Heat Exchangers and Pumps 1

[Morfa]

Hello Folks, I am designing a chill water system where my cooling load capacity is over 500 tons. I am installing 4 heat exchangers (plate frame) my process loop will have a flow of over 300 gpm at a pressure of 75 psig (at the discharge of the heat exchangers). I have asked several experienced engineers in the fluid flow field and there are mix opinions on where to place the main circulation pumps. Should I place them on the supply side or the return side of the heat exchangers? Can you elaborate on your answers? Thanks in advance for your tips.

 

[BigInch]

What's between the return side and the supply side?

 

[Morfa]

My Process Equipment, the ones that need the chill water to operate i.e. Compressors, Vacuum Pumps, Water Stills, etc. Thanks for your prompt response.

 

[Morfa]

See Attached Scenarios

 

[ash9144]

You show no storage tanks for either chilled water loop. Is this correct? I assume you have two water loops out of concern of contaminating the process stream and not wanting to put that water through the chiller?

 

[Morfa]

Yeap,no storage tanks and there are two separate loops, see my attached drawng.

 

[nihili]

I rather prefer option one since the power consumption will be lower since the density of the water pumped will be higher (due to the lower temp). Although this difference will not be very high since the density of the water does not experience great changes.

 

[BigInch]

Well, you've got to put it at least where you run out of pressure due to the head loss of all that stuff. But I'd also put it where you still have a low enough temperature to be sure that your NPSHa is still good, not for saving power based on the water density. Rembering all the while that the lower the pressure you can get the most expensive piece(s) of equipment to operate at, the lower the pressure rating will be and the lower the cost of that equipment will tend to be too.