spiral-prismatic packing

[Capt-Cudellez]

The specification claims that the 4mm version will give 30-40 theoretical plates per m and the 3mm 40-50 ( Capt'n do you reckon that I am reading their chart correctly.)

That's how I read it - but that is unbelievably efficient, with my SPP according to Riku (author of building automatic stills book - and a good experimenter) I am getting about 20 plates per meter.
I would take anything I have seen on Alibaba with a pinch of salt - some of the still builders on the other sites have found pictures of their still being used in the adverts - pictures from their kitchens gleamed off the forums.

[billmcc]

Manu quoted for 1 litre of spp £32.15 by sea wich will take three to four month delivery or £45.40 air mail wich will take three to four week,he will also accept payment by Paypal
cheers

[YHB]

Nice One Bill

Thats less than I can find the wire for in the UK without factoring in that I may lose a couple of fingers during the manufacturing process.

I have received an initial quotation from the Chinese Manufacturer of the Dixon Rings, He has offered to Airfrieght me three litres of the stuff as a "sample" for 375 USD.

Guess who is favourite?

[ant]

Any progress to report on using this?

[YHB]

Ant,

I have put the idea on hold, I have not been able to find wire at a cost that makes it attractive, I am going to China in a few months, wire is one of the things that is on my list of things to look for, ready made packing is another, there are a few other forms available and I want to look at them.

Have you made any progress making it with your welding wire and your lathe?

Brian

[Capt-Cudellez]

Any progress to report on using this?

Well I haven't been running much recently - so the jury is still out on this. On the couple of runs I have done I have had trouble with flooding and the still is much easier to destabilise, before it was rock solid at holding the temp when I had it packed with scrubbers.
When I ran with a bubble plate and stainless scrubbers I was able to put a lot more power in to the column, the increased power meant I could take off more output while maintaining a good reflux ratio.
With the SPP it floods at the higher powers so I'm running it about the same power as I was without the BB (1500w) and taking off at about the same rate too. This is producing a very clean product and is as good as double distilled stuff I had ran previously, it also lets me produce 95.6% straight from 11% wash which was something I couldn't do before - I'm not sure if I'll do this again as the product was not acceptable for me, and its slower doing 3 column strips than doing 3 full out pot still strip to get enough low wines for the spirit run.

So for now its not letting me run faster, but the product is noticeably better, I think this would greatly improve a small columns performance - but something like the T500 would probably need power control to prevent flooding.

Things I have been thinking about........

If I ran the BB with a scrubber column on the strip - then did an SPP spirit run I might get the best of both worlds - Would really need 2 still heads as packing SPP is a PITA.

If I changed the still design to allow a portion of the reflux to be returned to the boiler externally to the column (perhaps a LM slanted plate above the VM take off), it may reduce the flooding meaning being able to run at the faster rates.

In the meantime, I'm going to keep playing about with the process and see if I can start to get a handle on what's going on

[YHB]

[quote="Capt-Cudellez"]

If I changed the still design to allow a portion of the reflux to be returned to the boiler externally to the column (perhaps a LM slanted plate above the VM take off), it may reduce the flooding meaning being able to run at the faster rates.

Capt'n

Can't get my head around that one - running at a faster rate - producing more distillate - dumping excess back into boiler and reducing amount of reflux.

Why is the net result ie reduced reflux, different from running at a lower rate to produce less reflux?

Must be missing something .

[Capt-Cudellez]

I'm thinking the flooding is caused by the vapour holding up the large amount of reflux travelling back down through the packing.

I think by taking off say half the reflux via a LM take off and returning it externally there is less liquid to get held up in the packing so no flooding.

Ideally I wouldn't want to return it to the boiler as it would just get watered down again, so if I had an inline thumper or deep bubble plate to return it to it would be more efficient.

No idea if it will work - that one is actually keeping me awake some nights - I need to get a life.
If it didn't work the LM\Vm combo could still be used in a more standard way to remove heads via LM, then the hearts via the VM for a sharper cut, as your not washing heads out the condenser with good product - so it is probably worth a punt.

[ant]

Hi Brian

The lathe is a lovely little Drummond but the countershaft that came with it was pants. Real bodge job. No rigidity, no bearings, lots of bounce, vibration, friction and heat. Seller was honest it needed changing so no complaints. Building a new one from a small piece of steel I beam and the roller bearing mounted shaft from a tumble drier motor. The motor plate and the pulley block are both usable. Just all needs moving around.

This has taken a place on the back burner as my van died. Diff bearing has shattered and VW don't supply the oddball size any more. Need someone with a better skill set then me to tweak it to take a standard taper bearing. Or a new rear axle. Or a new (old) van.

Tracking down the right parts, four possible diffs, then finding out they were obsolete has taken up too much time.

Anyway back to the point. No I have only had a half hearted play using a battery drill and three quickly ground mandrels to see what happened simply feeding the wire in by hand. Not very good. To get a 4mm dia coil I eventually moved down to a 2.5mm mandrel. Started with a 4mm. Tried square and two triangles. Washer backing the tip of each one. Triangles looked better when coiled. Coil ran over itself without pushing off the mandrel. Three times. Blah. Needs a proper set up with constant but adjustable tension I think.

Capt'n

Yes I've been reading about the flooding problem. People seem to be able to get good results despite it. Reduced power is supposed to be an advantage of the SPP less fuel cost per product. Speculation is that the flooding area may even be doing useful work. You use 4mm SPP in a 2" column don't you? Do you think increasing the dia of the top section of column would help reduce the flooding effect? larger spp in that section and a slowing down of vapour speed might help. As Brian knows expediency was making me consider a 4" column as a first attempt. I have the stainless and a ready wound reflux coil for it. I have since got hold of some 2" SS tube so am scaling down my ambition. Toyed with the idea of a 4" final stage though, Just so I can use the nice coil I have. Contemplating a moving coil VM with no valve at all. There is knitpicking over whether it is VM or CM but it is splitting hairs really. You do manage the cooling of the column but you don't manage the cooling of the coil. You just move the coil to manage the vapour. So it's both in a sense. No valve, no pooling, no or reduced contamination from heads.

Did you try the spp with and without the BB and what conclusion did you draw from the difference?

[Capt-Cudellez]

Those condenser control stills are pretty cool, and a good option if stilling with reduced head room.

Yes I ran with and without the BB - only difference was the power it took to flood it, 1600w without and around 2200w with. Was still able to pull 95.6% from wash. I can't comment on larger diameter columns, only ever ran a 2", I believe you need reflux centring devices to stop channelling and the shear weight of the packing might also be an issue, I now probably wont use the full column on my small boiler now its so heavy.

[ant]

I live in an industrial environment surrounded by my bits and bobs so a support structure is not out of the question. Now you have some experience what hight would you make a 2" column that was using SPP? Small boiler? Don't you use a beer keg? Must be 50kg with wash?

[Capt-Cudellez]

I have a keg and a T500 boiler - the keg is rock solid no issues there. The lid on the T500 wasn't meant to support any real weight and there is a bit of flex in it, it wasn't brilliantly stable before I added heavy packing.
I used to use the column on the T500 for the spirit run as at the time I had a phase angle controller that could handle the 2kw, but not the 3kw of the keg, also it takes 11 litres just to cover the element in the keg, so I like to fill it with a large charge - doing 20lts of 40% in the T500 is fine, I'd want to add a bit of water if running that in the keg in case of exposing the element.



The T500 boiler has had a new dress since I took that photo


As for what height would I make it, I haven't done any testing as to how little packing it would take to reach azeotrope (95.6%) so I cant really even hazard a guess.

[ant]

Constant pressure control seems to be a key element in running Spp well according to the Polish and Russians. This seems to be their way to address the flooding issue. So what is the shortest you have run the column so far with the Spp?

[Almanac]

The underlying basis of the type of stills most of us run is that pressure, of any kind, is avoided by having open vented systems where the buildup of pressure is specifically prevented.

Any type of system requiring any level of pressure buildup, for any purpose, is patently dangerous.

Let's not forget this http://www.mirror.co.uk/news/top-stories/2011/07/14/five-killed-after-explosion-at-suspected-illegal-vodka-factory-in-lincolnshire-115875-23269424/

AM

[YHB]

Aidan,

Your warnings are well taken, however a little inaccurate in this instance. To say that there is no pressure build-up in a column is incorrect, there is a pressure build up, but very very small and this is what Ant is refering to.

Imagine a constant flow of vapour rising through the column, then condensate is introduced into the column which takes up some of the volume previously occupied by the vapour. You then have a the same amount of vapour restricted to a smaller volume hence the "increase in pressure" the more liquid(reflux) the more pressure.

It is this pressure along with vapour speed and a few other physical phenomenons that my pigeon sized brain fails to grasp, that hold up the liquid and eventually cause flooding.

Holding up the liquid to increase exchange is desirable, holding up too much liquid is not.

The home distillation enthusiasts are trying to emulate distillation columns that have been used in industrial applications for a long time. Even with the vast resources available to professional applications they are still researching flooding and how to control it. Part of the research revolves around pressure control.

Try "Googling" - "controlling flooding in distillation columns" and have a look at the research being done in other industrial applications, I got lost after the first paper and gave up.