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garage chemist
chemical wizard
Posts: 1803
Registered: 16-8-2004
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A tube heater for the laboratory is probably best made by oneself. New tube furnaces are generally very expensive.
I am in the process of doing this, expect a documentation when I'm done.
Basically, you wind heating wire around a ceramic tube, coat it with insulation paste (a simple MgO+Al2O3 mix), surround the thing with thermal
insulation, and put it in a housing. Add an electronic thermometer with its thermocouple inside the tube and a thyristor circuit for regulating the
heating power.
Use a quartz (or even stainless steel, for ketene) tube inside the ceramic tube as the working tube in which the cracking of acetone will occur.
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Sauron
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The VA method, is not a high priority for me. At the present I am preoccupied with trying to get my large fume hood installed (main obstacle is $$$)
and also getting my Parr autoclave shipped from California.
Sic gorgeamus a los subjectatus nunc.
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Fashist
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| Quote: | Originally posted by Sauron
The VA method, is not a high priority for me. At the present I am preoccupied with trying to get my large fume hood installed (main obstacle is $$$)
and also getting my Parr autoclave shipped from California. |
I Hope you success in hood setup.
I have not important news:probably i will come to thai(pataya)3 mounth later. 
Mr sauron Do you work with your tube heater and new ketene method?
God keep you.
| Quote: | Originally posted by garage chemist
A tube heater for the laboratory is probably best made by oneself. New tube furnaces are generally very expensive.
I am in the process of doing this, expect a documentation when I'm done.
Basically, you wind heating wire around a ceramic tube, coat it with insulation paste (a simple MgO+Al2O3 mix), surround the thing with thermal
insulation, and put it in a housing. Add an electronic thermometer with its thermocouple inside the tube and a thyristor circuit for regulating the
heating power.
Use a quartz (or even stainless steel, for ketene) tube inside the ceramic tube as the working tube in which the cracking of acetone will occur.
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you are very Clever and you have Perseverance
bravo
sure your system will work well. but i think better i buy one tube heater(i write the company link before)
I think the result will be better if we use of copper tube.what is your idea?
i am Amorous Mr NERV Ketene system.
Do you test your anhydrid with water?
what is purity?are you Acquiescent?
i think i should start celloluse acetate business in small Quantity.
thank you
[Edited on 28-11-2007 by Fashist]
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MagicJigPipe
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I happen to be very amorous for him as well!
God keep you!
*laughing uncontrollably*
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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Fashist
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I dont Know why Nobody answer my questions?
I think I am Buffoon for most of user like Mr MagicJigPipe and Other
Why?really why?
I think i can explain my problem here.not for laughing.
This is Great Request?
Thx
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MagicJigPipe
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I'm sorry, it's just that amorous, in English, usually implies strong feelings of love (sometimes even a sexual connotation) and that is why I was
laughing.
I have nothing against you nor am I making light of your situation. I understand English is a difficult language to learn.
So, please accept my apologies if I offended you. Just don't use the word amorous again unless you're talking about your wife or girlfriend!
** second edit**
Sauron, could you please unblock me on U2U? I need to ask you a question.
[Edited on 28-11-2007 by MagicJigPipe]
[Edited on 28-11-2007 by MagicJigPipe]
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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Sauron
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Fashist (Hector), I have not done anything with my tube furnace but, I really do not want to work with ketene. It is a carcinogen. Cancer may get me
one of these years but I do not wish to hasten the process just to make a little Ac2O.
There are much safer ways to do so.
Sic gorgeamus a los subjectatus nunc.
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Fashist
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Excuse me.
Always I translate My word by Online Dictionary(and has some Technical Problem)
Mr sauron one questin? may copper tube make better than quartz tube(ketene)?
If we use of copper tube the temp should be 700c?
thx
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Sauron
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I think I gave you a file with everything I have on kete already, fashist. I believe what you asked is answered in there. There's nothing else to add.
Sic gorgeamus a los subjectatus nunc.
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Fashist
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Yes it is True.
Excuse Me.
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JohnWW
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Ebook - Ketenes: http://rapidshare.com/files/35523052/ket.rar 6 Mb
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not_important
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Copper tubing works well for making ketene from acetone, copper does not catalyse the decomposition of ketene.
I posted a PDF that is a chem. eng. project to make acetic anhydride from acetone and acetic acid. It discusses some of the concerns in making an
efficient convertion, the best way to absorbe the ketene, and other things you need to deal with when doing this in a large scale lab or pilot plant
setting.
Contact time, temperature, and temperature distribution are all important to a successful process. The low the conversion in a pass the higher the
overall yield, with recycling of unreacted acetone. Quick quenching of the gases is also important, that study above discusses this.
Also see :
Ketene Production and Utilization Experimental Study
Morey, Ind. Eng. Chem., 31, No. 9: September 1939 1129-1132
DOI: 10.1021/ie50357a016
including information on the reaction tube they used.
JIC here's that project, seeing as it's a small file.
[Edited on 30-11-2007 by not_important]
Attachment: Project00.1.pdf (73kB)
This file has been downloaded 1271 times
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Fashist
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Mr not important thanks
I have one request and Two question. 
(?)If we use of copper tube again we will have DUST of carbon(in the tube)?
(?)What temp require if we use of copper tube (700 or more?)
(!)I want to buy one tube heater(from lenton company) but it is very expensive(3000$)do you know cheaper source?
Thanks
[Edited on 30-11-2007 by Fashist]
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not_important
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In the Ind Eng Chem article they used temperatures in the range of 580-650 C or so. While 700 C is often used, you need good regulation and heat
distribution to avoid overheating the gases.
HOWEVER - there is no turnkey solution, you can't read some papers and expect something like a DIY kit. Experimentation will be needed to optimise
your plant, and maybe even to get it to given a useful output at first. Things like formation of carbon are going to depend on a number of factors,
if I was good predicting what will happen in your case I'd retired off of the stock market and betting winnings long ago.
I'm not into buying pilot plant scale equipment right now, I expect that making your own might be the cheapest given your circumstances.\
While this is the acetic acid to acetic anhydride route, which while it goer through ketene is a bit different, this recent study for an industrial
plant may prove useful:
http://www.lassc.ulg.ac.be/bibli/heyen-2003-1.pdf
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Fleaker
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Having actually done this before (you saw the pictures which NERV and I took), I can say copper would be suitable. A 40cm or so long by 2.5cm inner
diameter stainless tube packed with copper wool (to increase contact time) was what we used and we operated at 700*C. Yield was ~33% or something
around there. There was zero carbon dust formation whatsoever, it was very clean.
If you have a big 20L flask and are boiling a lot of acetone, this method would work well, it would make a lot of Ac2O. It is still necessary to
fraction your Ac2O from your acetic acid. Also, you might remember the round bottom flask on the output (ketene) end of the tube? It would be really
smart to have it setup so any acetone that condenses in the condensers and collects in the flask would be rerouted into the boiling flask on the input
side.
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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Bromide
Harmless
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| Quote: | Originally posted by Sauron
Fashist (Hector), I have not done anything with my tube furnace but, I really do not want to work with ketene. It is a carcinogen. Cancer may get me
one of these years but I do not wish to hasten the process just to make a little Ac2O.
There are much safer ways to do so. |
Sauron, what leads you to assert that ketene is a carcinogen? I ask because you've raised this concern in a couple of previous posts, but my casual
perusal of Google, etc., have all lead to documents claiming that ketene is in fact not suspected to be a
carcinogen (although it is known to be toxic, of course--see here, for example).
My question is not meant to be impertinent or a challenge; I'm simply interested to learn what additional insight you have into ketene's
carcinogenicity.
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not_important
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When I made my ketene generator I got some carbon at first, this appeared to be from too slow of a flow through the tube. Higher flow rates had no
carbon formation when run for several days at a time.
The highest yields come with fairly low conversion of acetone, the overall yield is based on recycling the acetone. The conditions that give lower
per-pass conversion also suppress side reactions.
And here, thanks to solo, is the research paper, for those without reference section access. While their target is butyl acetate and not acetic
anhydride, the ketene production is the same.
Note that they used two absorption towers, plus a bubbler filled with aniline in benzene. The project on anhydride production recommends holding the
acetic acid/ketene reaction towers at 80 C.
Attachment: Ketene Production and Utilization Experimental Study.pdf (518kB)
This file has been downloaded 1182 times
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Fashist
Hazard to Self
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Thanks Mr Not_Important
Very useful Article.
In this Article there is unintelligible Image of Keten System.
May you simplify it for Anhydrid?
Again thanks.Bravo
I am building My ketene System But i Need to your Advise.
According Mr Nerv and Mr garage chemist System
-My ballon is 10lit and made of aluminium(for boiling acetone)
-My tube made of three part.two linker with 1cm diameter and one part with 3.5cm diameter.all af them made of copper.
Tube heater Provide 700c(it element made of ni/cr)
- acetone collector(3 way ballon) made of aluminium 5lit
- condenser made of copper 1meter
-cylinder glass container 4lit
What is your idea?
Every thing is ok?
Thanks
[Edited on 2-12-2007 by Fashist]
Attachment: Untitled-1.zip (407kB)
This file has been downloaded 652 times
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not_important
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No. It can't be made simpler, unless your goal is to make 50 ml of anhydride. For large scale production the apparatus will be more complex, at least
if you want any sort of decent yield.
You need to read the apparatus section in the PDF, between that and the drawing I found it very clear. You also need to reread Project00.1.pdf as
well.
Your tube in the furnace is too large in diameter. Both of those documents make it clear that quick and complete heating must be do, which a simple
large diameter tube will not do. Both documents also make it clear that the gases exiting the furnace must be quickly cooled. the newer document does
this using a water spray on the outside of the tube while the anhydride plant does this using a spray of acetic acid, acetic anhydride, and acetone.
Ketene does not react extremely quickly with neutral and mildly acidic compounds, thorough contact must be had for sufficient time. A single simple
absorber will likely have much unreacted ketene escaping it, resulting in both low yields and the problem of lots of free ketene drifting about.
Expect only 10 to 20 percent of the acetone fed through the furnace to be converted to ketene, so your condensing receiver must be nearly as large as
the boiler.
You'll also need to worry about oxidation of the outside of the copper tubing in the furnace; the more recent reference solved this by driving the
copper tube through a stainless steel pipe forming a jacket for the copper.
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Fashist
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Valuable advise.thanks
My tube in the furnace is too large because my pressure increased(my acetone boiler is 10lit then more acetone will come.)what size is suitable for
this system?
in the picture my cooler system is near to my condenser.isnt it?
Very good advise for cover of copper but difficult to do.
Mr not important please advise me more for this system
i am sending your patent for expert translate(this translate is very expensive 10$ per page)
[Edited on 2-12-2007 by Fashist]
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not_important
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You only have to cover the copper tube that is in the furnace. The items needed to do so were a steel pipe, some hydrochloric acid, and a hammer.
Your proposed system with a 10 liter boiler is five times as large as the example large scale lab production unit in "Ketene Production and
Utilization..." This should tell you some time - if you wish to make a proof-of-concept apparatus, don't make it so large and you can make it a bit
simpler, if you want large scale production then it will be more complicated.
As an example, a simple proof of concept setup would not attempt a high volume of acetone boil-off. It could have a large boiler as a convenience to
allow it to run for many hours without stopping to refill, just use a fairly low boil rate. But if you want to make a lot of anhydride per hour you
will need multiple tubes with manifolds at each end of the oven to distribute and collect the gases.
Very quick cooling of the exit gases to 200 C or lower is needed to keep yields up. In "Ketene Production..." this was done by spraying water on the
exit side of the copper tube, note that they still had the acetone condenser a bit further on. In the "Project00" example this was to be done by very
quickly quenching the hot gases in the absorption tower with cool liquid containing acetone that would vapourise.
On a small scale a simple absorption method is OK, provided you have a good train of scrubbers to catch the unused ketene. Low yields, possibly high
backpressures. On a large scale you need proper absorption towers designed for low backpressures while providing good contact between liquid and gas.
On a large scale you are going to need to address the flammable non-condensible gases exiting the absorption section.
Sorry I can't help with translations, my Pārsi is pretty much limited to asking where to eat and "do you know someone who speaks Komi or Strine?"
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Fashist
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Oh My God.Very Difficult.
If I use this system(according to my picture)probably i will have 100ml anhydrid per Day or little more.
What is your advise(what boiler?how long tube?..)
I want to make 5-10 lit anhydrid per day.what is your suggestion?
Mr not important really thanks
| Quote: | Originally posted by not_important
Sorry I can't help with translations, my Pārsi is pretty much limited to asking where to eat and "do you know someone who speaks Komi or Strine?"
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This Mean That i Dont ask Question?
[Edited on 2-12-2007 by Fashist]
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WizardX
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KETENE http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0330
Albert Einstein - \"Great ideas often receive violent opposition from mediocre minds.\"
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not_important
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Very true, but if you had read the thread you would have seen that it was discussed early on, and is not suitable for the application in question.
Too small of a production rate, the filament requires frequent cleaning, and the apparatus is fragile.
| Quote: | Originally posted by Fashist
Oh My God.Very Difficult.
If I use this system(according to my picture)probably i will have 100ml anhydrid per Day or little more.
What is your advise(what boiler?how long tube?..)
I want to make 5-10 lit anhydrid per day.what is your suggestion? |
Things like the tube length a somewhat dependent on flow rate and heat transfer. Too long of a time at the high temperatures leads to excessive
breakdown of the ketene.
I'd start with that "Ketene Production..." model for the tube, go ahead and use your boiler. Carefully control the heat input to the boiler, do
several test runs at a given boil-up rate and tube temperature, figure out anhydride yield and acetone boil-up rate which will give you the
approximate flow velocity through the tube. Repeat with a bit higher heat input to the boiler, and repeat again until the yield drops off or
excessive amount of acetone distill (remember than maybe 20% will be converted and likely less).
And put a real effective absorption train after the anhydride absorber, you must keep ketene from getting out.
Once you've done that you knw the basic parameters for your tube furnace. You can then build a larger oven and run multiple tubes through it, with
manafolds at each end so a single boiler can feed them and their output is collected for feeding to the absorption unit for making anhydride.
You will likely need to refine the absorption/quenching section to optimise yields. This section will resemble a fractionating column, as that gives
good contact between gas and liquid.
Outside of that I've already given you all the advice I have - it's in those PDFs and test books that cover the processes used.
| Quote: |
| Quote: | Originally posted by not_important
Sorry I can't help with translations, my Pārsi is pretty much limited to asking where to eat and "do you know someone who speaks Komi or Strine?"
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This Mean That i Dont ask Question?
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No, it means I can't do the translations for you. I suspect you already know good places to eat, so that exhausts my Pārsi :-)
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Fashist
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Thanks Mr not_important
If i use single boiler and multiple copper tube then i must use Multiple condenser and Multiple container for anhydrid?
| Quote: | Originally posted by not_important
No, it means I can't do the translations for you. I suspect you already know good places to eat, so that exhausts my Pārsi :-)
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This is difficult for understand your PHRASE.
because there is diffrent between Farsi phrase and english
again thanks(i dont konw better word for thanks)
Mr sauron you have no idea?(You are my master)
[Edited on 2-12-2007 by Fashist]
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