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Co2 Slippage From Dryer


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#1 Ranga v

Ranga v

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Posted 23 February 2020 - 09:58 AM

Problem relates to air separation plant in PPU.CO2 observed to slip ( max 2.5 PPM) in one of the dryers at the end of service (30 mints). Dryers cycle time are 4 hrs each service & regeneration.Media are AA & MS. Regeneration temp peaks are in fact higher in under performing dryer.

What can be the probable reason.

 



#2 Bodhisatya

Bodhisatya

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Posted 24 February 2020 - 09:37 PM

Problem relates to air separation plant in PPU.CO2 observed to slip ( max 2.5 PPM) in one of the dryers at the end of service (30 mints). Dryers cycle time are 4 hrs each service & regeneration.Media are AA & MS. Regeneration temp peaks are in fact higher in under performing dryer.

What can be the probable reason.

 

Assuming PPUs are vertical : 

 

(a) Check for the Mesh screen that separates AA and MS. Mixing of Adsorbents is one of the common cause for Breakthroughs in ASUs.

(B) How long does it take to complete the Depressurization and Re-Pressurization steps ?Fast De/Re Pressurization lend to attrition ,thus degrading Bed Performance..

© Check by physical inspection if Desiccants Top-Up is required or not ? How long ago was the 2 beds inspected?

(d) As the slippage tends to happens at the end of the cycle ,by all probable means ,adsorbents are at End of Run stage.

(e) Check at the PPU inlet drain , in a timely fashion ,if free moisture is getting carried over from the Pre-Cooling section or not.

 

Meanwhile reduce the Cycle Time of the struggling bed by half an hour and adjust the Heating and Cooling time ,regenerate the bed at a higher Heater Outlet temp.

 

Regards

Bodhisatya



#3 Ranga v

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Posted 01 March 2020 - 09:03 AM

Thanks Sir for valuable feed back  ..Pressurization /depressurization gets completed by normal 17mints( pressure control ramp up valve ).

Struggling Bed media was replaced last 4 yrs back & other bed 8 yrs back which is normal.

 

For any inspection shutdown is required which is opportunity based.Cycle time for B is reduced. Pre cooling is direct contact HX with cooling water & concern during summer when ambient goes by 40 deg C then more slippage are expected.

 

Is any calculation sheet or software to access the media life on process conditions.






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