27 replies to this topic

[Max3008]

Dear Mr Art Montemayor,
Could you help me to explain the reason of using "restriction orifice" in the pressurization and depressurization line? 
Thanks in advance,

Hoang.

[Art Montemayor]

Hoang:

 

If you are dealing with an adsorption dryer unit that is probably on a PSA (Pressue Swing Adsorption) cycle – which I suspect is what you are referring to – then the main reason for controlling the rate of pressurization and de-pressurization of the adsorption beds as they go through their regeneration phase is to avoid any pressure and flow turbulence within the beds that will result in bed movement and severe adsorbent attrition and dusting.

 

In an adsorption process that consists of fixed beds on a time cycle, you need to maintain the adsorbent totally immobile and fixed in a static position.  Any movement or vibration of the bed or the individual pellets will cause attrition and material break-up with resulting “dust”.  This effect will defeat the process and you will have to stop and replace the adsorbent.  A restriction orifice (RO) is placed in the fill and blowdown lines in order to establish sonic flow that essentially fixes the mass flow rate of the flowing gas.  This effect will result in steady, pre-designed and constant flow rate that minimizes any bed movement.  Other resulting effects are less noise and pipe vibration – all desirable features of any process.

 

 

[Max3008]

I get it now. Thank you so much, Sir