Tank with a double stirring system, primarily a curdling tank

A tank in shape of a vertically oriented container comprising two mutually intersecting, circular container sections, each of said circular container sections including a stirring device having a vertical axis for rotation of the stirring device, a drive shaft, and at least one partly open stirring blade radially projecting from said driving shaft, said at least one partly open stirring blade extending from the drive shaft substantially to a wall of the respective circular container section, said at least one partly open stirring blade extending form substantially a top of each of the circular container sections and extending substantially to a bottom portion of the vertically oriented container, the bottom portion including closeable outlet means located at a lower area of one of the circular cylindrical container sections or between each of the circular cylindrical container sections, said bottom portion being downwardly inclined from said drive shaft towards said lower area, said lower area including a bottom of a ring shaped area around the drive shaft, the ring shaped area having a concentric groove, said concentric groove having a downwardly substantially pointed shape and a groove bottom, the bottom portion being downwardly sloping towards the groove bottom, said groove bottom having a diameter meeting another diameter of another groove bottom between the drive shaft of each of the circular container sections.