BromicAcid - 24-2-2005 at 20:24
Recently I was considering some reactions that require the use of catalyst tubes. And many of these tubes require somewhat high temperatures 100 <
T < 250C I was considering just using one of my existing Liebig condensers for this job. Pack it with the catalyst material, use my existing
glassware, etc.
The problem is of course the heat. Solved if I could find a pump that I could drop in a pan that could pump hot oil through the condenser. High
temperature hoses are widely avalible for the automotive industry, some radiator hoses rated for over 375C, so I can just run the oil or whatever with
that. But the pump, I was thinking maybe some sort of fuel injector but I'm welcoming any other suggestions.
Peristaltic Pump
chemoleo - 24-2-2005 at 20:39
If you have a high temp resistant hose, you could I guess make yourself a peristaltic pump, using silicone tubing or something. I have one back at
home, and find them very efficient, and easy to make.
All it needs is a slow electric motor, a wheel with small rolling weels on the perimeter, and the tubing. You could either suck up the cold oil and
heat it after the pump (continuously, requires good heater), or you could simply suck up the hot oil, which then goes through the peristaltic pump and
straight into the condenser.
[Edited on 2-3-2005 by chemoleo]
Organikum - 24-2-2005 at 22:21
I wouldnt use a Liebig for this. A glass or whenever feasible a metaltube, some NiCr wire and a dimmer I would say.
Lightubes are ok . the thin glass makes an excellent heattransfer, metal is better of course.
/ORG
BromicAcid - 24-2-2005 at 22:27
That was actually my origional plan, I can buy burets cheap so I was just going to use a 50 ml buret as my catalyst tube and wrap in Ni-Cr and
fiberglass insulation, but the Liebig seemed easier, no dimmer or Ni-Cr wire to buy. I mean, as always it's going to be awhile before I get
anything done, but it still didn't seem like a bad idea to me. What would make you prefer the dimmer to the Liebig anyway, except the
possibility of a hose flying off and spraying 200C oil everywhere without mercy and possibly leading to a fire?
frogfot - 24-2-2005 at 23:17
Wire heater sure sounds cleaner.. maby a layer of heat leading material around the wire would help to keep even temp and make it possible to measure
it..
The simplest solution with oil pump would be to connect both hoses from condenser to a vertical metallic pipe. Top hose should be connected to the
metal pipe through a T connection an thereby make a hole in the system (to prevent overpressurising). The metallic pipe should be heated.. Hopefully
this will circulate the oil.. This should give better heat control than the wire heating.
tube heater
bio2 - 25-2-2005 at 02:02
If you are set on a fluid type heating system I think frogfoot is on the right track here but you will probably need some sort of small expansion tank
not just a hole which will possibly fume out the lab. Even Therminol high temp transfer oil has to be in a sealed system as degradation occurs from
air contact at the higher temps and the vapor pressure is high enough that it will fume somewhat (smells like burning brake fluid). Silicone oil not
so much but since you have to heat the oil anyway I would go with Organikums suggestion.
Using oil a pump probably isn't needed as a strategically located expansion tank with correct tubing sizing will circulate effectively by
convection for this application. Take a look at the Aldrich catalog as they have a convection condensor cooler that will show you the concept.
One thing to keep in mind is that oil not only has a large thermal lag compared to just a coil
it also stores considerable heat. You may want this but if you need to lower the temp in a hurry due to an exotherm etc. you ain't gonna be able
to do it. A NiCr coil with the proper phase control (dimmer) will keep a steady temp even set manually provided the voltage doesn't drift. Or use
the thermocouple or RTD you will measure with to control the triac. A PID control isn't cheap though.
searat - 25-2-2005 at 05:46
heat the oil up(any way), then use argon to force it throught the pipe.
neutrino - 25-2-2005 at 07:33
How dows that work in a continuously circulatiung system?
BrAiNFeVeR - 1-3-2005 at 09:54
Perhaps you can make yourself some sort of archimedes screw-like pump ?
Not that hard to construct with limited materials, although some welding or turning skills could come in handy.
If you have pressurized inert gas you can use that injected in a vertical pipe type mammoth pump, but the gas will carry away quite a bit of heat ...
If you are going to use that you might aswell cool the oil using a heat exchanger (another liebig cooler perhaps ?) and pump it with a low temperature
pump to your higher reservoir.
The only energy efficiënt method is buy a high temperature pump I'm afraid.
Or use the peristaltic pump idea, that good too, but harder too construct.
Twospoons - 1-3-2005 at 13:18
Get a used car oil pump from a wreckers yard. Add an electric motor to dive the thing and voila! a high temp electric oil pump!
BrAiNFeVeR - 5-3-2005 at 15:16
Yes, that would be ideal, but finding a proper and safe coupling to connect your motor and the wreckers oil pump is often the biggest problem.
I've been having the same problems with my pump 
Twospoons - 7-3-2005 at 20:02
V-belt and pulleys from engineering shop. The oil pump probably has a v-belt pulley on it already.
kyanite - 8-3-2005 at 15:19
Hydraulic Sytems are beautiful. If you could find a mini pump or if your desparate, a piston(add flow check valves). They're designed for oil,
are very sturdy, and can take alot of pressure.
Just make sure you get the right connectors and that theyre sealed... Vegie oil spills are a pain to clean and if it's not tight it can goes all
over the place. 
The oil wasnt hot but its happened to me before. This partner of mine doesn't do any checks(the manifold was the problem) and when he
went to test the system, the whole area was sprayed with vegie oil and it got onto everything....
sorry for being the OT
[Edited on 8-3-2005 by kyanite]
[Edited on 10-3-2005 by kyanite]