Solids exclusion device for a seal chamber

Abstract

A solids excluder device is mountable within a seal chamber to protect a shaft structure, such as a mechanical seal. The excluder device fits within a conventional seal chamber and circumferentially surrounds a shaft wherein the bushing includes circulation inducing formations which face towards a shaft surface and generate a flow of process fluid away from the mechanical seal or other pump components. The excluder bushing prevents the accumulation of solids within the seal chamber by generating a flow of process fluid out of this seal chamber. The flow carries solid particulates and other solid contaminants out of the seal chamber and away from the mechanical seal or other pump components to prevent the accumulation of solids within the seal chamber.

1 . In a solids excluder bushing for equipment having a rotating shaft, said equipment including an equipment housing having an interior which includes said shaft extending axially therethrough and defines first and second chambers disposed axially next to each other, a process fluid being disposed within said first and second chambers, comprising the improvement wherein said bushing has an annular shape which surrounds said shaft with said bushing being disposed between said first and second chambers, and said bushing includes an inside bushing surface which faces radially inwardly toward an outer shaft surface of said shaft, said inside bushing surface including flow inducing formations which generate a flow of process fluid from said second fluid chamber toward said first fluid chamber to remove solid matter contained in said process fluid from said second chamber, said flow inducing formation comprising at least one circumferential flow slot which extends circumferentially along said inside bushing surface and are separated from each other by circumferentially extending slot walls, said flow inducing formations further comprising at least one angled flow slot extending through each said slot wall to generate an angled flow of said process fluid through said slot wall to generate a fluid flow in response to shaft rotation which displaces said process fluid from said second chamber into said circumferential flow slots and then into said first chamber.  
   
   
       2 . The solids excluder bushing according to  claim 1 , wherein said inside surface of said bushing is spaced radially from said outer shaft surface to permit a return flow of said process fluid axially from said first chamber to said second chamber.  
   
   
       3 . The solids excluder bushing according to  claim 1 , wherein said circumferential flow slot and said slot walls are circumferentially continuous.  
   
   
       4 . The solids excluder bushing according to  claim 3 , wherein a downstream end of each said angled flow slot is circumferentially spaced away from an upstream end thereof in the direction of shaft rotation and is disposed axially farther away from said second chamber than said upstream end.  
   
   
       5 . The solids excluder bushing according to  claim 1 , wherein a mechanical seal is disposed within said second chamber and said solids excluder bushing draws said process fluid and solids associated therewith away from said mechanical seal.  
   
   
       6 . The solids excluder bushing according to  claim 1 , wherein said inside bushing surface is disposed closely adjacent to said shaft surface such that said fluid flow of said process fluid is generated by shaft rotation which generates a circumferential flow of said process fluid through each said circumferential flow slot and an angled flow through each said angled flow slot.  
   
   
       7 . The solids excluder bushing according to  claim 6 , wherein at least one said angled flow slot has an upstream open end which opens into said second chamber for receiving process fluid therefrom and at least one said angled flow slot has a downstream open end which opens toward said first fluid chamber for discharging said process fluid from said solids excluder bushing during shaft rotation.  
   
   
       8 . The solids excluder bushing according to  claim 1 , wherein said solids excluder bushing includes at least three said slot walls and at least two said circumferential flow slots separated from each other and from said first and second chambers by said slot walls wherein each said slot wall includes at least one said angled flow slot extending therethrough.  
   
   
       9 . The solids excluder bushing according to  claim 1 , wherein said solids excluder bushing includes one said circumferential flow slot separated axially from said first and second chambers by respective ones of said slot walls wherein each said slot wall includes at least one said angled flow slot therein.  
   
   
       10 . A solids excluder bushing for mounting to an equipment housing which surrounds a rotatable, axially-elongate shaft to generate a flow of process fluid from an outboard chamber to an inboard chamber, said solids excluder bushing comprising: 
 an annular ring defined by an outer circumferential surface, an inner circumferential surface, an outboard end and an inboard end, said inner circumferential surface having flow inducing formations which generate a flow of said process fluid axially between said inboard and outboard chambers, said flow inducing formations comprising a plurality of slots which extend circumferentially in side by side relation and open radially inwardly toward a surface of said shaft wherein said circumferential flow slots are separated axially from each other and from said inboard and outboard chambers by intermediate slot walls, said flow inducing formations further including transverse flow slots which extend axially through said slot walls wherein at least one said transverse flow slot is provided in each said slot wall between an axially adjacent pair of said circumferential flow slots to permit a flow of said process fluid from an upstream one of said circumferential flow slots to a downstream one of said circumferential flow slots, said inner circumferential surface adapted to be disposed closely adjacent to said outer shaft surface such that shaft rotation effects circumferential flow of said process fluid through said circumferential flow slots and a simultaneous axial flow of said process fluid between said upstream and downstream ones of said circumferential flow slots.    
   
   
       11 . The solids excluder bushing according to  claim 10 , wherein said circumferential flow slots are circumferentially continuous.  
   
   
       12 . The solids excluder bushing according to  claim 11 , wherein said outer circumferential surface includes an elastomeric member which is adapted to frictionally engage an opposing surface within an equipment housing to maintain said solids excluder bushing stationary during shaft rotation.  
   
   
       13 . The solids excluder bushing according to  claim 12 , wherein said elastomeric member is an O-ring.  
   
   
       14 . The solids excluder bushing according to  claim 10 , wherein said bushing is split so as to be defined by first and second bushing sections which couple together to define said annular ring.  
   
   
       15 . The solids excluder bushing according to  claim 10 , wherein said transverse flow slots extend between upstream and downstream ends thereof, said transverse flow slot extending circumferentially and axially away from said upstream end in the direction of shaft rotation such that said transverse flow slot is angled relative to said circumferential flow slot.  
   
   
       16 . A solids excluder bushing for mounting to an equipment housing which surrounds a rotatable shaft to generate a flow of process fluid from an outboard chamber to an inboard chamber, wherein said bushing is an annular ring having opposite first and second ends and an inner circumferential surface extending axially therebetween, said inner circumferential bushing including slot walls that project radially inwardly and extend circumferentially in side by side relation to define one or more circumferential flow slots which open radially inwardly toward the shaft, each said slot wall further including at least one tangentially angled flow slot which extends between and opens into any of said circumferential flow slots adjacent thereto wherein each said angled flow slot between an adjacent pair of circumferential flow slots permits fluid flow from an upstream one of said circumferential flow slots to a downstream one of said circumferential flow slots, at least one of said angled flow slots opening axially from a first end of said bushing and another said angled flow slot opening axially from an opposite end of said bushing to permit discharge of said process fluid axially therethrough during shaft rotation, said inner circumferential surface being configured to be in close association with an outer shaft surface such that movement of the outer shaft surface relative to said inner circumferential surface generates a circumferential flow of said process fluid wherein said process fluid moves circumferentially through said circumferential flow slots and also through said angled flow slots to move said process fluid from said first bushing end toward said second bushing end.  
   
   
       17 . The solids excluder bushing according to  claim 16 , wherein said circumferential flow slots and said angled flow slots are deep grooves which permit the flow of said process fluid as well as solids associated with said process fluid.  
   
   
       18 . The solids excluder bushing according to  claim 17 , wherein said bushing is adapted for non-movable engagement with a support housing of the equipment to prevent rotation of said solids excluder bushing during shaft rotation.  
   
   
       19 . The solids excluder bushing according to  claim 16 , wherein said inner circumferential surface is adapted to be spaced outwardly from a shaft surface to permit axially circulation of said process fluid along said shaft surface in the direction opposite to the direction of axial fluid flow generated through said circumferential and angled flow slots.  
   
   
       20 . The solids excluder bushing according to  claim 16 , which is defined by a plurality of semi-circular bushing sections joined in end to end relation to define said annular ring.