impeller-type flash-mixersReading time:
Cylindrical (steel) or cubes (concrete), these appliances are equipped with a propeller-operated mixer that has a high speed of rotation (figure 1). Due to construction constraints, contact time will vary from 1 to 3 minutes in the larger units. These units have a velocity gradient of 200 to 1 000 s–1 depending on the application. The reagent is injected into the area of greatest turbulence, either above or below the propeller, depending on whether it is downward or upward flow.
For some applications depending on whether the velocity gradient has to be adjusted for temperature or pollution conditions, the propeller-operated mixer must be equipped with a speed regulator.