A shield for a plug valve is provided to prevent debris from hindering the movement of moving components of the plug valve. The shield prevents larger sized debris from accumulating at an opening in a wall in which the plug valve is mounted, the wall defining a confined space, such as the interior of a vessel, at least in part. The shield encloses but is spaced from the plug valve and a device is located within a space between the shield and the plug valve for directing a purging gas through the space to sweep away or purge smaller sized debris from the space.
1. For use with a plug valve adapted to control the flow of a fluid between a first confined space and a second confined space having an opening that provides for fluid communication between the first confined space and the second confined space, the plug valve including (a) a first section that alternatively closes off flow of the fluid and allows flow of the fluid between the first confined space and the second confined space through the opening in the second confined space when the plug valve is actuated to close off the flow or allow the flow, respectively, (b) a second section that is mounted in an opening in a wall that defines the first confined space at least in part and (c) an intermediate section that connects the first section and the second section of the plug valve and includes one or more moving components that are exposed to the fluid in the first confined space and move in the direction of the opening in the wall in which the second section of the plug valve is mounted when the plug valve is actuated to either close off or allow the flow of fluid between the first and second confined spaces, the improvement comprising:
a shield for the plug valve, the shield extending between a first end located toward the first section of the plug valve and a second end located adjacent the second section of the plug valve and the opening in the wall in which the second section of the plug valve is mounted and enclosing at least a portion of the intermediate section of the plug valve in a spaced relationship so as to establish a space therebetween in which the moving components of the intermediate section of the plug valve move, the shield preventing the accumulation of at least some of the debris in the space between the shield and the intermediate section of the plug valve.
2. The shield of claim 1 wherein the space between the shield and the intermediate section of the plug valve at the first end of the shield forms a passageway between the first confined space and the space between the shield and the intermediate section of the plug valve, the passageway being sufficiently narrow so as to prevent the passage of at least some of the debris through the passageway.
3. The shield of claim 2 including means for directing a purging gas into the space between the shield and the intermediate section of the plug valve and out the passageway.
4. The shield of claim 3 wherein the means for directing a purging gas includes a device located in the space between the shield and the intermediate section of the plug valve adjacent the second section of the plug valve and substantially encircling the plug valve, the device including a plurality of outlets for directing the purging gas, together with any debris, out the passageway.
5. The shield of claim 4 wherein the shield has a generally cylindrical exterior with a truncated generally conical exterior at the first end of the shield, the truncated end of the truncated generally conical exterior of the shield and the intermediate section of the plug valve forming the passageway between the first confined space and the space between the shield and the intermediate section of the plug valve.
6. The shield of claim 1 wherein the shield is positioned to prevent the debris from hindering movement of the moving components of the intermediate section of the plug valve between the shield and the intermediate section of the plug valve in the direction of the opening in the wall in which the second section of the plug valve is mounted.
7. The shield of claim 1 wherein the intermediate section of the plug valve includes as one of its moving components a protective shroud for at least a portion of the intermediate section of the plug valve, the shroud having a first end and a second end, the first end of the shroud being located adjacent the first section of the plug valve and the second end of the shroud lying within the space between the shield and the intermediate section of the plug valve.
8. The shield of claim 7 wherein the first end of the shield is spaced from the shroud so as to establish a passageway between the first confined space and the space between the shield and the intermediate section of the plug valve, the passageway being sufficiently narrow so as to prevent the passage of the larger sized debris through the passageway.
9. The shield of claim 8 including means for directing a purging gas into the space between the shield and the intermediate section of the plug valve and out the passageway.
10. The shield of claim 9 wherein the means for directing a purging gas includes a device located in the space between the shield and the intermediate section of the plug valve adjacent the second section of the plug valve and substantially encircling the plug valve, the device including a plurality of outlets for directing the purging gas, together with any entrained at least smaller sized debris, out the passageway.
11. The shield of claim 10 wherein the shield has a generally cylindrical exterior with a truncated generally conical exterior at the first end of the shield, the truncated end of the truncated generally conical exterior of the shield and the shroud forming the passageway between the first confined space and the space between the shield and the intermediate section of the plug valve.
12. The shield of claim 7 wherein the shield is positioned to prevent the debris from hindering movement of the moving components of the intermediate section of the plug valve between the shield and the intermediate section of the plug valve in the direction of the opening in the wall in which the second section of the plug valve is mounted.
13. A plug valve adapted to control the flow of a fluid between a first confined space and a second confined space having an opening that provides for fluid communication between the first confined space and the second confined space, the plug valve including (a) a first section that alternatively closes off flow of the fluid and allows flow of the fluid between the first confined space and the second confined space through the opening in the second confined space when the plug valve is actuated to close off the flow or allow the flow, respectively, (b) a second section that is mounted in an opening in a wall that defines the first confined space at least in part and (c) an intermediate section that connects the first section and the second section of the plug valve and includes one or more moving components that are exposed to the fluid in the first confined space and move in the direction of the opening in the wall in which the second section of the plug valve is mounted when the plug valve is actuated to either close off or allow the flow of fluid between the first and second confined spaces;
a shield for the plug valve, the shield extending between a first end located toward the first section of the plug valve and a second end located adjacent the second section of the plug valve and the opening in the wall in which the second section of the plug valve is mounted and enclosing at least a portion of the intermediate section of the plug valve in a spaced relationship so as to establish a space therebetween in which the moving components of the intermediate section of the plug valve move, the shield preventing the accumulation of at least some of the debris in the space between the shield and the intermediate section of the plug valve.
14. The plug valve of claim 13 wherein the intermediate section of the plug valve includes as one of its moving components a protective shroud for at least a portion of the intermediate section of the plug valve, the shroud having a first end and a second end, the first end of the shroud being located adjacent the first section of the plug valve and the second end of the shroud lying within the space between the shield and the intermediate section of the plug valve.