Patent Application
20050245381
Not applicable.
Not applicable.
The embodiments of the present invention relate generally to systems for removing solids suspended in a liquid slurry. More particularly, the embodiments relate to systems for processing drilling fluids using a centrifuge.
One key component of a drilling rig is the drilling fluid circulation system or mud system, which circulates drilling fluid (mud) through the wellbore. The circulation system is also used to maintain the density of the drilling fluid by removing drilled cuttings from the fluid, and adding other solids to the fluid as may be desired. Among other drilling parameters, the density of the drilling fluid is critical to hole cleaning, rate of penetration, and pressure control in the well. Hole cleaning and rate of penetration are important factors in the efficiency of the drilling process, while pressure control is critical to safely drilling a well.
In general operation, drilling fluid is pumped by high-pressure pumps through the drill string and into the wellbore. The fluid exits the drill string at the bit and returns to the surface through the annulus between the drill string and the wellbore, carrying cuttings from the hole to the surface. The hydrostatic pressure created by the column of drilling fluid prevents fluids from the surrounding formation from entering the wellbore and potentially causing a loss of well control.
At the surface, the drilling fluid is then processed, in order to maintain the desired density, before it is pumped back through the drill string into the hole. Solids control equipment such as shakers, degassers, desilters, desanders, and centrifuges may be used to process the drilling fluid at the surface by removing solids and entrained gases from the fluid. Centrifuges are well known in the art for separating higher and lower density drilling fluid to permit the reuse of the drilling fluid.
One type of industrial centrifuge common in the drilling industry includes a rotating conveyor mounted concentrically within a rotating, cylindrical bowl. The conveyor typically incorporates helical blades on the outer surface and a hollow interior where the drilling fluid enters. As the drilling fluid enters the interior of the conveyor, it engages an accelerator mounted within the interior of the conveyor. The accelerator redirects the drilling fluid outward where it then exits the conveyor through one of the openings on the conveyor's outer surface. This process subjects the drilling fluid to the high centrifugal acceleration forces necessary to separate the varying densities of drilling fluid.
Because of the extremely abrasive nature of the drilling fluid and the high speed at which the centrifuge and its components rotate, the surfaces exposed to the drilling fluid are susceptible to wear and deterioration. Specifically, the accelerator may significantly wear, deteriorate, or become damaged over time such that it no longer provides the desired acceleration force to the drilling fluid. Many conventional centrifuges do not provide an economical or efficient means for accessing and replacing worn internal parts such as an accelerator. In such conventional centrifuges, the accelerator is usually permanently attached inside the conveyor by welding or an equivalent essentially permanent means. Thus, removal of the accelerator requires cutting and potentially destroying part of the conveyor.
Thus, it is desirable to have the ability to easily repair or replace a worn or deteriorated accelerator after the useful life of the part has expired. The embodiments of the present invention are directed to methods and apparatus for providing a centrifuge accelerator system that seeks to overcome certain limitations of the prior art.
Provided herein are methods and apparatus for a centrifuge accelerator system releasably mounted within a centrifuge assembly by a detachable connector, thereby improving the accessibility of the accelerator. The centrifuge assembly includes a hollow bowl, a rotating conveyor, a drive shaft, and an accelerator. The conveyor is rotatably mounted concentric with the rotating bowl. A helical blade is positioned on the outer surface of the rotating conveyor. The interior of the rotating conveyor is substantially hollow and drilling fluid is pumped into the interior. A series of detachable connectors are used to mount the drive shaft and accelerator within the centrifuge assembly. The detachable connectors provide a repeatable technique for gaining access to the accelerator without damaging or destroying the rotating conveyor or drive shaft.
In one preferred embodiment, the drive shaft is releasably mounted to the rotating conveyor by a detachable drive shaft connector, and a first end of the drive shaft extends into the hollow interior of the rotating conveyor. The accelerator is positioned on the first end of the drive shaft within the rotating conveyor and mounted to the first end of the drive shaft by a detachable accelerator connector. The detachable drive shaft and accelerator connectors are preferably characterized by a plurality of evenly spaced, circumferentially positioned threaded bolts and securing nuts. The detachable, non-permanent connection of the drive shaft to the rotating conveyor allows the drive shaft and accelerator to be extracted from the rotating conveyor as a single, unitized assembly without localized destruction of the rotating conveyor. Similarly, the detachable, non-permanent connection of the accelerator to the drive shaft allows for removal of the accelerator from the drive shaft for the purpose of replacing the accelerator without damaging the rotating conveyor or drive shaft.
In another embodiment, the rotating conveyor is removed from the centrifuge assembly in order to provide access to the accelerator. The detachable drive shaft connector securing the rotating conveyor to the drive shaft is disengaged, freeing the rotating conveyor from the drive shaft and providing access to the accelerator. The detachable, non-permanent connection of the rotating conveyor to the drive shaft allows the rotating conveyor to be extracted from the centrifuge assembly, thereby providing access to the accelerator without localized destruction of the rotating conveyor.
In other embodiments, the detachable drive shaft connector for releasably mounting the drive shaft to the rotating conveyor is characterized by a plurality of evenly spaced, circumferentially positioned threaded lugs and securing lug nuts. Similarly, the detachable accelerator connector for releasably mounting the accelerator within the rotating conveyor to the first end of the drive shaft is characterized by a plurality of evenly spaced, circumferentially positioned threaded lugs and securing lug nuts.
Thus, the present invention comprises a combination of features and advantages that enable it to provide for an easily accessible and repairable centrifuge accelerator system. These and various other characteristics and advantages of the preferred embodiments will be readily apparent to those skilled in the art upon reading the following detailed description and by referring to the accompanying drawings.
For a more detailed understanding of the preferred embodiments, reference is made to the accompanying Figures, wherein:
In the description that follows, like parts are marked throughout the specification and drawings with the same reference numerals, respectively. The drawing figures are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. The present invention is susceptible to embodiments of different forms. There are shown in the drawings, and herein described in detail, specific embodiments of the present invention with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that illustrated and described herein. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce the desired results.
Referring now to
Drive shaft connector 40 releasably mounts second end 22 of drive shaft 20 to mounting flange 13 of rotating conveyor 10. Drive shaft connector 40 is disengaged to release drive shaft 20 and accelerator 30 from rotating conveyor 10. Once released, drive shaft 20 and accelerator 30 can be extracted from rotating conveyor 10 along the primary axis of the conveyor. Accelerator connector 41 mounts first end 21 of drive shaft 20 to accelerator 30. Accelerator connector 41 can be disengaged, such that accelerator 30 is released from drive shaft 20, once drive shaft 20 is removed from conveyor 10.
Referring now to
Referring back to
The exiting fluid contacts bowl 32, which is rotated in the opposite direction of conveyor 10. The liquid and solid portions of the drilling fluid are separated by the rotational movement of conveyor 10 and bowl 32. Helical blade 15 moves the solid portion of the drilling fluid to a discharge point (not shown) at one end of bowl 32, while the liquid portion of the drilling fluid flows to a discharge point (not shown) on the opposite side of the bowl.
Because drilling fluid is often abrasive, repeated exposure to drilling fluid may cause accelerator 30 to wear and deteriorate. In one preferred embodiment, assembled drive shaft 20 and accelerator 30 can be extracted from rotating conveyor 10 as one unit. After assembled drive shaft 20 and accelerator 30 are extracted from rotating conveyor 10 as one unit, accelerator 30 can be removed from drive shaft 20 in order to replace or repair accelerator 30.
Upon completion of the repair or replacement of accelerator 30, detachable accelerator connector 41 is refastened to remount accelerator 30 to first end 21 of drive shaft 20. Assembled drive shaft 20 and accelerator 30 is reinstalled into rotating conveyor 10 along the centrifuge assembly's main axis of rotation. Second end 22 of drive shaft 20 is remounted to rotating conveyor 10 at mounting flange 13 by refastening detachable drive shaft connector 40, thereby returning assembled drive shaft 20 and accelerator 30 to its operating position.
In certain other embodiments, the drive shaft may be comprised of multiple connected sections that may provide for easier installation, handling, and component replacement. For example, the flange at first end 22 (see
The embodiments set forth herein are merely illustrative and do not limit the scope of the invention or the details therein. It will be appreciated that many other modifications and improvements to the disclosure herein may be made without departing from the scope of the invention or the inventive concepts herein disclosed. Because many varying and different embodiments may be made within the scope of the present inventive concept, including equivalent structures or materials hereafter thought of, and because many modifications may be made in the embodiments herein detailed in accordance with the descriptive requirements of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.
