Centrifugal Pump Recycle

[Essbee16]

Can someone please explain why a restriction orifice is required at the recycle line of a centrifugal pump? Where is the best position along the line to install it? Does the RO serve the high pressure build-up or the increased flow and velocity purpose. I understand the use of th flow valve on the recycle line and a flowmeter on the pump discharge. Also I understand the use of the ARC valves but not the RO.

 

[Pumpsonly]

The RO in the recycle line is to create pressure loss / friction in the recycling line. It is sized to give the required recycling flow ,usually the minimum allowable flow of the pump. The DP across the RO would be the pump difference pressure(head)at the required recycling flow less the other pressure losses of the fittings and piping. RO is usually used when a continuous recycling flow is necessary such as when the process flow rate is lower than the pump minimum allowable flow.
It can be installed any where along the recycle line.

 

[knapee]

In Bechtel Design practice, the minimum flow can vary form 10 to 50 percent of the rated flow.

If a continuous minimum flow is provided by means of a continuous flow recirculation line with a restriction orifice, the recirculating flow should be added to the rated flow. Hope this help.