Patent Grant
9759047
The present invention relates to apparatus and methods for perforating pipe, and more particularly to existing vertical landfill gas (LFG) extraction wells and other piping installations having constricted areas and corrosive environments.
Landfills are often prolific contributors of greenhouse gases, particularly methane (CH4), which according to the EPA, is a greenhouse gas that is approximately 21 times more potent than carbon dioxide (CO2). As a byproduct of waste disposal and aerobic and anaerobic digestion by microbes of organic matter, landfills produce a variety of gases, including methane and carbon dioxide and others. Some of these gases, typically composed of mostly methane and carbon dioxide, may be collected in compliance with state and federal regulations and combusted in a flare system. However, methane, in particular, may be utilized with contemporary technology to generate electricity by combustion, fuel industrial boilers, or be converted to pipeline quality High-BTU gas so there is inherent value in using methane. In addition to obvious economic advantages derived from using methane as a fuel, flaring methane from the landfill reduces greenhouse gas emissions relative to the situation where methane is neither utilized as a fuel nor flared.
Landfills frequently have gas extraction systems to capture landfill gases. The gases are typically drawn out of a landfill with a low pressure vacuum via a wellfield collection and control system (GCCS). The wellfield typically consists of multiple gas extraction wells that extend deep beneath the surface of the landfill to pull methane from a location near the bottom of the landfill. Each extraction well extends up to the surface of the landfill and is connected with other wells, creating a piping matrix, so that a vacuum can be pulled with one centralized blower or compressor.
Landfill gas extraction wells are perforated along their lengths to allow the gases to be extracted from the waste deposits. There are many factors that influence the effectiveness of a landfill gas extraction well. For example, there may be a liquid-level blockage, insufficient perforation coverage, failed perforations, or non-perforated risers that prohibit the vacuum from being applied to the surrounding waste and therefore decrease the efficiency of gas extraction.
In the instance of a high liquid level, a dewatering pump is often installed in the extraction well to remove the liquid and allow the vacuum to pull on the waste through the perforations again. But in the other three aforementioned instances, there is very little to nothing that can be done to restore the extraction well. Therefore, there is a need for an apparatus and method to restore these poorly performing or non-performing LFG extraction wells.
The subject invention is a multi-directional drill-type device that can be shuttled vertically through well casings of various diameters to add new perforations at the desired spacing to optimize well performance. The apparatus is designed to add perforations to well casings of existing vertical LFG extraction wells.
The invention will be better understood and its numerous objects and advantages will be apparent by reference to the following detailed description of the invention when taken in conjunction with the following drawings.
The invention will now be described in detail with reference to the drawings. The invention comprises a drill-type perforation apparatus, well mount structures that support the perforation apparatus, and an electrical controller that controls operation of the perforation apparatus.
With reference now to the drawings, a first illustrated embodiment of a perforation apparatus 10 according to the present invention is illustrated in an assembled condition and in isometric view in
As detailed below, in normal use the apparatus 10 is inserted into an existing pipe that is typically extending vertically relative to a nominally horizontal ground plane. As such, at times in this description the relative positions of structural components of the apparatus 10 are described using relative directional terms. In all cases, these terms are based upon the vertical orientation of apparatus 10 as it is positioned in a vertically oriented pipe. The upper or top end of the apparatus 10 is thus the upper end of the apparatus as shown in the view of
The assembled perforation apparatus 10 as seen in
The motor casing 102 features a custom electrical connector fitting 108 in cap 105 that is completely sealed and designed to withstand corrosive environments such as those encountered in LFG extraction wells. A suspension loop 110 attached to the top of the cap 105 and allows a suspension cable to be attached to the apparatus 10 as detailed below. As also detailed below, a centering skid assembly 140 that helps to maintain the position of apparatus 10 within pipe 402 during operations is attached to the cap 105 of motor casing 102. Specifically, an upper centering skid assembly 140 is attached to the cap 105 and a lower centering skid assembly 140 is attached to the bottom plate 342 of the lowermost drill assembly module. The centering skid assemblies thus define a mechanism for maintaining the position of apparatus 10 near the axial center of the pipe while drilling operations are taking place.
The relative orientation of the three primary structural components, the motor assembly 100, the drive assembly 200 and the drill assembly 300, are shown in
The motor casing 102 may comprise multiple cylinders that are fit together with centering rings and O-rings to provide a safety seal against landfill gas intrusion. The multiple cylinders that comprise casing 102 and their connections to one another is best illustrated in the exploded views of
A motor drive linkage 120 meshes via a keyed socket 122 with a cooperatively formed key 124 on the drive shaft 112. As explained below, the motor drive linkage 120 interconnects the output of motor 114 to the drive components of drive assembly 200. It will be appreciated that the structure of the motor assembly 100 allows for easy disconnection of components by removing attachment bolts and the like and then separating the components for maintenance purposes.
The motor assembly 100 attaches to the drive assembly 200 with four mending brackets 203 that are spaced around the periphery of the cylindrical housing components. More specifically, the mending brackets 203 are attached to and spaced around the motor drive linkage casing 132 that is the lowermost portion of motor drive assembly 100 and interconnect the motor assembly 100 to the drive assembly 200. The entire motor assembly 100 is sealed to prevent leakage of gas from, or into the assembly, and is fabricated to allow ease of maintenance. The brackets 203 along with the drive linkage design specifically allow ease-of-maintenance. And as may be seen in the exploded view of
The drive assembly 200 is shown in exploded view in
A drive cylinder plate 252 is retained within drive input casing 201 and has two bores 254 and 256 into which roller bearings 258 and 260 are fitted. An output drive shaft 282 has its inner end received in roller bearing 260 and includes a pair of helical gears 262 and 264 attached thereto that mesh with helical gears 266 and 268 on upper shaft 270, which has its inner end received in roller bearing 258. The paired, meshed helical gears 262 and 266, and 264 and 268 are provided due to the relatively high torque inherent in the device and to insure that the teeth on the gears do not shear. A second drive miter gear 272 is attached to the outer end of upper shaft 270, including a roller bearing 274. The outer ends of drive shaft 282 and 270 are secured in bores in an outer plate 276. From the exploded view of
The drive assembly 200 is shown in partial cross section in
The drive assembly 200 is also shown in isolation in
Turning to
Each drill assembly module 301, 302, etc., is identical to the others and comprises a drill cylinder or housing 310 having an opening 312 into which a front plate 314 is attached. A drill bit 316 extends through central opening 318 in plate 314 and has its square base 332 extending through a square opening 319 in drill bit socket (or chuck) 320. A drill bit helical gear 322 is attached to socket 320 and a thrust bearing 324 is interposed between the gear 322 and drill bit thrust screw housing 326. A drill bit thrust screw 328 has a cylindrical outer surface 334 that is threaded and which threads into threaded opening 330 in the thrust screw housing. When assembled, as the helical gear 322 (which meshes with helical gear 264 in drive assembly 200) is rotated the drill bit socked 320 simultaneously rotates, which causes the drill bit 316 to rotate. The base end 332 of the drill bit 316 is received in the square central opening 336 of thrust screw 328. Accordingly, as the bit 316 rotates the thrust screw 328 also rotates. It will be understood, therefore, that as helical gear 322 rotates in a first direction the bit 316 rotates in the same rotational direction and is simultaneously driven outward from the housing 310 (and thus into the wall of the pipe in which the apparatus 10 is residing) as thrust screw rotates in thrust screw housing 326. The drive motor 114 is a variable speed reversible motor, preferably with encoder feedback. When the output shaft of the motor is reversed, the drill bit 316 rotates in the opposite axial direction and the thrust screw is threaded back into the thrust screw housing to retract the bit back to the home position.
The pitch diameter of the helical gear 322 has the same pitch diameter as the helical gears 262 and 264 in drive assembly 200 so as to not modify the torque ratio from motor 114 to drill bit 316.
Each drill assembly module is composed of individual components as shown and as described, which may all be removed and replaced individually, allowing any component to be easily replaced in the event of a mechanical failure.
The front plate 314 allows the drill bit 316 to project out from its face and drill through the wall of the pipe 402 into which apparatus 10 is inserted. The diameter of opening 318 is sized to restrict waste and chips from the drilling process from entering the drill cylinder. The front plate 314 is also designed to support the thrust bearing 324 and a thrust bearing 338 on the opposite side of socket driver 320 and, in turn, the drill bit socket driver, which is fastened to helical gear 322. A back plate 340 is attached to and closes a rear opening of the housing 310.
In the event that outside waste or chips from the drilling process enter the front plate opening, they are blocked from progressing into the drill cylinder's internal components by multiple thrust bearings and tight tolerances. The drill bit 316 is machined with a filleted transition between its square drive shank to the drill portion to eliminate the possibility of outside material and waste from becoming smashed between the drill bit and the cylinder as it retracts back into the drill cylinder.
The drill bit's profile is such that its cutting edges are sufficient to drill all the way through the desired pipe material. The drill bit is preferably composed of cobalt steel, which tends to be less likely to shatter when drilling through a ductile plastic, such as HDPE, and then hits 1″ to 3″ gravel.
The method for replacing a drill bit is designed to be quick when out in the field. The back plate 340 is quickly removed with four screws, where the one screw (not shown) that connects the drill bit 316 to the driving mechanism defined by the thrust screw 328 and thrust screw housing 326 is exposed. Once the connecting screw is removed, a worn or damaged drill bit is easily replaced with a new drill bit.
The drill bit socket driver 320, which drives the drill bit, is wedged between two thrust bearings 324 and 338 to constrain its motion in the lateral direction. It is then fitted around the drive mechanism with a sleeve bearing 321 between thrust bearing 324 and the socket driver 320 to restrict motion to only rotation.
Continuing with a description of the mechanisms that translate the rotation of the motor drive shaft to rotation of the drill bit on an axis normal to the axis of the motor drive shaft, the drive mechanism contains a drill bit thrust screw 328 that has a square socket 336 to receive the square end 332 of the drill bit 316 and transmit power to the drill bit. The drill bit thrust screw preferably features 32 pitch threads on its external surface 334, which meshes with the internally threaded opening 330 of thrust screw housing 326, to provide a precise travel speed outward or inward as the drill bit 316 rotates. The drive mechanism works with the rotation of the helical gears to cause the drill bit to project out of the drill cylinder and drill the desired pipe. The drive assemblies thus facilitate rotation of the drill bits about an axis normal to the axis about which the motor drive shaft rotates.
The drill assembly modules such as 301, 302, 304, 306 are exactly the dimension with the height being the same as the pitch diameter of the driving helical gear, so that the gears can mesh perfectly with each other—spaced by the single-drill modules.
As noted, plural drill assembly modules can be stacked such that they operate simultaneously with adjacent drill assembly modules. Apparatus 10 can thus operate with anywhere from one to four drill assembly modules, with the associated drill bits oriented at 90 degree angles around the perimeter of the apparatus where four drill assemblies are utilized.
Adjacent drill assembly modules are fitted with either a right-hand or left-hand helical gear 322 and oriented so that the helical gears can mesh directly without the need of an intermediary gear to correct the direction of travel for the drill bit.
It has been found that helical gears 322 are preferred over miter, bevel, or other gears due to their greater efficiency from gear-to-gear and their ability to mesh without the need of an intermediary gear to correct the direction of rotation. Nonetheless, other types of gears will work to translate the axial rotation of the drive motor's output shaft into axial rotation of the drill bit normal to the axis of rotation to the drive motor output shaft.
A drill assembly module 302 is shown in partial cross section in
The bottom plate 342 on the drill assembly features a drain port 346 with a threaded plug 348 to evacuate any unwanted fluid buildup within the drill cylinder section of the device. It will be appreciated that the bottom of the apparatus 10 may optionally be fitted with a downwardly pointing conical cap so that the apparatus 10 will be able to push debris out of the way as it descends downwardly in a pipe 402.
With continuing reference to
All materials within the drill-type device are designed to withstand corrosive environments.
A well mount support 400 is illustrated in
The main arm 404 of the well mount support 400 may be separated into pieces as shown in
A winch having a support cable that attaches to loop 110 of apparatus 10 is used to shuttle the apparatus into and out of pipe 402. The winch is not shown in the drawings, but may be and typically is attached at an appropriate location, for instance, to main arm 404. The winch is preferably electric and under the control of a central controller, but a manual winch may be used if appropriate for some installations.
Pulley assembly 406 is attached to the upper end of main arm 404 and includes a pulley wheel 420 that is rotatably mounted between a pair of opposed mounting plates 422, 424. Pulley wheel 420 functions as the support for the electrical power and control cable that has one end attached to apparatus 10 and its opposite end attached to the controller. Separately, an encoder pulley wheel 426 is rotatably mounted between head plates 422, 424 and includes an encoder 428. As illustrated in the exploded view of
The electronic control module 500 for apparatus 10 is shown in
The main panel of the electrical control module 500 has a standard 120 V 60 Hz AC outlet input, a 24 V 10 A DC output to the drill device (including power and data lines to the motor positioning encoder, also located in the drill device), and as noted a main power switch 502, and three that select the maximum distance the drill bits may travel outwards from the drill device, namely, a step in button 504 that steps the bits inwardly, the step out button 506 that steps the bits outwardly, and a set max button 508 that sets the maximum travel of the bits.
The 120 V AC power is converted to 24V DC via AC to DC converter 530. From the 24 V, programmed PLC 504 and relays 532 and 534 are powered.
As with the other components described herein, all materials within the electrical control module 500 are designed to withstand harsh environments. Specifically, the case in which control module 500 is housed is selected to be waterproof and not easily damaged. It will be appreciated that there are numerous styles of interfaces that may be used with control module 500 as the human-machine-interface (“HMI”), such as use of touch screen displays, etc.
In use, a well mount support 400 is connected to a pipe 402 as detailed above, with a winch mounted to winch attachment plate 414. An apparatus 10 with the desired number of drill assembly modules is assembled and the free end of a suspension cable 430 is attached to loop 110—the suspension cable is wound around the winch. The electrical power and control cable (not shown) at electrical connector fitting 108, utilizing a keeper 434 (
The assembled and readied apparatus 10 is then inserted vertically into the pipe 402 and is dropped with the winch to the desired location in the pipe—the position of the apparatus 10 in pipe 10 is known by virtue of encoder 428, which is electronically interfaced with controller 500. The drill modules are then operated to perforate the walls of the pipe. The apparatus may be indexed upwardly and downwardly with the winch to drill perforations in the pipe at desired locations.
While the present invention has been described in terms of preferred and illustrated embodiments, it will be appreciated by those of ordinary skill that the spirit and scope of the invention is not limited to those embodiments, but extends to the various modifications and equivalents as defined in the appended claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 2066409 | Loring | Jan 1937 | A |
| 2306670 | Sutliff | Dec 1942 | A |
| 5183111 | Schellstede | Feb 1993 | A |
| 7823632 | McAfee | Nov 2010 | B2 |
| 20020005286 | Mazorow | Jan 2002 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20150260020 A1 | Sep 2015 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61951164 | Mar 2014 | US |
