U.S. patent application number 13/949891 was filed with the patent office on 2014-01-30 for relief valve for extracting sub-surface gas.
Invention is credited to Michael R. AYERS, Delaney LEWIS, Jose URRUTIA.
Application Number | 20140026987 13/949891 |
Document ID | / |
Family ID | 49993699 |
Filed Date | 2014-01-30 |
United States Patent
Application |
20140026987 |
Kind Code |
A1 |
AYERS; Michael R. ; et
al. |
January 30, 2014 |
RELIEF VALVE FOR EXTRACTING SUB-SURFACE GAS
Abstract
A relief valve for extracting sub-surface gas from beneath a
geomembrane includes a valve body for permitting gas to flow
therethrough and includes an inlet, an outlet, a vertical run
communicating with the inlet, and a lateral run communicating with
the vertical run and the outlet. A ball valve comprising a ball
seat is positioned within the vertical run. A lightweight valve
ball positioned within the vertical run. The valve ball is movable
therewithin between a lowered position against a ball seat and an
elevated position distal therefrom. The valve ball is lightweight
enough that minimal upward gas flows within the vertical run cause
the valve ball to rise and become unseated from the ball seat such
that stoppage of such vertical flows or reverse flows cause the
valve ball to drop back to its ball seat and seal against reverse
flows through the ball valve.
Inventors: |
AYERS; Michael R.;
(Alpharetta, GA) ; LEWIS; Delaney; (West Monroe,
LA) ; URRUTIA; Jose; (Suwanee, GA) |
Family ID: |
49993699 |
Appl. No.: |
13/949891 |
Filed: |
July 24, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61675071 |
Jul 24, 2012 |
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Current U.S.
Class: |
137/533.11 |
Current CPC
Class: |
Y10T 137/791 20150401;
E21B 34/02 20130101; E21B 34/00 20130101 |
Class at
Publication: |
137/533.11 |
International
Class: |
E21B 34/00 20060101
E21B034/00 |
Claims
1. A relief valve for extracting sub-surface gas comprising: a
valve body having an inlet, an outlet, a vertical run communicating
with the inlet, and a lateral run communicating with the vertical
run and with the outlet; a ball valve comprising a ball seat
positioned within the vertical run; the ball valve further
comprising a valve ball positioned within the vertical run and
being movable therewithin between a lowered position against the
ball seat and an elevated position distal therefrom, the valve ball
being lightweight such that minimal upward gas flows within the
vertical run cause the valve ball to rise and be unseated from the
ball seat and such that stoppage of such vertical flows or reverse
flows cause the valve ball to drop back to its ball seat and seal
against reverse flows through the ball valve; whereby large or
small positive pressures beneath the inlet cause flow up through
the ball valve and out through the outlet, but even small negative
pressures below the inlet cause the ball valve to close and prevent
flows down through the ball valve in the vertical run.
2. The relief valve as claimed in claim 1 wherein the lateral run
includes a horizontal portion and a vertical portion.
3. The relief valve as claimed in claim 2 wherein the horizontal
portion of the lateral run is partly horizontal and partly
vertical.
4. The relief valve as claimed in claim 2 wherein the lateral run
includes a first portion that extends laterally and downwardly.
5. The relief valve as claimed in claim 4 wherein the lateral run
includes a second portion that extends downwardly.
6. The relief valve as claimed in claim 1 wherein the valve body
includes a threaded portion adjacent the inlet for connecting the
relieve valve to a header or conduit.
7. The relief valve as claimed in claim 1 wherein the valve ball is
hollow.
8. The relief valve as claimed in claim 7 wherein the valve ball is
filled with a lighter-than-air gas.
9. The relief valve as claimed in claim 1 wherein the valve seat is
cup-shaped.
10. The relief valve as claimed in claim 1 wherein the valve seat
is tapered.
11. The relief valve as claimed in claim 1 wherein the relief valve
is operable to work at pressure differentials below 3 psi.
12. The relief valve as claimed in claim 1 wherein the relief valve
is operable to work at pressure differentials below about 1.0
psi.
13. The relief valve as claimed in claim 1 wherein the relief valve
is operable to work at pressure differentials as low as about 0.1
psi.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority benefit of U.S.
Provisional Patent Application Ser. No. 61/675,071, filed Jul. 24,
2012, which is hereby incorporated herein by reference.
BACKGROUND
[0002] As described in published U.S. Patent Application Number
20060034664, conventional gas extraction wells at landfills often
involve deep wells attached to a network of pipes and a gas pump
(blower) that applies vacuum to extract the gas from the stored
waste. The profile of surface emission flux is recognized to lead
to potential for some emissions away from the wells under most
circumstances. Note also that there is almost always entrainment of
gas, whether LFG or atmospheric air, through the surface area most
proximate to deep collection. Both LFG emission far from wells, and
air entrainment proximate to subsurface collection, are well
recognized as deleterious to collection efficiency. A "tradeoff"
exists between extracting or "pulling" at too high a flow rate and
entraining excessive atmospheric air, and pulling too little and
recovering less LFG. This poses one dilemma of conventional
extraction.
[0003] A prior art arrangement according to the above published
patent application is shown in FIG. 1. Landfill 1 containing waste
2 generates biogas (biogas flows shown by the arrows). Biogas is
collected and extracted through well 3. The well 3 includes a
gas-collecting wellhead 16 and a gas-impermeable conduit 17 linking
the wellhead to the surface to draw biogas from the wellhead to the
surface. Overlaying the majority of the waste 2 is a gas-permeable
layer 5. The term "wellhead" refers to a section of the
gas-extraction well where gas can enter the well, e.g. a section of
pipe having slots or other gas-flow apertures cut in it. Often, the
wellhead is also surrounded with gravel. The gas-permeable layer is
typically composed of a conductive porous matrix with gas flow
paths. Often it is composed of rigid or semi-rigid particles of a
large enough size to leave a significant void volume between
particles. For instance, the gas-permeable layer may contain
gravel, wood chips, or shredded tires. Above the gas-permeable
layer is a gas-containment layer 7. Biogas that rises from the
landfill reaches the gas-permeable layer where it is trapped by the
overlying gas-containment layer 7. The biogas migrates horizontally
in the gas-permeable layer until it comes close to a well. Gas
extraction from the well creates a vacuum that draws gas into the
well. This vacuum draws biogas from the overlying gas-permeable
layer down through the waste mass of the landfill to reach the
well. The area immediately beneath the gas-permeable high
conductivity layer 5 through which a substantial fraction (at least
30%) of the biogas from the gas-permeable layer passes as it
travels to the gas-collection wellhead is the entrainment zone 9.
On its passage through the waste 2, the gas from the gas-permeable
layer mixes with biogas produced in the waste mass that has not
gone through the gas-permeable layer. This helps to give a
consistent content to the biogas that is withdrawn from the well.
If gas is withdrawn directly from the gas-permeable conductive
layer, the gas composition will vary more dramatically over time,
sometimes containing a high air content and sometimes not. It is
sometimes desirable to place an even more impermeable layer, such
as geomembrane 15, directly over the zone of entrainment of gas
from the permeable layer that is created by the deep well.
Moreover, sometimes the entire landfill is covered with such a
membrane.
[0004] FIG. 2 shows another prior art arrangement, this time
showing a more shallow wellhead 26 used to withdraw sub-surface gas
from beneath a membrane M capping a waste W. The wellhead 26 is
attached to an above-ground conduit by way of a vertical pipe.
Where the pipe extends through the membrane M, such is prone to gas
leakage out and/or air leakage in (depending on the relative
pressures in the waste W and the atmosphere). To address this, it
has been known in the prior art to install a polymer boot B which
typically is bonded (welded or glued) to the membrane M and bonded
or clamped to the pipe P. Unfortunately, such boots are rather
prone to leakage and the seal provided thereby is less than
ideal.
[0005] Accordingly, it can be seen that there exists a need for a
better way for extracting sub-surface gas from near the surface of
landfills. It is to the provision of solutions to this and other
problems that the present invention is primarily directed.
SUMMARY OF THE INVENTION
[0006] In a first example form the present invention comprises a
relief valve for extracting sub-surface gas from beneath a
geomembrane. The relief valve includes a valve body for permitting
gas to flow therethrough. The valve body includes an inlet, an
outlet, a vertical run communicating with the inlet, and a lateral
run communicating with the vertical run and the outlet. A ball
valve comprising a ball seat is positioned within the vertical run.
The ball valve comprises a valve ball positioned within the
vertical run. The valve ball is movable therewithin between a
lowered position against the ball seat and an elevated position
distal therefrom.
[0007] Preferably, the valve ball is lightweight such that minimal
upward gas flows within the vertical run cause the valve ball to
rise and become unseated from the ball seat such that stoppage of
such vertical flows or reverse flows cause the valve ball to drop
back to its ball seat and seal against reverse flows through the
ball valve.
[0008] Preferably, large or small positive pressures beneath the
inlet cause flow up through the ball valve and out through the
outlet, but even small negative pressures below the inlet cause the
ball valve to close and prevent flows down through the ball valve
in the vertical run.
[0009] In one example form, the relief valve is mounted directly to
the geomembrane for providing the extraction of sub-surface gas
below the same.
[0010] In another example form, the relief valve is mounted to a
wellhead for providing the extraction of sub-surface gas below the
geomembrane.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0011] FIG. 1 is a schematic illustration of a first prior art
wellhead for extracting sub-surface gas from a waste landfill.
[0012] FIG. 2 is a schematic illustration of a second prior art
wellhead for extracting sub-surface gas from a waste landfill.
[0013] FIG. 3 is a schematic sectional view of a relief valve for
extracting sub-surface gas from a waste landfill according to a
preferred example form of the present invention.
[0014] FIGS. 4-6 are cross-sectional views of example embodiments
of the valve ball of the relief valve of FIG. 3.
[0015] FIG. 7 is a schematic sectional view of a relief valve for
extracting sub-surface gas from a waste landfill according to
another example form of the present invention.
[0016] FIGS. 8 is a schematic view of a wellhead for cooperation
with the relief valve of FIG. 3 for extracting sub-surface gas from
a waste landfill according to another example form of the present
invention.
[0017] FIG. 9A is a schematic partially-exploded perspective view
of the wellhead of FIG. 8.
[0018] FIG. 9B is a schematic partially-exploded perspective view
of a wellhead having a generally circular plenum.
[0019] FIG. 10 is a schematic, partially-exploded sectional view of
a wellhead for cooperation with the relief valve of FIG. 3 for
extracting sub-surface gas from a waste landfill according to
another example form of the present invention
[0020] FIGS. 11A and 11B are schematic, partially-exploded
sectional and perspective views respectively of a wellhead for
cooperation with the relief valve of FIG. 3 for extracting
sub-surface gas from a waste landfill according to another example
form of the present invention.
[0021] FIG. 12 is a schematic, partially-exploded view of a
wellhead having a component removable therefrom to allow for
cooperation with the relief valve of FIG. 3 for extracting
sub-surface gas from a waste landfill according to another example
form of the present invention.
DESCRIPTION OF EXAMPLE EMBODIMENTS
[0022] The present invention provides a relief valve for extracting
sub-surface or sub-surface gas from near the surface of landfills
typically containing a geomembrane capping a waste. The geomembrane
is generally impermeable to contain or cap the waste below, thereby
restricting the sub-surface gas from flowing into the atmosphere
and restricting atmospheric air from flowing into the waste below
the geomembrane. In example forms, the relief valve directly or
indirectly couples to the geomembrane to provide for the extraction
of sub-surface gas from below the geomembrane; and to also prevent
the atmospheric air from flowing into the soil or zone below the
geomembrane. Optionally, the relief valve can couple to a wellhead
mounted near the geomembrane (as will be described below).
[0023] FIG. 3 shows a partial cross-sectional view of the relief
valve 10 according to a preferred example embodiment of the present
invention. The relief valve 10 has a substantially rigid valve body
12 having an outer surface 13, and an inner surface 15 generally
opposite the outer surface 13. The rigid valve body 12 has an inlet
14, an outlet 16 and an interior passageway 17 communicating
therebetween within the inner surface of the valve body 12. In one
example form, the valve body 12 is shaped to include a vertical run
20 extending between inlet 14 and a top end 19. The valve body 12
also has a lateral run 22, with both the vertical run and the
horizontal run defined by the inner surface such that the vertical
run 20 communicates with the inlet 14, and the lateral run 22
communicates with the vertical run 20 and the outlet 16.
[0024] Optionally, the vertical run can be purely vertical while
the horizontal run can be partly horizontal with some verticality,
as depicted. Indeed, as shown the horizontal run 22 includes a
first portion 22a which extends laterally and partly downwardly and
a second portion 22b which extends downwardly.
[0025] In example embodiments, the vertical run 20 and the lateral
run 22 are substantially cylindrical in shape, however alternate
shapes can be used as desired, for example, rectangular, octagonal
(or additional sides as desired), oval or others. Preferably, the
valve body 12 has external threads 24 near the inlet 14 for
directly or indirectly coupling to the geomembrane M, thereby
providing effective sealing of the inlet 14 to the geomembrane M.
Optionally, other forms of coupling features may be provided for
coupling the same.
[0026] A ball valve 30 is positioned within the relief valve 10 to
allow for one-way gas flows to flow therethrough, for example,
within the vertical run 20 or other portions of the relief valve
10, thereby permitting the extraction of sub-surface gas capped
below the geomembrane M, and preventing air or gas present in the
atmosphere from flowing within the geomembrane M. For example,
small or large positive pressures below the geomembrane M or
beneath the inlet 14 cause flow up through the ball valve 30 and
out through the outlet (see gas flow F), but even small negative
pressures below the inlet cause the ball valve to close, thus
preventing flows down through the ball valve and in the vertical
run. In one form, the ball valve 30 generally includes a ball seat
32 and a valve ball 34 positioned within the vertical run 20,
wherein the ball seat 32 is engaged with the inner surface of the
valve body 12 and the valve ball 34 is movable therewithin between
a lowered position against the ball seat 32 (see valve ball shown
in solid lines) and an elevated position proximal or distal
therefrom (see valve ball shown in dashed lines).
[0027] The ball seat 32 preferably is sized and/or shaped to engage
the inner surface of the valve body 12 and define at least one
aperture 33 extending therethrough. Preferably, a portion of the
ball seat 32 proximal the orifice includes a defined contact
surface having an angled or cone-like shape for providing uniform
contact and consistent positioning of the valve ball 34 against the
ball seat 32. For example, as depicted in FIG. 3, the valve ball 34
rests against an angular-shaped contact surface of a frusto-conical
portion of the ball seat 32 to provide effective sealing of the
valve ball 34a to the contact surface of the ball seat 32.
Preferably, the contact surface is annular or ring-like in shape
for providing a generally circular contact patch.
[0028] The valve ball 34 preferably is a spherical or ball-like and
has a substantially smooth outer surface to allow for good sealing
contact with the defined contact surface of the ball seat 32. Thus,
any orientation of the valve ball 34 when contacting the defined
contact surface provides substantially similar contact with contact
surface.
[0029] Preferably, the valve ball 34 has a diameter greater than
that of the aperture 33 and the internal dimension (typically a
diameter) of the lateral run 22, thereby remaining within the
vertical run 20. In example forms, the valve ball 34 is preferably
lightweight to become buoyant upon positive pressures beneath the
inlet 14, for example, small positive pressures provide minimum
valve ball suspension (see the ball shown in dashed lines just
above the ball shown in solid line) and large positive pressures
provide substantially maximum valve ball suspension (see 34c).
Additionally, the valve ball 34 is preferably configured to remain
in contact with the ball seat 32 upon negative pressures beneath
the inlet 14, or upon equilibrium, wherein the pressure beneath the
inlet 14 and the atmospheric pressure proximal the outlet 16 are
substantially similar so that the force of gravity acting on the
valve ball 34 keeps the same seated therein.
[0030] FIGS. 4-6 show the valve ball 34 having cross sections of
various thicknesses, for example, completely or substantially
solid, substantially thin-walled or hollow, and any form
therebetween (moderately thin-walled). In one form, the valve ball
34 has is substantially solid in cross section 35a (see FIG. 4)
rather than being hollow. In another form, the valve ball has a
substantially thin-walled or hollow cross section 35b (see FIG. 5).
Optionally, the valve ball 34 has a cross section 35c generally
thicker than the cross section 35b and generally thinner than the
cross section 35a (see FIG. 6). Also optionally, the interior
surface of the valve ball 34 may be shaped as desired, for example,
an interior surface fully or partially shaped to include
projections or other features. Preferably, the valve ball 34 can be
constructed from a plurality of materials, for example, plastics,
polymers, composites, or other materials or lightweight materials,
or combinations thereof. Optionally, the hollow portion of the
valve ball 34 may be filled with a less dense gas to accommodate
and/or provide optimal buoyancy upon positive pressures below the
inlet.
[0031] According to another example embodiment of the present
invention, the defined contact surface of the ball seat 32 can be
cup-shaped (see FIG. 7), or otherwise shaped as desired to provide
the valve ball 34 with proper positioning and effective sealing
contact against the ball seat 32. Optionally, the defined contact
surface of the ball seat 32, or additional portions thereof, can
include an integral or fitted layer 35 to alter the composition of
the defined contact surface in contact with the valve ball 34a, for
example, a soft material or other material suitable to enhance the
contact and/or sealing capabilities.
[0032] The relief valve 10 can be constructed from a plurality of
materials, for example, metals, plastics, composites, or other
materials, or combinations thereof.
[0033] In additional example embodiments, the relief valve 10 can
mount to a wellhead and provide for the extraction of the
sub-surface gas or positive pressures below the geomembrane or
inlet 14 of the relief valve 10. FIGS. 8-12 show examples of
wellheads that can be used with the present invention. However,
other wellhead designs can work with the present invention also.
For example, the wellhead 100 (plenum 110 or 115, conduit 120)
shown in FIGS. 8-9B, the wellhead 200 (plenum 210, conduit 220)
shown in FIG. 10, the wellhead 300 (plenum 310, conduit 320) shown
in FIGS. 11A-B, and/or the wellhead 400 shown in FIG. 12. For
example, FIG. 12 shows the wellhead 400 having a removable
component or cap 402 to allow for the relief valve 10 to couple
thereto when the cap 402 is removed therefrom.
[0034] Advantageously, the relief valves according to the present
invention can operate at very low pressure differentials. Indeed,
the present invention provides a relief valve that can work with
pressure differentials below 3 psi (typical prior art relief valves
typically require a pressure differential of 10 psi or more). The
novel relief valves of the present invention even work at
fractional (sub-1.0 psi) pressures, even as low as pressure
differentials of about 0.1 psi. Thus, the present invention
provides a very sensitive relief valve, which is well suited to
working with sub-surface gas extraction where even small positive
pressures can cause problems.
[0035] The relief valve of the present invention can be used with
various types of wellheads in a variety of situations, including
conventional wellheads and near-surface wellheads. Moreover, in
addition, the present invention can be used with a variety of gas
types, including landfill gas, natural gas, etc.
[0036] Preferably, the wellhead can be of various forms, wherein
the conduit sealingly engaged with the plenum (sealingly engaged
below the geomembrane M) provides for the attachment of the relief
valve 10. Preferably, the external threads 24 of the relief valve
10 and the external threads of the conduit can be sized and shaped
accordingly to sealingly engage a threaded nut therebetween,
thereby sealingly engaging the relief valve 10 to the conduit of
the wellhead. Optionally, additional engagement features and/or
mounting features can be provided for sealingly engaging the same,
for example, inter-engagement features, screws, bolts, threaded
members, fasteners, couplings, or others as desired.
[0037] It is to be understood that this invention is not limited to
the specific devices, methods, conditions, or parameters described
and/or shown herein, and that the terminology used herein is for
the purpose of describing particular embodiments by way of example
only. Thus, the terminology is intended to be broadly construed and
is not intended to be limiting of the claimed invention. For
example, as used in the specification including the appended
claims, the singular forms "a," "an," and "one" include the plural,
the term "or" means "and/or," and reference to a particular
numerical value includes at least that particular value, unless the
context clearly dictates otherwise. In addition, any methods
described herein are not intended to be limited to the sequence of
steps described but can be carried out in other sequences, unless
expressly stated otherwise herein.
[0038] While the invention has been shown and described in
exemplary forms, it will be apparent to those skilled in the art
that many modifications, additions, and deletions can be made
therein without departing from the spirit and scope of the
invention as defined by the following claims.
* * * * *