2 replies to this topic

[mgarc]

Hi all,

I was hoping someone could help me solve a problem.

I have a packed bed with 1/16" extrudate (pellets) which is currently sock loaded; and an approximate DP of 20 kPa across the bed. The bed is currently used for adsorption separation of 2 streams and I would like to propose dense loading of the bed in order to improve the separation.

What is the best method to calculate the change in pressure drop of dense loading the same material?

What other factors do I have to consider if I opt to dense load the bed?

Thank you in advance for your help.

[Art Montemayor]

Mgarc:

20 kPa of pressure drop is equal to 2.0 meters of water column. That's a relatively small pressure drop for an adsorber under pressure operation.

Please explain what the term "dense" loading means. Is this similar to "structured" packing? Normally, the Ergun equation is employed to calculate the pressure drop across an adsorber. Is this what you have previously used on the existing bed? What have you used and what do you propose?

Where has the term "dense" come from? If it is explained in a text book or by a manufacturer, then that should be also the source of a pressure drop equation.

[mgarc]

Hi Art,

I apologise for not being more specific regarding my question.

The adsorber bed in question contains 1/16" molecular sieve pellets that were originally sock loaded to the bed. I have used the Ergun equation (modified, based on GPSA engineering databook) and found that the pressure drop was 13 kPa from the calculation.

The intention is to use the same pellets in the bed but to use a dense-loading machine such that the bulk density in the bed is increased from 694 kg/m3 (sock loaded) to 769 kg/m3 (dense loaded). The calculations indicate that this will result in 30 kPa pressure drop across the bed.

Thanks for the advice!

mgarc