5 replies to this topic

[duongbq]

Hi all

 

I have one pump system as attached file, please give solution to calculate NPSHa and discharge pressure for each pump.

 

When two pumps run is same time, which flow rate will be select to calculate NPSHa and discharge for each pump to ensure two pumps can run at the same time

 

Thanks so much!

Attached Files

•  model.pdf   2.31KB   96 downloads

[breizh]

Hi ,

 

You need to learn about the basic for centrifugal pump . A lot of material is available in this forum , use the search engine .

Pumps working in // is also  covered , Curves ( TDH vs QV) for  each pump are required .

For NPSH a , you should consider each pump . Data important to collect is the  vapor tension of your product .

 

Intersection between system and pump curves (//) is the answer .

 

Post your work and we will help you .

 

Good luck,

 

Breizh

Edited by breizh, 12 March 2016 - 11:36 PM.

[fallah]

duongbq,

 

For each pump running individually the NPSHA calculation can be performed by traditional method:

 

Corresponding head of absolute pressure at the top of the liquid in the tank+static head from the low liquid level in the tank till pump suction nozzle+suction velocity head (might be negligible)-frictional head at the suction line-corresponding head of the liquid vapor pressure at he operating temperature

 

For running two pumps simultaneously, at first it should be analysed with having pumps curves and other necessary info in hand then to calculate the NPSHA for each pump...

Edited by fallah, 12 March 2016 - 11:28 PM.

[duongbq]

Thanks a lot

 

My project about bitumen terminal, the pumps station have 5 pumps with two function (ship loading and truck loading):

- 2 pumps for ship loading with flow rate is 200 m3/h for each pump.

- 3 pumps for truck loading with flow rate is 60m3/h for each pump.

 

My client mentions one scenario as below:

- all pumps for ship loading (2 x 200m3/h and 3 x 60m3/h), one suction line (16") is designed from the one tank to pump station.

- Discharge line from pump station to the jetty with diameter is 14" and pipe length is 1100m.

 

Please give me solution to sizing pumps above to ensure 5 pumps an discharge bitumen to jetty with flow rate about 580m3/h

 

Regards,

[duongbq]

Sorry to you, all pumps are PD pumps

[ChemEng01]

If your pumps are positive displacement pumps then they are constant volume pumps. Your flow will therefore be the rated flow from the pump at the specified rpm. 

 

For PD pumps you need to ensure there is sufficient NIPR (Net inlet pressure required).

 

The discharge pressure will be the backpressure created when pumping the required flow. 

 

Note that PD pumps will keep going no matter what the downstream pressure so can damage themselves. PSVs are normally installed downstream if there is a blocked outlet / possible overpressure scenario. 

 

If your pumping at min bitumen pumping temp your pressure drop should be minimal.

Edited by ChemEng01, 18 March 2016 - 01:54 AM.