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Max. Pump Out Rate From Tank


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#1 123sm

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Posted 27 September 2009 - 12:07 PM

Hi,
I am working in Tank farm area of FEED project and have following query while calculating nitrogen inbreathing rate in tank.

The stored chemical in tank is used for followin services:
1) To transfer chemical to jetty using Jetty transfer pump
2) To transfer chemical to truck using truck transfer pump
3) Unit transfer pump to refinery unit.

Now as the pump operation philosophy not clear hence while calculating Nitrogen demand or inbreathing rate for tank can it be comsidered that all the pumps are opearating or consideration of only max pump out rate for any of the above service ( i.e. either jetty or truck loading or unit tranfer pump ..which has highest flow rate )is realistic approach?
From my view point design case i.e.consideration of highest flow rate case among all above services to be considered while calculating nitrogen inbreathing rate. what's your opinion?

#2 ankur2061

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Posted 27 September 2009 - 01:04 PM

Hi,
I am working in Tank farm area of FEED project and have following query while calculating nitrogen inbreathing rate in tank.

The stored chemical in tank is used for followin services:
1) To transfer chemical to jetty using Jetty transfer pump
2) To transfer chemical to truck using truck transfer pump
3) Unit transfer pump to refinery unit.

Now as the pump operation philosophy not clear hence while calculating Nitrogen demand or inbreathing rate for tank can it be comsidered that all the pumps are opearating or consideration of only max pump out rate for any of the above service ( i.e. either jetty or truck loading or unit tranfer pump ..which has highest flow rate )is realistic approach?
From my view point design case i.e.consideration of highest flow rate case among all above services to be considered while calculating nitrogen inbreathing rate. what's your opinion?


123sm,

Unless you have an instrumented permissive start system which prevents starting of one service pump while the other service pump is running, you have to consider that all the three pump-outs are occuring simultaneously and your inbreathing should be based on the summation of all three pump-out rates. The mode of pump-out from your tank should be clearly documented in your 'Basis of Design' document as well as in your 'Operation & Control Philosophy'.

Hope this helps.

Regards,
Ankur.

#3 proinwv

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Posted 27 September 2009 - 03:56 PM


Hi,
I am working in Tank farm area of FEED project and have following query while calculating nitrogen inbreathing rate in tank.

The stored chemical in tank is used for followin services:
1) To transfer chemical to jetty using Jetty transfer pump
2) To transfer chemical to truck using truck transfer pump
3) Unit transfer pump to refinery unit.

Now as the pump operation philosophy not clear hence while calculating Nitrogen demand or inbreathing rate for tank can it be comsidered that all the pumps are opearating or consideration of only max pump out rate for any of the above service ( i.e. either jetty or truck loading or unit tranfer pump ..which has highest flow rate )is realistic approach?
From my view point design case i.e.consideration of highest flow rate case among all above services to be considered while calculating nitrogen inbreathing rate. what's your opinion?


123sm,

Unless you have an instrumented permissive start system which prevents starting of one service pump while the other service pump is running, you have to consider that all the three pump-outs are occuring simultaneously and your inbreathing should be based on the summation of all three pump-out rates. The mode of pump-out from your tank should be clearly documented in your 'Basis of Design' document as well as in your 'Operation & Control Philosophy'.

Hope this helps.

Regards,
Ankur.



#4 proinwv

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Posted 27 September 2009 - 03:59 PM

Ankur is correct. If there is any possibility of all operating together, then that will determine your maximum pump out rate. This is an important safety consideration to prevent ingress of air, or even vacuum collapse.

#5 123sm

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Posted 28 September 2009 - 06:47 AM

Ankur is correct. If there is any possibility of all operating together, then that will determine your maximum pump out rate. This is an important safety consideration to prevent ingress of air, or even vacuum collapse.



#6 123sm

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Posted 28 September 2009 - 06:52 AM

Ankur is correct. If there is any possibility of all operating together, then that will determine your maximum pump out rate. This is an important safety consideration to prevent ingress of air, or even vacuum collapse.


Ankur2061 and proinwv
Thanks for your views.

#7 Dacs

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Posted 06 October 2009 - 09:38 PM


Ankur is correct. If there is any possibility of all operating together, then that will determine your maximum pump out rate. This is an important safety consideration to prevent ingress of air, or even vacuum collapse.


Ankur2061 and proinwv
Thanks for your views.

If N2 cost is important in your project, you can also consider adding breather valves on top of your N2 blanketing.

For instance, you have 2 pumps (1 operating / 1 standby), you can use the (one) pump rated flow to establish the N2 blanketing and use the 2 pumps operating scenario to size your breather valve.

It may introduce air in your tank, but IMHO this is a more economical approach rather than sizing your N2 supply to accomodate the 2 pumps operating scenario, especially if you have multiple tanks in your project.

Of course, this approach is applicable if air ingress can be tolerated by the system.

My 2 cents.

Edited by Dacs, 06 October 2009 - 09:43 PM.





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