12 replies to this topic

[blvn]

Hi all, I'm workings as a trainee engineer in the Oil industry, My sir assigned me a task, studying pump capacity and power required for 2 cases. I did calculations for 1st case based on the resources available in cheresources and other websites. 

 

I have to submit calculations in next week, here I uploaded excel sheet and GA sheets, please check my calculations and suggest me if there are any corrections and I have some doubts regarding calculations and please clarify me. 

 

I wrote my questions/doubt in the excel.

 

Thank you all in advance.

Attached Files

•  Pump Capacity.xlsx   1.17MB   61 downloads
•  PROPOSED GA-Model.pdf   180.91KB   30 downloads
•  PROPOSED ISOMETRIC-1-Model.pdf   52.19KB   25 downloads
•  Scanned GA with changes.pdf   1.56MB   25 downloads

[Zauberberg]

Is this a real facility? Why can't you simply read actual power consumption for several flowrates?

 

For theoretical exercise or for comparing actual vs. design you can read these parameters from pump curves (power, efficiency).

[blvn]

Yes, it is realfacility, I can get power required from pump curves, but the reason is I'm fresher, so to know the difficulties in design he assigned me this task.

[Zauberberg]

So what is your task then? To calculate theoretical pumping power at different flowrates?

[blvn]

Not at different flow rates, only for single flow rate, it's two cases, 1. Tank to loading point, 2. Unloading point to tank. I did calculations for 1st case, but I want to know is there are any errors in my calculation, and I have some doubts, I wrote them in excel, pl refer excel which I uploaded.
Thank you

[Bobby Strain]

That's an awful lot to ask! You should present summary information. Maybe someone will look at it.

 

Bobby

[gegio1960]

Dear blvn,

yuo've done a huge quantity of calculations that, at least, demonstrates passion and perseverance, essential things for a good trainee.

You should now look at some other aspects, in order to make clearer to your coordinator that you'll be a good engineers that, in the near future, will help him in saving time...

My (initial) suggestions (trying to expand the right advices of Zauz & Bobby):

1) you're working on two different items: a ) pressure drops in lines, b ) pump calculations. You can think I'm joking, but two good spreadsheets (and the relevant clear procedures) for these two items are the solid foundations of a good process department in a good engineering company. So, try to clearly separate the two items.

2) don't use the "scientific" notations in a spreadsheet but utilize simpler "engineering" notations (eg m3, not m³....). You'll save time and the spreadsheet will be clearer, saving the time of your coordinator. Moreover, formulas shall be reported for quality reasons, but they shall not be too many (if you need a lot it is better to separate them in a page of procedure).

3) a similar engineering/clever approach shal be applied to: a ) number of shown significant digits; b ) number of void rows. Both shall be minimized.

4) use the correct unit of measures and their symbols (eg m, not mtr; absolute and relative pressures shall be clearly indicated by a and g)

5) put a clear and simple but exhaustive sketch of the circuit at the top of the pump calculation spreadsheet; ISOMs & GAs shall be in your documentation

6) whenever you study an existing pump you shall obtain its original/updated data sheets and the relevant characteristic curves (flow vs H, NPSHR, eff, absorbed power. Design figures should be integrated by field data, according to Zauz post. Your assumption about efficiency is very poor: if you don't have the eff/abs power curve, try to find/utilize a published correlation (vs H and Q)

7)......

Good luck! 

Edited by gegio1960, 24 April 2017 - 12:50 PM.

[breizh]

Hi ,

I believe the document attached is a good material for you to develop your skill .

Good luck,

Breizh

[blvn]

gegio1960:

 

 

Thank you very much for your corrections and suggestions, sir.  I'm looking into that, and apart from that I have some queries that, if possible, could you clarify them?

1. Because of Gravity flow in suction side, Which flow rate I have to consider in suction side, Discharge flow rate (flow rate which is in discharge side) or   Q = Cd * A * sqrt(2gh) flow rate?
2. K values available in Perry's Chemical Engineer's Hand book 8^th edition for fittings/valves vary with diameter?
3. Actually, we use a concentric reducer and eccentric reducer, but due to unavailability of proper information, I considered sudden expansion and contraction losses, So can I proceed with these values or not?

Thanks in advance

 

Regards

Blvn

[gegio1960]

blvn,

1) you don't have gravity flow at the suction of a pump, by definition

2) Ks are constants

3) there are correlations for the reducers/expansions. if you don't find them, you can proceed with your approximation.

[blvn]

Thank you, sir, I have some more doubts, 

 

1. For air vents, I took k value as Tee Branch flow from perry's chemical engg's handbook, air vents installed with gate valve are closed all the time except to release the air, so I took  k value of gate valve as fully open, but here gate valve will close all the time, when I referred K value for gate valve full closed, it was not listed in the book, but k value for 3/4th open is 24, if I consider this then I will get huge head loss. is it reasonable to consider, if not how can I consider K valve for fully closed gate valve?

 

Thanks in advance.

[gegio1960]

come on... you have to only consider the fittings/valves where the fluid flows

[spchauhan12]

I will suggest that you may form Input & Output results for each of below items your Supervisor / Coordinator:

 

1) Line Hydraulics

 

2) Pump ( Suction Pressure, Discharge Pressure, Differential Pressure , NPSHA & Power (Hydraulic power)

 

 

Regards,

 

sp