Valve assembly having a compensating gate

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.

1 . A method of compensating for a misalignment between a valve seat and a corresponding gate used with a fluid catalyst cracker unit, comprising: 
 providing a valve having the gate on a lever arm and the valve seat within a passageway of the valve, wherein the passageway forms part of a fluid flow line of the fluid catalyst cracker;    isolating the fluid flow line of the fluid catalyst cracker unit by rotating the lever arm from a first position with a plane of the gate axially aligned with flow through the passageway to a second position with the plane of the gate rotated and the gate initially contacting the valve seat; and    pivoting the gate with respect to the lever arm such that the gate squarely contacts the valve seat to compensate for the misalignment.    
   
   
       2 . The method of  claim 1 , wherein a fluid tight seal is formed between the gate and the valve seat once the gate squarely contacts the valve seat.  
   
   
       3 . The method of  claim 1 , wherein the lever arm includes a plurality of support arms pivotally coupled to the gate by a pin extending across a centerline of the gate through apertures passing transversely through both the support arms and ribs attached to the gate.  
   
   
       4 . The method of  claim 1 , wherein the lever arm includes a single central support arm pivotally coupled to the gate by a ball-in-socket engagement therebetween.  
   
   
       5 . A system, comprising: 
 a fluid catalyst cracker unit having a fluid flow line;    a valve seat within the line of the fluid catalyst cracker unit;    a disc moveable between a first position in contact with the valve seat for blocking flow through the line and a second position axially aligned with flow through the line; and    at least one lever arm pivotally coupled to the disc and capable of rotating a plane of the disc to move the disc between the first and second positions.    
   
   
       6 . The valve assembly of  claim 5 , further comprising an additional line through the fluid catalyst cracker unit.  
   
   
       7 . The valve assembly of  claim 5 , wherein the plane of the disc in the first position is offset substantially 90° from the plane of the disc in the second position.  
   
   
       8 . The valve assembly of  claim 5 , wherein the disc includes a plurality of parallel ribs attached to a backside thereof.  
   
   
       9 . The valve assembly of  claim 8 , wherein the at least one lever arm includes a plurality of parallel lever arms interleaved among the plurality of parallel ribs.  
   
   
       10 . The valve assembly of  claim 9 , wherein the lever arms are pivotally coupled to the disc by a pin extending across a centerline of the disc through apertures passing transversely through both the ribs and the lever arms.  
   
   
       11 . The valve assembly of  claim 5 , wherein the at least one lever arm includes a single central support arm pivotally coupled to the disc by a ball at one end of the support arm that engages a socket portion connected to a central portion of the disc.  
   
   
       12 . The valve assembly of  claim 5 , wherein the at least one lever arm includes a single central support arm pivotally coupled to the disc by a socket at one end of the support arm that engages a ball portion of a central post connected to the disc.