Agitator, a circulatory cleaning device attached to the agitator, and a circulatory line system comprising the circulatory cleaning device

An agitator comprising:

• an agitating vessel comprising a fluid inlet in an upper part thereof, a fluid outlet at the bottom and having a cylindrical peripheral configuration;
• a rotating shaft extending vertically inside the agitating vessel;
• and
• a flat paddle blade mounted on said rotating shaft, the flat paddle blade having a bottom flat paddle blade portion which extends outwards from the bottom of the rotating shaft and a oblong upper flat paddle blade portion extending upward from an upper part of each side end of the bottom flat paddle blade portion, wherein the bottom flat paddle blade portion has a planar outer surface over substantial the width of the bottom flat paddle blade portion;
• and
• wherein the dimensional ratio (b/a) of the blade diameter (b) of the bottom flat paddle blade portion to the inner diameter (a) of the agitating vessel is from 0.6 to 0.9, the dimensional ratio (d/c) of the height (d) of the upper flat paddle blade portion to the height (c) of the bottom flat paddle blade portion is from 1 to 4, and the shaft and blade are embedded with a passage to pass a coolant medium inside the rotating shaft and the flat paddle blade, wherein the passage comprises a coolant path and has a substantially fixed width for the entire length of the passage within the blade, and wherein the coolant path is located in the blade.