4 replies to this topic

[Tolinorton]

Hello to everyone,

I would be very glad if you could help me solve this problem (see attachment EXAMPLE 7.1 page 139). When I'm trying to convert all units in SI, I get very low value of the total power input. In order to get the correct value of total power input (in WATT), I want to know how to increase dhe dimensions of floculator (length and width), because I think there is a mistake in these dimensions given.

Respecthully,

Chemtoli

Attached Files

•  Floculator Design.pdf   111.02KB   38 downloads

[ankur2061]

Mentor,

Equation for flocculator power input is as follows:

P = G²*mu*V

where:

P = Theoretical Power input to water, W
G = velocity gradient, s^-1
V = Flocculator Volume, m³
mu = Dynamic Viscosity of water, N.s / m² (1 cP = 0.001 N.s / m²)

Optimum flocculation occurs when G is in the range 10-100 inverse seconds (Page 25-65, Perry's Handbook, 7th Ed.)

The overall volume of the flocculator tank (rectangular) would be L X W X D

You can adjust G in the above equation for a given rectangular tank volume to arrive at the desired power input. Alternatively for a given G and P value you can determine the flocculator tank volume. As you might have noted in the above equation volume is an input and not the dimensions. The dimensions can be adjusted in practical terms to arrive at the given or calculated flocculator volume.

Regards,
Ankur.

[Tolinorton]

Dear Ankur,

Thank you very much for your explanations. They were very helpful.

[Tolinorton]

Ankur sorry if I bother you,

In fact I want to determine Theoretical Power input to water,P without knowing the value of G.
Is there any methode to determine this value because I couldn'n understand the example that is in the attachment. And how to adjust G for a given rectangular tank volume to arrive at the desired power input. I mean is there any chart or mathematical expression.

[ankur2061]

Mentor,

I don't know any other method than what I have mentioned in my post. Probably the best way to approach the problem would be to approach some flocculator manufacturer.

Regards,
Ankur.