U.S. patent application number 12/858664 was filed with the patent office on 2010-12-09 for sewage fluid interface barrier.
Invention is credited to Shahriar Eftekharzadeh.
Application Number | 20100310317 12/858664 |
Document ID | / |
Family ID | 43300856 |
Filed Date | 2010-12-09 |
United States Patent
Application |
20100310317 |
Kind Code |
A1 |
Eftekharzadeh; Shahriar |
December 9, 2010 |
SEWAGE FLUID INTERFACE BARRIER
Abstract
A sewer comprising a barrier disposed to prevent or reduce the
flow of air in the headspace, oppose the escape of gases and/or
liquid droplets from within the liquid into the headspace of the
sewer, and also oppose the drawing in and entrainment of headspace
air and gases into the liquid contained within the sewer. The sewer
comprises a conduit and a barrier fixed within the interior of the
sewer, which extends longitudinally along the sewer conduit so as
to separate the sewer conduit into a liquid conductive channel
disposed below the barrier and a gas conductive channel disposed
above the barrier. The barrier may move up and down within the
sewer responsively with varying water flow within the sewer. The
barrier may comprise an elastomeric sheet. The barrier may be
tubular at areas of steep plunge.
Inventors: |
Eftekharzadeh; Shahriar;
(Torrance, CA) |
Correspondence
Address: |
ITALIA IP
3500 WEST OLIVE AVE., SUITE 300
BURBANK
CA
91505
US
|
Family ID: |
43300856 |
Appl. No.: |
12/858664 |
Filed: |
August 18, 2010 |
Current U.S.
Class: |
405/129.75 |
Current CPC
Class: |
E03F 3/04 20130101; E03F
7/00 20130101 |
Class at
Publication: |
405/129.75 |
International
Class: |
E03F 3/00 20060101
E03F003/00 |
Claims
1. A sewer construction provided with a barrier to prevent or
reduce the dragging of the air within the sewer headspace by the
flowing liquids thereby preventing or reducing the flow of air in
the headspace, opposing the escape of dissolves gases and/or liquid
droplets from the liquids into the headspace of the sewer, and also
opposing the drawing in and entrainment of headspace air and gases
into the liquid contained within the sewer, comprising: a sewer
conduit having a circumferential wall for confining liquids within
the sewer and a longitudinal axis, and comprising at least one
entry opening which opens the interior of the circumferential wall
to the environment, for allowing access to the interior of the
sewer for maintenance, enabling inflow or outflow of air, or
enabling collection of liquids to be discharged, and a discharge
opening for discharging collected liquids contained within the
sewer conduit to the exterior of the sewer conduit; and a barrier
fixed to the sewer conduit within the interior of the sewer
conduit, wherein the barrier is disposed to extend longitudinally
along the sewer conduit and to separate the sewer conduit into a
liquid conductive channel disposed below the barrier for conducting
liquids and a gas conductive channel disposed above the barrier,
wherein the barrier is disposed to move radially with respect to
the longitudinal axis so as to vary the respective volumes of the
liquid conductive channel and the gas conductive channel.
2. The sewer construction of claim 1, wherein the barrier is
disposed to move radially with respect to the longitudinal axis so
as to vary the respective volumes of the liquid conductive channel
and the gas conductive channel spontaneously responsive to the
volume of liquid contained within the liquid conductive
channel.
3. The sewer construction of claim 1, wherein the barrier comprises
a flexible material.
4. The sewer construction of claim 1, wherein the barrier is
partially liquid impermeable.
5. The sewer construction of claim 1, wherein the barrier is fully
liquid impermeable.
6. The sewer construction of claim 1, wherein the barrier is
partially gas impermeable.
7. The sewer construction of claim 1, wherein the barrier is fully
gas impermeable.
8. The sewer construction of claim 1, wherein the barrier comprises
a sheet.
9. The sewer construction of claim 1, wherein the barrier comprises
a sheet along some of the length of the sewer conduit and a tube
along other portions of the length of the sewer conduit.
10. The sewer construction of claim 9, wherein the barrier
comprises a sheet along its entire length.
11. The sewer construction of claim 9, wherein the barrier
comprises a tube along its entire length.
12. A method of operating a sewer which contains both liquid and
also air within a headspace located above the liquid, comprising
the steps of: providing a barrier within the sewer along at least a
portion of the length of the sewer, which barrier extends
longitudinally along the sewer and is interposed between the liquid
and the air of the headspace.
13. The method of claim 12, comprising the further step of
anchoring a first end of the barrier at a point within the
sewer.
14. The method of claim 13, comprising the further step of
anchoring a second end of the barrier at a second point within the
sewer
15. The method of claim 12, comprising the further step of enabling
the barrier to move radially with respect to the longitudinal axis
of the sewer so as to vary the respective volumes of the sewer
above the barrier and below the barrier.
16. The method of claim 15, comprising the step of causing the
barrier to move radially with respect to the longitudinal axis of
the sewer spontaneously responsive to the volume of liquid
contained within the liquid conductive channel.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to sewers, and more
particularly to improvements thereto for reducing interaction
between liquid flow in a sewer and air occupying the space above
the liquid level, referred to herein as the "headspace", by
imposing a physical barrier between liquid and air.
BACKGROUND OF THE INVENTION
[0002] Sanitary and storm sewers conduct fluent wastes away from
infrastructure such as buildings and roads. Most sewers rely upon
gravity to induce flow of fluent wastes. Both gravity operated and
pressurized sewers are open to ambient air at one point or another.
Sewers are susceptible to formation of objectionable gases and
other substances which may be formed in fluent wastes and released
to ambient air. Hydrogen sulfide is one such gas which arises from
bacterial decomposition of organic materials such as sewage solids
which are mixed with water to form a fluent mixture. Also, other
substances and hydrocarbon compounds such as methane can form with
other chemical products of sewage systems. Methane itself is a
colorless odorless gas which is objectionable because it is
flammable and because in sufficient quantity, it can displace
oxygen. Sulfur and other compounds typically generate objectionable
odors and may also be reactive and even toxic. Air within the
headspace in sewers is dragged along by the flowing sewage
resulting in airflow within the sewer headspace. Flowing air in the
sewer headspace may result in sewer pressurization, particularly at
locations where there is a change in sewer cross section,
junctions, changes in longitudinal slope, inverted siphons, and
other obstacles to sewer air flow. This in turn causes the sewer
air and its objectionable gases to be forced out of the sewer into
the surrounding atmosphere and neighborhoods.
[0003] In addition, flowing sewer air becomes entrained with liquid
sewage, particularly at locations where liquid sewage falls steeply
or vertically into downstream sewers or standing liquid sewage.
Downstream of such locations, increased turbulence from energy
dissipation results in increased sewer pressurization accompanied
with sewage aerosol droplets and release of entrained air. This, in
turn, causes increased potential for the release of sewer air and
its objectionable gases to the surrounding atmosphere and
neighborhoods.
[0004] Sewers typically extend for long distances and in so doing
pass by many occupied buildings. Release of objectionable gaseous
or gas borne contaminants into the ambient air near these buildings
is objectionable, and occurs if no steps are taken to prevent this
from happening. A mixture of sewer air, hydrogen sulfide, methane,
and diverse chemical contaminants escaping from a sewer system and
entering into areas of human activity is objectionable and
intolerable.
[0005] Sewer air treatment facilities have been developed to remove
and treat the liquid borne gases from the sewer air. While such
facilities have been proven relatively effective at removing the
objectionable gases from the sewer air, they are treating the
symptom and not dealing with the underlying causes, which is the
flow of air in the headspace and its contamination with sewage born
gases. Another approach has been to use chemicals for neutralizing
sewage components that generate the objectionable gases. However,
these require extensive and continuous use of potentially harmful
chemical that must be used in proportion to need, can be depleted
by reacting with sewage before the entire length of the sewer has
been remediate by chemical neutralization, and may also be depleted
by evaporation or entrainment with gases escaping from liquid
sewage.
[0006] There remains a need for eliminating or reducing the flow of
air in the headspace of sewers, its contamination with sewage borne
gases, and entrainment and re-release of sewer air into and out of
liquid sewage within sewer conduits.
SUMMARY OF THE INVENTION
[0007] The present invention provides an answer to the above stated
need by interposing a physical barrier between liquid sewage and
the headspace thereabove. The barrier may be flexible and movable
in a direction perpendicular to liquid flow so as to accommodate
fluctuations in volume of flow while still providing the barrier
function.
[0008] The barrier may for example take the form of a flexible
water impermeable, gas impermeable blanket which spans the interior
diameter of an associated sewer conduit and is supported at least
at one end within the sewer conduit so as to rest on liquid sewage
occupying the sewer conduit. The end opposite that which is
supported may be unattached to the sewer conduit or alternatively
may be supported within the sewer conduit. The blanket may isolate
the liquid sewage from air occupying the headspace above the liquid
sewage. This will both oppose the air within the headspace from
being dragged along into the liquid sewage that establishes a
current of air within the headspace, and will also prevent the
sewer air from being drawn in and entrained in the sewage. It will
further entrap and oppose escape of gases and sewage droplets which
may come out of suspension within the liquid sewage or be sprayed
out at locations of turbulence. All of these occurrences will
assist in preventing fouling of ambient air outside yet near the
sewer.
[0009] The barrier may be arranged to rise and fall within a sewer
conduit for example, to accommodate fluctuations in depth of liquid
sewage.
[0010] The barrier may be formed in serial sections to collectively
cover long expanses of sewer. Each of these serial sections may be
independently supported to the interior wall of the sewer.
[0011] The barrier may be of floatable material itself or portions
of the barrier may incorporate floats to assure that the barrier
remain above liquid contained within the sewer.
[0012] The barrier may be formed with some portions along which the
barrier forms a sheet and others wherein the barrier forms a tube.
The latter situation may come into play at locations where the
sewer undergoes a vertical or steep non-vertical plunge or the
like. In such situations, the barrier may be tubular, so as to
conduct liquid sewage past the plunge. In such situations, sheet
construction of the barrier could potentially interfere with
intended operation.
[0013] It is an object of the invention to provide a barrier at the
liquid-to-gas interface within a sewer for opposing drag-induced
air flow and migration of gases along the headspace of the sewer
and also opposing drawing of headspace gases into entrainment
within the liquid as well as preventing the release of entrained
gases within the sewage.
[0014] It is an object of the invention to provide improved
elements and arrangements thereof by apparatus for the purposes
described which is relatively inexpensive, dependable, and fully
effective in accomplishing its intended purposes.
[0015] These and other objects of the present invention will become
readily apparent upon further review of the following specification
and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Various objects, features, and attendant advantages of the
present invention will become more fully appreciated as the same
becomes better understood when considered in conjunction with the
accompanying drawings, in which like reference characters designate
the same or similar parts throughout the several views, and
wherein:
[0017] FIG. 1 is a cross sectional view of a sewer construction
according to at least one aspect of the invention.
[0018] FIG. 2 is a cross sectional view taken along line 2-2 in
FIG. 1.
[0019] FIG. 3 is a cross sectional view similar to FIG. 2, but
showing a slightly decreased volume flow of liquid contained within
the sewer construction from that of FIG. 1.
[0020] FIG. 4 is a cross sectional view similar to FIG. 2, but
showing a slightly increased volume flow of liquid contained within
the sewer construction from that of FIG. 1.
[0021] FIG. 5 is a cross sectional view similar to FIG. 2, but
showing the sewer construction entirely filled with liquid.
[0022] FIG. 6 is a cross sectional view similar to FIG. 1, but
showing a greater length of the subject sewer construction.
[0023] FIG. 7 is a cross sectional view of a sewer construction
according to the tubular aspect of the invention, wherein there is
an abrupt change in elevation of the system.
DETAILED DESCRIPTION
[0024] Referring first to FIG. 1, there is shown a sewer
construction according to at least one aspect of the invention
wherein the sewer construction is provided with a barrier
preventing the imposition of drag forces at the surface of flowing
liquid 102 in sewer 100, upon the air within the sewer headspace
104, thereby preventing the flow of air in the headspace. The
barriers is also opposing the escape of gases and droplets (not
visible) generated within liquids 102 contained within the sewer
100 into the headspace 104 of the sewer 100 and also opposing the
drawing in and entrainment of headspace air and gases into the
liquid 102 contained within the sewer 100. The sewer 100 will be
understood to be a system comprising of at least one sewer conduit
106 and ancillary components such as a manhole, a vent, or another
sewer 108 which opens to the exterior of the sewer 100 to permit
air and or liquids to enter the sewer 100.
[0025] The sewer conduit 106 is typically made from concrete, cast
iron, steel, brick, and other durable substances, and comprises a
circumferential wall 110 for confining liquids such as the liquid
102 within the sewer 100 and a longitudinal axis 112. The liquid
102 may be any liquid intended to be collected for conveyance
and/or disposal, such as water from rainfall, domestic wastewater
containing solid waste, or any liquid which is collected in a
system which is open to the environment as opposed to a sealed
system such as a pressurized domestic water supply. The sewer
conduit 106 may have an entry opening 114 such as that shown formed
in the manhole or vent 108. The entry opening opens the interior of
the circumferential wall 110 to the environment, for allowing
access to the interior of the sewer for maintenance, enabling
inflow or outflow of air, or enabling collection of liquids to be
discharged. The sewer 100 terminates in a discharge opening (not
shown) for discharging collected liquids contained within the sewer
conduit 106 to the exterior thereof, such as the head works of a
sewage treatment plant.
[0026] The sewer conduit 106 is provided with a suitable support
mechanism for fixing or holding the barrier in operable position
within the interior of the sewer conduit 106. The barrier may
comprise an elastomeric sheet 116 for example. It is preferred that
the barrier be gas impermeable, water impermeable, and flexible.
Many available elastomeric substances such as natural and synthetic
rubbers and plastics, among others, satisfy these demands and are
suitable for forming the barrier. The support mechanism may
comprise a hoop 118 provided with an pivotally supported arm 124
pivotally anchored to the hoop 118 at a swivel joint 122. The arm
124 may comprise a clamp 120 for grasping the elastomeric sheet
116. Of course, the support structure may take any convenient form
such that it solidly engages the circumferential wall 110 and
reliably holds the barrier. Similarly, the arm 124 may be replaced
by different arrangements, including but not limited to the direct
fastening of the barrier blanket itself to the wall of the
sewer.
[0027] The barrier is disposed to extend longitudinally along the
sewer conduit 106, generally parallel to the longitudinal axis 112.
Most sewer systems are gravity operated, and are built with slight
inclination from a purely horizontal direction to promote flow in a
desired direction. Therefore, the support mechanism is located
upstream from the barrier where the barrier may be supported at
only one end. As will be described hereinafter, it is possible to
support the barrier at more than just one point.
[0028] The barrier separates the sewer conduit into a liquid
conductive channel disposed below the barrier for conducting the
liquid 102, and a gas conductive channel disposed above the
barrier. It will be understood that the air conductive channel,
which comprises the headspace 104 and the liquid conductive
channel, which is that space occupied by the liquid 102, are to be
regarded as semantic distinctions as these channels are not
separate physical elements unto themselves. Rather, the channels
refer to the spaces occupied respectively by air 104 and by the
liquid 102. These spaces or volumes vary with the flow of the
liquid 102, as flow refers to volume of the liquid 102 occupying
the sewer 100. To facilitate this variation while simultaneously
performing its function of segregating the liquid 102 from gases of
the headspace 104, the barrier is disposed to move radially with
respect to the longitudinal axis 112. That is, the barrier may be
located at any of many points ranging from proximate the bottom of
the sewer conduit 106 to proximate the top thereof, as seen in FIG.
1.
[0029] It should be noted at this point that orientational terms
such as top and bottom refer to the subject drawing as viewed by an
observer. The drawing figures depict their subject matter in
orientations of normal use, which could obviously change with
different sewer systems. Therefore, orientational terms must be
understood to provide semantic basis for purposes of description,
and do not limit the invention or its component parts in any
particular way.
[0030] The motion of the barrier is enabled by a pivotal connection
120 of the arm 124. The pivotal connection 120 enables the arm 124
to swing in an arcuate motion through an arc 126. Of course, the
arm 124 could be replaced by a linearly moving device for example
or other arrangement provided it enables the barrier to track
height of the liquid 102 within the sewer conduit 106, including
the barrier blanket itself. Any motion which effectively enables
the barrier to track height of the liquid 102 will be referred to
as radial motion as that motion extends in directions which radiate
from the longitudinal axis 112.
[0031] The barrier may also have the characteristic that it
responds spontaneously to variations in the height or volume of the
liquid 102. Where the barrier is provided by the elastomeric sheet
116, it will be seen that with the elastomeric sheet 116 secured to
the sewer conduit 106 at a fixed point, the liquid 102 itself and
gravity will combine to impose forces which raise and lower the
elastomeric sheet 116 with rising and falling flow or volumes of
the liquid 102. This action is spontaneous in that no external
controls or motive forces need be applied to cause the elastomeric
sheet 116 to accommodate variation in flow or volume.
[0032] FIG. 2 shows the elastomeric sheet 116 spanning the interior
diameter of the sewer conduit 106, as it would with the liquid 102
occupying about half of the total cross sectional area of the sewer
conduit 106.
[0033] Variations of height of the liquid 102 within the sewer
conduit 106 may be accommodated in part by the ability of the
elastomeric sheet 116 to have its edges 128, 130 turn upwardly
(FIG. 3) or downwardly (FIG. 4) as the volume of the liquid 102
varies. FIG. 5 shows how the elastomeric sheet 116 may deflect
should the sewer conduit 106 fully fill with the liquid 102.
[0034] FIG. 6 shows a serial arrangement of barrier elements within
a sewer construction 200. It will be appreciated that as the
elastomeric sheet 116 becomes longer and longer, installation,
removal, and maintenance thereof become increasingly problematic.
Extremely long runs of elastomeric sheet 116 may cause problems in
orderly operation, such as twisting or other deformations which
could prevent effective operation. To forestall such problems, the
barrier may be formed in repeating sections.
[0035] The sewer construction 200 may comprise a sewer conduit 206
in which a first elastomeric sheet 216A and a second elastomeric
sheet 216B are provided serially so as to provide essentially
continuous coverage of the liquid 202 contained within the sewer
conduit 206 apart from minor gaps which may be present
therebetween, particularly at junctions and locations of lateral
inflow by other sewers. Each barrier element such as the
elastomeric sheets 216A, 216B may be secured at the top of the
sewer conduit 206 by respective support mechanis, which may
comprise a hoop such as the hoop 118 of FIG. 1, or which may take
other forms. Regardless of its form, the support structure may
include a swivel 222A or 222B for pivotally anchoring a respective
arm 224A or 224B comprising a respective clamp 220A or 220B adapted
to engage and operably support its respective elastomeric sheet
216A or 216B, which may be continuous as shown or in distinct
separate sections. The respective clamp 220A or 220B may simply be
the direct fastening of the respective elastomeric sheet 216A or
216B to the sewer. The serial arrangement of barrier elements
depicted in FIG. 6 may be extended along the entirety of the sewer
conduit 206 to implement a sewer construction 200 protected along
its entire length against interaction of headspace gases and the
liquid 202.
[0036] Flow of the liquid 202 is in a direction indicated by an
arrow 228. It will be seen that the swivels 222A, 222B are located
upstream with respect to flow of the liquid 202 from their
respective elastomeric sheets 216A, 216B. Spacing of the swivels
222A, 222B and the respective elastomeric sheets 216A, 216B from
one another may be modified to suit conditions so as to minimize
any portion of the liquid 202 which may be exposed to the headspace
204 between adjacent elastomeric sheets 216A, 216B.
[0037] FIG. 7 shows further aspects of the invention. In FIG. 7, a
sewer construction 300 includes an abrupt drop in elevation wherein
a first generally horizontal section 306 of sewer conduit
communicates with a vertical section 340 of sewer conduit, which in
turn communicates with a second generally horizontal section 342 of
sewer conduit. The sewer construction 300 copes with this abrupt
drop by providing a barrier which negotiates the expanse of drop is
in the form of a tube 344.
[0038] It will be seen that the distal end 346 of a barrier element
in the form of a sheet 348, the same configuration as the
elastomeric sheet 116 of FIG. 1, may terminate at the same
anchorage point 350 as that used to support a proximal end 352 of
the tube 344, or may terminate either downstream or upstream of
point 350 as appropriate or deemed necessary by practical
considerations. The tube 344 may be supported about the full
circumference of its proximal end by a hoop structure 354 formed as
part of that structure providing the anchorage point 350. The tube
344 may distend and collapse depending upon the volume of liquid
302 flowing therethrough at any one time. The tube 344 may be
superseded by another sheet barrier element (not shown) at the
distal termination (not seen in FIG. 7) of the tube 344. The sewer
construction 300 may be summarized as comprising a barrier which in
turn comprises a sheet (such as the sheet 348) along some of the
length of the associated sewer conduit assembly (comprising for
example the sewer conduits 306, 340, and 342) and a tube (such as
the tube 344) along other portions of the length of the sewer
conduit assembly. Although the sewer conduits 306, 340, 342 may be
provided in sections for ease of fabrication and assembly, it will
be recognized that after assembly, they collectively form a single
sewer conduit.
[0039] The invention may also be considered a method of operating a
sewer which contains both liquid and also air within a headspace
located above the liquid. The method may comprise a fundamental
step of providing a barrier within the sewer along a portion or the
majority of the length of the sewer, which barrier extends
longitudinally along the sewer and is interposed between the liquid
contained within the sewer and the air of the headspace.
[0040] The method may also include the steps of anchoring a first
end of the barrier at a fixed point within the sewer, anchoring a
second end of the barrier at a fixed point within the sewer,
enabling the barrier to move radially with respect to the
longitudinal axis of the sewer so as to vary the respective volumes
of the sewer above the barrier and below the barrier, and causing
the barrier to move radially with respect to the longitudinal axis
of the sewer spontaneously responsive to the volume of liquid
contained within the liquid conductive channel.
[0041] The steps of the method refer to apparatus shown and
described with connection to FIGS. 1-7. The steps may be practiced
in any feasible order and combination independently of other
steps.
[0042] Although presented in terms of a sewer the usual purpose of
which is to dispose of storm water or sewage or both, the present
invention is obviously adaptable to the purpose of other liquid
systems which rely on gravity for at least a portion of their
extent. For example, irrigation and liquid transfer systems,
canals, tunnels and other liquid transport and conveyance systems,
fire suppression systems, and still others will be understood to
fall within the scope of the term "sewer" as employed herein.
[0043] The present invention is susceptible to modifications and
variations which may be introduced thereto without departing from
the inventive concepts. For example, a barrier or a portion thereof
may be rigid rather than flexible. Sewer conduits may be oblong,
rectangular, or otherwise configured in cross section (such as the
cross section shown in FIG. 2.
[0044] While the present invention has been described in connection
with what is considered the most practical and preferred
embodiment, it is to be understood that the present invention is
not to be limited to the disclosed arrangements, but is intended to
cover various arrangements which are included within the spirit and
scope of the broadest possible interpretation of the appended
claims so as to encompass all modifications and equivalent
arrangements which are possible.
* * * * *