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Topic: "paralell" chromatography  (Read 2716 times)

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Offline Enthalpy

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"paralell" chromatography
« on: February 10, 2013, 09:18:14 PM »
Gudenlau, sorry to go temporarily off-topic...

This is how I figure a chromatography "column" can use a finer adsorbent without increasing the pressure drop nor getting too slow: increase the cross-section and reduce the path length. This must be done in accord with the grain size reduction so that separation stays efficient.

In a first step, the flow can go radially through the adsorbent instead of axially. Then, you can have many inlets and outlets through the adsorbent, say on a chessboard pattern, to define many short paths in parallel. In a remote step, if the inlets and outlets become too thin, they can be shortened and grouped in parallel to arteries and veins.

If the adsorbent is partially sintered to be a porous solid, nothing special to add. But a powder needs to be hold in place. Tubes of porous ceramic could do that, or thin filters hold in good shape by a stronger internal helix of metal, plastic... Besides the coffee filter paper and variations, it's possible to make many small holes in a plastic or metal using a laser, or even by ionizing rays that degrade locally a polymer subsequently etched. All the setup depends on the cleaning needs, supposedly.

But isn't it always done that way?

Marc Schaefer, aka Enthalpy

Offline curiouscat

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Re: "paralell" chromatography
« Reply #1 on: February 11, 2013, 02:58:37 AM »
Gudenlau, sorry to go temporarily off-topic...

This is how I figure a chromatography "column" can use a finer adsorbent without increasing the pressure drop nor getting too slow: increase the cross-section and reduce the path length. This must be done in accord with the grain size reduction so that separation stays efficient.

In a first step, the flow can go radially through the adsorbent instead of axially. Then, you can have many inlets and outlets through the adsorbent, say on a chessboard pattern, to define many short paths in parallel. In a remote step, if the inlets and outlets become too thin, they can be shortened and grouped in parallel to arteries and veins.

If the adsorbent is partially sintered to be a porous solid, nothing special to add. But a powder needs to be hold in place. Tubes of porous ceramic could do that, or thin filters hold in good shape by a stronger internal helix of metal, plastic... Besides the coffee filter paper and variations, it's possible to make many small holes in a plastic or metal using a laser, or even by ionizing rays that degrade locally a polymer subsequently etched. All the setup depends on the cleaning needs, supposedly.

But isn't it always done that way?

Marc Schaefer, aka Enthalpy

I think you ought to do a little more actual model building. I'd love to see photos / videos of a prototype of your idea or even some actual lab data on pressure drops etc.


Offline Arkcon

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Re: "paralell" chromatography
« Reply #2 on: February 11, 2013, 09:08:55 AM »
I don't know if this is applicable to chromatography, but this seems very similar to tangential flow filtration.  Of course, you do realize, your radial flow column no longer uses the length to perform the separation, but now uses the radial width.  That is a vastly shortened length.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Enthalpy

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Re: "paralell" chromatography
« Reply #3 on: February 13, 2013, 06:54:42 PM »
Sure! It's exactly the trick used by filters to accelerate the flow with a give pressure. Or heat exchangers, or lungs, kidneys... Human technology wasn't first...

Separation is done over a shorter distance. This is to combine with a finer powder to keep or improve the selectivity. I claim that the wider+shorter+finer combination can improve both selectivity and speed.

My own doubts and interrogations are more about cleaning and other practical aspects.

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