Municipal Mixing with Reciprocating Motion Disk
A reciprocating motion disk for mixing wastewater in a tank of a treatment plan is optimized for geometry, along with cycling speed and stroke length, to cause effective mixing velocity throughout the tank.
1 . In a wastewater treatment tank, a reciprocating mixer disk for mixing liquids or slurries by cyclical up and down motion of the mixer disk within the tank, comprising:
a polygonal or essentially circular solid ring with an outer diameter and an inner diameter, the inner diameter of the ring defining a central essentially open area A open , the solid ring having a closed area A closed ,
essentially radial struts supporting the solid ring, extending from the solid ring inwardly to a central hub, the solid ring having a width from the outer diameter to the inner diameter,
the disk in service reciprocating at a cycle rate of C cycles per minute, at a stroke length S in inches,
and the product of C×S×(A open +A closed )/A open being in the range of about 1530 to 8750 .
2 . The wastewater treatment tank apparatus of claim 1 , wherein said product is in the range of about 2000 to about 5000.
3 . The wastewater treatment tank apparatus of claim 1 , wherein said product is in the range of about 2400 to about 3750.
4 . The wastewater treatment tank apparatus of claim 1 , wherein said outer diameter and said inner diameter of the solid ring define a ratio in a range of about 2.0 to 2.5.
5 . The wastewater treatment tank of claim 4 , wherein said outer diameter and said inner diameter of the closed ring define a ratio in a range of about 2.2 to 2.3.
6 . The wastewater treatment tank of claim 1 , wherein the disk is operated in reciprocating vertical motion at a peak disk speed in the range of about 3 to 5 feet per second.
7 . The wastewater treatment tank of claim 1 , wherein a factor A f is in a range of 0.25 to 0.75, where A f =A open /A x , and A x is the area of liquid displaced inwardly to the open area as the disk is advanced.
8 . The wastewater treatment tank of claim 7 , wherein the factor A f is in a range of 0.35 to 0.65.
9 . The wastewater treatment tank of claim 7 , wherein the factor A f is about 0.5.
10 . The wastewater treatment tank of claim 1 , wherein the disk is operated in reciprocating vertical motion at a peak disk speed in the range of about 2 to 6 feet per second.