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In this Discussion
- Fiji_Spirits January 2017
- GD50 December 2016
- grim January 2017
- jacksonbrown January 2017
- punkin December 2016
- Smaug December 2016
- TheMechWarrior October 2016
- Unsensibel October 2016
Comments
I'm looking at it from a different perspective. The feed flow rate being determined by the vapor knockdown requirements in the dephlegmator and product condenser, and that these need to be closely balanced/matched for optimal distillation and energy efficiency.
The mismatch scenario being that if the flow rates required by the condensers is higher than the column can efficiently process (undersized condensers), the bottoms product abv will be higher than expected - wasteful strip. And on the oversize side, with flow rates lower than the column can handle, it means lower abv on the strippate and longer run times (less energy efficiency).
Oversize is probably easier to correct, as long as you can add more plates and increase the feed rate. Undersize means replacing condensers with larger units, or adding supplemental water cooling (which means lower efficiency).
I am making the assumption that there is operating in a standard beer stripper fashion, with a set of stripping plates below the feed, and a set of rectification plates above, at a ratio of about 1/3 rectification to stripping.
I think this can be effective with about 10-13 plates, 3 above the feed, 7-10 below the feed.
Unless we're talking solids input, then disc/donut plates below the feed, bubble caps above. Probably need significantly more plates in this scenario, since the feed rate needs to be sufficient to keep the plates self-cleaning.
What I'm calling ideal is to have 100% of the energy transfer associated with PC/RC condensing to be captured in the wash preheat, such that the wash preheat is entering the column near BP and not upsetting equilibrium, at the ideal feed rate for the column.
I believe the Carl beer stripper is a total of about 20 plates - 5 above the feed, 15 below - and will produce an output of 80%.
But the vapor knockdown requirements are also governed by the feed rate. It's just a ratio which is dependent on how much water you can pull out and the efficiency. I personally don't like the disc/doughnut idea but being able to add more plates to fix issues is the way to go. It will increases the feed rate window too.
Too small is definitely an issue for a condenser but you can easily measure the exact heat removed using T1, T2 and the flow rate. So you could tune it by controlling a preheat element that varies T1.
I don't think that is an issue though.
An LM type split of condensate with a single condenser would be a better approach. This is what petro chem plants use i believe.
Have the analiser column as I stated above and treat it as a contained unit. This then becomes the 'boiler' for an LM type column directly on top for rectification. Take off purity is controlled by the liquid split.
The single condenser on top is the first preheat stage for the feed which then goes on to the bottoms heat exchanger, then injection.
For it to balance quickly (and acualy work) it's critical that you can feed it a controlled, rock solid feed rate.
Either a VSD with a pressure transmitter at the injection point (or a flow transmitter) or a PD pump.
I'm thinking I'd not even try to balance input flow with reflux. Might be most flexible to deal with required reflux the supplement pre heating somehow.
As for plates and rectification 10-13 plates is way more than I had planned or even thought. It'd be nice to get the strip to 70% at least.
Why can't I get this with like 6-7 plates?
What about a packed column? How tall would I need?
What are you feeding it for a start?
Sugar wash at 82f. 8-10%
You might be able to get packing to work as that stuff won't foam as bad. What's the HETP? 50 to 100mm? So 1.5m would work for the analyzer and to get 70%ABV maybe another 0.5m above the injection point? Target feed rate would govern the diameter I guess.
I think the required reflux rate would have more to do with the output ABV rather than the flowrate of the feed. Like I said, treat everything above the injection point as a separate system.
If the RR is out of whack i.e to maintain the correct takeoff ABV, the rec column is flooding 'cause it can't shed enough product, I'd just add in more packing/plates.
You would need a sufficient amount of plates below the beer feed to insure that you are not loosing alcohol to bottoms. Plates above the beer feed would dictate the type of collection strength you'd be looking to achieve.
StillDragon North America - Your StillDragon® Distributor for North America
In terms of simplistic build - I thought this would be elegant, if it works. :)
I would imagine more stages are necessary.
The reflux condensers could be preheaters.
But this is not designed for maximum efficiency.
Another StillDragon Continuous Design
And this was the best doc I've ever come across.
ALCOHOL DISTILLATION: BASIC PRINCIPLES, EQUIPMENT, PERFORMANCE RELATIONSHIPS, AND SAFETY
Check out tables 1-5 near the bottom.
Grim. I'm not sure I totally understand your design. It takes product off all three columns? Are liquid levels between the columns managed by gravity only? Are there any plates or packing anywhere?
Jackson and Smaug. Ideally I'd like to strip 500l of wash in about 8 hours. Not sure if that's realistic for a 4" that I wanna play with tho. Might take more time or lower proof. Might be easier to add a shift somewhere in the week to get closer to output goals.
This design here. Seems to lend itself to modularity.
I quite like the reliability aspect of heating the beer directly rather than dealing with balancing it with reflux alone.
I kinda liked the idea of steam injection heating the falling beer but was thinking maybe I could provide that with a small boiler at the bottom that catches the bottoms and sends up heat. Would start with a water charge to heat column then start beer flow.
I guess that's really similar to grims design but I think it has some flaws.
So that's 1litre a minute (17.4ml/sec)
At a guess that's about the same liquid as a 20kW still on full reflux.
I don't think you'll get that much power through a 4" column.
My "design" is basically 3 cascading batch stills. The take-off is only off the first column, the other columns will run in 100% reflux, with all the reflux being fed to the preceding column. They are all connected to the PC for safety reasons. The temp gradient would rise as you get towards the bottom drain.
It's really crude, my primary thought was how quick and dirty could you be to make a functional stripper? Subsequently, I thought it would be interesting to add a single plate to the top of each column for the reflux to drain into.
Really though, get an 8" mild steel pipe, fill it with packing, drill a hole for the feed, inject steam at the bottom. Probably a whole lot more quick and dirty.
I had been looking at it as an output per hour problem. Basically that'd be about 6-8 l per hour output. I agree that's really pushing a 4". Trying keep capex reasonable during experimental stage.
Your pic shows feed on left and bottoms on right. Shouldn't that be reversed then?
That setup could prove to be blazing fast and still use 4" TC pipes for my application.
I'm still not totally clear on liquid levels in each chamber. Is it only moved by reflux?
Also Seems like a high possibility of exposing the elements to flammable reflux...