Copper foil and retaining mechanisms in an SPP column
I'm in final stages of putting together a VM/LM column with SPP packing. The column itself is stainless, with a copper-tubing/worm-type reflux condenser. I'm planning to use a ~4-inch wide coiled sheet of copper foil at the top of the packing to help minimize sulfur compounds.
I realise there aren't any hard-and-fast rules, but I'm wondering about the best way to pack it.
I have some stainless scrubbers to help hold the SPP in place. Is there a better way?
Should the copper foil sit by itself, above the packing? Or is it better to pour SPP around it, to fill in the space (and thereby get a few more plate-equivalents)?
Comments
I don't use spp, but I use a 4" packed section and I have a couple of large scrubbers each end, with plenty of reasonable tight packed smaller scrubbers in between. They don't move at all.
You can use a filter disk or perhaps a blank plate but that requires another section and clamp to hold together. The filter disk will need the holes to be drilled out a bit bigger as it can flood or stop flow at times (too much power or sudden reflux changes only, in my experience)
A better way would to have a disk or cage in the bottom of the column as a semi permanent setup. A simple tack of weld on the column inside and opposite each other with a disk/cage that has a slot or small cut out to suit, means slip in and twist to hold in place.
Others have said to simply add a handful of copper off cuts/ pieces to the top of the spp or packing to look after any sulfur issues.
A rough pic !
fadge
The thing about the copper catalyst at the top of the column is that you may find that there is an occasional need to remove it for deep cleaning. With this in mind it may be more convenient to have it completely separate from the packing and not mixed in with it.
I have used several methods to hold the SPP.
SD Filter plates are inexpensive and work great.
And copper mesh all balled up is great top and or bottom to add the copper catalyst, spread reflux and retain SPP.
DAD... not yours.. ah, hell... I don't know...
@fadge, nice idea -- though I have close to zero welding skill, and no equipment. My SPP is only about 2mm long, so it would need a fairly tight mesh on the disk or cage.
@dad, those filter plates might be just the ticket. Any idea what the mesh hole size is?
Photo attached, in case it's helpful to see what I'm working with (plus a 2-inch stainless column). (the blue tinge on the copper happened after being exposed to the vinegar-washed SPP, while on the other side of the scrubber).
Some SD folk can tell you the hole size exactly, but they are smaller than 2mm...the disk only has to hold the scrubby and the scrubbie holds up the SPP
Before the SD disks I used this as it also got copper in the mix. Copper mesh is now on top of SPP. Easier to clean...
DAD... not yours.. ah, hell... I don't know...
I'll look into the filter plates and some copper mesh. In the meantime, which approach looks better:
Or:
Or:
I'm a little worried about one scrubber being enough to keep the packing in place. Having it fall into the boiler would not be fun.
Also, what's a good way to clean that blue off of the copper foil? I imagine it's copper acetate, from the acetic acid in the vinegar. I guess this shows that it will be important to rinse well after my planned cleaning run with vinegar.