Patent Publication Number: US-2022212205-A1

Title: Decanter centrifuges and associated acceleration pipes and methods

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from Italian Patent Application No. 102021000000035, filed on Jan. 4, 2021, the entire disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     Drilling fluids may be used in hydrocarbon drilling processes to maintain the structural integrity of the borehole, cool the drill bit, and/or carry cuttings from the drill bit to the surface. To remove cuttings from the drilling fluid for reuse, decanter centrifuges may be used to separate phases of a suspension including drilling fluid and cuttings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is best understood from the following detailed description when read with the accompanying Figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. 
         FIG. 1  is an isometric cross-sectional view of a decanter centrifuge in accordance with a first example of the present disclosure. 
         FIG. 2  is a cross-sectional view of a portion of the decanter centrifuge of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the acceleration pipe of the decanter centrifuge of  FIG. 1 . 
         FIG. 4  is a cross-sectional view of another example of an acceleration pipe that can be used with the decanter centrifuge of  FIG. 1 . 
         FIG. 5  is a cross-sectional view of a portion of the decanter centrifuge of  FIG. 1  including another example of a hub of a screw conveyor. 
         FIG. 6  is a cross-sectional view of a portion of the decanter centrifuge of  FIG. 1  including another example of a screw conveyor. 
     
    
    
     DETAILED DESCRIPTION 
     Illustrative examples of the subject matter claimed below will now be disclosed. In the interest of clarity, not all features of an actual implementation are described in this specification. It will be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions may be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort, even if complex and time-consuming, would be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. 
     Further, as used herein, the article “a” is intended to have its ordinary meaning in the patent arts, namely “one or more.” Herein, the term “about” when applied to a value generally means within the tolerance range of the equipment used to produce the value, or in some examples, means plus or minus 10%, or plus or minus 5%, or plus or minus 1%, unless otherwise expressly specified. Moreover, examples herein are intended to be illustrative only and are presented for discussion purposes and not by way of limitation. 
     The examples disclosed herein relate to decanter centrifuges having acceleration pipes that are used to rotate a suspension including drilling fluid/cuttings. The suspension may be referred to as a slurry or a mixture. The acceleration pipe rotates the suspension prior to the suspension being received within an acceleration chamber of the decanter centrifuge. Imparting rotational motion to the suspension prior to the suspension being received within the acceleration chamber allows the acceleration chamber to more easily bring the suspension to a desired rotational speed for separation to occur and allows for the centrifuges to work less or be more efficient at achieving a threshold separation result. 
     Additionally, providing the decanter centrifuges with the acceleration pipes allows for feed pipes that are used to flow the suspension into the centrifuge to extend a lesser length into a drum of the centrifuge. Reducing the length of the feed pipe may reduce the likelihood that the feed pipe achieves a resonance that may cause the feed pipe to come into contact with rotating components of the decanter centrifuge. Reducing the length of the feed pipe may also reduce the likelihood that solids buildup within the decanter centrifuge urge the feed pipe into contact with these rotating components of the centrifuge. Contact between the feed pipe and the rotating components of the centrifuge may damage the feed pipe or otherwise cause down time. Thus, by providing decanter centrifuges with the example acceleration pipes, the disclosed examples allow centrifuges to more easily rotate a suspension more efficiently as compared to some prior art examples and/or reduce unscheduled downtime due to maintenance. 
     Referring now to the drawings,  FIG. 1  is a cross-sectional isometric view of a decanter centrifuge  100  in accordance with a first example of the present disclosure. In the example shown, the decanter centrifuge  100  includes a drum  102 , a screw conveyor  104 , a drive assembly  106 , and an acceleration chamber  108 . 
     The drum  102  is mounted for rotation. In the example shown, the drum  102  is journaled between a pair of pillow blocks  110 ,  112 . The pillow blocks  110 ,  112  may be coupled to a stand or other support structure. 
     The drum  102  includes a cylindrical portion  114  and a frustoconical portion  116 . The cylindrical portion  114  and the frustoconical portion  116  are coupled at a flanged interface  117 . Fasteners may be used to couple the cylindrical portion  114  and the frustoconical portion  116 . Other methods may be used to couple the cylindrical portion  114  and the frustoconical portion  116 . For example, the cylindrical portion  114  and the frustoconical portion  116  may be welded at the flanged interface  117 . 
     The drum  102  has a first drum end  118  and a second drum end  120 . The drum  102  also includes a drum inlet  122 , one or more solids outlets  124 , and a liquid outlet  126 . In one or more embodiments, the drum  102  may include a plurality of solids outlets  124  radially spaced about the drum  102 . However, the present disclosure is not limited thereto and in other embodiments, the plurality of solids outlet  124  may be differently arranged. 
     The drum inlet  122  and the solids outlet  124  are positioned adjacent the first drum end  118 , and the liquid outlet  126  is positioned adjacent the second drum end  120 . In other examples, the drum inlet  122 , the solids outlet  124 , and/or the liquid outlet  126  may be differently arranged. For example, the liquid outlet  126  may be on the same end as the drum inlet  122 , and the solids outlet  124  may be on a different side as the drum inlet  122 . 
     The screw conveyor  104  is rotatably mounted within the drum  102 . The screw conveyor  104  includes a helical screw blade  131 . In the example shown, the screw conveyor  104  has a cylindrical portion  128  disposed within the cylindrical portion  114  of the drum  102  and a frustoconical portion  130  disposed within the frustoconical portion  116  of the drum  102 . 
     The drive assembly  106  is operatively coupled to the drum  102  and the screw conveyor  104 . The drive assembly  106  may be a planetary gear assembly. In some examples, the drive assembly  106  is arranged to rotate the drum  102  at a first speed and the screw conveyor  104  at a second speed. 
     The acceleration chamber  108  is disposed within the drum  102  and arranged to rotate with the screw conveyor  104 . The acceleration chamber  108  may be centrally positioned between the first drum end  118  and the second drum end  120  and is arranged to receive a suspension fed into the drum  102 . The acceleration chamber  108  may be adapted to accelerate the received suspension to a rotational speed associated with separating phases of the suspension (e.g., liquids from solids). 
     In the example shown, the centrifuge  100  also includes an acceleration pipe  132  and a feed pipe  134 . The acceleration pipe  132  has an acceleration pipe body  135 . The acceleration pipe  132  is coupled to the screw conveyor  104  and is arranged to rotate with the screw conveyor  104 . The acceleration pipe  132  is disposed between the drum inlet  122  and the acceleration chamber  108 . 
     The feed pipe  134  is in flow communication with the acceleration chamber  108 , via the drum inlet  122  and the acceleration pipe  132 . A flow path  136  runs from the feed pipe  134 , through the acceleration pipe  132 , to the acceleration chamber  108 . 
     In operation, the acceleration pipe  132  is adapted to receive a suspension from the feed pipe  134  and to rotate the suspension, based on corresponding rotation of the screw conveyor  104 , prior to the suspension exiting the acceleration pipe  132  and being received by the acceleration chamber  108 . The acceleration pipe  132  acts as a radial accelerator that provides the suspension with an initial and gradual radial motion prior to the suspension being received by the acceleration chamber  108 . Because the acceleration pipe  132  is coupled to rotate with the screw conveyor  104 , rotating the screw conveyor  104  also rotates the acceleration pipe  132 . 
     Still referring to  FIG. 1 , the acceleration pipe  132  includes an acceleration pipe inlet  140 , an acceleration pipe outlet  142 , and an acceleration pipe flow path  144 . The acceleration pipe flow path  144  extends between the acceleration pipe inlet  140  and the acceleration pipe outlet  142 . In the example shown, a feed pipe outlet  146  is disposed within or immediately adjacent the acceleration pipe inlet  140 . Additionally, in the example shown, the feed pipe outlet  146  is spaced from the acceleration pipe outlet  142 . Thus, the feed pipe outlet  146  is closer to the acceleration pipe inlet  140  than the acceleration pipe outlet  142 . As a result, the feed pipe  134  is arranged to flow the suspension into the acceleration pipe flow path  144  and the acceleration pipe  132  is arranged to flow the suspension into the acceleration chamber  108 . 
     In the example shown, a solids hub  148  is coupled to the first drum end  118  and a liquids hub  150  is coupled at the second drum end  120 . The solids hub  148  may be coupled to the first drum end  118  via a flanged interface  152 . Fasteners may be used to couple the liquids hub  150  to the drum  102 . 
     The feed pipe  134  is shown being coupled to the solids hub  148 . The feed pipe  134  extends through a feed pipe support  154 . The feed pipe support  154  includes a bottom portion  156  and a top portion  158 . The bottom portion  156  and the top portion  158  are coupled using fasteners and define a support through hole  160 . The feed pipe  134  extends through the support through hole  160  and is clamped within the feed pipe support  154 . 
       FIG. 2  is a cross-sectional view of a portion of the decanter centrifuge  100  of  FIG. 1 . In the example shown, the screw conveyor  104  includes a hub  162 . The acceleration pipe  132  is coupled within the hub  162 . The hub  162  may be cylindrical and may be referred to as a conveyor. 
     In the example shown, the hub  162  includes a plurality of radial hub holes  164 . When the centrifuge  100  is operated without the acceleration pipe  132  installed, the radial hub holes  164  may be used in association with barite recovery. When the acceleration pipe  132  is installed within the hub  162 , as shown, the acceleration pipe  132  covers the radial hub holes  164 . As a result of the acceleration pipe  132  covering the radial hub holes  164 , when the acceleration pipe  132  is received within the hub  162 , the hub  162  and the radial hub holes  164  may not be used for barite recovery. In other examples, such as the example shown in  FIG. 5 , the hub  162  may not include the radial hub holes  164 . 
     Still referring to  FIG. 2 , the acceleration pipe  132  includes an exterior surface  165  that defines mounting holes  166 . The mounting holes  166  may be referred to as locating holes. The hub  162  includes corresponding mounting holes  168 . In the example shown, a fastener  170  is received within each of the mounting holes  166  to couple the acceleration pipe  132  to the hub  162 . 
     The mounting holes  166 ,  168  may be threaded and the fastener  170  may be a screw. Coupling the acceleration pipe  132  within the hub  162  using screws (or another removable fastener) allows the acceleration pipe  132  to be removed for cleaning or other reasons. Additionally, coupling the acceleration pipe  132  within the hub  162  using screws (or another removable fastener) allows the centrifuge  100  to be provided with the acceleration pipe  132  during separating operations that do not involve barite recovery and allows the centrifuge  100  to operate without the acceleration pipe  132  during separating operations that involve barite recovery. While the fasteners  170  are mentioned coupling the acceleration pipe  132  within the hub  162 , the acceleration pipe  132  may be coupled within the hub  162  in different ways. For example, the acceleration pipe  132  may be welded within the hub  162 , dowel rods may be pounded into the mounting holes  166 ,  168  to provide an interference fit, etc. As another example, the hub  162  and the acceleration pipe  132  may be integral as shown in  FIG. 6 . 
     To retrofit the centrifuge  100  to include the acceleration pipe  132 , in some examples, a longer feed pipe (not shown) is uncoupled from the solids hub  148 . Prior to uncoupling the longer feed pipe from the solids hub  148 , a feed pipe outlet of the longer feed pipe may be positioned to directly flow a suspension into the acceleration chamber  108  of the screw conveyor  104 . Thus, the removed longer feed pipe may extend further into the screw conveyor  104  than the feed pipe  134  shown in  FIG. 2 . 
     The solids hub  148  may be uncoupled from the first drum end  118 . Uncoupling the solids hub  148  from the drum  102  provides access to an interior of the drum  102 . 
     The acceleration pipe  132  may be coupled within the screw conveyor  104  to rotate with the screw conveyor  104 . In the example shown, the acceleration pipe  132  is coupled within the screw conveyor  104  using the fasteners  170 . 
     The solids hub  148  is recoupled to the first drum end  118 , and the feed pipe  134  is coupled to the solids hub  148  to allow the feed pipe outlet  146  to flow the suspension into the acceleration pipe  132  prior to the suspension being received by the acceleration chamber  108 . In some examples, the feed pipe  134  is formed by shortening the length of the longer feed pipe used with the centrifuge  100  prior to the retrofit process occurring. In some examples, the centrifuge  100  is balanced. The balancing process may be performed after the acceleration pipe  132  is coupled within the screw conveyor  104 . 
       FIG. 3  is a cross-sectional view of the acceleration pipe  132  of the centrifuge  100  of  FIG. 1 . In the example shown, the acceleration pipe body  135  is integral. As another example, the acceleration pipe body  135  may be formed of more than one component that are coupled together (see, for example,  FIG. 4 ). 
     The acceleration pipe  132  includes an interior surface  172  that defines the acceleration pipe flow path  144 . The interior surface  172  extends between the acceleration pipe inlet  140  and the acceleration pipe outlet  142 . The interior surface  172  is inwardly tapered toward the acceleration pipe inlet  140 . Inwardly tapering the interior surface  172  may deter or otherwise prevent backflow of the suspension within the acceleration pipe  132 . Put another way, inwardly tapering the interior surface  172  encourages fluid flow from the acceleration pipe inlet  140  to the acceleration pipe outlet  142 . The interior surface  172  widens toward the acceleration pipe outlet  142 . 
     The interior surface  172  may be frustoconical. In the example shown, the interior surface  172  is inwardly tapered at a relatively consistent slope between the acceleration pipe outlet  142  and the acceleration pipe inlet  140 . The interior surface  172  may have a tapered surface  174  having an angle of between about 0.5 degrees and about 6 degrees relative to a longitudinal axis  178  of the acceleration pipe  132 . Specifically, in the example shown, the tapered surface  174  has an angle of about 4.0 degrees. Other angles may prove suitable. For example, the tapered surface  174  may have an angle relative to the longitudinal axis  178  of less than about 0.5 degrees or greater than about 6 degrees. As another example and as shown in  FIG. 4 , the interior surface  172  of the acceleration pipe  132  may include more than one tapered surface 
     The interior surface  172  may include projections  180 . The projections  180  may be adapted to encourage the flow of the suspension from the acceleration pipe inlet  140  to the acceleration pipe outlet  142  and/or the projections  180  may be adapted to impart rotation to the suspension. The projections  180  may include inwardly extending helical fins, flights, and/or ribs. However, other types of projections may prove suitable or the projections  180  may be eliminated. 
     The acceleration pipe  132  includes an inlet end  182  and an outlet end  184 . A collar  186  extends from a face  188  at the inlet end  182  of the acceleration pipe  132 . The collar  186  may have a circular cross-section and is shown defining at least part of the acceleration pipe inlet  140 . In other examples, the collar  186  may extend further or less from the face  188  or the collar  186  may be eliminated. 
     Mounting holes  190  may be defined by the face  188  at the inlet end  182  of the acceleration pipe  132 . The mounting holes  190  may be used to secure the acceleration pipe  132  within the screw conveyor  104 . For example, fasteners may be received by the mounting holes  190  to secure the acceleration pipe  132  relative to the solids hub  148 . 
     In the example shown, the exterior surface  165  includes a circumferential groove  192 ,  194  adjacent each of the inlet end  182  and the outlet end  184  of the acceleration pipe  132 . The circumferential grooves  192 ,  194  may be used to locate the acceleration pipe  132  within the hub  162  and/or may be used to otherwise secure the acceleration pipe  132  relative to the screw conveyor  104 . In some examples, the circumferential grooves  192 ,  194  are adapted to receive gaskets. The gaskets may sealingly engage an interior surface of the hub  162 . The engagement between the gaskets and the interior surface of the hub  162  may deter the ingress of fluid and/or may encourage alignment of the acceleration pipe  132  within the hub  162 . In other examples, the grooves  192 ,  194  may be eliminated. 
       FIG. 4  is a cross-sectional view of another example of an acceleration pipe  300  that can be used with the decanter centrifuge  100  of  FIG. 1 . The acceleration pipe  300  of  FIG. 4  is similar to the acceleration pipe  132  shown in  FIGS. 1-3 . However, in contrast, the acceleration pipe  300  of  FIG. 4  includes an outer body  302 , an inner body  304 , and a pair of end caps  306 ,  308 . 
     The inner body  304  includes the acceleration pipe inlet  140 , the acceleration pipe outlet  142 , and the acceleration pipe flow path  144 . In the example shown, the acceleration pipe inlet  140  has a first diameter  310  and the acceleration pipe outlet  142  has a second diameter  312  larger than the first diameter  310 . 
     The end caps  306 ,  308  define through holes  314 ,  316  and are coupled at ends  318 ,  320  of the outer body  302 . The end caps  306 ,  308  may be coupled to the ends  318 ,  320  of the outer body  302  using fasteners, adhesive, welding, etc. Other methods of coupling the end caps  306 ,  308  to the outer body  302  may prove suitable. 
     In the example shown, the inner body  304  extends through the outer body  302  and out of the through holes  314 ,  316  of the end caps  306 ,  308 . More specifically, the acceleration pipe inlet  140  and the acceleration pipe outlet  142  extend from outward faces  322 ,  324  of the corresponding end caps  306 ,  308 . While the acceleration pipe inlet  140  and the acceleration pipe outlet  142  are shown extending from the end caps  306 ,  308  a particular amount and form, for example, collars, in other examples, the acceleration pipe  300  may be a different length. For example, the acceleration pipe inlet  140  and/or the acceleration pipe outlet  142  may extend further or less from the end caps  306 ,  308  or may end flush with the end caps  306 ,  308 . 
     The inner body  304  includes an interior surface  326  that inwardly tapers toward the acceleration pipe inlet  140 . Specifically, in the example shown, the inner body  304  includes a first tapered portion  328  having a first taper and a second tapered portion  330  having a second taper. The first tapered portion  328  and the second tapered portion  330  may be frustoconical and, thus, may be referred to as frustoconical portions. The first and second tapers are different. The first tapered portion  328  and the second tapered portion  330  may each have an angle of between about 0.5 degrees and about 6 degrees relative to a longitudinal axis  332  of the acceleration pipe  300 . In the example shown, the first tapered portion  328  may have an angle of about 0.5 degrees relative to the longitudinal axis  332 . In the example shown, the second tapered portion  330  may have an angle of about 2.86 degrees relative to the longitudinal axis  332 . Other angles may prove suitable. For example, the first tapered portion  328  and/or the second tapered portion  330  may each have an angle of less than about 0.5 degrees or an angle greater than about 6 degrees relative to the longitudinal axis  332 . While the first tapered portion  328  and the second tapered portion  330  are shown having a particular length, the tapered portions  328 ,  330  may include different lengths. For example, the tapered portions  328 ,  330  may have similar lengths relative to one another such that an interface between the tapered portions  328 ,  330  is positioned in the middle of the acceleration pipe  300 . In other examples, more than two frustoconical portions may be included. 
       FIG. 5  is a cross-sectional view of a portion of the decanter centrifuge  100  of  FIG. 1  including another example of a hub  400  of the screw conveyor  104 . The hub  400  of  FIG. 5  is similar to the hub  162  of  FIGS. 2 and 3 . However, in contrast, the hub  400  of  FIG. 5  does not include the radial hub holes  164 . As a result, the centrifuge  100  of  FIG. 5  may not be used for barite recovery in a similar manner as the centrifuge  100  of  FIG. 2 . 
       FIG. 6  is a cross-sectional view of a portion of the decanter centrifuge  100  of  FIG. 1  including another example of a screw conveyor  500 . The screw conveyor  500  of  FIG. 6  is similar to the screw conveyor  104  of  FIG. 5 . However, in contrast, the screw conveyor  500  of  FIG. 6  includes the acceleration pipe  132 . Thus, the screw conveyor  500  of  FIG. 6  and the acceleration pipe  132  are shown being integral. 
     From the foregoing, it will be appreciated that the above disclosed apparatus, methods and articles of manufacture enable suspensions to be rotated prior to being received within an acceleration chamber of a corresponding decanter centrifuge. 
     In accordance with one example, a decanter centrifuge includes a drum, a screw conveyor, a drive assembly, an acceleration chamber, an acceleration pipe, and a feed pipe. The screw conveyor includes a cylindrical portion and a frustoconical portion. The drum includes a drum inlet, a solids outlet, and a liquid outlet. The screw conveyor is rotatably mounted within the drum and has a cylindrical portion disposed within the cylindrical portion of the drum and a frustoconical portion disposed within the frustoconical portion of the drum. The drive assembly is operatively coupled to the drum and the screw conveyor. The drive assembly is arranged to rotate the drum at a first speed and the screw conveyor at a second speed. The acceleration chamber is disposed within the drum and arranged to rotate with the screw conveyor. The acceleration pipe is coupled to the screw conveyor and is arranged to rotate with the screw conveyor. The acceleration pipe is disposed between the drum inlet and the acceleration chamber. The feed pipe is in flow communication with the acceleration chamber, via the drum inlet and the acceleration pipe. The acceleration pipe is adapted to receive a suspension from the feed pipe and to rotate the suspension, based on a corresponding rotation of the screw conveyor, prior to the suspension exiting the acceleration pipe and being received by the acceleration chamber. 
     In accordance with a second example, an acceleration pipe for use with a decanter centrifuge including a feed pipe and a screw conveyor having an acceleration chamber includes an acceleration pipe body adapted to be coupled to and rotate with the screw conveyor. The acceleration pipe body includes an acceleration pipe inlet and an acceleration pipe outlet. The acceleration pipe body defines an acceleration pipe flow path extending between the acceleration pipe inlet and the acceleration pipe outlet. The acceleration pipe body is adapted to receive a suspension at the acceleration pipe inlet from the feed pipe and to rotate the suspension, based on a corresponding rotation of the screw conveyor, prior to the suspension exiting the acceleration pipe outlet and being received by the acceleration chamber of the screw conveyor. 
     In accordance with a third example, a method of retrofitting a decanter centrifuge includes uncoupling a first feed pipe from a solids hub. The first feed pipe having a first feed pipe outlet. The solids hub is coupled at a first drum end of a drum. The drum includes the first drum end and a second drum end opposite the first drum end. The method includes uncoupling the solids hub from the first drum end. The method includes coupling an acceleration pipe to a screw conveyor to rotate with the screw conveyor. The acceleration pipe includes an acceleration pipe inlet, an acceleration pipe outlet, and defines an acceleration pipe flow path extending between the acceleration pipe inlet and the acceleration pipe outlet. The method includes recoupling the solids hub to the first drum end. The acceleration pipe is positioned between the solids hub and an acceleration chamber. The method includes coupling a second feed pipe having a second feed pipe outlet to the solids hub to allow the second feed pipe outlet to flow the suspension into the acceleration pipe prior to being received by the acceleration chamber of the screw conveyor. 
     In accordance with a fourth example, a decanter centrifuge includes a drum, a solids hub, a liquids hub, a pair of pillow blocks, a feed pipe, a screw conveyor, an acceleration pipe, and a gear assembly. The drum includes a cylindrical portion and a conical portion and includes a drum inlet, a solids outlet, and a liquid out. The drum includes a first drum end and a second drum end opposite the first drum end. The drum inlet and the solids outlet are positioned adjacent the first drum end. The liquid outlet is positioned adjacent the second drum end. The solids hub is coupled at the first drum end. The liquids hub is coupled at the second drum end. The pair of pillow blocks support the first drum end and the second drum end. The feed pipe is coupled to the solids hub and has a feed pipe outlet. The screw conveyor is disposed within the drum and has a central screw conveyor portion including an accelerator. A first screw conveyor end is disposed adjacent the first drum end and a second screw conveyor end is disposed adjacent the second drum end. The acceleration pipe is disposed within the central screw conveyor portion and is coupled to rotate with the screw conveyor. The acceleration pipe is positioned between the solids hub and the accelerator. The acceleration pipe includes an acceleration pipe inlet, an acceleration pipe outlet, and defines an acceleration pipe flow path extending between the acceleration pipe inlet and the acceleration pipe outlet. The gear assembly is positioned adjacent one of the pillow blocks and is adapted to rotate the drum and the screw conveyor at different speeds. The feed pipe outlet is disposed within or immediately adjacent the acceleration pipe inlet. The acceleration pipe is adapted to receive a suspension at the acceleration pipe inlet from the feed pipe and to rotate the suspension, based on corresponding rotation of the screw conveyor, prior to the suspension exiting the acceleration pipe outlet and being received by the accelerator of the screw conveyor. 
     In accordance with a fifth example, a decanter centrifuge includes a drum, a screw conveyor, a drive assembly, an acceleration chamber, an acceleration pipe, and a feed pipe. The drum includes a cylindrical portion and a conical portion. The drum includes a drum inlet, a solids outlet, and a liquid outlet. The screw conveyor is rotatably mounted within the drum and has a cylindrical portion disposed within the cylindrical portion of the drum and a conical portion disposed within the conical portion of the drum. The drive assembly is operatively coupled to the drum and the screw conveyor. The drive assembly is arranged to rotate the drum at a first speed and the screw conveyor at a second speed. The acceleration chamber is disposed within the drum and arranged to rotate with the screw conveyor. The acceleration pipe is coupled to the screw conveyor and arranged to rotate with the screw conveyor. The acceleration pipe is disposed between the drum inlet and the acceleration chamber. The feed pipe is in flow communication with the acceleration chamber, via the drum inlet and the acceleration pipe. A flow path runs from the feed pipe, through the acceleration pipe, to the acceleration chamber. The acceleration pipe is adapted to receive a suspension from the feed pipe and to rotate the suspension, based on corresponding rotation of the screw conveyor, prior to the suspension exiting the acceleration pipe and being received by the acceleration chamber. 
     In further accordance with the foregoing first, second, third, fourth, and/or fifth examples, an apparatus and/or method may further include any one or more of the following: 
     In accordance with an example, the screw conveyor includes a hub, and the acceleration pipe is coupled to the hub. 
     In accordance with another example, the acceleration pipe includes an exterior surface defining mounting holes, and the decanter centrifuge further includes a plurality of fasteners. Each fastener is received within a respective mounting hole and couples the acceleration pipe to the hub. 
     In accordance with another example, the acceleration pipe is an integral body. 
     In accordance with another example, the acceleration pipe has an acceleration pipe inlet, an acceleration pipe outlet, and an interior surface that encircles a flow path defined by the acceleration pipe. 
     In accordance with another example, the interior surface tapers toward the acceleration pipe inlet. 
     In accordance with another example, the interior surface widens toward the acceleration pipe outlet. 
     In accordance with another example, the interior surface is frustoconical. 
     In accordance with another example, the interior surface is inwardly tapered at a relatively consistent slope between the acceleration pipe outlet and the acceleration pipe inlet. 
     In accordance with another example, the interior surface has one or more tapered surfaces each having an angle of between about 0.5 degrees and about 6 degrees relative to a longitudinal axis of the acceleration pipe. 
     In accordance with another example, the interior surface includes projections that are adapted to encourage the flow of the suspension from the acceleration pipe inlet to the acceleration pipe outlet. 
     In accordance with another example, the acceleration pipe includes an inlet end, an outlet end, and an exterior surface extending between the inlet end and the outlet end. The exterior surface defines a circumferential groove at each of the inlet end and the outlet end. 
     In accordance with another example, the acceleration pipe includes an outer body, an inner body, and a pair of end caps defining through holes. The end caps are coupled at ends of the outer body, and the inner body extends through the outer body and out of the through holes of the end caps. 
     In accordance with another example, the inner body includes a first frustoconical portion having a first taper and a second frustoconical portion having a second taper. 
     In accordance with another example, the screw conveyor includes the acceleration pipe. 
     In accordance with another example, the acceleration pipe body has an interior surface that encircles the acceleration pipe flow path and extends between the acceleration pipe inlet and the acceleration pipe outlet. The interior surface being inwardly tapered toward the acceleration pipe inlet. 
     In accordance with another example, the interior surface includes a first tapered portion having a first angle relative to a longitudinal axis of the acceleration pipe body and a second tapered portion having a second angle relative to the longitudinal axis of the acceleration pipe body. 
     In accordance with another example, further including forming the second feed pipe by shortening a length of the first feed pipe. 
     In accordance with another example, further including balancing the decanter centrifuge. 
     Further, while several examples have been disclosed herein, any features from any examples may be combined with or replaced by other features from other examples. Moreover, while several examples have been disclosed herein, changes may be made to the disclosed examples within departing from the scope of the claims. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the disclosure. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the systems and methods described herein. The foregoing descriptions of specific examples are presented for purposes of illustration and description. They are not intended to be exhaustive of or to limit this disclosure to the precise forms described. Obviously, many modifications and variations are possible in view of the above teachings. The examples are shown and described in order to best explain the principles of this disclosure and practical applications, to thereby enable others skilled in the art to best utilize this disclosure and various examples with various modifications as are suited to the particular use contemplated. It is intended that the scope of this disclosure be defined by the claims and their equivalents below.