30 replies to this topic

[Dmitry]

Hello,

 

What is the effect of running two centrigugal pupms in series. The first pump has less head/flow than second. I am looking for question is any impact on total head or total flow downstream all pumps?

 

Many thanks for answer

 

Dmitry

[Santoshp9]

Dear,the flow and head is depend on its upstream and downstream headloss.check loss upstream and downstream to both pumps and relate it with respective pumps characteristic curve.

[fallah]

Dmitry,

 

In general, normally total flow and especially total head will be increased; but to evaluate precisely it should be investigated using two pumps curves and also the system curve...

[Santoshp9]

Dear,the flow and head is depend on its upstream and downstream headloss.check loss upstream and downstream to both pumps and relate it with respective pumps characteristic curve.

[breizh]

http://centrifugal-p...lel_series.html

 

Dmitry ,

Consider reading the resource attached .

 

Breizh 

Edited by breizh, 10 January 2015 - 06:06 AM.

[gegio1960]

the most important parameter is the shutoff pressure at the discharge of the 2nd pump (ie shutoff of shutoff)....

[Dmitry]

Hello Dear,

 

Thanks for yours reply. The problem is that these pumps has different head/flow rates and engines power. I attached curves for both pumps

1-st. stage  pump (P-501)

2-nd. stage pump (P-503)

 

The pumps should pumped oil into 30 000 meters pipeline - 168 mm outside D., 8 mm wall thickness. Required pressure on pipeline outlet is 0,8 barg.

 

My question is will it works and what flow rate can we achieve with two pumps?

Attached Files

•  LSN 125-100-315 S1 NL1 Operation curve (P-501).JPG   159.54KB   5 downloads
•  RX 125-400 Operation curve (P-503).JPG   127.08KB   4 downloads

[breizh]

Dmitry ,

Refer to the booklet page 103 ( pumps in series with different curves) . Of Course you need individual pump curve from vendor to be accurate then let you draw H versus Qv ; for pump in series H1+H2 @ Q=Q1=Q2 except the part where the characteristic  does  not cover the same range  : Q=Q1 = Q2 but  H =H1 or H2 only !

 

Of course you need to calculate the system curve and compare it with the pump curve ( 2 pumps in series) . The intersection will give you the operating point .

 

Hope this helps

 

Breizh

[Dmitry]

Dmitry ,

Refer to the booklet page 103 ( pumps in series with different curves) . Of Course you need individual pump curve from vendor to be accurate then let you draw H versus Qv ; for pump in series H1+H2 @ Q=Q1=Q2 except the part where the characteristic  does  not cover the same range  : Q=Q1 = Q2 but  H =H1 or H2 only !

 

Of course you need to calculate the system curve and compare it with the pump curve ( 2 pumps in series) . The intersection will give you the operating point .

 

Hope this helps

 

Breizh

 

Hello Breizh,

 

Thanks for your reply. Let me clarify above.

So I need to go to pumps manufacture and request individual curve H-Q? These existing curves can not give a full picture of pumps perfomance?

Then I need to add curves on one plot (as per Fig 3.2.6 - Two different sized pumps connected in series on page 103) - here I am confuse a little bit

 

Note that I've got a Aspen Hysys software, where I can put these curves in pump raring/curves tab. Can I model it as well?

 

Dmitry

[breizh]

Yes Dmitry , you need to perform the exercise with accurate documents !

 

Sorry about Aspen I'm not knowledgeable .

 

Good luck

 

Breizh

[Dmitry]

Yes Dmitry , you need to perform the exercise with accurate documents !

 

Sorry about Aspen I'm not knowledgeable .

 

Good luck

 

Breizh

Hello,

 

Ok, I requested vendor to provide these data. Could you give an exaple or similar or more details how to compare curves and how to calculate the system curve and compare it with the pump curve?

 

Dmitry

[breizh]

Dmitry ,

Go to page 96 and following you will see what I'm talking ! most probably the pump curve (Pump1 +2 ) will be similar to fig  3.2.6 .

I cannot offer more right now.

Hope this helps

Breizh

[breizh]

Dmitry ,

Let you download PSIM on internet from AFT , go through the examples , there is one with a pump and pump curve . You can then build your own model with 2 pumps in series .

Input data : Fluid properties , System ( piping , material ,..) , pump curve (H vs Q, Efficiency , ..)

 

Output : Pressure , flow rate per section .

 

Good luck .

 

Breizh

[Dmitry]

Dmitry ,

Let you download PSIM on internet from AFT , go through the examples , there is one with a pump and pump curve . You can then build your own model with 2 pumps in series .

Input data : Fluid properties , System ( piping , material ,..) , pump curve (H vs Q, Efficiency , ..)

 

Output : Pressure , flow rate per section .

 

Good luck .

 

Breizh

Hello Breizh,

 

Thanks for advice, I went to AFT site - http://www.aft.com/psim

But there is problem with downloading this software, I will try to contact with them to check it.

Have you got experiance with this software? Can I do it only with software?

 

I attached accurate curves for both pumps, given by manufacture

 

Dmitry

Attached Files

•  RX125-400_1450.pdf   173.67KB   40 downloads
•  LSN 125-100-315 S1NL1_ch1.jpg   188.62KB   2 downloads

Edited by Dmitry, 02 February 2015 - 03:12 AM.

[breizh]

Dmitry,

yes it works fine !

What about the pumps which one is the right one 1,2,3,4 ( attachment) ? what about the system ? what about the properties of the liquid?

 

Breizh

[Dmitry]

Hello Breizh,

 

Please see data

 

Fluid - crude oil

Density - 720 kg/m3

Temperature - 8 deg. C.

Required flow rate - 201 bbls/d

 

Oil goes to first pump (LSN) thns to the second (RX)

From RX discharge oil goes to underground pipeline (D=168 mm, w.t.=8mm. lenght=30 000 m.) to the storage tanks

Required pressure on end of pipeline is 70 kpag

 

Dmitry

[breizh]

Dmitry ,

Viscosity @ operating point?

Suction pipe pressure and altimetry ?

discharge pressure 70kpag , altimetry ?

distance between suction line and 1st pump ,

distance between the 2 pumps ,

Cross country flat ?

No valves , no bends ,no etc , just straight pipe from I guess a well or a Storage tank .

A Sketch will help ! 

 

RX125-400 , which curve is the correct one (1 or 2 or 3 or 4?

 

I'm trying to help you but you don't provide enough data .Did you ever design a suitable pump for a particular system ?

 

cheers

 

Breizh

Edited by breizh, 02 February 2015 - 07:09 AM.

[Dmitry]

Dmitry ,

Viscosity @ operating point?

Suction pipe pressure and altimetry ?

discharge pressure 70kpag , altimetry ?

distance between suction line and 1st pump ,

distance between the 2 pumps ,

Cross country flat ?

No valves , no bends ,no etc , just straight pipe from I guess a well or a Storage tank .

A Sketch will help ! 

 

RX125-400 , which curve is correct one (1 or 2 or 3 or 4?

 

I'm trying to help you but you don't provide enough data .Did you ever design a suitable pump for a particular system ?

 

cheers

 

Breizh

Hello,

 

Ok, I understood you, sorry for not all data

I will come back tp you later.

 

Dmitry

[breizh]

Dmitry ,

Something is wrong , if I consider the pumps curves and the flow rate :201 bbl/d # 1.3 m3/h !

Please check you input data

 

Breizh

[Dmitry]

Dmitry ,

Something is wrong , if I consider the pumps curves and the flow rate :201 bbl/d # 1.3 m3/h !

Please check you input data

 

Breizh

Sorry it's my mistake, the flow rate is in bbls/hr. Again sorry for it. I've sent request to manufacture about what curve for RX pump is correct. I am prepearing a sketch for piping now, so we can get all pipes lenghts, elbows numbers and valves.

 

Dmitry

[laketoba]

I plan to run pumps in series

 

4 x 25,000 bpd in series with 2 x 50,000 bpd

 

the pipeline length between 2 pumps is about 1 KM

 

What is industry best practice to protect the pipeline from vacuum? pressure switch low at suction of  downstream pump station is adequate or not?

Edited by laketoba, 04 February 2015 - 01:46 AM.

[Dmitry]

 

Dmitry ,

Something is wrong , if I consider the pumps curves and the flow rate :201 bbl/d # 1.3 m3/h !

Please check you input data

 

Breizh

Sorry it's my mistake, the flow rate is in bbls/hr. Again sorry for it. I've sent request to manufacture about what curve for RX pump is correct. I am prepearing a sketch for piping now, so we can get all pipes lenghts, elbows numbers and valves.

 

Dmitry

 

 

Dmitry ,

Something is wrong , if I consider the pumps curves and the flow rate :201 bbl/d # 1.3 m3/h !

Please check you input data

 

Breizh

Sorry it's my mistake, the flow rate is in bbls/hr. Again sorry for it. I've sent request to manufacture about what curve for RX pump is correct. I am prepearing a sketch for piping now, so we can get all pipes lenghts, elbows numbers and valves.

 

Dmitry

 

 

 

 

 

Hello Breizh,

 

Please see data:

 

Oil storage tank T-500  - P-501 - P-503 - Oil export pipeline 

Fluid - crude oil

Density  740 kg/m3

Viscosity 1,0 cP

Temperature  8 deg. C.

Pressure upstream P-501 25 kpag

Export ipeline (D=168 mm, w.t.=8mm. lenght=30 000 m.) 

Ambient 0 deg. C, pipeline is inderground

Required pressure on end of pipeline is 65 kpag

 

What flow rate could be achieved using two pumps is series?

What pressure will be downstream P-501 and P-503?

Attached Files

•  From T-500 to P-501P-503.pdf   27.17KB   17 downloads
•  From P-503 to export.pdf   46.15KB   13 downloads

[breizh]

Dmitry ,

I' m confused .

What is the unit for length on your drawing ? mm, " ?  you mentioned 30 Km length  please clarify from where to where ?

Correct me , should be from P503 to export ? check your drawing .

What are the pressure in T 500 and Level ?

is the pressure Upstream P 501  stable and equal to 25Kpa g?

What is the delta P of the metering package ?

What is the distance between 2 pumps ?

No info about the pumps' curve : 1-2-3- 4?

 

Breizh

Edited by breizh, 05 February 2015 - 01:36 AM.

[Dmitry]

Dmitry ,

I' m confused .

What is the unit for length on your drawing ? mm, " ?  you mentioned 30 Km length  please clarify from where to where ?

Correct me , should be from P503 to export ? check your drawing .

What are the pressure in T 500 and Level ?

is the pressure Upstream P 501  stable and equal to 25Kpa g?

What is the delta P of the metering package ?

What is the distance between 2 pumps ?

No info about the pumps' curve : 1-2-3- 4?

 

Breizh

Dear Breizh,

 

 

What is the unit for length on your drawing ? mm, " ?  you mentioned 30 Km length  please clarify from where to where ?

Lenght of export pipeline is 30 km

 

Correct me , should be from P503 to export ? check your drawing .

Yes, drawing is updated

 

What are the pressure in T 500 and Level ?

Pressure is atmospheric, the level could be 12 meters above pump suction nozzle during start pumping and become 1 meters pump suction nozzle when pumping complete

 

is the pressure Upstream P 501  stable and equal to 25Kpa g?

Sorry, the pressure is tank is atmosphere

 

What is the delta P of the metering package ?

Delta P is 20 Kpag

 

What is the distance between 2 pumps ?

2 meters, drawing is updated

 

No info about the pumps' curve : 1-2-3- 4?

Pump P-501 (LSN) is middle curve, I marked by red

Pump P-503 (RX) is curve 2, I marked by red

 

All files in attachments

 

Regards,

Dmitry

Attached Files

•  From P-503 to export.pdf   46.24KB   18 downloads
•  From T-500 to P-501_P-503.pdf   27.32KB   20 downloads
•  LSN 125-100-315 S1NL1_ch1.jpg   195.31KB   2 downloads
•  RX125-400_1450.pdf   178.25KB   14 downloads

[breizh]

Dmitry ,

Based on the data you submitted and my understanding of your query , I found that the flow rate you can get with 2 pumps in series should be around 40m3/h taking account the level in the T500 ( 1-12 m) , the static pressure at the discharge of the first pump should be between 3.2 bars and 4 bars  and at the discharge of the 2nd pump between  6.2 bars and 7 bars  , the pressure at the outlet of the pipe ( after 30 km run) being 1.18 bar .

 

I encourage you to perform the exercise using whatever software or by hand .

 

Good luck .

Breizh