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

2

Multistage Compressor Mcompr In Aspen Plus V10


8 replies to this topic
Share this topic:
| More

#1 Geetanjali

Geetanjali

    Junior Member

  • Members
  • 21 posts

Posted 16 June 2021 - 06:18 PM

Hello everyone,

 

I intend to compress a vapor stream from 5.06 bar to 28 bar using a multistage compressor MCOMPR. I input 2 stages and a discharge pressure of 28 bar. I get the following warning. Please help me understand why is the warning appearing and how to resolve it?

 

 

 

*  WARNING
   TWO PHASES ENTERING STAGE =   2 AND NO LIQUID SEPARATION IS SPECIFIED
 
*  WARNING
   OUTLET STREAM BELOW DEW POINT
 
Appreciate your help. Please see the supporting documents attached. 
 
Thank you,
Geetanjali

Attached Files



#2 Bobby Strain

Bobby Strain

    Gold Member

  • Members
  • 3,030 posts

Posted 16 June 2021 - 10:30 PM

Add a separator after the cooler.

 

Bobby



#3 Geetanjali

Geetanjali

    Junior Member

  • Members
  • 21 posts

Posted 17 June 2021 - 11:17 AM

Hi Bobby,

 

Thanks for your response. Indeed having a separator would help as when I see the stream components, it is 0.21 liquid fraction and rest is vapor which is what causing the two phase entering issue. However, I do not know how to add a separator within the intercoolers of multi-stage compressors. should I do it separately - meaning, having a normal compressor - cooler - separator, another compressor, cooler - separator and so on, until I get the final discharge pressure of 28 bar and T of 2 deg C? 

 

Thanks

Geetanjali


Edited by Geetanjali, 17 June 2021 - 04:46 PM.


#4 Pilesar

Pilesar

    Gold Member

  • Members
  • 795 posts

Posted 17 June 2021 - 12:04 PM

Try connecting a stream from the 'liquid knockout' port on the Mcompr unit.



#5 Geetanjali

Geetanjali

    Junior Member

  • Members
  • 21 posts

Posted 17 June 2021 - 04:44 PM

Yes, it worked with a "liquid knockout" port. No more warnings anymore. Thank you !  :)

 

Thanks Pilesar and Bobby for your time and assistance.

 

Best regards,

Geetanjali



#6 Bobby Strain

Bobby Strain

    Gold Member

  • Members
  • 3,030 posts

Posted 17 June 2021 - 10:13 PM

So, did you get the right interstage pressure? And would you recognize it as such?

 

Bobby.



#7 Geetanjali

Geetanjali

    Junior Member

  • Members
  • 21 posts

Posted 18 June 2021 - 02:55 PM

Yes Bobby, I got good interstage pressure. First it goes from 5.26 to 12.14 bar in the first stage (Pressure ratio = 2.3), and then from 12.14 to 28 bar in the second stage (Pressure ratio = 2.3). But one thing, the power requirement is more now (1655 kW than previously i.e. 179 kW when I did not use a liquid separator).

 

I combine the liquid outlet from knock out port with the outlet from MCOMPR in order to feed in to a distillation column.

Attached Files


Edited by Geetanjali, 18 June 2021 - 02:58 PM.


#8 Bobby Strain

Bobby Strain

    Gold Member

  • Members
  • 3,030 posts

Posted 18 June 2021 - 04:21 PM

Equal compression ratios is not necessarily consistent with best manufacturer offerings. But this is likely only an academic exercise? And, it may be more effective to feed the vapor and liquid to different trays in the column. Something a designer would explore.

 

Bobby



#9 Geetanjali

Geetanjali

    Junior Member

  • Members
  • 21 posts

Posted 06 July 2021 - 06:36 PM

Thank you Bobby. Yes, it is an academic exercise. and I am feeding the vapor and liquid feeds to different trays in the column.

 

Thank you for your valuable suggestion. 

Geetanjali






Similar Topics