Hot water ring main design question

[CheemaJ]

Hi,

I am installing a hot water ring main to serve a number of end users in a factory. The main is fed via. a 20 m3 buffer tank with a centrifugal pump on an inverter drive, it returns back to the same tank.

The average demand I have calculated will be 15 m3/h.

The pump will be spec'd to deliver a peak flow rate of 20 m3/h.

To maintain flow to each take off I plan on using a back pressure regulator just before the return leg reaches the buffer tank.

For pump sizing I have calculated the discharge losses in the system are 5.37 bar.

I have a couple of questions:

1) How do you normally go about setting the pressure on the backpressure regulator? Is there any advantage in setting this higher?
2) Once the pressure is set, for the purposes of pump sizing, am I right in thinking the total losses are: 5.37 bar + set pressure of regulator?
2) When the system is "idle" I want to be able to slow the pump right down to minimise energy consumption. Would it be best to install a downstream pressure transmitter and control the pump speed off this?

Thanks

 

[mk3223]

A sketch of the system configuration can be a good tool for better understanding of the design intend.
Some thoughts to share,
1) The backpressure regulator with higher setting may need the higher discharge head of pump and have higher flow.
2) Also to include the static head to the pump size calculation
3) Be caution to the minimum flow requirement of the pump

 

[bimr]

Grundfos sells a pump controller that perform the control function.

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https://www.grundfos.com/.../grundfos-controlmpc-pumpcontroller.html