Abstract:
Methods and apparatus for selectively blocking or redirecting flow with a valve that compensates for misalignment between a seat and a gate are disclosed. In one aspect, a valve includes a gate having two discs spaced from one another, first and second seats within first and second passageways of the valve, respectively, and at least one lever arm coupled to an actuator for rotating the gate, thereby diverting flow. The lever arm is disposed between the discs and pivotally couples to the gate such that the pivoting movement of the gate enables compensation for the misalignment. A method includes rotating a gate from a first position with a plane of the gate axially aligned with flow to a second position with the disc initially contacting a seat and compensating for the misalignment by pivoting the gate with respect to the lever arm such that the gate squarely contacts the seat.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Embodiments of the present invention generally relate to a valve assembly for selectively blocking or redirecting flow. More particularly, embodiments of the invention relate to a valve assembly having a gate that compensates for misalignment with a seat of the valve assembly. 
     2. Description of the Related Art 
     Industrial valves have many uses for selectively blocking or redirecting a flow of fluids such as gases and liquids, solids and mixtures thereof. Examples of industries that commonly utilize valves include water utilities, power plants, refineries and chemical manufacturing. Open/close type valves may be used to selectively block flow through a conduit. On the other hand, diverter type valves effectively block flow through one passageway of the valve and open flow through a diverted passageway of the valve depending upon the position of the valve. These diverter valves have particular utility in permitting isolation of one line due to, for example, an emergency condition such as a line rupture or construction on a portion of the line that is blocked by the valve while permitting flow though another line such as a bypass. 
     One type of valve which may be referred to as a “flapper valve” utilizes a gate or disc that pivots about one end thereof in order to permit a face of the disc to make positive contact to a valve seat within the valve. In the open position, the disc is rotated (e.g., 90°) such that the plane of the disc is substantially axially aligned with a flow of fluid through the valve and does not substantially interfere with the fluid flow. Rotation of the disc toward the valve seat closes the valve to fluid flow once the disc makes contact with the valve seat. Contact between the disc and the valve seat may form a seal to completely prevent fluid flow through the valve. 
     A variation of the flapper valve may be configured as a diverter valve which may be referred to as a “flip-flop diverter valve.” A disc of the flip-flop diverter valve can rotate between a first position and a second position. The disc contacts a first seat along a first fluid passageway of the valve when in the first position and contacts a second seat along a second fluid passageway when in the second position. Thus, the flip-flop diverter valve operates similar to the flapper valve to selectively block fluid flow through the first passageway of the valve and thereby open fluid flow through the second fluid passageway. 
     Proper sealing between the disc and the valve seat requires that the disc be properly aligned with respect to the valve seat such that the entire perimeter of the disc tightly contacts the valve seat when closed. Even if manufactured with a correct initial alignment, the alignment between the valve seat and the disc can change due to possible movements of the valve seat, thereby causing a loose contact between the disc and the valve seat that may prevent proper sealing. For example, temperature changes of the valve can cause expansion or contraction of the valve or valve seat itself, which may cause the surface of the valve seat that the disc contacts to move relative to the disc fixed within the valve. In the case where the valve seat includes a cone within the valve, the cone grows as the temperature rises such that the valve seat and disc may not be properly aligned due to the reduced spacing therebetween. Manufacturing a predetermined alignment between the disc and the valve seat in order to compensate for the movements still only accommodates the valve seat at one particular location and fails to account for applications of the valve having various temperatures and for the inability to determine the exact temperature of operation and amount of movement of the valve seat. 
     Therefore, there exists a need for a valve assembly having a gate or disc that compensates for misalignment with a valve seat when rotated into contact therewith. There exists a further need for a diverter valve having a gate or disc that rotates between two valve seats and that compensates for misalignments between the valve seats and the gate. 
     SUMMARY OF THE INVENTION 
     The present invention generally relates to methods and apparatus for selectively blocking or redirecting flow with a valve that compensates for misalignment between a seat and a gate. In one aspect, a valve includes a gate having two discs spaced from one another, first and second seats within first and second passageways of the valve, respectively, and at least one lever arm coupled to an actuator for rotating the gate, thereby diverting flow. The lever arm is disposed between the discs and pivotally couples to the gate such that the pivoting movement of the gate enables compensation for the misalignment. A method includes rotating a gate from a first position with a plane of the gate axially aligned with flow to a second position with the disc initially contacting a seat and compensating for the misalignment by pivoting the gate with respect to the lever arm such that the gate squarely contacts the seat. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
         FIG. 1  is a section view of a diverter valve having a disc and lever arm assembly that rotates to selectively divert flow between two different passageways. 
         FIG. 2  is a section view of the diverter valve shown in  FIG. 1  with fluid flow diverted to the other passageway. 
         FIG. 3  is a side view of the diverter valve shown in  FIG. 1 . 
         FIG. 4  is a top view of the disc and lever arm assembly of the diverter valve shown in  FIG. 1 . 
         FIG. 5  is a section view of an alternative embodiment of a diverter valve having a disc and lever arm assembly that includes a ball-in-socket arrangement. 
         FIG. 6  is a section view of an alternative embodiment of a diverter valve having a disc and lever arm assembly that includes a ball-in-socket arrangement. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention generally relates to a valve assembly for selectively blocking or redirecting a flow of fluids such as gases and liquids, solids and mixtures thereof through the use of a gate that compensates for misalignment with a valve seat when the gate rotates to contact the valve seat. The gate may include one or more discs having a circular outer diameter or any other shape that is capable of seating against the valve seat. Preferably, contact between the disc and the valve seat forms a seal to substantially prevent fluid flow between the disc and the valve seat. Since the valve assembly may be used in any application, the valve assembly is not limited to any particular range of temperatures, pressures, angles of diversion or diameters. 
       FIG. 1  illustrates a diverter valve  100  having a disc and lever arm assembly  102  that rotates about the center of an axle or shaft  104  to selectively divert flow between a first passageway  106  and a second passageway  108  that are defined by an outer housing  110  of the valve  100 . The interior of the housing  110  includes a first seat  112  within the first passageway  106  and a second seat  114  within the second passageway  108 . The first and second seats  112 ,  114  each have a surface for respective contact with a first and a second disc  113 ,  115  of the lever arm assembly  102 . In a first position of the disc and lever arm assembly  102  shown in  FIG. 1 , the second disc  115  contacts the second seat  114  to block flow through the second passageway  108  and permit flow through the first passageway  106 . As shown, the plane of the disc and lever arm assembly  102  is substantially axially aligned with a flow of fluid through the first passageway  106 . 
     In operation, the disc and lever arm assembly  102  rotates about the center of the shaft  104  to move the disc and lever arm assembly  102  from the first position to a diverted or second position as illustrated in  FIG. 2 . The first disc  113  contacts the first seat  112  to block flow through the first passageway  106  and permit flow through the second passageway  108  when the disc and lever arm assembly  102  is in the second position. Thus, rotation of the disc and lever arm assembly  102  diverts flow through either the first or second passageway  106 ,  108  depending on whether the disc and lever arm assembly  102  is in the first position or the second position. Moving the disc and lever arm assembly  102  between the first and second position rotates the plane of the discs  113 ,  115  about an axis at the center of the shaft  104 , which is located adjacent the discs  113 ,  115 . 
     Referring back to  FIG. 1 , the housing  110  of the valve  100  may be made of any suitable material based upon the application such as carbon steel or stainless steel. Preferably, the housing  110  is made of carbon steel if the valve is used in high temperature (e.g., about 1400° F.) applications in order to avoid cracking. Furthermore, an optional refractory lining  116  on the inside surface of the housing  110  may be added to provide insulation and resistance to abrasion. The valve  100  may additionally include one or more seat purges  118  spaced around the perimeter of the first and second seats  112 ,  114  to supply a pressurized cleaning fluid to the seats  112 ,  114  to clean any debris that may be present on the seats prior to the discs  113 ,  115  rotating into contact with their respective seat. The seat purges  118  can be individual nozzles or a single ring following the circumference/perimeter of each seat  112 ,  114  that may be separate from or integral to the seats  112 ,  114 . 
     The first seat  112 , which is structurally analogous to the second seat  114 , includes a cone shaped member  120  affixed to the inside of the housing  110  such as by a weld. Orientation of the cone shaped member  120  faces an apex of the cone shaped member toward the flow through the first seat  112 . A tubular shaped ring  122  affixed to the smallest inside diameter of the cone shaped member  120  provides a seat surface  124  directed toward the first disc  113  when the disc and lever arm assembly  102  is in the second position. Any known connection such as a weld may affix the tubular shaped ring  122  to the cone shaped member  120 . The seat surface  124  and an inside surface of the tubular shaped ring  122  may include a surface finish having a high resistance to abrasion and erosion such as but not limited to a Stellite #1 coating welded thereto. Similarly, a peripheral portion of the disc  113  that contacts the seat surface  124  may include a surface finish having a high resistance to abrasion and erosion such as but not limited to a Stellite #1 coating welded thereto and finished by machining or grinding. The surface finishes on the seats  112 ,  114  and/or discs  113 ,  115  help ensure proper sealing when in contact with each other. While the seats  112 ,  114  are shown having the cone shaped member  120  and the tubular shaped ring  122 , the actual design or structure of the seats  112 ,  114  of the valve  100  can include any arrangement that provides the seat surface  124 . For example, a top surface of a singular stainless steel tubular ring welded, bolted or clamped directly to the inside surface of the housing  110  can provide the seat surface  124 . 
     In a particularly advantageous aspect, the design and operation of the disc and lever arm assembly  102  enables the discs  113 ,  115  to compensate for misalignments and provide mating contact with the valve seats  112 ,  114  regardless of the precise location of the valve seats  112 ,  114  with respect to the disc and lever arm assembly  102 . The disc and lever arm assembly  102  includes the discs  113 ,  115  separated by a plurality of parallel ribs  126  attached thereto, a plurality of parallel support arms  128  interleaved among the parallel ribs  126 , and a hollow cylindrical hub  130  that one end of the support arms  128  secure to. The ribs  126  may be welded to the backside of the discs  113 ,  115  and run substantially the entire length between the discs  113 ,  115  in order to provide support for the discs  113 ,  115 . Furthermore, the ribs  126  are plates arranged perpendicular to the discs  113 ,  115  and have a height sufficient to separate the discs  113 ,  115  by a distance greater than the height of the support arms  128 . A long cylindrical pin  134  extends across a centerline of the discs  113 ,  115  through apertures  136  passing transversely through both the ribs  126  and the support arms  128 . Thus, the support arms  128  only need to extend from the hub  130  far enough to allow for locating the apertures  136  at the centerline. The discs  113 ,  115  can pivot about the pin  134  without interfering contact by the support arms  128  since the discs  113 ,  115  are not attached directly to any of the support arms  128  and are separated by the distance greater than the height of the support arms  128  that is sufficient to permit the pivotal movement of the discs  113 ,  115  through the full temperature range desired. The pin  134  couples the support arms  128  that are secured to the hub  130  to the ribs  126  that are attached to the discs  113 ,  115  such that rotation of the hub  130  rotates the entire disc and lever arm assembly  102  including the discs  113 ,  115 . 
     In operation, an actuator  300  (shown in  FIG. 3 ) turns the shaft  104 , which provides rotation of the disc and lever arm assembly  102  since the hub  130  is mounted to the shaft  104 . A portion of the shaft  104  extends into an interior of the hub  130  to mount the hub  130  on the shaft  104 . Two keys  132  insert into apertures in the hub  130  and corresponding recesses in the shaft  104  to prevent relative rotation between the hub  130  and the shaft  104 . The keys  132  may be held in place by a weld. Thus, the actuator  300  for the valve  100  turns the shaft  104  approximately 90° back and forth in order to move the disc and lever arm assembly  102  between the first and second positions. 
     The rotation of the disc and lever arm assembly  102  forces one of the discs  113 ,  115  into contact with a respective one of the valve seats  112 ,  114  depending on whether the disc and lever arm assembly  102  is in the first or second position. The ability of the discs  113 ,  115  to pivot about the pin  134  enables the discs  113 ,  115  to compensate for misalignments by permitting the discs  113 ,  115  to squarely contact the valve seats  112 ,  114  regardless of the precise location of the valve seats  112 ,  114  with respect to the disc and lever arm assembly  102 . For example, the first valve seat  112  may be aligned too far forward such that the disc and lever arm assembly  102  does not complete the entire 90° rotation prior to the first disc initially contacting the first valve seat  112 . However, the disc and lever arm assembly  102  still forces the first disc  113 , which pivots about the pin  134  to compensate for the premature contact, into mating contact with the first valve seat  112 . On the other hand, the first disc  113  may pivot about pin  134  in the opposite direction if the first valve seat  112  is aligned too far back from the disc and lever arm assembly  102  such that the disc and lever arm assembly  102  rotates more than 90° to force the first disc  113  into mating contact with the first valve seat  112 . 
       FIG. 3  illustrates a side view of the valve  100  with hidden elements such as the support arms  128  and the ribs  126  shown in dashed lines to reveal their arrangement within the valve  100 .  FIG. 4  shows a top view of the disc and lever arm assembly  102  with details having cut away portions of the second disc  115  and one of the support arms  128 . 
     Referring to  FIG. 4 , each of the support members  128  include a vertical member  400  disposed between an upper plate  402  and a lower plate  404  to form an I-beam having an end plate  406 . One end of the upper and lower plates  402 ,  404  and vertical member  400  of each support members  128  may be welded to the hub  130 . The apertures  136  that permit passage of the pin  134  extend through an opposite end of the vertical members  400 . On each end of the pin  134  adjacent the outside face of the outside rib  126 , a washer  408  having a diameter greater than the apertures  136  is welded to the pin  134  to prevent the pin  134  from sliding axially through the apertures  136  in the support arms  128  and ribs  126 . Also visible in  FIG. 4  is a top shield  410  that substantially prevents flow through the area between the discs  113 ,  115  as the disc and lever arm assembly  102  moves from the first position to the second position. The top shield  410  is a curved plate perpendicular to the discs  113 ,  115  that has a height equivalent to the height of the ribs  126  and extends across a top edge of the discs between at least the two outside ribs  126  to block flow between the ribs disposed inside of the two outside ribs. 
       FIG. 5  is a section view of an alternative embodiment of a diverter valve  500  having a disc and lever arm assembly  502  that includes a ball-in-socket arrangement. The disc and lever arm assembly  502  moves between a first position and a second position in order to divert flow between a first passageway  506  and a second passageway  508  as described above with reference to the valve shown in  FIGS. 1–4 . However, the disc and lever arm assembly  502  of the valve  500  includes discs  513 ,  515  separated by a plurality of parallel ribs  526  attached thereto, a single central support arm  528  positioned between two centermost ribs  526 , and a hollow cylindrical hub  530  that the support arm  528  secures to. The support arm  528  extends from the hub  530  to a center of the discs  513 ,  515  where a central post  550  having an enlarged ball shaped middle section is secured to the discs  513 ,  515 . Each end of the central post  550  attaches to the back side of one of the discs  513 ,  515 . A socket assembly  552  of the support arm  528  surrounds the ball shaped middle section of the central post  550 . Due to the ball-in-socket arrangement between the support arm  528  and the central post  550  attached to the discs  513 ,  515 , the discs  513 ,  515  can pivot about 360° without interfering contact by the support arm  528  since the ribs  526  separate the discs  513 ,  515  by a sufficient distance greater than the height of the support arms  128 . Similar to the discs capable of pivoting in one direction as described above, the ability of the discs  513 ,  515  to pivot about 360° enables the discs  513 ,  515  to compensate for misalignment with valve seats  512 ,  514  as the discs are forced into contact with the valve seats  512 ,  514 . 
       FIG. 6  is a section view of an alternative embodiment of a diverter valve  600  having a disc and lever arm assembly  602  that includes a ball-in-socket arrangement that is reversed from the ball-in-socket arrangement shown in  FIG. 5 . Specifically, a support arm  628  has a ball shaped end  606  that mates with a socket portion  604  centrally secured to the discs  613 ,  615 . The diverter valve  600  operates as described herein to enable the discs  613 ,  615  to move or adjust in order to close flow paths through the valve  600 . 
     The disc and lever arm assemblies described herein may be used with open/close valves that do not divert flow to another passageway but rather simply open and close flow to a single fluid passageway through the valve such as the first fluid passageway  106  shown in  FIG. 1 . As such, the open/close valve does not include a second passageway or a second valve seat and the second disc may be omitted or replaced with any member capable of providing structural support to the disc and lever arm assembly. For example, a ball may be attached to a single disc that is engaged by a socket on a lever arm for applications similar to  FIG. 5  except utilizing a single disc. 
     Examples of industries that can benefit from valves as described herein include water utilities, power plants, refineries and chemical manufacturing. In one example of an application using the invention, a valve according to embodiments described above can be part of a fluid catalyst cracker unit and can be used to isolate one line therein (e.g., the second passageway  134 ) for a desired purpose such as an emergency situation or to construct/repair the line. As another example, a valve according to embodiments described above can control flow from an ethylene unit during the production of plastics. 
     While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.