Is it advisable to have 2 dedicated suction nozzles on a drum for 2 pumps operation? Do I have to consider the nozzle spacings to prevent suction interference ? What’re the pitfall for operating 2 pumps from 2 suction nozzles?
Additional information :
- The drum is gas liquid separator
- Operational cases - 1 pump running, spare pump running and 2 pumps running
- Two nozzles are 4"
Instead of having two different nozzles of 4" size you can have one single nozzle of 6" size. This will avoid no. of fittings in the suction line which will improve NPSHA. The 6" line should go up to the suction of both the pumps. Even if only one pump is running the suction velocity will be less than during both the pumps running. This will further reduce frictional head loss in the suction line improving the NPSHA.
If this is Gas liquid separator, then location of outlet nozzle should be kept furthest away from inlet nozzle to allow sufficient retention for bubble rising. So, please check the suitability of pump nozzle location to avoid/ minimize bubble getting into pump suction line.
Two pumps running… one pump stop instantaneously. The forward flow stop and then would create a wave return back to the vessel itself. This may create some level of liquid movement in the vessel and increase opportunity of vapor getting into second running pump… above is my guess… Make sure you have vortex breaker to minimize vapor getting into pump suction nozzle.