Landfill pump having inlet extension

Abstract

Landfill well pump (10) pneumatically powered to pump liquid from a wellbore (12). The landfill pump includes an inlet extension (16) that extends below a main body portion of the landfill pump. The inlet extension increases the length of the landfill pump to shift a fluid inlet (22) of the landfill pump downward relative to a chamber of the landfill pump.

Description

[0001] LANDFILL PUMP HAVING INLET EXTENSION

[0002] CROSS-REFERENCE TO RELATED APPLICATION(S)

[0003] This application claims priority to U.S. Provisional Application No. 63 / 620,642 filed January 12, 2024 and entitled “LANDFILL PUMP HAVING INLET EXTENSION,” the disclosure of which is hereby incorporated by reference in its entirety.

[0004] BACKGROUND

[0005] The present disclosure concerns landfill pumps. More particularly, the present disclosure concerns pneumatically powered landfill pumps that are partially or fully submerged in liquid within a wellbore.

[0006] Landfill pumps are disposed within wellbores at locations around landfills and other refuse collection sites. The landfill pumps are configured to pump landfill liquid from the landfill wellbore. The landfill liquid can be costly to collect and properly dispose of due to the contaminated nature of the landfill liquid. The supply of compressed gas provided to the landfill pump to cause pumping by the landfill pump and the exhaust of compressed gas from the landfill pump is regulated to control outflow from the pumps. Typically, such liquid is formed by water flowing through waste materials and extracting dissolved or suspended contaminants, which can include debris and / or can be highly corrosive on components of the pump. The environment in a landfill well can be particularly hot because of the ongoing decomposition reaction of the landfill contents. Accordingly, the pumps require robust materials and have a design that minimizes wear, binding, and failure points.

[0007] SUMMARY

[0008] According to an aspect of the disclosure, a landfill pump for pumping a liquid out of a wellbore includes a case elongate along a pump axis; a pump chamber located at least partially within the case; an upper cap mounted on a top end of the case; a lower cap mounted on a bottom end of the case; a discharge regulator that regulates evacuation of the liquid out of the chamber, the liquid moving through and further above the upper cap when being evacuated; and an inlet extension mounted to the lower cap and extending below the lower cap, the inlet extension including an extension tube and a fluid inlet.

[0009] According to an additional or alternative aspect of the disclosure, a landfill pump for pumping a liquid out of a wellbore includes a case elongate along a pump axis; a pump chamber located at least partially within the case; an upper cap mounted on a top end of the case; a lower cap mounted on a bottom end of the case; a discharge regulator that regulates evacuation of the liquid out of the chamber, the liquid moving through and further above the upper cap when being evacuated; a lower valve disposed within the case, the lower valve allowing flow of the liquid into the chamber when in a lower valve open state and preventing backflow of the liquid from the chamber when in a lower valve closed state; and a valve assembly including a pressure actuated valve, the valve assembly supported by the lower cap, the pressure actuated valve disposed below the lower cap and upstream of the lower valve, wherein the pressure actuated valve is biased to a normally closed state.

[0010] According to another additional or alternative aspect of the disclosure, a landfill pump for pumping a liquid out of a wellbore includes a case elongate along a pump axis; a pump chamber located at least partially within the case; an upper cap mounted on a top end of the case; a lower cap mounted on a bottom end of the case; a discharge regulator that regulates evacuation of the liquid out of the chamber, the liquid moving through and further above the upper cap when being evacuated; a lower valve disposed within the case, the lower valve allowing flow of the liquid into the chamber when in a lower valve open state and preventing backflow of the liquid from the chamber when in a lower valve closed state; and an inlet extension mounted to the lower cap and extending below the lower cap. The inlet extension includes an extension tube; an intake having a fluid inlet; and a valve assembly including a pressure actuated valve, the pressure actuated valve disposed below the lower cap, downstream of the fluid inlet, and upstream of the lower valve, wherein the pressure actuated valve is biased to a normally closed state.

[0011] According to yet another additional or alternative aspect of the disclosure, a method of operating a landfill pump that pumps a liquid form a wellbore includes blocking pressurized gas from entering a chamber of the landfill pump with a pressure actuated valve; and permitting the liquid to enter the pumping chamber by passing through the pressure actuated valve due to combined forces of pressure head of the liquid and the pressurized gas opening the pressure actuated valve.

[0012] BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a diagram showing a submersible pump in a wellbore.

[0014] FIG. 2 is a side elevational view of a submersible pump having an inlet extension.

[0015] FIG. 3 is an exploded view of a submersible pump.

[0016] FIG. 4 is an enlarged detail view of a discharge regulator for a submersible pump.

[0017] FIG. 5A is an enlarged view of detail A in FIG. 2.

[0018] FIG. 5B is a cross-sectional view taken along line B-B in FIG. 5A showing detail of an inlet extension. DETAILED DESCRIPTION

[0019] The present disclosure relates generally to landfill pumps. Landfill pumps are configured to pump liquid from a wellbore at a refuse collection site. Pumps according to the disclosure are configured to pump liquid from a sump, which can be a landfill wellbore. Such liquid could be any type of liquid which accumulates in a well at a site utilized for underground refuse collection, such as for bioprocessing (e.g., a bioreactor, conventional landfill, etc.). Typically, such liquid is water containing contaminants, which includes debris and / or can be highly corrosive on components of the pump. The environment in a landfill well can be particularly hot because of the ongoing decomposition reaction of the landfill contents. Accordingly, the landfill pumps must be made of particularly robust materials and have a design that minimizes wear, binding, and failure points.

[0020] Landfill pumps can be float-actuated to cause cycling by the pump. The float can cause valving to actuate open to allow inflow of compressed gas to the pump, thereby pumping the landfill liquid from the pump. Travel of the float is both upward within the pump and downward within the pump. The float can actuate the valving closed to stop flow of compressed gas into the pump and thus stop pumping by the pump.

[0021] Landfill wells can be sources of methane gas and other pollutants. Technicians can install equipment to try and capture as much of the pollutants as possible. Wellheads on top of wellbores can capture the gas within the wellbore. Wells can be injected with pressurized gas, which helps push the pollutant gas longer distances through pipes to collection points and up wellbores. Wells can also be pressurized for various other reasons. Landfill pumps according to aspects of the disclosure can be placed in positively pressurized wellbores.

[0022] Landfill pumps according to various aspects of the disclosure include an inlet extension that projects from a lower end of a pump body of the landfill pump. The inlet extension lengthens the landfill pump and places the inlet for admitting liquid into the landfill pump further down into the wellbore. The inlet extension extends the length of the pump to place the fluid inlet further below the liquid level in the wellbore to avoid the liquid from falling below the fluid intake of the landfill pump. The liquid level falling below the fluid intake can allow the positive pressure gas in the landfill well to enter into the pump interior, which can cause the pump to lose prime and stop working and which can also allow the positive pressure gas, which can contain landfill gas (LFG) (primarily methane), to enter into the pump and escape to atmosphere.

[0023] Landfill pumps according to various additional or alternative aspects of the disclosure, include a pressure actuated valve. The pressure actuated valve is biased to the closed state and can be actuated open to allow admission of fluid into the interior of the pump. The pressure actuated valve can be spring biased to the closed state. According to aspects of the disclosure, a spring rate of the spring biasing the pressure actuated valve closed can be varied to account for the positive pressure gas in the wellbore and to prevent gas ingestion into the pump. The pressure actuated valve can be configured such that the gas pressure in the wellbore is insufficient to cause the pressure actuated valve to open, while a combination of head pressure from the liquid in the wellbore and the gas pressure can cause the pressure actuated valve to open to allow admission of liquid into the pump.

[0024] Components can be considered to radially overlap when those components are disposed at common axial locations along an axis. A radial line extending from the axis will extend through each of the radially overlapping components. Components can be considered to axially overlap when those components are disposed at common radial and circumferential locations relative to an axis such that an axial line parallel to the axis extends through the axially overlapping components. Components can be considered to circumferentially overlap when aligned about the axis, such that a circle centered on the axis passes through the circumferentially overlapping components.

[0025] FIG. 1 is a diagram showing landfill pump 10 at a refuse collection site. Landfill pump 10 is disposed in wellbore 12. Pump casing 14, inlet extension 16, pneumatic inlet 18, pneumatic outlet 20, fluid inlet 22, and liquid outlet 24 of landfill pump 10 are shown. Gas inlet 26 and gas outlet 28 of wellbore 12 are shown.

[0026] Landfill pump 10 is at least partially disposed in wellbore 12. It is understood that wellbore 12 can be considered to form a sump and that the landfill pump 10 can be considered to form a submersible pump. Landfdl pump 10 is configured to be at least partially submerged within liquid in the wellbore 12. The liquid level LL is shown in FIG. 1. While landfill pump 10 is shown as vertically oriented, such that the pump axis PA is vertical, it is understood that not all examples are so limited. For example, landfill pump 10 can be disposed in a wellbore 12 that is sloped to extend both vertically and horizontally.

[0027] Landfill pump 10 is typically lowered into a well of refuse collection site, such as a landfill (e.g., a conventional landfill, bioreactor, etc.), on a cable assembly. The cable assembly can include a pneumatic supply hose 30 supplying pneumatic gas under pressure supplied from the surface. The cable assembly can include a pneumatic exhaust hose 32 in various examples. The pneumatic exhaust hose 32 can route gas from the interior of the landfill pump 10 out of wellbore 12, such as to the surface for exhausting. The cable assembly can further include fluid discharge hose 34 that carries discharge liquid from the landfill pump 10 up to the surface to be expelled, such as into a container for collection and disposal. A wellhead can sit atop the wellbore to collect pollutant gas.

[0028] Landfill pump 10 includes pump casing 14. Pump casing 14 can be a cylindrical tube made of metal, polymer, epoxy composite, and / or other material. Pump casing 14 defines an interior chamber into which pollutant liquid from the wellbore 12 can accumulate to be pumped out of the landfill pump 10 during a pumping cycle.

[0029] Gas inlet 26 is fluidly connected to wellbore 12 and is configured to provide pressurized gas, such as inert gas such as nitrogen, or ambient gas such as pressurized air, into the interior of the wellbore 12. Gas outlet 28 is fluidly connected to wellbore 12 and is configured to receive the pressurized gas from wellbore 12 such that the pressurized gas can be removed. The pressurized gas provided to the wellbore 12 can mix with gasses within the wellbore 12, such as LFG, which can be transported downstream from the wellbore 12 through the gas outlet 28.

[0030] The pressurized gas provided to the wellbore 12 can positively pressurize the interior of the wellbore 12 relative to the interior of the landfill pump 10. The pressurized gas can positively pressurize the interior of the wellbore 12 relative to atmosphere. In some examples, the interior of the landfill pump 10 is connected to atmosphere, such as via pneumatic outlet 20 and pneumatic exhaust hose 32, such that the interior of the landfill pump 10 can be considered to reference atmospheric pressure while the interior of the wellbore 12 is positively pressurized relative to the reference pressure of the interior of the landfill pump 10.

[0031] Landfill pump 10 includes inlet extension 16. Inlet extension 16 extends from a lower end of the pump casing 14. The inlet extension 16 increases the length of the landfdl pump 10. The inlet extension 16 projects below the pump casing 14 and is at least partially disposed below the liquid level LL of the liquid in the wellbore 12. The fluid inlet 22 of the landfdl pump 10 is formed in the inlet extension 16. The fluid inlet 22 is disposed at a distal end of the inlet extension 16 opposite the end of the inlet extension 16 connected to the main body portion of landfdl pump 10.

[0032] Inlet extension 16 includes an exterior screen 36, in the form of a screen in this example, which filters out large debris from the liquid preventing the debris from entering the landfill pump 10. The landfill pump 10 is at least partially submerged in liquid within the landfill wellbore 12 such that the inlet extension 16 is at least partially underneath the surface level LL of the liquid and is able to readily bring the surrounding liquid into the landfill pump 10. In the example shown, the main body of the landfill pump 10 is not below the liquid level LL or disposed in the liquid. In this example, the inlet extension 16 projects from the main body portion of the landfill pump 10 and into the liquid in the wellbore 12.

[0033] As further discussed herein, the inlet extension 16 provides advantages in various pumping conditions, in particular when pressurized gas is used in the wellbore 12. The pressurized gas can push down the liquid level LL in the wellbore 12, which may push the liquid level below the inlet of a conventional landfill pump. Such a drop in the liquid risks introducing pressurized gas into the landfill pump through its liquid inlet, which can significantly interfere with the operation of the landfill pump. The inlet extension 16 lowers the fluid inlet 22 of the landfill pump 10 relative to a more conventional design, as well as providing other advantages that will be discussed, for dealing with pressurized gas in the wellbore 12.

[0034] Landfill pump 10 is configured to operate in serial pump cycles. Each pump cycle includes a filling phase and an evacuation phase. During the filling phase, liquid from the landfill wellbore can flow into the interior of landfill pump 10 to fill landfill pump 10 with the landfdl liquid. During the evacuation phase, compressed gas is admitted into the interior of landfill pump 10 to drive the liquid within landfill pump 10 out of landfill pump 10. The landfill pump 10 transitions back to a filling phase after completing an evacuation phase.

[0035] FIG. 2 is a side elevational view of landfill pump 10. FIG. 3 is an exploded view of landfill pump 10. FIG. 4 is an enlarged detail, partial cross-sectional view of a top end of landfill pump 10. FIGS. 2-4 are discussed together. Pump casing 14, inlet extension 16, pneumatic inlet 18, pneumatic outlet 20, fluid inlet 22, liquid outlet 24, upper cap 38, lower cap 40, discharge pipe 42, lower pump valve 46, upper pump valve 48, and discharge regulator 50 of landfill pump 10 are shown. Adaptor 52, extension tube 54, valve assembly 56, and intake 58 of inlet extension 16 are shown. Discharge regulator 50 includes float 60, control rod 62, and rocker assembly 64.

[0036] Landfill pump 10 is configured to evacuate liquid from a wellbore (e.g., wellbore 12), which wellbore can be considered to form a sump. Pump casing 14 encloses various other components of landfill pump 10. Pump casing 14 is elongate along a pump axis PA. Chamber 66 is disposed within pump casing 14. Liquid accumulates within chamber 66 within pump casing 14 during filling of landfill pump 10. The liquid is evacuated from chamber 66 within pump casing 14 during evacuation of landfill pump 10. Liquid outlet 24 is disposed at a top end of the landfill pump 10. Liquid outlet 24 can connect to a discharge hose (e.g., fluid discharge hose 34) that routes liquid discharge from the landfill pump 10 up to the surface.

[0037] Pneumatic inlet 18 is disposed at a top end of the landfill pump 10. Pneumatic inlet 18 can include a fitting for attaching to a hose (e.g., pneumatic supply hose 30) supplying pneumatic gas to the landfill pump 10, such hose extending to the surface where the supply of pressurize gas is located. During pumping operations, pressurized gas is introduced to the chamber 66 via pneumatic inlet 18. Such pressurized gas can drive the liquid out of the chamber 66 and out from pump 10 through liquid outlet 24.

[0038] Pneumatic outlet 20 is disposed at a top end of the landfill pump 10. Pneumatic outlet 20 can connect with a fitting of an outlet hose (e.g., pneumatic exhaust hose 32) that extends to the surface to exhaust gas from the landfill pump 10. It is understood that in various examples, pneumatic outlet 20 can exhaust gas directly into the wellbore 12 without a hose.

[0039] Upper cap 38 is disposed at the top end of the landfill pump 10. Upper cap 38 can be connected to casing 14. In some examples, upper cap 38 can be directly connected to the pump casing 14, such as via interfaced threading among other options. In some examples, upper cap 38 is press fit on pump casing 14. Upper cap 38 can be a manifold. Upper cap 38 can route various fluids (e.g., pressurized gas, liquid) between various fittings the interior of landfill pump 10. Pathways for routing of the fluid can extend fully through the upper cap 38, such as between a top end of the upper cap 38 oriented away from the chamber 66 and a lower end of the upper cap 38 oriented towards the chamber 66. In the example shown, the pathways for admitted compressed driving gas into chamber 66 (e.g., from pneumatic inlet 18) and for exhausting the compressed driving gas from chamber 66 (e.g., through pneumatic outlet 20) are formed through upper cap 38. The pathway for liquid evacuation (e.g., through liquid outlet 24) can extend through upper cap 38.

[0040] In the example shown, a top end of the pump casing 14 extends around part of, and seals with, the upper cap 38. The upper cap 38 can extend into the pump casing 14 to be partially disposed within the pump casing 14 and can extend above the pump casing 14. A portion of the upper cap 38 can project radially outward to axially overlap with the pump casing 14.

[0041] One of more of liquid outlet 24, pneumatic inlet 18, and / or pneumatic outlet 20 can be part of or otherwise extend from upper cap 38. Upper cap 38 can be formed from metal, such as stainless steel, among other options. Upper cap 38 can, in some examples, extend at least partially into pump casing 14. Upper cap 38 can, in some examples, extend above a top end of the pump casing 14. Upper cap 38 can be a plate. Upper cap 38 can be a disc.

[0042] Lower cap 40 is disposed at a lower end of the landfill pump 10. Lower cap 40 can be connected to casing 14. In some examples, lower cap 40 can be directly connected to the pump casing 14, such as via interfaced threading among other options. In some examples, lower cap 40 is press fit on pump casing 14. Lower cap 40 can be mounted on a bottom end of the pump casing 14.

[0043] In the example shown, the bottom end of the pump casing 14 extends around part of, and seals with, the lower cap 40. The lower cap 40 can extend into the pump casing 14 to be partially disposed within the pump casing 14 and can extend below the pump casing 14. A portion of the lower cap 40 can project radially outward to axially overlap with the pump casing 14.

[0044] Lower cap 40 can be formed from metal, such as stainless steel, among other options. Lower cap 40 can, in some examples, extend into the pump casing 14. Lower cap 40 can, in some examples, extend below the bottom end of the pump casing 14. Lower cap 40 can be a plate. Lower cap 40 can be a disc. In the example shown, aperture 68 extends through lower cap 40. The aperture 68 provides a pathway for liquid flow into chamber 66 from inlet extension 16.

[0045] Chamber 66 is disposed within an interior of landfill pump 10. Chamber 66 is formed as a pumping chamber. The circumferential exterior of chamber 66 can be defined by the inside of the pump casing 14. The top and the bottom of the chamber 66 can be defined by the upper cap 38 and the lower cap 40, respectively.

[0046] The upper cap 38, lower cap 40, and casing 14 can be considered to form a main body portion of the landfill pump 10. The chamber 66 is disposed within the main body portion of the landfill pump 10. In some examples, the casing 14 can be clamped between the upper cap 38 and the lower cap 40 to form the main body portion of the landfill pump 10.

[0047] Discharge pipe 42 is disposed at least partially within case 14. Discharge pipe 42 can extend from a lower pump valve 46 to the upper cap 38. In some examples, the discharge pipe 42 extends through the upper cap 38 and above the upper cap 38 to form the liquid outlet 24. In some examples, the discharge pipe 42 can be directly connected to the upper cap 38, such as by interfaced threading, a press fit connection, a bayonet connection, among other options. Discharge pipe 42 is fluidly connected to chamber 66 and liquid outlet 24 to provide liquid to liquid outlet 24. Discharge pipe 42 extends from a bottom end of the landfill pump 10 to the top end of the landfill pump 10.

[0048] One or more discharge ports 70 are formed through discharge pipe 42. Discharge ports 70 provide passages for landfill liquid to flow from the chamber 66 within pump casing 14 into an interior of the discharge pipe 42. Discharge port 70 is disposed at a bottom end of the discharge pipe 42. Discharge port 70 is located at the end of discharge pipe 42 opposite the upper cap 38. Discharge port 70 can be oriented radially relative to the pump axis PA, among other options. Landfill pump 10 includes discharge regulator 50 that is configured to control landfill pump 10 between various operating states. The discharge regulator 50 can place the landfill pump 10 in an evacuation phase in which the compressed driving gas is provided to chamber 66 to evacuate liquid from chamber 66. The discharge regulator 50 can place the landfill pump 10 in a fill state in which the compressed driving gas is not provided to chamber 66 and liquid can fill into chamber 66 to fill landfill pump 10.

[0049] In the example shown, landfill pump 10 includes float 60 that is configured to actuate landfill pump 10 between various operating states (e.g., between evacuation and filling phases). Float 60 is disposed at least partially around discharge pipe 42. While the example shown includes float 60, it is understood that not all examples are so limited.

[0050] Float 60 can be made of a material that is less dense than the liquid such that the float 60 is buoyant when partially submerged in the liquid that fills the chamber 66. The float 60 is attached to a control rod 62 such that movement of the float 60 up-and-down within the chamber 66 can move the control rod 62 up-and-down. Such up-and-down movement can actuate a discharge regulator 50 to which the control rod 62 is attached. It is understood that, in various examples, float 60 may not be fixed to control rod 62 such that float 60 can move up-and-down within casing 14 relative to the control rod 62.

[0051] The discharge regulator 50 can open and close one or more valves to release pressurized gas from the pneumatic inlet 18 into the chamber 66 and, in some examples, control exhaust of compressed gas from the pneumatic outlet 20. For example, float 60 rising with a rising liquid level and reaching an upward travel limit can actuate the pneumatic valving to a discharge state allowing admission of the compressed driving gas and the float 60 falling with a falling liquid level and reaching a lower or downward travel limit can actuate valve assembly 56 to a fill state.

[0052] In the example shown, the discharge regulator 50 includes rocker assembly 64.

[0053] Rocker assembly 64 is configured to actuate and, in some examples can include components of, the pneumatic valving to control admission of compressed gas into the landfill pump 10. The rocker assembly 64 can be pivoted by the float 60 via the control rod 62 to alternately open and close valves associated with the pneumatic inlet 18 and the pneumatic outlet 20. While a rocker assembly 64 is shown herein, various other mechanisms or controls can be substituted.

[0054] Lower pump valve 46 is disposed at a lower end of the landfill pump 10. Lower pump valve 46 is disposed at a bottom end of the casing 14. Lower pump valve 46 is configured to provide for one-way liquid flow into the chamber 66 within pump casing 14. The lower pump valve 46 includes lower valve seal 72 that can engage with lower valve seat 74 to close the lower pump valve 46. Lower valve seal 72 being spaced from lower valve seat 74 opens the lower pump valve 46 to allow admission of fluid into chamber 66. Lower valve seal 72 can be buoyant so that lower valve seal 72 floats with rising level of the liquid into the chamber 66. In the example shown, the lower pump valve 46 is not biased open or closed. The lower pump valve 46 does not include a spring or other biaser for biasing the lower pump valve 46 to an open or closed state.

[0055] The lower valve seal 72 can be forced downward to engage with lower valve seat 74 and close lower pump valve 46 by fast evacuation of liquid during an evacuation cycle, as further discussed herein. For example, admission of the compressed driving gas pushes the liquid in chamber 66 downward and the increased pressure can drive the lower valve seal 72 into engagement with lower valve seat 74 to close the lower pump valve 46. In some examples, the lower valve seat 74 can be formed by lower cap 40. Lower valve seat 74 can be formed by a portion of the lower cap 40 defining aperture 68 through lower cap 40.

[0056] Valve retainer 76 is disposed at least partially around lower valve seal 72. Valve retainer 76 is configured to maintain alignment of the lower valve seal 72 with the lower valve seat 74. In the example shown, valve retainer 76 is formed by a plurality of posts that are arrayed around the lower valve seal 72. The valve retainer 76 can also be referred to as a spider assembly.

[0057] The posts of the valve retainer 76 can be mounted to the lower cap 40. In the example shown, fasteners 78 extend through lower cap 40 and interface with the posts of valve retainer 76 to fix lower cap 40 and valve retainer 76 together. The valve retainer 76 can interface with the lower cap 40 to locate a lower end of the discharge pipe 42 on the pump axis PA, to which the valve retainer 76 is connected, and maintain discharge pipe 42 in an axial alignment between upper cap 38 and lower cap 40. As discussed above, the casing 14 can, in some examples, be clamped between the upper cap 38 and the lower cap 40. The upper cap 38 can be fixed to the discharge pipe 42. The lower cap 40 can be fixed to the discharge pipe 42 via the connection of the valve retainer 76 with the lower cap 40. The upper cap 38 and the lower cap 40 can then be fixed relative to each other by the discharge pipe 42 with the casing 14 captured between the upper cap 38 and lower cap 40.

[0058] Upper pump valve 48 can be disposed at a top end of the landfill pump 10. The upper pump valve 48 can, in some examples, be mounted on the upper cap 38. The upper pump valve 48 is configured to allow the flow of the liquid passing upwards through the discharge pipe 42 to continue to move upwards and out from landfill pump 10 while preventing flow of the liquid back down after leaving the landfill pump 10. The upper pump valve 48 can comprise a ball and a seat, among other valving options.

[0059] Inlet extension 16 is axially elongate. Inlet extension 16 can be disposed on the pump axis PA. Inlet extension 16 can be disposed coaxially with discharge pipe 42. Inlet extension 16 can be disposed coaxially with the lower pump valve 46. Inlet extension 16 extends below the bottom end of the pump casing 14. Inlet extension 16 spaces the fluid inlet 22 of the landfill pump 10 axially away from the bottom end of the pump casing 14.

[0060] As shown, the inlet extension 16 includes the fluid inlet 22 of the landfill pump 10. Liquid enters into the landfill pump 10 through the inlet extension 16. The fluid inlet 22 can include screen 36, which can be formed as a screen, to filter out debris from the liquid. Inlet extension 16 can be vertically elongate and the pump casing 14 can also be vertically elongate. The inlet extension 16 can be axially elongate along pump axis PA while pump casing 14 is also axially elongate. The inlet extension 16 can extend vertically and be aligned with the pump casing 14 such that the inlet extension 16 is coaxial with the pump case 14. Pump casing 14 can be generally cylindrical. Inlet extension 16 can also be generally cylindrical.

[0061] The inlet extension 16 has a smaller diameter than the pump casing 14. In the example shown, a largest diameter portion of inlet extension 16 has diameter D 1 while a smallest diameter portion of the pump casing 14 has diameter D2. Diameter D 1 is less than diameter D2. As such, any and all parts of the pump casing 14 can have a wider diameter than any and all parts of the inlet extension 16. As shown in FIG. 1, the inlet extension 16 can place the fluid inlet 22 at or below the openings that admit liquid into the wellbore 12. The smaller diameter of the inlet extension 16 does not inhibit flow of liquid into the wellbore 12, providing for efficient flow and efficient operation of pump 10. In the example shown, the inlet extension 16 has length LI between a top end of the inlet extension 16 and the fluid inlet 22. Pump casing 14 has length L2. Length LI is less than length L2. With the landfill pump 10 oriented vertically, the length LI of the inlet extension 16 can also be referred to as the height of the inlet extension 16. In the example shown, the length LI of the inlet extension 16 is greater than a largest diameter D2 of the pump casing 14.

[0062] The length LI can be between about 2 inches (in.) (about 5.08 centimeters (cm)) and about 18 in. (about 45.72 cm), inclusive. In some examples, the length LI can be between about 4 in. (about 10.16 cm) and about 12 in. (about 30.48 cm). In some examples, the length LI can be between about 4 in. (about 10.16 cm) and about 10 in. (about 25.4 cm). In some examples, the length LI can be at least about 4 in. (about 10.16 cm). In some examples, the length LI can be at least about 5 in. (about 12.7 cm). In some examples, the inlet extension 16 can be at least about 10 in. (about 25.4 cm). In some examples, the inlet extension 16 can be at least about 11 in. (about 27.94 cm).

[0063] The length LI of the inlet extension 16 extends the overall length of the landfill pump 10 relative to having a pump inlet at the lower end of the pump casing 14 (e.g., at lower cap 40). The inlet extension 16 is elongate to place the fluid inlet 22 below the liquid level LL of the liquid in the wellbore 12. The elongate inlet extension 16 maintains the fluid inlet 22 in a submerged state below the liquid level LL during operation of landfill pump 10, both during an evacuation phase and a filling phase.

[0064] In the example shown, inlet extension 16 includes adaptor 52. Adaptor 52 is configured to connect inlet extension 16 to the main body portion of landfill pump 10. In some examples, the adaptor 52 can be directly connected to lower cap 40, among other options. For example, adaptor 52 can include a threaded exterior which can thread into, and be received within, the aperture 68 of the lower cap 40. The aperture 68 can be internally threaded to interface with threading of the adaptor 52.

[0065] Adaptor 52 provides both structural and fluid connection between the inlet extension 16 and the main body portion of landfill pump 10. The adaptor 52 structurally connects the inlet extension 16 to landfill pump 10. The adaptor 52 is configured to route the liquid to the chamber 66 in the interior of casing 14.

[0066] Adaptor 52 includes adaptor opening 80 for receiving the extension tube 54 to connect with the extension tube 54. The adaptor 52 can be configured to receive the extension tube 54 inside of the adaptor 52. Such a connection can be a threaded connection, such as between exterior threading of the extension tube 54 and interior threading of the adaptor 52.

[0067] Extension tube 54 is connected to adaptor 52 and extends from adaptor 52 away from casing 14. Extension tube 54 tat least partially defines the fluid flowpath through the inlet extension 16. The length LI of the inlet extension 16 can be varied to adapt landfill pump 10 for a desired operating environment. For example, an extension tube 54 having a first length can be removed from adaptor 52 and valve housing 82 of valve assembly 56 and replaced with a different extension tube 54 having a second length different from the first length. The overall length LI of the inlet extension 16 can thus be easily varied to adapt to the environment and dimensions of the wellbore 12 while ensuring that the fluid inlet 22 remains submerged throughout operation.

[0068] In the example shown, the inlet extension 16 includes valve assembly 56, though it is understood that not all examples are so limited. Valve assembly 56 includes a pressure actuated valve. The pressure actuated valve is disposed within valve housing 82 of valve assembly 56. The pressure actuated valve is configured as a one-way valve that allows liquid to flow into casing 14 and prevents backflow to fluid inlet 22. As discussed in more detail below, the pressure actuated valve is configured to be opened by pressure from the liquid in wellbore 12 and is configured to remain in a closed state when acted on by only the pressurized gas in wellbore 12. The valve assembly 56 is configured to resist the positive pressure gas in wellbore 12 and to open in response to liquid such that liquid, not the positive pressure gas, is admitted to chamber 66 through inlet extension 16.

[0069] Valve housing 82 is connected to extension tube 54 in the example shown. Valve housing 82 is connected to an opposite end of extension tube 54 from the end of extension tube 54 connected to adaptor 52. It is understood that, in various other examples, the valve housing 82 can be directly connected to the extension tube 54, such as by exterior threading on an upper end (closest to pump casing 14) of the valve housing 82. In the example shown, the valve housing 82 is directly connected to the extension tube 54. The valve assembly 56 can be connected to the extension tube 54 in any desired manner, such as by interfaced threading among other options. While inlet extension 16 is shown as including valve assembly 56, it is understood that not all examples are so limited. Some examples of inlet extension 16 do not include a pressure actuated valve.

[0070] Intake 58 is disposed at a lower end of inlet extension 16. Fluid inlet 22 is formed in intake

[0071] 58. Intake 58is disposed at an opposite end of inlet extension 16 from adaptor 52. Intake

[0072] 58 is disposed at a distal end of the inlet extension 16. Intake 58 is connected to valve housing 82 in the example shown. For example, intake 58 can be connected to the valve housing 82 by interfaced threading, among other options. In the example shown, the intake 58 includes exterior threading that interfaces with interior threading of the valve housing 82.

[0073] Intake 58 includes screen 36 configured to filter out large debris. Screen 36 is supported by and depends from the body of the intake 58 that connects intake 58 to other components of inlet extension 16. Liquid enters into landfill pump 10 through the screen 36 such that the intake 58 can form the fluid inlet 22 for the landfill pump 10. Screen 36 can be considered to form a screen. Screen 36 can include wire mesh, foil, or other screening component which allows liquid to flow past while keeping out debris.

[0074] Landfill pump 10 is configured to operate in serial pump cycles by alternating between a filling phase and an evacuation phase in each cycle. In the filling phase, liquid from outside the landfill pump 10, into which liquid the landfill pump 10 is partially or fully submerged, flows through the inlet extension 16 and past the lower pump valve 46 into the chamber 66. During the filling phase, the lower pump valve 46 is open. The liquid level within the chamber 66 rises to partially submerge the float 60 and eventually causes the float 60 to start rising within the chamber 66.

[0075] The rocker assembly 64 can be tripped to a first state or a second state. In the first state, corresponding to the filling phase, a pneumatic inlet valve being supplied with pressurized air from the pneumatic inlet 18 is closed. With the pneumatic inlet valve closed, the chamber 66 within landfill pump 10 is at the pressure at the pneumatic outlet 20. As discussed above, the pneumatic outlet 20 can be connected to atmosphere, such as via pneumatic exhaust hose 32. A pneumatic outlet valve of the rocker assembly 64 can be in an open state during the filling phase, such that the chamber 66 within landfill pump 10 references atmospheric pressure.

[0076] Rising of the float 60 causes rising of the control rod 62 which trips the rocker assembly 64 of the discharge regulator 50. For example, the float 60 can traverse along the control rod 62 and then reach a stop at an upward end of travel along the control rod 62. The float 60 can continue to rise after encountering the upper stop, which continued rising causes the control rod 62 to rise and trip the rocker assembly 64.

[0077] Upward movement of the control rod 62 trips the rocker assembly 64 to the second state in which the pneumatic inlet valve is opened. The rocker assembly 64 can cause a pneumatic outlet valve to close when in the second state, preventing exhaust of compressed driving gas from chamber 66. Opening of the pneumatic inlet valve transitions the landfill pump 10 to the evacuation phase in which pressurized driving gas is released from the upper cap 38 (or from elsewhere) into the chamber 66. Such release of pressurized driving gas pushes the liquid within the chamber 66 downward to close the lower pump valve 46 and force the liquid within the chamber 66 into the lower end of the discharge pipe 42 and up the discharge pipe 42 and out the liquid outlet 24, passing the upper pump valve 48.

[0078] Evacuation of the liquid from landfill pump 10 causes the liquid level within the chamber 66 to lower, which correspondingly causes the float 60 to move downward as well as the control rod 62 to move downward, tripping the discharge regulator 50 back to the first state, which closes the pneumatic inlet valve to prevent further release of pressurize driving gas into the chamber 66. For example, the float 60 can traverse along control rod 62 until encountering a lower stop defining a downward travel limit for the float 60 along control rod 62. The float 60 can continue to travel downward after encountering the lower stop, shifting the control rod 62 and tripping the discharge regulator 50.

[0079] In the first state, a pneumatic outlet valve, which can also be referred to as a vent valve, that is part of or attached to the upper cap 38 can be opened by the rocker assembly 64 which allows any remaining pressurized driving gas in the chamber 66 to evacuate. With pressure within the chamber 66 decreased, the evacuation phase ends and the landfill pump 10 transitions to the filling phase as liquid can move through the inlet extension 16, through the lower pump valve 46, and into the chamber 66 to start the cycle once again.

[0080] As best seen in FIG. 4, the rocker assembly 64 includes a counterweight which balances the control rod 62. The discharge regulator 50 can be pivoted relative to the discharge pipe 42 between the first state and the second state as previously described. In this example, inlet valve seal 86 is mounted on the rocker assembly 64 and forms a portion of the pneumatic inlet valve. With the rocker assembly 64 in the first state, the inlet valve seal 86 engages an orifice in the upper cap 38 to close the pneumatic inlet valve. When the discharge regulator 50 is tripped to the second state, the rocker assembly 64 can pivot to disconnect the inlet valve seal 86 from the seat (e.g., by withdrawing the inlet valve seal 86 away from the upper cap 38) to allow the release of pressurized driving gas into the chamber 66 in the evacuation phase. When transitioning back to the filling phase, the discharge regulator 50 can be tripped to the first state in which the inlet valve seal 86 again engages the upper cap 38 to plug the orifice to close the pneumatic inlet valve.

[0081] With the landfill pump 10 in the filling phase, the liquid in the wellbore 12 can flow into the chamber 66 through inlet extension 16. The landfill pump 10 filling can cause the level LL of the liquid in the wellbore 12 to drop as the liquid is filling into the landfill pump 10. If the liquid level within the wellbore 12 goes below the fluid inlet 22 of the landfill pump 10, then pressurized gas from wellbore 12 can enter into the chamber 66, which can result in pumping inefficiency, reduced liquid evacuation per cycle, and potentially pump malfunction. As discussed above, landfill pump 10 is particularly suited for use in an environment in which the wellbore 12 is positively pressurized relative to the chamber 66.

[0082] It is understood that discussions related to positive pressure in wellbore 12 relate to the difference in pressure between the wellbore 12 outside of the landfill pump 10 and the pressure inside of landfill pump 10. A wellbore 12 can be considered to be positively pressurized when the gas pressure in the wellbore 12 is greater than the gas pressure in the interior of the landfill pump 10. The positive pressure in the wellbore 12 causes the water column in the chamber 66 to be higher than the water column outside of the chamber 66 in the wellbore 12. For example, about 1 pound per square inch (psi) (about 6.89 kilopascal (kPa)) of positive pressure in wellbore 12 can result in about a 27.72 in. (about 70.41 cm) difference in water column height between the liquid outside of the landfill pump 10 and the liquid inside of the landfill pump 10. As such, if the wellbore 12 is positively pressurized by Ipsi relative to the chamber 66, the liquid in chamber 66 can be about 27.72 in. higher than the liquid in wellbore 12.

[0083] During the evacuation phase, pressurized driving gas is introduced to chamber 66 to drive liquid within chamber 66 downward within chamber 66 and towards a bottom end of chamber 66 and then upwards through discharge pipe 42 and out of landfill pump 10. After the evacuation phase ends, the landfill pump 10 transitions to the filling phase in which the chamber 66 is disconnected from the flow of pressurized driving gas that facilitates evacuation. The chamber 66 is not further pressurized during the filling phase and can instead reference atmospheric pressure, or some other pressure lower than the gas pressure in wellbore 12. The landfill pump 10 can be configured to exhaust the pressurized driving gas from chamber 66 to locations outside of the wellbore 12 (e.g., to atmosphere) as exhausting the pressurized gas from chamber 66 can dilute the gasses in wellbore 12 making such gasses harder to utilize. For example, the exhaust gas can dilute methane in wellbore 12 making such methane more difficult to bum.

[0084] Once landfill pump 10 transitions to the filling phase, the liquid in wellbore 12 can flow into landfill pump 10 through inlet extension 16 and lower pump valve 46. The liquid being admitted into the landfill pump 10 can cause the liquid level LL in the wellbore 12 to drop as the liquid is admitted into the landfill pump 10. Without inlet extension 16, such a drop in the liquid level LL can cause the liquid in the wellbore 12 to fall below the fluid inlet of a landfill pump that does not include an inlet extension 16. If the liquid level falls below the fluid inlet, the gas from within the wellbore 12 can flow into the interior of the landfill pump 10 and the positive pressure in the wellbore 12 can prevent the liquid level LL from again rising above the top end of the pump inlet to submerge the pump inlet. Such gas ingestion into the landfill pump 10 can cause the landfill pump to stall as the float 60 cannot be actuated by liquid as liquid is not entering the chamber 66. The landfill pump will then need to be removed from the wellbore 12 and reset, which can be time consuming and labor intensive.

[0085] Inlet extension 16 provides multiple aspects which help mitigate the risk of unintended introduction of pressurized gas from the wellbore 12 into the chamber 66. Inlet extension 16 lowers the intake 58, and thus the fluid inlet 22, below where an inlet to a landfill pump would conventionally be located. Thus, even if the pressurize gas is pushing the liquid level down, such liquid level is still above the intake 58 such that the inlet extension 16 only takes in liquid and not gas. The extension tube 54 can facilitate lowering of the intake 58, such that a longer extension tube 54 can further lower the intake 58.

[0086] Another aspect which may be, but is not necessarily, present in the inlet extension 16 is a pressure actuated valve assembly 56. The pressure actuated valve assembly 56 can block the flow of pressurized gas through the inlet extension 16 while permitting the liquid to pass into the chamber 66, as further discussed herein.

[0087] FIG. 5 A is an enlarged view of detail A in FIG. 2. FIG. 5B is a cross-sectional view taken along line B-B in FIG. 5A. FIGS. 5A and 5B are discussed together. Adaptor 52, extension tube 54, valve assembly 56, and intake 58 of inlet extension 16 are shown. Adaptor 52 includes adaptor opening 80, adaptor bore 88, adaptor head 90 and adaptor shank 92. Extension tube 54 includes tube body 94, upper tube end 96, and lower tube end 98. Valve assembly 56 includes valve housing 82 and pressure actuated valve 100. Pressure actuated valve 100 includes extension valve seal 102, extension valve seat 104, and spring 106. Valve seal 102 includes seal head 108 and seal shaft 110. Intake 58 includes connector 84 and screen 36.

[0088] Inlet extension 16 is connected to the main body portion of landfill pump 10. In the example shown, the inlet extension 16 is connected to and extends from lower cap 40. Inlet extension 16 is configured to shift the fluid inlet 22 downwards and away from the main body portion of the landfill pump 10 as compared to conventional landfill pumps. Inlet extension 16 shifts the fluid inlet 22 axially away from the main body portion of landfill pump 10. The inlet extension 16 places the fluid inlet 22 further axially away from pump casing 14 than traditional landfill pumps. The elongate inlet extension 16 is configured to prevent ingress of pressurized gas into the chamber 66 of the landfill pump 10 by maintaining all portions of the fluid inlet 22 below the liquid level LL of the liquid in the wellbore 12 throughout both the evacuation and filling phases of the landfill pump 10. Inlet extension 16 is cantilevered from the main body of landfill pump 10. In the example shown, the inlet extension 16 is cantilevered from lower cap 40.

[0089] Adaptor 52 connects inlet extension 16 to other components of landfill pump 10. In the example shown, the adaptor 52 is configured to connect to lower cap 40 of the landfill pump 10. Adaptor bore 88 extends fully through adaptor 52 and at least partially defines a flowpath for liquid through inlet extension 16 and into chamber 66. Adaptor opening 80 is disposed at a lower end of the adaptor 52. Adaptor opening 80 includes interior threading in the example shown. The adaptor 52 is configured to connect with extension tube 54 by interfacing within adaptor opening 80. In the example shown, the adaptor 52 connects to the extension tube 54 by interfaced threading between interior threading within adaptor opening 80 and exterior threading on upper tube end 96 of extension tube 54.

[0090] Adaptor shank 92 extends from adaptor head 90. Adaptor shank 92 is configured to interface with the lower cap 40 in the example shown to connect adaptor 52 to the main body portion of landfill pump 10. In the example shown, adaptor shank 92 includes exterior threading that interfaces with interior threading within cap aperture 68. Adaptor head 90 projects radially outward from adaptor shank 92. Adaptor head 90 can include facets or other surface features that provide a tool interface for connecting adaptor 52 to lower cap 40. For example, a wrench can interface with adaptor head 90 to torque adaptor 52 to thread or unthread adaptor 52 on lower cap 40.

[0091] Extension tube 54 extends between and connects adaptor 52 and valve assembly 56. The extension tube 54 is axially elongate and at least partially defines a flowpath for the liquid to flow through inlet extension 16 and to chamber 66. In the example shown, the extension tube 54 extends between an upper tube end 96 connected to adaptor 52 and a lower tube end 98 connected to valve housing 82. Extension tube 54 increase the length of the inlet extension 16 to place the fluid inlet 22 below the liquid level in the wellbore 12. As discussed above, some examples of inlet extension 16 are configured such that the overall length LI of the inlet extension 16 is adjustable. For example, the extension tube 54 can be removed and replaced with an extension tube 54 having a different length to change the length LI of the inlet extension 16.

[0092] In the example shown, extension tube 54 extends at least partially into adaptor 52 and at least partially into valve assembly 56 to interface with adaptor 52 and valve assembly

[0093] 56. In this example, upper tube end 96 includes exterior threading that interfaces with interior threading within adaptor 52 to connect extension tube 54 and adaptor 52. Lower tube end 98 includes exterior threading in this example that interfaces with interior threading within valve housing 82 to connect extension tube 54 and valve housing 82. While extension tube 54 is shown as threadedly connected to adaptor 52 and valve housing 82, it is understood that not all examples are so limited.

[0094] Valve assembly 56 is configured to regulate fluid flow through inlet extension 16. Valve assembly 56 regulates fluid flow into chamber 66 such that pressurized gas from the wellbore 12 is unable to cause valve assembly 56 to open. Valve assembly 56 thus prevents ingestion of the positive pressure gas from wellbore 12 into landfill pump 10. Valve assembly 56 is configured to open in response to liquid pressure (head pressure) such that liquid from wellbore 12 is able to open valve assembly 56 and flow into chamber 66. Valve assembly 56 is connected to extension tube 54 and is supported by extension tube 54 in this example. Valve housing 82 can form at least a part of an exterior portion of the inlet extension 16. The valve housing 82 can be made of metal, amongst other options.

[0095] Intake 58 is disposed at a distal end of inlet extension 16. Fluid enters into inlet extension 16, and thus into landfill pump 10, through intake 58. In the example shown, intake 58 is connected to and depends from valve assembly 56. Connector 84 of intake 58 is connected to valve housing 82. In the example shown, the connector 84 extends into valve housing 82 to interface with and connect to valve housing 82. In this example, connector 84 includes exterior threading that interfaces with interior threading of the valve housing 82 such that intake 58 is connected to valve assembly 56 at a threaded interface. It is understood, however, that other connection types are possible. In some examples, connector 84 and valve housing 82 can be formed as a single component (e.g., monolithically). In some examples, the screen 36 can be directly connected to the valve housing 82.

[0096] Intake 58 includes screen 36 that is supported by connector 84. Screen 36 includes one or more openings therethrough such that fluid can flow through the screen 36 to enter into inlet extension 16 and thus landfill pump 10. The screen 36 is configured to filter out large debris and prevent such debris from entering into landfill pump 10. The fluid inlet 22 can be considered to be formed at the bottom end of the connector 84, at which location fluid can flow through the screen 36 and enter into inlet extension 16.

[0097] Pressure actuated valve 100 is disposed at least partially within valve housing 82.

[0098] Pressure actuated valve 100 is normally closed and is configured to be opened by pressure acting in the downstream axial direction AD2. In the example shown, the pressure actuated valve 100 is a one-way valve that is configured to allow flow in downstream direction AD2 while preventing retrograde flow in upstream direction ADI. The pressure actuated valve 100 is biased closed in this example. A crack pressure is required to cause the pressure actuated valve 100 to open and allow flow through the pressure actuated valve 100. The crack pressure is a threshold pressure at which the biasing force maintaining pressure actuated valve 100 in the closed state is overcome such that pressure actuated valve 100 opens.

[0099] Pressure actuated valve 100 includes valve seal 102 that is movable relative to valve seat 104. The valve seal 102 engages with valve seat 104 to close the pressure actuated valve 100 and prevent fluid flow across the pressure actuated valve 100. The valve seal 102 is spaced from the valve seat 104 to open pressure actuated valve 100 and allow fluid flow across the pressure actuated valve 100. Valve seal 102 and valve seat 104 can both be formed from metal such that pressure actuated valve includes a metal-to-metal sealing interface. Such a configuration is robust and particularly suited for the harsh environment in a wellbore 12. It is understood, however, that not all examples are so limited.

[0100] In the example shown, valve seal 102 includes seal head 108 that is configured to engage with valve seat 104 to place pressure actuated valve 100 in the closed state. Seal shaft 110 projects from seal head 108. The valve seal 102 can be fixed to the seal shaft 110, such as both being formed as a single piece of material. As such, valve seal 102 and seal shaft 110 can be formed monolithically, though it is understood that other configurations are possible. For example, seal shaft 110 can be formed separately from valve seal 102 and connected to valve seal 102, such as by a threaded interface (e.g., by exterior threading on seal shaft 110 interfacing with interior threading in valve seal 102).

[0101] Seal shaft 110 interfaces with brace 118 in the example shown. Seal shaft 110 is at least partially disposed in brace 118 in the example shown. Seal shaft 110 is movable relative to brace 118 and can translate axially in both the upstream direction ADI and the downstream direction AD2. The brace 118 can guide the seal shaft 110, and thus the valve seal 102, such that the valve seal 102 only reciprocates axially, thereby aligning the valve seal 102 with the valve seat 104. Brace 118 can maintain valve seal 102 in axial alignment.

[0102] In the example shown, brace 118 is formed as a portion of valve housing 82. However, it is noted that the brace 118 may be formed by other components that are not part of the valve housing 82 in various other examples. For example, the brace 118 can be formed as a ring or other structure that is separate from and connectable to valve housing 82, such as by interfaced threading among other options. The brace 118 can perform several functions. As shown, the brace 118 receives seal shaft 110, which can reciprocate within the brace 118 such that the seal shaft 110 only reciprocates axially. The brace 118 can also engage the spring 106 to allow the spring 106 to push the valve seal 102 against valve seat 104. Windows 112 are formed through brace 118 and provide openings that allow for fluid flow past brace 118.

[0103] Spring 106 is disposed within valve housing 82. Spring 106 is configured to bias pressure actuated valve 100 towards the closed state. The spring 106 interfaces with valve seal 102 and biases valve seal 102 in upstream direction ADI and towards engagement with valve seat 104. In the example shown, spring 106 is disposed between brace 118 and seal head 108 of valve seal 102. The brace 118 can engage the spring 106 to define a downstream limit of the spring 106 such that the spring 106 can be compressed between brace 118 and valve seal 102 and such that the spring 106 can thus bias valve seal 102 towards valve seat 104.

[0104] Valve seal 102 is urged against valve seat 104 by the spring 106. Valve seat 104 can be formed from the valve housing 82, or can be formed from a different structure. In the example shown, the valve housing 82 includes housing portions 114a, 114b that are formed separately from each other and connected together. Housing portion 114a includes brace 118 and housing portion 114b includes valve seat 104. The valve housing 82 being formed from multiple components can allow for a user to swap out the spring 106 such as to change the spring rate of the spring 106 of pressure actuated valve 100, thereby change the threshold crack pressure of the pressure actuated valve 100. Such a configuration provides for quick and easy reconfiguration of the inlet extension 16 to allow for operation in wellbores 12 having different positive gas pressures.

[0105] Valve seal 102 can annularly engage valve seat 104 to block flow in the upward (downstream) direction AD2 past the interface of the valve seal 102 and valve seat 104. Sufficient pressure on the face 116 of the valve seal 102 can overcome the spring 106 to move the valve seal 102 out of engagement with the valve seat 104 to open the pressure actuated valve 100.

[0106] The spring 106 can be one of a plurality of springs each with a different spring constant (spring rate). The spring 106 can be chosen based on the pressure of the pressurized gas introduced into the wellbore 12 as well as the expected liquid depth of the fluid inlet 22 of the landfill pump 10 (e.g., expected depth below the top of the liquid in the wellbore 12). The pressure actuated valve 100 is configured such that the positive gas pressure in the wellbore 12 alone is insufficient to move the valve seal 102 off of the valve seat 104. For example, if the positive pressure in the wellbore 12 is set at Ipsi, then the spring rate of spring 106 can be set at a value equal to or greater than Ipsi (e.g., at 1.5psi, at 2psi, etc.). Such a configuration prevents ingestion of the positively pressurized gas in the wellbore 12.

[0107] While the pressurized gas alone is insufficient to open pressure actuated valve 100, that same pressurize gas pushing on a column of liquid within the wellbore 12 above the valve seat 104 (e.g., when the liquid level is at or above the pressure actuated valve 100) can generate enough pressure to overcome the spring 106 and move the valve seal 102 off of the valve seat 104 to allow flow. As such, gas pressure alone is not sufficient to open the pressure actuated valve 100, but gas pressure together with head pressure from liquid acting on the pressure actuated valve 100 can open the pressure actuated valve 100. As such, pressure actuated valve 100 can keep out pressurize gas but can let liquid pass.

[0108] Landfill pump 10 can include a series of one-way admission valves that control flow into chamber 66 and that are configured to prevent retrograde flow from chamber 66. In the example shown, the landfill pump 10 includes lower pump valve 46 and pressure actuated valve 100 that form the one-way admission valves. The one-way admission valves can be disposed coaxially with each other. In the example shown, the landfill pump 10 includes one one-way admission valve that is biased (e.g., pressure actuated valve 100) and includes another one-way admission valve that is unbiased (e.g., lower pump valve 46). The pressure actuated valve 100 is disposed closer to the fluid inlet 22 than the unbiased lower pump valve 46. The pressure actuated valve 100 is the upstream valve of the series of one-way valves and the unbiased lower pump valve 46 is the downstream valve of the series of one-way valves. The series of one-way valves in landfill pump 10 provide for efficient pump cycling while preventing ingestion of pressurized gas from wellbore 12.

[0109] During an evacuation phase, the compressed gas admitted into the chamber 66 causes the unbiased lower pump valve 46 to shift to a respective closed state, and the spring 106 may bias the valve seal 102 into sealing engagement with valve seat 104 to close pressure actuated valve 100. Liquid can be captured in inlet extension 16 at locations between the pressure actuated valve 100 and the lower pump valve 46. Such accumulated liquid remains in the inlet extension 16 during the evacuation phase. The liquid in the inlet extension 16 can also assist in maintaining the pressure actuated valve 100 in the closed state in the event that the liquid level in the wellbore 12 falls below the fluid inlet 22.

[0110] During operation, the landfill pump 10 operates in serial pump cycles each including an evacuation phase and a filling phase. With the landfill pump 10 initially in a filling phase, the liquid within the wellbore 12 can flow into the inlet extension 16 through the intake 58. The positive pressure in the wellbore 12 means that the liquid within the interior of the landfill pump 10 is at a higher height that the liquid outside of the landfill pump 10. The liquid fills into the chamber 66 through inlet extension 16 and lower pump valve 46.

[0111] The landfill pump 10 transitions to the evacuation phase after the filling phase. The liquid within chamber 66 is evacuated from chamber 66 through discharge pipe 42 and upper pump valve 48. After the evacuation phase, the landfill pump 10 transitions back to a filling phase.

[0112] With landfill pump 10 transitioned to a filling phase after the evacuation phase, the landfill pump 10 is ready to again be filled with liquid for another evacuation phase. The chamber 66 is connected to a reference pressure (e.g., atmosphere) that is less than the gas pressure in the wellbore 12, such that the wellbore 12 is considered to be positively pressurized.

[0113] The positive pressure in the wellbore 12 can drive the liquid into the landfill pump 10. However, the liquid level LL in the wellbore 12 can drop as the landfill pump 10 is filling. Such a drop can cause the liquid level LL to fall below the fluid inlet 22, such that the liquid level LL is below any opening that fluidly connects the interior of the wellbore 12 with the interior of the landfill pump 10 (e.g., an uppermost opening of screen 36). In such an event, the positive pressure gas from the wellbore 12 can begin flowing into the landfill pump 10, which can cause the landfill pump 10 to stall and render the landfill pump 10 inoperable until reset.

[0114] Inlet extension 16 can counteract and prevent gas ingestion into landfill pump 10. The inlet extension 16 elongates the overall length of the landfill pump 10 such that the fluid inlet 22 is spaced further from the lower pump valve 46. Such an elongate configuration of the inlet extension 16 positions the highest possible ingress point for fluid into landfill pump 10 (e.g., an uppermost opening of screen 36) further axially away from the main body portion of landfill pump 10. The elongate inlet extension 16 can maintain the fluid inlet 22 below the liquid level even when the liquid level drops during a filling phase.

[0115] Inlet extension 16 can, in some examples, actively prevent ingestion of gas into chamber 66. Pressure actuated valve 100 prevents ingestion of gas into chamber 66 while allowing ingestion of liquid into chamber 66. Spring 106 biases the pressure actuated valve 100 towards the closed state. A spring rate of the spring 106 is set such that the positive pressure gas in the wellbore 12 cannot overcome the spring 106 and cause the pressure actuated valve 100 to open. As such, the liquid level in the wellbore 12 falling below the fluid inlet 22 does not result in compressed gas flowing into chamber 66, which free flow of the gas into chamber 66 can stall landfill pump 10 and prevent the liquid level in wellbore 12 from rising to again fully submerge the fluid inlet 22.

[0116] Pressure actuated valve 100 is configured to open based on liquid pressure acting on the pressure actuated valve 100. With the pressure actuated valve 100 closed during the filling phase, the liquid and gas from within the wellbore 12 are not ingested by the landfill pump 10. If the liquid level falls below the fluid inlet 22 such that gas is able to enter into the inlet extension 16, the pressure acting on the face 116 of the valve seal 102 of the pressure actuated valve 100 drops as the positive pressure gas is acting on the pressure actuated valve 100 but liquid is not. The pressure actuated valve 100 returns to the normally closed state (e.g., by spring 106) and inhibits gas from flowing into landfill pump 10. With the pressure actuated valve 100 closed, the positively pressurized gas in wellbore 12 cannot enter into chamber 66 and instead remains in the wellbore 12. The liquid level in the wellbore 12 is able to rise as liquid fills into the wellbore 12. The liquid level will continue to rise and can reach the height of the pressure actuated valve 100. The liquid can then act on the pressure actuated valve 100 to reopen the pressure actuated valve 100 and again allow flow of liquid into the chamber 66.

[0117] Inlet extension 16 can, in some examples, be configured as a retrofit for existing landfill pumps. In such an example, the inlet extension 16 can be connected to an existing landfill pump at a lower end of the landfill pump, or the existing landfill pump can be retrofit with the lower cap 40 and inlet extension 16. Inlet extension 16 can thus allow for quick and inexpensive updating of a landfill pump for use in positive pressure wells.

[0118] Inlet extension 16 provides significant advantages. Inlet extension 16 elongates the landfill pump 10. The inlet extension 16 moves the fluid inlet 22 axially away from the lower pump valve 46 that is at a lower end of the chamber 66. Such a configuration provides a greater reach for the landfill pump 10 down into the wellbore 12 and into the liquid within the wellbore 12. Spacing the fluid inlet 22 axially away from and below the lower pump valve 46 maintains the desired trigger point (height of liquid in chamber 66) for actuating the landfill pump 10 from the filling phase to the evacuation phase while providing a greater reach for the landfill pump 10 to access the liquid.

[0119] As an additional or alternative aspect, the pressure actuated valve 100 prevents ingression of gasses into landfill pump 10 that could stall or otherwise deteriorate operational efficiency of the landfill pump 10. Pressure actuated valve 100 is disposed upstream of chamber 66 and can regulate fluid flow into chamber 66. The pressure actuated valve 100 is biased closed and can be actuated open by liquid pressure. Pressure actuated valve 100 is configured such that the positive gas pressure in wellbore 12 is insufficient to open the pressure actuated valve 100 when acting alone. Instead, liquid pressure is required to open the pressure actuated valve 100. Such a configuration prevents the positive pressure gas in the wellbore 12 from freely flowing into the chamber 66 in the event the liquid level drops to expose the fluid inlet 22 to the wellbore gas. Pressure actuated valve 100 can thus maintain landfill pump 10 in an operable state throughout filling and evacuation phases by inhibiting ingestion of wellbore gas while allowing ingestion of wellbore liquid.

[0120] While the invention(s) has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention(s) without departing from the essential scope thereof. Therefore, it is intended that the invention(s) not be limited to the particular embodiment(s) disclosed, but that the invention(s) may include all embodiments falling within the scope of the appended claims. Any single feature, or any combination of features from one embodiment show herein, may be utilized in a different embodiment independent from the other features shown in the embodiment herein. Accordingly, the scope of the invention(s) and any claims thereto are not limited to the particular to the embodiments and / or combinations of the features shown herein, but rather can include any combination of one, two, or more features shown herein.

Claims

CLAIMS:

1. A landfill pump for pumping a liquid out of a wellbore, the landfill pump comprising: a case elongate along a pump axis; a pump chamber located at least partially within the case; an upper cap mounted on a top end of the case; a lower cap mounted on a bottom end of the case; a discharge regulator that regulates evacuation of the liquid out of the chamber, the liquid moving through and further above the upper cap when being evacuated; and an inlet extension mounted to the lower cap and extending below the lower cap, the inlet extension including an extension tube and a fluid inlet.

2. The landfill pump of claim 1, wherein the inlet extension comprises an inlet screen disposed below the extension tube, the inlet screen allowing the landfill liquid to pass from outside the extension tube into the extension tube through the inlet screen while blocking at least some particulate matter from passing from outside the extension tube into the extension tube through the inlet screen.

3. The landfill pump of any one of claims 1 and 2, wherein the inlet extension extends downward from the lower cap by at least two inches.

4. The landfill pump of claim 3, wherein the inlet extension extends downwards from the lower cap by at least four inches.

5. The landfill pump of claim 4, wherein the inlet extension extends downward from the lower cap by at least five inches.

6. The landfill pump of claim 5, wherein the inlet extension extends downward from the lower cap by at least ten inches.

7. The landfill pump of any one of claims 1-3, wherein the inlet extension extends downwards from the lower cap by between four and twelves inches, inclusive.

8. The landfill pump of claim 7, wherein the inlet extension extends downwards from the lower cap by between four and ten inches, inclusive.

9. The landfill pump of any one of claims 1-3, wherein the inlet extension extends downwards from the lower cap by up to eighteen inches.

10. The landfill pump of any one of claims 1-9, wherein the inlet extension further comprises an inlet adaptor that inserts into an aperture of the lower cap.

11. The landfill pump of claim 10, wherein the extension tube is directly connected to the inlet adaptor and the inlet adaptor is directly connected to the lower cap.

12. The landfill pump of claim 11, wherein the extension tube extends into the inlet adaptor to connect to the inlet adaptor.

13. The landfill pump of any one of claims 10-12, wherein the inlet adaptor is threadedly connected to the lower cap and the extension tube is threadedly connected to the inlet adaptor.

14. The landfill pump of any one of claims 1-13, wherein the inlet extension further comprises a valve assembly.

15. The landfill pump of claim 14, wherein the valve assembly is disposed below the extension tube.

16. The landfill pump of any one of claims 14 and 15, wherein the valve assembly includes a pressure actuated valve that is normally closed.

17. The landfill pump of claim 16, wherein the pressure actuated valve is biased closed.

18. The landfill pump of any one of claims 16 and 17, wherein the pressure actuated valve includes: a valve seat; a valve seal movable relative to the valve seat, the valve seal sealing with the valve seat with the pressure actuated valve in a closed state; a spring configured to urge the valve seal against the valve seat; wherein pressure of the landfill liquid urges against the valve seal and upon reaching a threshold pressure overcomes the spring to unseat the valve seal from the valve seat allowing the landfill liquid to flow from outside the inlet extension through the inlet extension and into the chamber19. The landfill pump of claim 18, wherein the pressure actuated valve is configured so that pneumatic well pressure is insufficient to open the pressure actuated valve without the landfill liquid acting on the valve seal, and the pressure actuated valve configured so that the pneumatic well pressure and at least partial submergence of the inlet extension in the landfill liquid is sufficient to open the pressure actuated valve.

20. The landfill pump of any one of claims 18 and 19, wherein the spring is one of a plurality of different springs having different spring constants, respectively, theplurality of different springs being substitutable in the pressure actuated valve to adjust for different pneumatic pressures in the well bore.

21. The landfill pump of any one of claims 14-20, wherein the pressure actuated valve assembly includes a valve housing connected to and disposed between the extension tube and the fluid inlet.

22. The landfill pump of claim 21, wherein the valve housing is connected to the extension tube by interfaced threading.

23. The landfill pump of claim 14, wherein the valve assembly comprises: a valve housing connected to the extension tube and extending below the extension tube and disposed above the fluid inlet; and a pressure actuated valve at least partially disposed in the valve housing, the pressure actuated valve including a valve seal biased into sealing contact with a valve seat by a spring.

24. The landfdl pump of claim 23, wherein the valve seal includes a seal head configured to sealingly interface with the valve seat and the valve seal includes a stem projecting away from the seal head.

25. The landfill pump of claim 24, wherein the stem is at least partially disposed in a brace, the brace limiting the stem to linear displacement.

26. The landfill pump of claim 25, wherein the brace is formed by the valve housing.

27. The landfill pump of any one of claims 25 and 26, wherein the spring is disposed between and braced by the brace and the seal head.

28. The landfill pump of any one of claims 18-20 and 23-27, further comprising: a lower pump valve disposed at a lower end of the case, the lower pump valve configured to regulate fluid flow into the pump chamber, the lower pump valve opening to allow the liquid to pass from the inlet extension into the chamber during a filling phase of the landfill pump, and closing to prevent flow of the liquid from the chamber back through the inlet extension during an evacuation phase.

29. The landfill pump of claim 28, wherein the lower pump valve is not biased open or closed.

30. The landfill pump of any one of claims 28 and 29, wherein the lower pump valve includes a lower valve seal that is configured to float in the liquid and rise duringingress of the liquid into the chamber from the inlet extension during the filling phase, the lower valve seal being pushed downward to close the lower pump valve and prevent the liquid within the chamber from flowing back through the inlet extension during the evacuation phase.

31. The landfill pump of any one of claims 28-30, wherein the lower pump valve and the pressure actuated valve are disposed coaxially.

32. The landfill pump of any one of claims 28-31 , wherein the pressure actuated valve is disposed upstream of the lower pump valve such that the liquid passes first through the pressure actuated valve and then through the lower pump valve to enter into the pump chamber.

33. The landfill pump of any one of claims 28-32, wherein a seat of the lower pump valve is formed by the lower cap.

34. The landfill pump of claim 33, wherein the inlet extension is mounted to a first end of a bore through the lower cap and the seat of the lower pump valve is formed at a second end of the bore through the lower cap.

35. The landfill pump of any preceding claim, further comprising: a discharge pipe at least partially within the case, the discharge pipe having a pipe inlet within the chamber, wherein the liquid being evacuated from the pump chamber moves from the pump chamber, through the pipe inlet of the discharge pipe, and then up the discharge pipe.

36. The landfill pump of claim 34, wherein the discharge pipe extends through the upper cap.

37. The landfill pump of any one of claims 1-36, wherein the upper cap extends inside of the case and above the case.

38. The landfill pump of any one of claims 1-37, wherein the lower cap extends inside of the case and below the case.

39. The landfill pump of any one of claims 1-38, wherein the discharge regulator includes a float located within the chamber, the float configured to rise within the case as the liquid fills the chamber until a threshold height is met which causes the discharge regulator to evacuate the liquid from the chamber.

40. The landfill pump of any one of claims 1-39, wherein the discharge regulator includes a rocker.

41. The landfill pump of any one of claims 1-40, wherein the discharge regulator blocks ingress of a pressurized gas into the chamber when the discharge regulator is in afill state which allows ingress of the liquid into the chamber, and the discharge regulator permits ingress of the pressurized gas into the chamber when the discharge regulator is in an evacuation state, the ingress of pressurized gas into the chamber forcing the liquid within the chamber to be evacuated through the upper cap.

42. The landfill pump of any one of claims 1-41, wherein the inlet extension has a first length, the case has a second length, and the first length is less than the second length.

43. The landfill pump of claim 42, wherein the case has a case diameter, and wherein the first length is greater than the case diameter.

44. The landfill pump of claim 42, wherein a smallest diameter portion of the case is larger than a largest diameter portion of the inlet extension.

45. A landfill pump for pumping a liquid out of a wellbore, the landfill pump comprising: a case elongate along a pump axis; a pump chamber located at least partially within the case; an upper cap mounted on a top end of the case; a lower cap mounted on a bottom end of the case; a discharge regulator that regulates evacuation of the liquid out of the chamber, the liquid moving through and further above the upper cap when being evacuated; a lower valve disposed within the case, the lower valve allowing flow of the liquid into the chamber when in a lower valve open state and preventing backflow of the liquid from the chamber when in a lower valve closed state; and a valve assembly including a pressure actuated valve, the valve assembly supported by the lower cap, the pressure actuated valve disposed below the lower cap and upstream of the lower valve, wherein the pressure actuated valve is biased to a normally closed state.

46. The landfill pump of claim 45, wherein the pressure actuated valve is disposed in a valve housing that extends below the lower cap.

47. The landfill pump of claim 46, further comprising an extension tube disposed between the lower cap and the valve housing, the extension tube at least partially defining a flowpath between the pressure actuated valve and the lower valve, and the extension tube connecting the valve housing to the lower cap.

48. The landfill pump of claim 47, further comprising an inlet adaptor disposed between and connecting the extension tube and the lower cap, wherein the inlet adaptor at least partially defines the flowpath.

49. The landfill pump of claim 48, wherein the inlet adaptor is directly connected to the lower cap and directly connected to the extension tube.

50. The landfill pump of any one of claims 46-49, wherein the pressure actuated valve comprises: a valve seat; and a valve seal movable relative to the valve seat to place the pressure actuated valve in an open state, allowing fluid flow through the pressure actuated valve, and a closed state, preventing fluid flow through the pressure actuated valve.

51. The landfill pump of claim 50, wherein the valve seal comprises: a seal head configured to interface with the valve seat to place the pressure actuated valve in the closed state; and a stem extending from the seal head and towards the lower pump valve.

52. The landfill pump of claim 50, wherein the stem is at least partially disposed in a brace that limits the stem to linear displacement.

53. The landfill pump of claim 52, wherein the stem is moveable axially relative to the brace and is prevented from moving radially by the brace.

54. The landfill pump of any one of claims 52 and 53, wherein the brace is formed by the valve housing.

55. The landfill pump of any one of claims 50-54, wherein the valve housing comprises: an upstream housing portion connected to a downstream housing portion, wherein the valve seat is formed by the upstream housing portion.

56. The landfill pump of claim 55, further comprising: a spring interfacing with the valve seal and biasing the valve seal towards the valve seat.

57. The landfill pump of claim 45, further comprising: an inlet extension connected to the lower cap and extending from the lower cap, the inlet extension including an extension tube and the valve assembly, wherein the valve assembly is connected to the extensiontube such that the extension tube is disposed between the valve assembly and the lower pump valve.

58. The landfill pump of claim 57, wherein a largest diameter of the inlet extension is less than a smallest diameter of the case.

59. The landfill pump of any one of claims 57 and 58, wherein the inlet extension has a first length, and the first length is greater than a case diameter of the case.

60. The landfill pump of any one of claims 57-59, wherein the inlet extension further comprises: an inlet adaptor connecting the extension tube to the lower cap.

61. The landfill pump of claim 60, wherein the inlet adaptor is direction connected to the lower cap by interfaced threading.

62. The landfill pump of any one of claims 60 and 61, wherein the inlet adaptor is connected to the lower cap at a lower opening of an aperture through the lower cap and wherein a lower valve seat of the lower valve is formed about an upper opening of the aperture.

63. The landfill pump of claim 62, wherein the inlet adaptor extends into the lower opening to connect to the lower cap.

64. The landfill pump of any one of claims 57-63, wherein the inlet extension further comprises: an intake connected to the valve housing and disposed upstream of the pressure actuated valve.

65. The landfill pump of claim 64, wherein the intake includes a screen configured to filter out debris.

66. The landfill pump of any one of claims 64 and 65, wherein an intake body of the intake is directly connected to the valve housing.

67. The landfill pump of any one of claims 46-66, further comprising: a discharge pipe disposed at least partially within the casing, the discharge pipe having a pipe inlet within the pump chamber, wherein the liquid being evacuated from the pump chamber moves from the pump chamber, through the pipe inlet of the discharge pipe, and then up the discharge pipe.

68. The landfill pump of claim 67, wherein the discharge pipe and the pressure actuated valve are disposed coaxially.

69. The landfill pump of claim 68, wherein the lower valve and the discharge pipe are disposed coaxially.

70. A landfill pump for pumping a liquid out of a wellbore, the landfill pump comprising: a case elongate along a pump axis; a pump chamber located at least partially within the case; an upper cap mounted on a top end of the case; a lower cap mounted on a bottom end of the case; a discharge regulator that regulates evacuation of the liquid out of the chamber, the liquid moving through and further above the upper cap when being evacuated; a lower valve disposed within the case, the lower valve allowing flow of the liquid into the chamber when in a lower valve open state and preventing backflow of the liquid from the chamber when in a lower valve closed state; and an inlet extension mounted to the lower cap and extending below the lower cap, the inlet extension including: an extension tube; an intake having a fluid inlet; and a valve assembly including a pressure actuated valve, the pressure actuated valve disposed below the lower cap, downstream of the fluid inlet, and upstream of the lower valve, wherein the pressure actuated valve is biased to a normally closed state.

71. The landfill pump of claim 70, wherein the valve assembly includes a valve housing connected to the extension tube and connected to the intake.

72. The landfill pump of claim 71, wherein the intake extends into the valve housing to connect to the valve housing, and wherein the extension tube extends into the valve housing to connect to the valve housing.

73. The landfill pump of any one of claims 70-72, wherein the valve assembly includes a spring biasing the pressure actuated valve to the normally closed state.

74. The landfill pump of claim 73, wherein the spring is one of a plurality of different springs having different spring constants, respectively, the plurality of different springs being substitutable in the pressure actuated valve to adjust for different pneumaticpressures in the well bore and the valve assembly including only one of the plurality of different springs at a time.

75. A method of operating a landfill pump that pumps a liquid form a wellbore, the method comprising: blocking pressurized gas from entering a chamber of the landfill pump with a pressure actuated valve; and permitting the liquid to enter the pumping chamber by passing through the pressure actuated valve due to combined forces of pressure head of the liquid and the pressurized gas opening the pressure actuated valve.

76. The method of claim 75, wherein the pressure actuated valve is located within an inlet extension of the landfill pump.

77. The method of any one of claims 75 and 76, wherein blocking the pressurized gas from entering the chamber of the landfill pump with the pressure actuated valve comprises blocking the pressurized gas while a level of the liquid is below an inlet of the landfill pump such that the liquid does not exert pressure on the pressure actuated valve and the pressurized gas that does exert pressure on the pressure actuated valve generates insufficient force to open the pressure actuated valve.

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