Water discharge and water level regulation method of air flotation device

After repeated comparison, the adjustment mechanism as shown in Figure 1 is finally determined. The principle of the mechanism is: the height of the regulating valve rod 4 and the regulating valve 5 is determined by adjusting the height of the pontoon connecting rod at the pontoon hinge point 2. The regulating valve directly acts on the rubber tube 8, changes the water passing area of the rubber tube, and controls the water discharge of the air flotation pool. When the water level in the pool rises, the pontoon rises and the lever moves up, driving the connecting rod 4 and the regulating valve 5 to move up, enlarging the water flow area of the rubber pipe and increasing the drainage volume; when the drainage volume increases, the water level of the air flotation pool will inevitably drop. On the contrary, if the water level of the air flotation pool drops, the pontoon will drop, driving the connecting rod 4 and the regulating valve 5 to move down, and the downward movement of the regulating valve 5 will inevitably reduce the water passing section of the rubber pipe and reduce the water discharge. After the water discharge is reduced, the water level of the air flotation pool will rise accordingly. In this way, as long as the water level height is determined according to the requirements of scum removal, the water level and drainage volume will be automatically balanced, saving people and labor. The device is simple in structure, ingenious and practical, and is suitable for small air flotation device.

2 hydraulic calculation

Calculation formula of orifice outflow:

Q=μω(2gH)1/2 （1）

Where: q-orifice water output, m3 / S;

μ - velocity coefficient;

ω - orifice area, m3, ω = π D2 / 4 (D is drainage pipe diameter);

H-water level, M.

According to the calculation method of (1) orifice outflow [1], the above regulating mechanism is simplified as shown in Figure 2:

If the water level goes up to △ h, the area of the drainage pipe must be reduced to keep the discharge Q constant. If the reduction area is △ ω, and the μ value remains unchanged after the orifice is deformed, the following formula is established.

ω(2gH)1/2=(ω-Δω)[2g(H+ΔH)]1/2 （2）

Transformation equation:

[ω/(ω-Δω]2=(H+ΔH)/H

If the transformed orifice area is ω 1, it is:

[(ω1+Δω)/ω1]2=(H+ΔH)/H      (3)

1+2(Δω/ω1)+(Δω/ω1)2=1+ΔH/H   (4)

If the value of △ ω / ω 1] 2 is too small to be ignored, then

2(Δω/ω1)=ΔH/H      (5)

The above formula can be written as:

ΔH/H=2(ω/ω1-1)      (6)

It can be seen from formula (6) that h and ω are constant values, and the change of Δ h is only related to ω 1. The derivation of this formula can be further proved theoretically for the feasibility of the regulation method.