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Figure 2: A tank cleaned with (a) two static spray balls and (b) one rotating jet head.
To test the influence of the TACT parameters, the author designed a tank-cleaning test incorporating two tank-cleaning devices
that generated different amounts of action. A static spray ball typically generates a wall shear stress of 2–5 Pa (i.e., falling
film stress, depending on liquid temperature). A rotating jet head typically generates a wall shear stress of 40–1000 Pa (i.e.,
jet impingement, depending on jet pattern mesh).
Table I: Parameters of two cleaning operations.
To clean the tank sufficiently, two static spray balls operated for 48 min at a flow rate of 20 m3/h and a system pressure of 2.5 bar. One rotating jet head, however, achieved better results when it operated for 14 min
at a flow rate of 6 m3/h and a system pressure of 5.0 bar (see Figures 2 and 3 and Table I).
Figure 3: TACT circles for (a) two static spray balls and (b) one rotating jet head.
The test showed that the theory of the TACT circle works in practice. To clean a certain residue from a certain surface, the
parameters in the TACT circle can be adjusted for cost optimization (see Figure 3). With increased action, it was possible
to reduce the time, the amount of chemicals, and the heating energy and still achieve an equal or better result. High shear
forces can remove residues from most surfaces by themselves without chemicals or high temperatures. This technique can reduce
the risk of contamination from cleaning chemicals and dramatically reduce cleaning costs.
