Detention tank design for water 1

[me1347]

Please, give me advice how to design a detention tank for water.

 

[RWF7437]

You need to clarify this. Are you talking about a settling basin to treat a water supply ? Are you talking about a storm water detention pond or retention pond ? If you hope to get an answer make your question more specific please and provide some details; especially numbers.

Good luck.

 

[me1347]

This detention tank is simply a tank which is going to keep the water and the injected chemical for 30 sec. .
the water is feed water for ultra filtration skids.
Although the length of the tank is enough, I have to consider 3 or more baffle for better mixing.
My question is how can I calculate the head loss for pasing over the baffles and how much thickness for baffle should i consider?

Thanks

 

[bargin]

The detention tank will depend on your design flow rate. For example, if your flow rate is 100 Us gallons per minute, a 50 gallon tank will hold the water for half a minute (30sec). Calculate cubic feet per gallon (0.13368cubic feet per gallon x 50 gallons) = 6.684 cubic foot tank. Depending on your space requirements or restrictions, determine your tank dimensions. For example if you tank is 2 feet diameter (V=A x H), A=pid2/4, you tank height will be 2.13 feet high.

 

[me1347]

thanks for your reply.
I know how to size the tank, what I am not sure about is how to calculate the pressure loss inside the tank when you have baffle inside.
I really appreciate your help.

 

[JedClampett]

I'm a structural guy, but I like to observe how the hydraulics are done. What I've noticed is that the hydraulic designers like to do is to slow the flow down so much that any losses over the baffles are not significant.
Then they argue, flip coins and pull numbers out of thin air based on experience. It usually comes out to a couple of inches.

 

[waterexpert]

Or if you wanted to be a bit more technical, have a look at my page on design of channels in water features:

http://www.expertise-limited.co.uk/Water Feature Design.htm

Enjoy

Seán

 

[EngrInfo]

It all comes down to the velocity gradient of the fluid and the minor losses as the water flows through the tank. You can then use Bernoulli's equation to estimate the headloss. Instead of baffels, consider using plastic media in the detention tank to increase mixing. Depending on the type of media added, determine the reduced crossectional area of the vessel and calculate the velocity gradient. Add minor losses created by fluid eddy currents. In any case, I would estimate the amount of headloss would be small especially when compared to the UF needs.