3 replies to this topic

[curious_cat]

I've a  compressor working with relatively low pressures / compression ratios (it is part of a vapor re-compression system in a multi effect evaporator). I need to size the vapor suction line. 

 

Is there a standard resource / guideline to do this? Is the pressure drop the governing criterion? 

 

One guideline I got from a previous thread on this forum was:

 

 not to exceed density x velocity ^2 value of 15000 (SI units) 

http://www.cheresour...for-compressor/

 

Is this a good guideline? e.g. For a case I was calculating (P=1 barg) it gives me line velocities of approx. 150 m/sec as still acceptable. 

 

These seem too high to my intuition. 

 

Another article gives the following guidelines:

 

 

"As a rule of thumb, suction and discharge lines should be sized for a maximum actual velocity of 30 ft/sec (1,800 ft/min) to 42 ft/sec (2,500 ft/min).'"

 

 

But this would mean a max velocity of only 10 m/sec. Way lower than what the 15000 limit on rho x v^2 seems to give. 

 

http://www.oilngaspr...ipe-sizing.html

 

 

A Norsok standard (Sec. 5.4.2) puts 60 m/sec as a general max limit for gas lines (nothing compressor specific)

 

http://www.standard....130/p-001r3.pdf

 

 

Are there other guidelines on max velocities? Why so much conflicting rules of thumb. 

Edited by curious_cat, 19 February 2017 - 07:15 AM.

[Bobby Strain]

Generally one sizes the inlet and discharge piping based either on noise criteria or pressure loss. Here is guides from Elliott.

 

Attached Files

•  CentrifPipe.pdf   317.97KB   139 downloads

[ankur2061]

Dear,

 

I would like to quote regarding compressor (centrifugal / reciprocating) from the standard of a globally reputed company:

 

 Sizing_Compressor_Lines.png   52.07KB   43 downloads

 

 

Additionally the most common sizing methodology would be based on source pressure and destination pressure (compressor inlet flange) i.e. the pressure drop in the suction system (piping / valves etc.)

 

Regards,

Ankur

Edited by ankur2061, 20 February 2017 - 04:07 AM.

[curious_cat]

Thank you very much Ankur and Bobby!