Stirring device

A stirring device comprising:

• a stirring tank that defines a stirring chamber;
• a circulating impeller that is disposed in the stirring chamber;
• a drive shaft that extends from a lower side of the stirring tank to an inside of the stirring chamber and rotationally drives a shear blade;
• a mechanical seal structure that is disposed radially outside the drive shaft and creates a seal between the stirring tank and the drive shaft,
• a drainage path for guiding a liquid discharged radially outward from the mechanical seal structure to a drainage portion;
• and
• a spacer;
• wherein the drive shaft includes:
• a first portion to which the shear blade is fixed, and
• a second portion that has a larger diameter than the first portion and is provided below the first portion,
• wherein the mechanical seal structure includes:
• a fixed ring provided in the vicinity of the lowermost portion of the stirring chamber, which includes an inner peripheral surface forming a radial gap between an outer peripheral surface of the first portion of the drive shaft,
• a rotating ring attached to the second portion of the drive shaft and disposed below the fixed ring, which includes a top surface facing a bottom surface of the fixed ring, and
• a spring that urges the rotating ring upward against the bottom surface of the fixed ring to form a sealing surface between the top surface of the rotating ring and the bottom surface of the fixed ring;
• wherein the spacer is disposed between the inner peripheral surface of the fixed ring and the first portion, and is attachable to and detachable from the drive shaft;
• and
• wherein the spacer widens at its base to substantially fill the space between the inner peripheral surface and the first portion.