Solids discharge centrifugal separator with disposable contact elements

A piston position sensing system for a solids discharge centrifugal separator, the system comprising:

• a separator bowl having an axially positioned optical port at its top end and an inlet port at its bottom end;
• a piston movably disposed against an inner surface of the bowl, the piston movable along the axis of the bowl for solids discharge through the inlet port, the piston comprising a mirror that reflects light upwardly;
• a laser for illuminating the mirror through the optical port;
• and
• a signal processor that receives laser light reflected from the mirror back through the optical port and provides an output value that indicates the position of the piston within the bowl.

A solids discharge centrifugal separator comprising a low shear separator bowl assembly, the bowl assembly comprising:

• a separator bowl having a cylindrical upper portion, a conical lower portion, and an inlet port at the bottom of the lower portion;
• a spindle shaft extending from the bowl upper portion for engaging a drive motor, the spindle shaft comprising an outlet port at the top thereof, the outlet port in fluid communication with the inside of the bowl through a fluid passage in the spindle shaft;
• and
• a piston within the bowl, the piston movably disposed against an inner surface of the bowl.

A solids discharge centrifugal separator comprising a piston position sensing system, the system comprising:

• a separator bowl having an axially positioned optical port at its top end and an inlet port at its bottom end;
• a piston movably disposed against an inner surface of the bowl, the piston movable along the axis of the bowl for solids discharge through the inlet port, the piston comprising a mirror that reflects light upwardly;
• a laser for illuminating the mirror through the optical port;
• and
• a signal processor that receives laser light reflected from the mirror back through the optical port and provides an output value that indicates the position of the piston within the bowl.

A hermetically sealed solids discharge centrifugal separator comprising:

• a separator housing comprising upper, middle, and lower portions, the upper portion comprising an upper bearing assembly and the lower portion comprising a lower bearing assembly;
• a separator bowl assembly disposed within the separator housing, the bowl assembly comprising
• a separator bowl having a cylindrical upper portion disposed within the middle portion of the housing, a conical lower portion disposed within the lower portion of the housing, and an inlet port at the bottom of the lower portion;
• a spindle shaft extending from the bowl upper portion into the upper portion of the housing, the spindle shaft coupled to a drive motor, the spindle shaft comprising an outlet port at the top thereof, the outlet port in fluid communication with the inside of the bowl through a fluid passage in the spindle shaft;
• and
• a piston within the bowl, the piston movably disposed against an inner surface of the bowl, wherein the bowl engages the upper bearing assembly through the spindle shaft of the bowl and engages the lower bearing assembly through the lower portion of the bowl;
• an upper valve assembly, the valve assembly providing a switchable fluid pathway between the outlet port of the bowl and a centrate port or an optical port, the valve assembly comprising one or more seals that hermetically seal the bowl interior during use;
• a lower valve assembly, the lower valve assembly providing a switchable fluid pathway between the inlet port of the bowl and a feed liquid port or a solids discharge port, the valve assembly comprising one or more seals that hermetically seal the bowl interior during use;
• and
• a variable speed drive motor that rotates the separator bowl through a coupling arrangement with the spindle shaft.

A method of operating a solids discharge centrifugal separator comprising:

• a separator bowl having a cylindrical upper portion, a conical lower portion, and an inlet port at the bottom of the lower portion;
• a spindle shaft extending from the bowl upper portion for engaging a drive motor, the spindle shaft comprising an outlet port at the top thereof, the outlet port in fluid communication with the inside of the bowl through a fluid passage in the spindle shaft;
• and
• a piston within the bowl, the piston movably disposed against an inner surface of the bowl;
• the method comprising the steps of:
• (a) flowing feed liquid into the separator bowl through the inlet port;
• (b) rotating the separator bowl, whereby solid components of the feed liquid accumulate on an inner surface of the bowl;
• (c) continuing to rotate the separator bowl while flowing feed liquid into the inlet port, whereby clarified centrate liquid flows out through the outlet port;
• (d) stopping bowl rotation and draining residual liquid from the bowl through the inlet port;
• and
• (e) flowing a fluid back through the outlet port, whereby the piston is displaced downward within the bowl and accumulated solids are discharged through the inlet port.

A method of operating a solids discharge centrifugal separator comprising:

• a separator bowl having a cylindrical upper portion, a conical lower portion, and an inlet port at the bottom of the lower portion;
• a spindle shaft extending from the bowl upper portion for engaging a drive motor, the spindle shaft comprising an outlet port at the top thereof, the outlet port in fluid communication with the inside of the bowl through a fluid passage in the spindle shaft;
• a piston within the bowl, the piston movably disposed against an inner surface of the bowl;
• an upwardly reflecting mirror on the piston;
• a laser for illuminating the mirror;
• and
• a signal processor that receives laser light reflected from the mirror and provides an output value that indicates the position of the piston within the bowl;
• the method comprising the steps of:
• (a) flowing feed liquid into the separator bowl through the inlet port;
• (b) rotating the separator bowl, whereby solid components of the feed liquid accumulate on an inner surface of the bowl;
• (c) continuing to rotate the separator bowl while flowing feed liquid into the inlet port, whereby clarified centrate liquid flows out through the outlet port;
• (d) stopping bowl rotation and draining residual liquid from the bowl through the inlet port;
• (e) flowing a fluid back through the outlet port, whereby the piston is displaced downward within the bowl and accumulated solids are discharged through the inlet port;
• and
• (f) illuminating the mirror with light from the laser and monitoring the movement of the piston using piston positional information from the signal processor.

A method of operating a solids discharge centrifugal separator comprising:

• a separator bowl having a cylindrical upper portion, a conical lower portion, and an inlet port at the bottom of the lower portion;
• a spindle shaft extending from the bowl upper portion for engaging a drive motor, the spindle shaft comprising an outlet port at the top thereof, the outlet port in fluid communication with the inside of the bowl through a fluid passage in the spindle shaft;
• and
• a piston within the bowl, the piston movably disposed against an inner surface of the bowl;
• a lower valve assembly providing a switchable fluid pathway between the inlet port and a feed liquid port or a solids discharge port;
• an upper valve assembly providing a switchable fluid pathway between the outlet port and a centrate port or an optical port;
• wherein the outlet port is fluidically coupled to a fluid pathway through the piston that allows fluid to be added to and removed from the bowl;
• and
• a shuttle valve that regulates the direction of fluid flow through the pathway in response to fluid pressure on either side of the valve;
• the method comprising the steps of:
• (a) flowing feed liquid into the separator bowl through the feed liquid port of the lower valve assembly;
• (b) rotating the separator bowl, whereby solid components of the feed liquid accumulate on an inner surface of the bowl;
• (c) continuing to rotate the separator bowl while flowing feed liquid into the feed liquid port at a flow rate sufficient to maintain the shuttle valve in an open configuration, whereby clarified centrate liquid flows out through the centrate valve;
• (d) stopping bowl rotation and draining residual liquid from the bowl through the feed liquid port, whereby the shuttle valve assumes a closed configuration;
• (e) purging liquid from the liquid pathway through the piston, the spindle shaft, the upper valve assembly, and the centrate port by flowing a fluid into the bowl through the feed liquid port at a flow rate sufficient to maintain the shuttle valve in an open configuration;
• (f) switching the lower valve assembly to open a pathway from the inlet port to the solids discharge port and flowing a fluid back through the centrate port at a rate sufficient to drive the shuttle valve into a closed configuration, whereby the piston is displaced downward within the bowl and accumulated solids are discharged through the solids discharge port.