2m production column...packing issues

[dixiedog72]

We have several 2m diameter chromatography columns in our process. One of these recently failed during operation and required the replacement of the acrylic tube. Since the tube was replaced, we have been unable to successfully pack the resin bed. We use a cellulose based resin. Water is the mobile phase. During flow pack, the bed channels pretty badly once the desired bed depth is achieved. The channeling occurs almost instantaneously around the entire circumference of the column. Seems like a flow distribution issue to me, but we've basically torn the system apart and can't identify anything mechanical (flow restrictions, bad seals, etc.). This column is identical to the others we have and the resin is the same in all columns. It's in parallel to the others too, so if there was a flow problem from the pump, we'd see it on the other columns as well. Also, we have all new bed supports installed. I'm at a loss...

Anyone have experience with big columns like this? I'm open to any and all suggestions at this point. What could be causing this channeling?

[tom jupille]

Just a guess, but if the new tube has hydrophobic patches, you might get different water flow there. ???

Maybe take the tube out of service and go over the inside with some super-fine sandpaper (600 or 1200 grit) to even things out. ???

[Rande]

I agree with Tom about "hydrophobic patches", BUT I would not put sandpaper to a plastic tube.

As with any new process equipment, there can be residual "cutting oils", "mold release agents" or whatever from the manufacturing process. I recomend a thorough cleaning with strong detergent and scrub brush or sponge. Then clean the empty assembled column with the typical sanitization / CIP cleaning used for your process. Then pack and qualify your column.

Good luck.

[JM]

Apart from the cleaning issue , Please check your distribution manifold ( look for blocked channels etc) .

Are you packing these columns under pressure or not? It is always good to have some back pressure while packing such columns. we can be of more help if you provide the packing procedure used.

JM

[dixiedog72]

We'll try a thorough cleaning of the tube today. Also, the distribution manifold has been thoroughly checked for blockages (none found).

Here is a summary of our packing procedure:
1. Column is rinsed with WPU until effluent conductivity is <10 μS.
2. Resin amount adjusted to required amount (based on dry weight).
3. Resin mixed into slurry (manually - by paddle).
4. 3 hour de-fine step.
5. Resuspension of slurried resin.
6. Air displaced from column after top of column installed.
7. WPU flow initiated to column (flow pack @ ~25 psig) - held 1 hour
8. If bed looks ok after 1 hour, top of column lowered to compressed bed height (25 cm).

We can get about 10 minutes into a flow pack before the bed starts to show defects (again, channeling or "cheesing" around circumference of column). Let me know if more info is needed.

[JM]

I would suggest to fill extra amount of resin in to the column and then compress, run mobile phase for 1/2 hrs or so and again compress. Normally "channels" would go off by this and pls keep your column under some pressure even when you r running it. "cheesing" around circumference can happen if your solvent sheep out from the outlet when there is no inlet flow. column outlet valve should be closed, when not in operation.

hope this will help.

JM

[Rande]

What type of column are you using, I would guess it it an older model (concidering you are using cellulose resin). I know many of the new process columns on the market claim that they have "new and improved" design of the distribution manifold. I interpret that to mean that they admit there problems with the old design. Most of the old columns have a gap between the top of the bed adapter and the compressed O-ring. I have usually had to push the bed adapter down 2 or 3 times after initially lowering the adapter to the top of the packed bed. Do you have new personell packing the column? Some people are "more aggressive" with forcing the adapter down. Sometimes this can result in too hard a packing, often it is needed to prevent gaps from forming on top of the packed bed, especially during loading.

Pressure packing is the preferred method for packing larger columns, make sure you are higher flow rate (and pressure) than what is used during column operation.

Also ... did you say the gap appreared suddenly? What did you do just before this happened?