Patent ID: 7368283

Claim:
A stirring tank for storing a part of a beer yeast slurry discharged from fermentation tanks where beer is fermented, and then returning said part of the beer yeast slurry to the fermentation tanks for reuse, comprising: a tank body having a substantially cylindrical shape with a bottom portion having an inverted cone shape, a jacket disposed on a periphery of the tank body within which a cooling medium is circulated so as to cool the beer yeast slurry, and a stirring impeller made up of vertically oriented surfaces with no main stirring surface that is slanted from vertical, said stirring impeller having a shape and size configured to achieve vertical flow of the beer yeast slurry, and positioned within the tank body of the stirring tank, and having lower paddle blades each,including a lower side with a slanting surface to match the inverted cone shape of the bottom portion of the tank body, said stirring impeller being so constructed that the maximum diameter of a rotation body defined by the rotation of the stirring impeller is 60-90% of the inner diameter of the stirring tank, and the height of the rotation body is 70% or more of the depth of the beer yeast slurry stored in the stirring tank.