 also normal to the outer faces 15, 17
so that when the faces 15, 17 are flatly applied one against
the other, as in Figure 2, and sealed or otherwise secured
together, the bores 7, 9 are coaxial and form a wastewater
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passage 23. Likewise, the bores 11, 13 register to define
an air passage 25. Two half cylindrical straight cavities
27, 29 are provided which, in assembly of the plates 3, 5
join together to define a wastewater outlet conduit 31
(Figure 2) extending laterally from the wastewater passage
23 and out of the header body through a port 33.
As said before, the module 1 further comprises air
feed means connecting the air passage 25 and the wastewater
outlet conduit 31 and so constructed as to draw air or
receive air under pressure from the air passage 25 and
deliver it into the outlet conduit 31 for mixing with the
wastewater flowing from the wastewater passage.
In the embodiment of Figures 1 and 2, the airfeed
means comprise a further pair of straight half-cylindrical
cavities 35, 37 which, when registering as in Figure 2,
define an air conduit 39 joining the air passage 25 and the
watewater outlet conduit 31. The air feed means further
comprise a venturi cone 41 located within the outlet conduit
31 as shown in dotted lines in Figure 1. The large base of
the cone is made solid with the inner wall of the outlet
conduit 31 upstream of the air conduit 39. The venturi cone
41 extends fully beneath the outlet opening of the air
conduit 35. In this manner and according to the Venturi
principle, wastewater under pump pressure in the passage 23
flows through the cone 41 and is subjected to a drop in
static pressure at the outlet of the cone which creates a
suction effect suitable to draw atmospheric air from the
passage 25 via the air conduit 39, which air mixes with the
wastewater in the conduit 31. Air can also be fed under
pressure.
As mentioned previously and for best performance,
the header module 1 is made entirely of fiberglass
reinforced polyester (F.R.P.) material.
In use of a jet aeration system for aerating
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wastewater in an aeration basin or lagoon, a plurality of
header modules 1 are disposed across the basin in spaced
apart relation and with their passages 23 and 25 coaxial.
As gathered from Figure 2, wastewater pipes 43
have their ends slid and secured into the sockets defined
by the passages 23 of successive modules so that the
assembly of the modules 1 and pipes 43 define a pressurized
wastewater plenum pipe-line feeding into the wastewater
outlet passages 31. Air pipes 45 are connected to the air
passages 25 of the spaced modules in the same manner.
Secondary jet nozzle (not shown in Figure 2) may be provided
in the parts 33 of the outlet conduit 31 to best suit the
actual applications.
As illustrated in Figure 1, the ends of the
wastewater pipes may be secured in sockets formed in each
body part 3, 5 by a counterbore 47 separated from the bore
49 of the passage 9 by a radial shoulder 51 against to which
the pipe end may abut. A similar construction may be
applied to the air passage 11. On the other hand and as
shown in Figure 2, the shoulder feature may be avoided and
the ends of adjoining pipes made to abut one another.
In the embodiment of Figures 3 and 4, the body of
the header module 53 comprises a first cylinder 55 which
defines the wastewater passage 23'; this first cylinder
having end sockets 57, 59 for the connection of wastewater
pipes 61, 63. A second cylinder 65, also having end sockets
67, 69 for air pipes 71, 73 defines the air passage 25'.
The wastewater outlet conduit here is a third cylinder made
up of a nipple 71 solid with and extending laterally of the
first cylinder 55; the transverse section of a T-pipe
coupling 73 of which one socketed end 74 is connected to the
nipple 71, and a nozzle 75 connected to the other socketed
end 76 of the T-coupling 73. A fourth arcuate cylinder 77,
part of the air feed means, joins a socketed end 78 of the
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stem section of teh T-coupling 73 and a nipple 80 on the
second cylinder 65. Finally, the air feed means venturi
cone 81 is provided in the nipple 71 and connected in the
same manner as the venturi cone 41 in the module of Figures
5 1 and 2. The cylinders and venturi cone are solid with one
another and form an integrated modular unit.
It will be noted that the first and second
cylinders 55, 65 are parallel while the third cylinder
(nipple 71, branch 74, 76 of T-coupling 73 and nozzle 75)
10 and the fourth cylinder 77 extend normal to the first and
second cylinders 55 and 65.
As in the first embodiment also, all components of
the header module 53 are molded in F.R.P. material.
The operation of the module 53 is obviously the
15 same as that in Figure 1.
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