30 replies to this topic

[Dmitry]

Hello, thanks!

Is this gauge pressure? Now I am using Hysys to do this calculation. I will add results later in this topic

Regards

Dmitry

Edited by Dmitry, 06 February 2015 - 12:27 AM.

[breizh]

Dmitry ,

No absolute pressure!

Breizh

[gegio1960]

dmitry,

my quick considerations:

1) shut-off pressure is around 8 barg, acceptable for a #150 pipe.

2) your pumps are too big for the requested service (ca 32 m3/h). you should verify the min flows with the vendors.

3) make an effort to make the calculation by hand... it will help you to clarify your big confusion and the way to prepare the basic data

4) hysys is not useful for this kind of problems

5) quick & dirty calculations as follows:

- your system will develop about 88 (ie 59+29) m of head (ca 6.3 bar for your fluid) from an initial (min) pressure of 0.1 barg.

- it will loose about 0.1 bar/km, so 3 bar totally, of distributed losses.

- the most difficult thing to predict is the sum of localized pressure drop: your data are unclear/incomplete. anyway a range of 1-2 bar could be realistic (without control valves)

- so, at the end of your line, at ground, you'll have 0.1+6.3-3-2= 1.4 barg (min)

- since you need 0.65 (or 0.8?) barg, you have 0.75 (or 0.6) bar available for a "control" valve

good luck!

[Dmitry]

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

Hello,

 

I have about 39 m3/hr of oil at 3 bar at the discharge of the first pump P-502 and at the discharge of the 2nd pump  7,2 bar  , the pressure at the outlet of the pipe ( after 30 km run) being 1.6 bar 

So it almost the same with your calculation.

Now I know that I've done well calculation and important hot to do it.

I attched results here.

 

I have one question now about operationg point on pumps curves.  Based on Hysys calculation pumps has low efficiency

 

P-502 - 48 % adiabiatic efficiency

P-503 - 22 % adiabiatic efficiency

 

Is this mean that pumps are not very goog working at this case?

 

Thanks

 

 

Dmitry

Attached Files

•  1.JPG   52.08KB   2 downloads
•  P-502 curve.JPG   73.15KB   1 downloads
•  P-503 curve.JPG   66.56KB   1 downloads

[breizh]

Dmitry ,

Definitely the performance of the pumps are bad ! The reason why it's important to get all the performances curves of the pump from Vendor .

Good effort

Breizh

[Dmitry]

Dmitry ,

Definitely the performance of the pumps are bad ! The reason why it's important to get all the performances curves of the pump from Vendor .

Good effort

Breizh

Yes I see it's bad, but I received all curves from vendor anr they are above in this post

Please advice

 

Dmitry