Jump to content



Featured Articles

Check out the latest featured articles.

File Library

Check out the latest downloads available in the File Library.

New Article

Product Viscosity vs. Shear

Featured File

Vertical Tank Selection

New Blog Entry

Low Flow in Pipes- posted in Ankur's blog

Pressure Drop In Hot Water Circulation System


This topic has been archived. This means that you cannot reply to this topic.
10 replies to this topic
Share this topic:
| More

#1 anverps

anverps

    Brand New Member

  • Members
  • 3 posts

Posted 20 May 2016 - 11:01 AM

Friends I have a doubt in the following matter:

We have a hot water generator of capacity 1million kCal/hr and 4 kg/cm2 @ 140 C. The circulation is closed loop, means hot water is circulating from generator to process and back to generator and so... Flow is created by a circulation pump of capacity 42 m3/hr.

My problem is the pressure drop between supply and is return is almost zero (0.1 or .2).

My process contains 15 heating coils and 8 shell and tube heat exchangers. We are expecting a pressure drop of 1.5 or 2.

Is in closed loop continuous pumping system pressure drop will not be evident?

Pls help

ANVER



#2 fallah

fallah

    Gold Member

  • ChE Plus Subscriber
  • 4,930 posts

Posted 20 May 2016 - 12:38 PM

 

We have a hot water generator of capacity 1million kCal/hr and 4 kg/cm2 @ 140 C. The circulation is closed loop, means hot water is circulating from generator to process and back to generator and so... Flow is created by a circulation pump of capacity 42 m3/hr.

My problem is the pressure drop between supply and is return is almost zero (0.1 or .2).

My process contains 15 heating coils and 8 shell and tube heat exchangers. We are expecting a pressure drop of 1.5 or 2.

Is in closed loop continuous pumping system pressure drop will not be evident?

 

 

ANVER,

 

On what basis you did conclude the pressure drop between supply and return in a closed loop circulation is almost zero, especially when there are many heating coils and HX's is that loop.

 

Eventually, all consuming head of a circulation pump in closed loop relates to the friction loss due to moving liquid inside the loop...please recheck the matter and let's know the result to assist...

 



#3 anverps

anverps

    Brand New Member

  • Members
  • 3 posts

Posted 21 May 2016 - 03:19 AM

Thanks for your reply sir.
Pressure drop is 0.2 as per the gauges in supply and return header.

#4 fallah

fallah

    Gold Member

  • ChE Plus Subscriber
  • 4,930 posts

Posted 21 May 2016 - 03:31 AM

Thanks for your reply sir.
Pressure drop is 0.2 as per the gauges in supply and return header.

 

ANVER,

 

You fail to specify the unit of pressure drop (psi, bar,..?)...but if all users (coils and HX's) are in parallel configuration you shouldn't expect having high pressure drop between supply and return headers...
 



#5 anverps

anverps

    Brand New Member

  • Members
  • 3 posts

Posted 21 May 2016 - 06:43 AM

Thanks
It is(pressure)in kg/cm2.
All the users are in parallel.

#6 fallah

fallah

    Gold Member

  • ChE Plus Subscriber
  • 4,930 posts

Posted 21 May 2016 - 07:17 AM

Thanks
It is(pressure)in kg/cm2.
All the users are in parallel.

 

ANVER,

 

Then you should check if the gauges are calibrated at the time of measuring...and if there is low fluid velocity it could be reasonable.... 



#7 latexman

latexman

    Gold Member

  • Admin
  • 1,672 posts

Posted 21 May 2016 - 08:13 AM

What is the elevation difference between supply header pressure gauge and return header pressure gauge?  Which header pressure gauge is highest? 



#8 fallah

fallah

    Gold Member

  • ChE Plus Subscriber
  • 4,930 posts

Posted 21 May 2016 - 11:39 AM

What is the elevation difference between supply header pressure gauge and return header pressure gauge?  Which header pressure gauge is highest? 

 

latexman,

 

In OP's query evaluation, it's logically supposed supply and return headers are at the same elevation...



#9 latexman

latexman

    Gold Member

  • Admin
  • 1,672 posts

Posted 22 May 2016 - 06:55 AM

Yes, I thought there was < a 10% chance it would not be so, so I asked.  I have seen at least one system (hot oil) where supply and return headers are on different elevations.  It is not common, but it does exist.



#10 fallah

fallah

    Gold Member

  • ChE Plus Subscriber
  • 4,930 posts

Posted 22 May 2016 - 07:03 AM

Yes, I thought there was < a 10% chance it would not be so, so I asked.  I have seen at least one system (hot oil) where supply and return headers are on different elevations.  It is not common, but it does exist.

 

Ok, actually the OP can clarify how much might your prediction be right... 
 



#11 latexman

latexman

    Gold Member

  • Admin
  • 1,672 posts

Posted 22 May 2016 - 03:45 PM

Sure, that's who I was doing this for.






Similar Topics