Water mixing in a 100 MG reservoir 1

[bichoo]

What is the most energy efficient method of obtaining proper mixing of water with no dead spots in a 100 Million gallon reservoir
The reservoir is 30 ft high

The inlet pipe to the reservoir will have a static head of 140 ft
The incoming flow varies from 80 cfs to 125 cfs

 

[RWF7437]

"The reservoir is 30 ft high

The inlet pipe to the reservoir will have a static head of 140 ft "


How is this possible ?
What do you mean by "efficient". Least energy ? Least cost?

 

[Artisi]

What are the dimensions / shape of the reservoir?
Please explain the static head / inlet pipe / 140ft.

 

[bichoo]

I mean to say the inlet pipe will have a head of 140 ft .. around 60 psi
We want to use this pressure to put water in to the reservoir and achieve proper mixing of water without any dead spots.
the shape of the reservoir is trapezoid of size 500 ft wide and 800 lg at one end and 600 ft lg at other
The inlet pipe size needs to be designed with n ( needs to be determined ) number of nozzles of size x ( needs to be determined ) to achieve proper mixing of water inside the reservoir

How to find the inlet pipe size and number and size of nozzle

 

[gerhardl]

A thought would perhaps have been to build your reservoir with several separate basins or chambers, with an open or closed feedstock arrangement mixing and distributing, and a similar system for outlet.

This is what is usually done in water treatment plants,enabling separate emptying, cleaning and control of the chambers, keeping the others running in the meantime.

If this is drinking water quality, or even anyway, you should consider how you plan to maintain and clean your system from growth and particles from your piping etc.

'Without any deadspots' would mean that you have to drain from an arranged lower point (or several lower points), as in a bathing tub, taking out with you all particles already in the water. Is this what you want?

A coarse check indicates that you have a fairly fast 'turnover' in your basin, and seemingly your reservoir is also open to atmospheric pressure.

If you choose needle valves, piston type with vaned ring, you can pipe in directly above the surface to distribute a spread of water mixed with air, and regulate the amount, and by this avoid valve cavitation.

You can do the same underwater, and direct your different outlets to create currents, utilizing needle valves, piston type with slotted cylinder.

Number and split between valves: 'as suited to your general arrangement and operating mode'.

(Hard to advice further without detailing and sizing the valve arrangement for the whole project. Perhaps 2 to 4 inlet valves? I have not calculated and sized the valves.)

 

[bichoo]

The reservoir is already designed and it does not have any basins
It will have multiple inlet and multiple outlet from the bottom
The objective is to have zero dead spots by proper alignment and location of the inlet and outlet nozzles
The reservoir is a storage that will receive and discharge water everyday.
The level will vary from 90 % to 20 % very often

If the reservoir has dead spots then that area of the reservoir will have stagnant and old water

 

[Artisi]

With such a high turnover would you expect any dead spots?

 

[bichoo]

Its a huge reservoir
CFD modelling shows many dead spots with various configuration

 

[Artisi]

bichoo, not my area of expertise so will leave it to the experts.

 

[RWF7437]

Please read FAQ 194-1462.
Please post a sketch.
Please define "CFD".

 

[gerhardl]

bichoo:

With the turnover and variation you have I cannot see deadspots to be much of a problem. What you want to do is to make a turbulent inlet spreading and varying throughout

Could you do this by one inlet each side directed against each other?

If not satisfactorily alternating with two others on opposite sides?

 

[greggy]

To achieve mixing passively you will have to use the dynamic energy of the incoming water to its fullest advantage. This may possibly be achieved by designing a manifolded bank of nozzles that will increase velocities to promote mixing throughout the reservoir. My experience is that dead spots will increase by baffling or increasing the number of compartments, although it's nice to have at least two compartments so you can take one side out of service for cleaning. An active system that uses additional energy would be to install a pump in or near the reservoir or install a rotating blade to force mixing.

 

[Artisi]

Flygt pumps have some excelent submersible mixers designed for this very purpose.

 

[hydrae]

Russ
CFD Computational Fluid Dynamics
Hydrae