Author Topic: Increase distillation rate  (Read 816 times)

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alchemy_bee

  • Guest
Increase distillation rate
« on: January 08, 2002, 03:31:00 PM »
What would be the best way to increase the rate of distillation of oils? SWIM has a nice bench vac pump, stirr/hot plate, and a large condenser. Just trying to reason out the mechanism of distillation, check my rationalization:

Oil vapors rising from the surface of the oil creates vapor pressure within the closed system, the condensing of the vapors inside the condenser draws more vapor into the condenser and so on.

SWIM is thinking that the best way to make distillation go faster would be to 1) increase the rate of vaporization further (from already stirring it) by increasing the surface area of the oil being distilled, maybe by using a wider flask, and also 2) to increase the rate of condensation.

Now would swim increase the rate of condensation by using more then one condenser, maybe coming out of a multi necked flask?

SWIM has this crazy idea of using a 5-neck flat bottom flask with a big addition funnel in the middle neck so the oil can be slowly dripped into keep the volume of the oil being heated lower (to promote better boiling), and having condensers coming out of each of the other 4 necks! Would a beast of that nature be an efficient way to distill oils faster?

noj

  • Guest
Re: Increase distillation rate
« Reply #1 on: January 08, 2002, 03:51:00 PM »
Slower distillation would mean purer distillate. If you are set on increasing the rate, try decreasing the amount of space between the surface layer of the oil and the downward slope of the condenser. This would decrease amount of vapor that refluxes back to solution before it reaches the condenser.

Another way is to properly insulate the glass up to the condenser.



No One's Jurisdiction

Rhodium

  • Guest
Re: Increase distillation rate
« Reply #2 on: January 08, 2002, 03:56:00 PM »
Never distill through multiple condensers at one time, or you will get next to no fraction separation. One way of increasing the distillation speed somewhat (such as in solvent evaporation) is to use a boiling flask with a very wide neck (such as NS45 or similar) and a good heating mantle.

If you are distilling a product or intermediate, never let the distillation speed go faster than 1-2 drops a second, or you won't achieve any acceptable purity.

blaztoff

  • Guest
Re: Increase distillation rate
« Reply #3 on: January 10, 2002, 10:33:00 PM »
You could use an inert carrier gass like argon but dont just set a tank of argon up and buble in. It requires some special fittings and such. But for Fractional dist with close evap points just take it slow. Slower the better.

___

  • Guest
Re: Increase distillation rate
« Reply #4 on: January 11, 2002, 06:11:00 AM »
the only time you want increase the distillation rate is when you KNOW you are on the highest boiling fraction.

Osmium

  • Guest
Re: Increase distillation rate
« Reply #5 on: January 11, 2002, 03:59:00 PM »
Within limits, yes.

LaBTop

  • Guest
Re: Increase distillation rate
« Reply #6 on: January 14, 2002, 01:56:00 AM »
The love of my life:

""The PILOT 15 is designed for throughputs between 10 and 80 lb/hr (4.5 to 35 kg/hr), depending on feed material characteristics.""
Keep that at the low end of that scale for ketones and freebases, still much MORE, much BETTER than ANY other system which occupies that SMALL space, and delivers those ultrahigh purities.

"" *Note: Because Myers Spinning Disk Technology replaces the material on evaporator heated surface at rates of 8 to 10 times faster than Wiped Film and similar technics, significantly less surface area is required. "" 
This one has only an 15 inch diam. rotor.
F.e. to reach these kinds of kg/hr's, you would need a 2.36 square foot normal molecular still system.


So ONLY for the pro's :

http://www.myers-vacuum.com/pilot15frameset.html

  READ all info on the page, and start to wonder why YOU didn't got such a system for your last birthday!

Start asking this one to get used to it for your next millionaire birthday, or when cashing in that unexpected LastWillfromUncleBill :

http://www.myers-vacuum.com/lab3frameset.html


""The LAB-3 has a 3-inch rotor with a throughput capability of about 0 - 2 lb/hr (0 to 1 kg/hr).
Like the other still models, the LAB-3 with the pumping system will operate around 1 X 10-3 Torr pressure.""

Don't forget, these fuckers are designed as a batch/continuous distillation unit!
 
I dare anyone to find this kind of throughput/purity per m2 space-occupied, by any other means.
I will be highly interested to learn if there is perhaps a (much?) cheaper one than the 15". LT/

PS: all the others, keep it at aiming at that nice, affordable 5 liter digitalized Rotavap from Heidolph or Buchi.
You have NO idea what these centrifugal molecular stills C O S T.

WISDOMwillWIN

Osmium

  • Guest
Re: Increase distillation rate
« Reply #7 on: January 14, 2002, 02:07:00 AM »
That thing is a rotovap substitute, and can also be used to separate a volatile compound from tars, but it won't work to fractionally distill essential oils.

LaBTop

  • Guest
Re: Increase distillation rate
« Reply #8 on: January 14, 2002, 04:13:00 AM »
Os, I got such a dark feeling that the poster on top has a few buckets with raw freebase standing around at certain intervals, and wants to know how to step up from his maximum achievable 2 drops per second in a certain collectorflask to a nice streaming freebasevideo.

As you said already, the question and all its (right) multiple answers, depend on the situation and mindset of the underground cook.


Any one having any thoughts about a special Underground Highvacuum StSteel cooking device, simple, but effective specifically for BIG amounts of VISCOUS oils and/or viscous intermediate products which take normally forever and ever to collect ??? Let's say between 20 and 72 liter capacity ?



I muse sometimes about those big old copper retorts, in the form of a tumbled 6, now with a double jacketed top surface on that folded-pear construction, thus creating a big downward running cooling surface (you pump coolant through that "plafond") where all your viscous products will condensate on and run together into the connector for the collection flask. Attach a vacuum alonge to the arm of the 6, and a heating oil jacket round the bottom part of the retort, would that piece of "nouveau art" distill more liters/hr viscous stuff than the more conservative designs?

What you want is short vapour path : big evapsurface very near to big cooling surface which is leading cool condensate to collector flask.

Let's say a cooled parasol over a hot plate. Now when you could spin that cool parasol without a coolant leakage, while boiling the plate fluid, would that speed up liters/hour??

, ahh, just remembered, but too long to explain, it's a poorman's rotavap, ehh, an RBVap.

BUT, let me hear what some of you come up with when you are tipsy or drunk. LT/

WISDOMwillWIN

Osmium

  • Guest
Re: Increase distillation rate
« Reply #9 on: January 14, 2002, 06:19:00 AM »
When you want to fractionally distill then you need a column. There's no way around it. This means a LONG distillation path. With a short one you simply evaporate everything that's volatile but achieve no separation efficiency.

If someone wants to fractionally distill 70 liters of something then that person better gets used to the thought that this might take some time. The only way to speed it up without losing separation efficiency is increasing the column diameter. Or just stick to regular glassware and use TWO stills made from regular commercial glass. There is no quick and dirty way to distill this amount in an hour or two, so let the distillations run 24/7. No big deal. At a rate of 1kg/hr it will take 3 days to distill 70 liters. What's wrong with that? Use two stills to double your throughput if necessary. In the case of sassy you will produce about 50kg of safrole per day, and the distillation requires close to zero user supervision during 80% of the time. Then you will need another still for ketone distillation, and another one for final honey. At that scale automated process controlling would be a good idea anyway, and if people can't pay the 20k per still then they shouldn't think about working at this scale. The three or four stills can run all day long without supervision.

halfapint

  • Guest
Re: Increase distillation rate
« Reply #10 on: January 14, 2002, 05:23:00 PM »
The spinning-disc technology LaBTop referred to in

Post 256183

(LaBTop: "Re: Increase distillation rate", Chemistry Discourse)
is generically known as a molecular still. It does provide greater plate separation than an extended column, in linear dimension. If spinning discs were stacked up, on the same spindle, the form factor could bee better than with a lot of long tubing.

turning science fact into <<science fiction>>

terbium

  • Guest
Re: Increase distillation rate
« Reply #11 on: January 14, 2002, 07:13:00 PM »
The only way to speed it up without losing separation efficiency is increasing the column diameter.
Or, if performing a vacuum distillation, and other factors allow, distill at a higher pressure?

terbium

  • Guest
Re: Increase distillation rate
« Reply #12 on: January 14, 2002, 07:25:00 PM »
The spinning-disc technology ... is generically known as a molecular still. It does provide greater plate separation than an extended column, in linear dimension. If spinning discs were stacked up, on the same spindle, the form factor could bee better than with a lot of long tubing.
I think that I have to disagree here. This spinning disk here is nothing like the spinning band in a spinning band still. The disk here is the heat source/evaporator, anything that is not immediately evaporated is spun off the disk into the bottoms receiver, multiple disks would have no function in this design. There is not even a one-plate liquid vapor equilibrium established. This device, as Os mentioned, is a rotavap for very low vapour pressure materials.

Vibrating_Lights

  • Guest
Re: Increase distillation rate
« Reply #13 on: January 14, 2002, 10:31:00 PM »
If you heat the liquid your boiling flask up to 5 degrees or so over what you expect your liquid to boil at under your vacume then quickly flash vacume on and off the distillation rate is incresed but requires constant attention works great for stripping solvents and such just make sure that the next highest boiling fraction is not going to come over with your small increse in tempature.
VL_