Hydraulic design w/ dead-end system

[rbjones]

Hello,

Does anyone have experience with hydraulic design in a dead-end system? Specifically, the application I am working on is for a branched process chemical supply system, with several reactors that will vary in demand quite a bit. To maintain pressure and keep the pump operating at a relatively constant point on its curve, we are considering a re-circ line back into the source tank.

I have been working on first-draft models using EPAnet...does anyone know of any other models that may prove more realistic, or does anyone have specific experience with this type of application? Thanks in advance for all of your input.

-Rick Jones

Rick Jones, EIT
Stearns and Wheler, LLC

http://www.stearnswheler.com

 

[Scotsinst]

I would set it up with a discharge flow controller controlling a spillback valve to the tank. The flow to the users will be controlled by the users.
The discharge flow controller can be set at the BEP of the pump, that way when the user demand falls below the BEP, the spillback valve will open. If the demand is higher than the BEP then the spillback will be closed and the pump will just run along its operating curve.
Operating at BEP will minimize wear on the pump (If you set the spillback rate at the vendor minimum flow setting, the pump will still vibrate and cause premature seal failure).

 

[1969grad]

Ever consider a variable speed pump?

 

[briand2]

Scotsinst,

Excuse my ignorance!! What do you mean by "BEP" of the pump.

Brian

 

[BRIS]

briand2
Best Efficiency Point

 

[fvincent]

In my company we use a software developed internally and named FNESS. It was developed exactly to cope with large multiloop circuits as cooling water systems of petrochemical plants. We distribute a free version of FNESS in

http://www.figener.com

but such version has capacity to handling problems with a maximum of 6 nodes only. I think I can provide a larger version if you wish (free, at least for a certain while) Just let me know

Regards

fvincent

 

[HenryME]

The solution selected is determined by the amount of flow variation. Suggestions of recirculation, varible speed drives are common methods. I am not familiar with a spillback valve. Other methods include using a constant discharge pressure valve(s) or an accumulator.
Do not overlook the operating speed of the opening and closing of the branch valves to the reactors (water hammer).