Reaction unit

A reactor comprising a cylindrical vessel elongated in a flowing direction of a liquid and provided with a liquid inlet and a liquid outlet, a drive shaft arranged coaxially with said cylindrical vessel and one or more plate-shaped or round-bar-shaped agitating elements extending in a direction perpendicular to said drive shaft, said drive shaft and agitating elements being arranged inside said cylindrical vessel, and baffles composed of plates or round bars or combinations thereof and/or coiled, tubular, plate-shaped or helical heat exchangers, said baffles and/or said heat exchangers being arranged on a side of an inner wall of said reactor, characterized in that said agitating elements each has a natural frequency greater than a value (K) at which said agitating element begins to vibrate, and said value is determined from the following formula:

• (K)=(4.317(D/H)2+0.867)(n/60)R/D/1−exp(−0.1404μ−0.8633)
• wherein
• n:
• rotating speed (rpm) of said agitating element,
• R:
• length (m) of said agitating element from a center of said drive shaft to each tip of said agitating element,
• D:
• width (m) of said agitating element projected on a plane parallel to said drive shaft as measured in a direction of said drive shaft,
• H:
• distance (m), as measured in said direction of said drive shaft, between centers of widths of said plates or round bars or combinations thereof or said coiled, tubular, plate-shaped or helical heat exchangers which are projected on said plane parallel to said drive shaft and interpose said agitating element, and
• μ:
• viscosity (poise) of said liquid inside said reactor.