3 replies to this topic

[processengbd]

I am doing preliminary sizing of Silica Gel Adsorption Tower

Based on the recommendation of this forum i followed 

Gas conditioning processing Vol 2 by John Campbell

I have prepared a calculation sheet.

 

But i am struck in the cycle time of adsorption column. Literature recommend 8-24 hr cycle time (GPSA). Other say that it should be set according to the operator shift change time.

 

But now as all the column switching is done by automation control. What should be the optimum cycle time?

 

But recently I came across two plant which use 45 min of cycle time. 

 

Can you please suggest me pros and cons of this low cycle time. To me this amount of cycle time would degrade the Silica Gel rapidly.

 

Thank you

 

 

Attached Files

•  Silica Gel.pdf   141KB   34 downloads

[ColinR33]

Cycle time varies from application to application.  Things like gas flow, gas composition/water content, contaminants that can foul or use up the bed, silica gel or molecular sieve capacity, number of beds, bed size, operating requirements, etc. can all impact the selected cycle time.  In my experience I have seen cycle times from 6 to 26 hours for dehydration using silica gels and molecular sieves, so the number in you calculation certainly seems reasonable although I cannot confirm its accuracy.  When I see a 45 minute cycle time I immediately think "HC dewpoint control" - these typically have much shorter cycle times due to the fact that C4/C5+ hydrocarbons tend to block off the pores in the gel very quickly.  You can also contact silica gel suppliers and get them to size the system for you and come up with the optimal cycle time.

 

Cheers,

[processengbd]

Dear Mr Collin,

 

Thank you very much. Can you please direct me to some literature or vendor datasheet for Hydrocarbon Dew Pint control using Silica Gel.

 

Processengbd

[ColinR33]

There are a number of suppliers, CECA Chemicals, BASF, Grace, among others.  An internet search will go a long way for you.

Cheers,