Screw conveyor shaft seal and related methods

A method of assembling a shaft seal, the method comprising:

• providing an inboard compression plate and an outboard compression plate with one of the inboard compression plate and the outboard compression plate at least partially defining an annular recess;
• positioning at least three sealing devices within the annular recess and situating the inboard compression plate, the outboard compression plate and the at least three sealing devices such that a shaft aperture extends axially therethrough;
• positioning an inboard sealing device along the shaft aperture axially between the inboard compression plate and an inboard frame plate such that the inboard sealing device is spaced axially inboard of the at least three intermediate sealing devices;
• positioning an outboard sealing device along the shaft aperture axially between the outboard compression plate and an outboard frame plate such that the outboard sealing device is spaced axially outboard of the at least three intermediate sealing devices;
• positioning a wear plate between the inboard compression plate and the inboard frame plate such that the wear plate is operative to limit wear of the inboard frame plate, the wear plate having an outer diameter and including a wear pin aperture formed in the wear plate through the outer diameter thereof;
• extending a wear pin outboard from an inner surface of the inboard frame plate and into the wear pin aperture in the wear plate thereby inhibiting rotational movement of the wear plate relative to the inboard frame plate;
• and,
• compressing the at least three sealing devices between the inboard compression plate and the outboard compression plate, the inboard sealing device between the inboard compression plate and the inboard frame plate, and the outboard sealing device between the outboard compression plate and the outboard frame plate such that the inboard sealing device and the outboard sealing device provide redundant seals in addition to the at least three intermediate sealing devices along a shaft extending axially through the shaft aperture.

A screw conveyor comprising:

• a backplate;
• a rotatable shaft extending through the backplate and including a radially outer surface;
• and,
• a shaft seal assembly secured along the backplate and sealingly engaging the rotatable shaft, the shaft seal assembly including:
• an outboard frame plate and an inboard frame plate that together define a shaft aperture extending axially therethrough;
• an outboard compression plate and an inboard compression plate situated between the outboard frame plate and the inboard frame plate;
• a wear plate inboard of the inboard compression plate, the wear plate dimensioned to limit wear of the inboard frame plate, the wear plate having an outer diameter and including a wear pin aperture formed in the wear plate through the outer diameter thereof;
• a wear pin extending outboard from an inner surface of the inboard frame plate and into the wear pin aperture in the wear plate;
• an annular recess at least partially formed along at least one of the outboard compression plate and the inboard compression plate;
• an inboard sealing device disposed between the inboard frame plate and the inboard compression plate along the shaft aperture;
• an outboard sealing device disposed between the outboard frame plate and the outboard compression plate along the shaft aperture;
• and,
• at least three intermediate sealing devices situated between the outboard compression plate and the inboard compression plate, the at least three intermediate sealing devices disposed within the annular recess with the inboard sealing device and the outboard sealing device spaced axially away from the at least three intermediate sealing devices in directions opposite one another;
• the rotatable shaft extending axially through the shaft aperture such that the inboard sealing device forms a seal along an axially-inboard portion of the radially outer surface, the outboard sealing device forms a seal along an axially-outboard portion of the radially outer surface, and the at least three intermediate sealing devices form a seal along an axially-intermediate portion of the radially outer surface with the inboard sealing device and the outboard sealing device forming redundant seals along the rotatable shaft in addition to the at least three intermediate sealing devices.