Steam Distillery Construction Questions

[Bond_DoubleBond]

Swim is planning construction of a steam distillation setup and thinks he has found a good container for the boiling water/plant mass section of the still.  The container has a threaded top to easily attach tubing, a pressure blow-off valve, a long thin side window, and a spigot at the bottom. 

The only problem is, the container has no large holes or openings to load/unload biomass.  Swim has no apprehensions about cutting the top off of this sucker, but is a little unsure about how to go about modifying it so that it can again be sealed, reopened, resealed, etc. 

This will only be used for steam distillations, and so the only performance requirement of the sealing is that it be waterproof and resistant to essential oils at 100c (not just certain special alkenes; swim plans to use this for a variety of oils).

The diameter of the container is about about 1 ft and swim imagines that the thickness of the steel is ~1/8".

Swim was thinking he could cut two ring-like discs from sheet steel with an inner diameter equal to that of the container, and an outer diameter about an inch or so more.  These would then be welded to the recently cut ends of the two container pieces.  From there, rubber or plastic or something would be set between the discs, creating a seal.  The two container pieces could then easilly be held together with clamps or bolts and wingnuts on the protruding outer parts of the discs.

Swim was thinking he could get some 1/8" or 1/4" plastic sheeting and cutting it to the same shape as the steel discs.  Swim thinks this should provide a sufficient seal if enough clamping pressure is used.

Swim's first question is, is there an easier way to do this?  Second, does anyone have any suggestions as to what material would be best to put between these two discs to seal them?  Any advice on what kind of plastic/rubber to use would be appreciated.

Any other comments or suggestions are welcome.

[Nicodem]

Swim's first question is, is there an easier way to do this?

I don't exactly understand your problem. What is wrong with the common houshold "pressure pot" or whatever it is called in english?

[Bond_DoubleBond]

The container swim found is of considerable more volume than your average pressure cooker.

[edit]
when swim said "is there an easier way to do this," he didn't mean "an easier way to extract oils."  he meant, is there an easier way to go about resealing the two pieces of the cut container in such a way that it could easily and efficiently be charged and discharged of plant matter.

[ApprenticeCook]

if your sealing it for a vacuum its alot harder....

for atmospheric pressure you could simply cut out a hole and use the cut out section with a rubber gromet and shim around the cut-out section, you can buy them at plumbing shops.

For vacuum... ie sassy disto shit it will be harder but not impossible, but you wont be able to have a big hole, prob max ~2" dia for vac use, as big as you want if its for atmospheric pressure use.

Is that what you wanted to know?

[Osmium]

http://www.zimmerlin.de/English/Produkte/Mannloch/manway-cover.pdf

[Nicodem]

Even though you are already determined to use your setup, you might consider using the usual distillation set for brandy production which is especially suitable to work with large quantities of plant material. There is no reason why it would not work for steam distillation. These things can be bought in sizes of 30 or more liters and the bigger ones are even equipped with a stirrer. Furthermore, you can also produce some strong alcoholic beverages with it. A perfect cover up for your activities.

[calcium]

Your tank has a glass window?

If so, it must have screwed or bolted flanges sealing it in place with a gasket. If it's big enough, just use the window/ sight glass as a way in.

When finished distilling, put a water hose into the threaded opening and flush everything out the same way it came in.

Otherwise cutting off the top and welding on a flange that can be bolted is a good idea... if you have access to the equipment!

A neoprene gasket will take the heat. Any industrial supply company will have it. You could also buy a pair of flanges ready to weld on.

Are the top and bottom domed or flat?

[Bond_DoubleBond]

the top is domed slightly with a threaded protruding pipe and the bottom is also domed slightly although there are two swivelling wheels and two stationary wheels connected to the bottom.  The window is long and thin and runs from the near top of the container all the way to the bottom (very usefull).

swim was thinking of producing heat by means of coiled copper wire in the bottom of the container and connecting a variac, outside of the container of course.  does anyone have any suggestions as to what a good power dissipation range would be to boil ~8 liters of water over a couple of hours?

will neoprene be resistant to all the things one might find in essentail oils at 100c?  alkenes, aldehydes, esters, etc.

[biotechdude]

What are you planning on distilling?

Standard essential oils can be extracted in your setup however some plants require basic conditions and the use of external steam for example.  That wont fly in your setup.

If u are just doing standard distillations of plant matter on a permeable stage above the boiling water below, than your equipment should stand up.

Also beware that internal heating wires can burn your plant matter.  Not a problem if you suspend the plant above the water though.

Kinda hard to give better advice with the givien info...

[ApprenticeCook]

biotechdude: "Also beware that internal heating wires can burn your plant matter."
from bdb: "outside of the container of course."

neoprene is pretty reistant so it should be ok, otherwise find a sheet of teflon (found same place as your neoprene gasket) and make a gasket from that. Expensive but it would work if for some reason neoprene failed.

Power useage will be huge.... how insulated is the container? for 8L and coil big enough to boil contents to 100^oC will use alot of power and take a long time.... what are you doing? what do you want to boil off e/o at 100^oC?? explain and we can help easier.

[Bond_DoubleBond]

the apparatus will be for steam distillation of essential oils.  hence the thread name.

as for heating, swim is gonna try to use two 12v 300w water heater elements.  should be sufficient.

swim's new toy is just a few parts and arc welds away  

[Osmium]

> swim is gonna try to use two 12v 300w water heater elements.



> should be sufficient.

I don't think so.

[Nicodem]

For each 10L of volume you should have at least 1kW of heating. That is a minimum assuming you have some insulation on the rest of the "pot". To get it distilling at a good rate you should have at least 2 or 3kW/10L with the possibility of regulation. The best would be a gas flame heater like the portable big ones used for cooking in big pots.

[ApprenticeCook]

two 12v 300w water heater elements

So your using this big contraption with 600W right.....

As osmium said, dont think so.... nicodem is right you need a shitload more power, so high that using a gas burner would bee more efficient.

Are you going to insulate the rest of the container?

And my question still remains, i know you are distilling e/o but what the hell are you distilling from it at 100^oC??? ie what e/o starter and what fraction you want to remove from it? at atmospheric pressure 100^oC wont get you much.

[calcium]

If you are boiling 8 liters of water, it sounds like a vessel that is too small to bother with.

Get a beer keg, and alter it to have a bolt-on top that is fitted to a condenser. Buy a 'fish cooker', which is a big propane stove burner that is used to heat a 10 gallon stock pot or a beer keg. Home brewers use them.

If you go to the trouble of building this thing you should go bigger.

Keep in mind the rate of return you'll get.

[Bond_DoubleBond]

thanks for the advice, osmium and nicodem.

these elements are advertised to be able to replace the 1.5-2.0kW elements in standard 40 gallon water heaters.  but, they are a little expensive.

swim will try instead two 2kW elements (cheaper) and play around with their output.