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enter image description hereenter image description hereI am gonna use a ceramic tape heater, but cannot wrap it around evenly. Is the glass column gonna be okay?

enter image description here

I am running some tests on plastic pyrolysis. I am using the reflux condenser to make the heavier hydrocarbons flow back into the boiling flask. I am also trying out various catalyst in the reflux condenser which will facilitate catalytic cracking.

I have decided to maintain the temperature at top of the reflux column to be of 150C and it will allow the lighter fraction to be removed off and the heavier fraction to be condensed back into the boiling flask.

The boiling flask is made up of quartz and the rest of the glassware is borosilicate.

I am gonna use the glass setup to test catalysts. If results are satisfactory, will get a microreactor made up of steel for further testing. I can better monitor and control temperature in a metal setup I think. Gonna try on only PE and PP types of plastic.

I am a structural engineer by profession and am new to organic chemistry. Thanks for you help in advance.

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    $\begingroup$ I take it "get a different reflux column" (e.g. one that will work with your heating tape) is out of the question? -- A big concern I would have is: if the shape of the reflux column is important, inadequate or uneven application of heat may yield results other than what you desire. Perhaps going into more details about why you're using that column and why you need to apply heat to the column may provide improved answers. $\endgroup$ – R.M. Jan 17 '18 at 3:17
  • $\begingroup$ Thanks R.M. The heating tape is not flexible as I want it to be. I am running some tests on plastic pyrolysis. I am using the reflux condenser to make the heavier hydrocarbons flow back into the boiling flask. I am also trying out various catalyst in the reflux condenser which will facilitate catalytic cracking. $\endgroup$ – Vanadium Jan 17 '18 at 5:42
  • $\begingroup$ I have placed an order for a heat gun which can heat upto. Planning to wrap the column in aluminum foil and use the heat gun on it. Gonna use the IR thermometer which I have to measure temperatures. $\endgroup$ – Vanadium Jan 17 '18 at 6:00
  • $\begingroup$ I am gonna use the glass setup to test catalysts. If results are satisfactory, will get a microreactor made up of steel for further testing. I can better monitor and control temperature in a metal setup I think. $\endgroup$ – Vanadium Jan 17 '18 at 6:00
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The first answer is great and the borosilicate glass can indeed survive harsh conditions. Here I'd like to suggest a DIY-project to improve the efficiency of the heater and make the column be warmed more evenly. Take a sheet of fiberglass cloth, sew the heating element in a serpentine pattern with the fiberglass threads, then wrap the crafted heating mantle around the column. The exact size can be estimated based on the height and the diameter of the wide part of the column. I sketched an approximate scheme:

enter image description here

Alternatively, you can leave a line of column uncovered (1-2 cm) for visual inspection. Fiberglass can withstand the same temperatures as your heating mantle, but I suppose you've already discovered it the hard way.

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    $\begingroup$ Hey andselisk, Thanks for the answer and great illustration. $\endgroup$ – Vanadium Jan 17 '18 at 5:14
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    $\begingroup$ I am also thinking of wrapping the reflux column with aluminium foil and then use the ceramic tape heater to wrap over the aluminium foil. I hope this will lead to a better heat distribution. $\endgroup$ – Vanadium Jan 17 '18 at 5:29
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    $\begingroup$ @Vanadium No, don't... Aluminium would block the heat radiation, which (arguably) is the primary mechanism for transferring heat in such a setup. You want to enclose the heat inside, not shield the equipment from the heater. $\endgroup$ – Stian Yttervik Jan 17 '18 at 9:29
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    $\begingroup$ Oh thanks. I assumed primary heat transfer is through conduction. And so wrongly thought it would help in even distribution via conduction. $\endgroup$ – Vanadium Jan 17 '18 at 9:37
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    $\begingroup$ @Vanadium No problem. Usually you do not even try to heat the whole column, you heat the liquid, which boils, then transfers heat up the column. you wrap the column to limit heat loss. If you need very precise temperature control or exactly the same temperature in the entire column you make a setup like the good mr Andelisk has so nicely drawn, and then wrap with a reflective material outside of that. Aluminium reflects well, and thus doesn't emit well, so it traps heat by not being able to emit it, in combination with high internal reflection. $\endgroup$ – Stian Yttervik Jan 17 '18 at 9:49
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That should pose no issue regarding the glass

Without images to see how unevenly you will apply the heat, I have to modify my instinctual reaction "That cannot possibly be an issue" to "Most likely it will be OK". I'd be much more worried about variation in the distilling if you are at some point drawing a distillate. If you cannot control the heat flux, the yield and temperature profile will be offset from the theoretical and can (if the process is delicate) lead to variation in the results.

But borosilicate glass is sturdy, you can probably heat it with a naked propane flame - it is designed to have a low thermal expansion coefficient. Directly from that, it will have a high thermal shock resistance.

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    $\begingroup$ @Vanadium This looks like some heavy duty industrial research... Well... First things first, at 150°C I have no doubt the column will do fine from a temperature point of view. But there is room for improvement in your setup. Add some clips, or in a pinch some steel wire to secure the wrap around the column, then add aluminium foil to reduce the stresses and heat loss. There are standard solutions for this, but wire and foil will get you far. Also, I can't see a cooling unit, is that on purpose? Or is it just hidden from view, behind the mounting rack? $\endgroup$ – Stian Yttervik Jan 16 '18 at 17:05
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    $\begingroup$ Yep, The condenser is just behind mounting rack. $\endgroup$ – Vanadium Jan 16 '18 at 17:14
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    $\begingroup$ I am gonna use the glass setup to test catalysts. If results are satisfactory, will get a microreactor made up of steel for further testing. I can better monitor and control temperature in a metal setup I think. $\endgroup$ – Vanadium Jan 16 '18 at 17:21
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    $\begingroup$ @Vanadium It should, but at 150°C you have plenty of options. Just make sure you keep some leftover money to get good temperature measurements. =) $\endgroup$ – Stian Yttervik Jan 16 '18 at 20:49
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    $\begingroup$ Tried covering the set up with aluminum foil. Works great. The column got up to 180C without external heating. Thanks Stian. $\endgroup$ – Vanadium Jan 22 '18 at 17:15

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