Sciencemadness Discussion Board - Reactor

Reactor

lvjrf - 29-8-2006 at 23:36

Hi all

Anyone tell me how made reactor with pressure control ?

thanks

lvjrf - 29-8-2006 at 23:41

Like as Autoclave

not_important - 29-8-2006 at 23:51

Try
http://www.sciencemadness.org/library/books/autoclaves_and_h...
for starters. Old, but has the basic concepts.

Quince - 1-10-2006 at 01:29

I want to know the opposite: how to make a vacuum furnace that can sustain vacuum at temperature where Pyrex would melt, so I can't just seal the item in a Pyrex tube and bake that.

not_important - 1-10-2006 at 02:17

Quote:

Originally posted by Quince
I want to know the opposite: how to make a vacuum furnace that can sustain vacuum at temperature where Pyrex would melt, so I can't just seal the item in a Pyrex tube and bake that.

Use fused silica, Vycor, alumina, sapphire , or mullite tubing. Or metal, with a sapphire window or windows if you need to see in.

Another possibility is to use pyrex, with a heating method that directly heats the load. The pyrex can only be heated by radiation through the vacuum, a air blast on the outside of the pyrex will keep it cool enough.

http://www.sentrotech.com/index.php

http://www.rayotek.com/index1.htm

http://www.graphitestore.com/items_list.asp/action/prod/prd_...

and many more

matei - 1-10-2006 at 02:49

Quote:

You can seal a pyrex tube with a methane/oxygen torch and than place it in an oven.

Quince - 1-10-2006 at 02:51

Quote:

Originally posted by matei

Quote:

You can seal a pyrex tube with a methane/oxygen torch and than place it in an oven.

matei, I said where it is too hot for Pyrex and that would melt. I could use a quartz tube, but I can't develop the heat to seal that (I don't have oxy-acetylene, just propane).

not_important - 1-10-2006 at 18:25

Get some quartz heaters, like these http://www.infraredheaters.com/quartz3.htm

Get a big pyrex tube

Trace out an ellipse that will have one of the heater tubes at one focus, and the center of the pyrex tube at the other.

Rotate the ellipse N times arround the focus at the center of the pyrex tube, erasing any part of an ellipse that falls within another ellipse so that you end up with a sort of N-point start except the star's points are ends of ellipse.

Make that star shape out of shiny aluminum or stainless steel sheet, long enough that it will extend to the end of a quartz heater. This is your reflector.

Mount the reflector with the pyrex tube a the center, and a quartz heater at the focus in each arm of the star. mounting clips and electrical connections for the lamps, end connections for the pyrex tube so you can pull vac and insert/support a holder for the sample.

Get a hunking big fan/blower. Make a end plate for the reflector that allows the HBF to blow air in that end, with the air flowing around the outsides of the heaters and pyrex tube.

Devise a support for the sample, an alumina rod or tube. The section that will be well within the pyrex tube, exposed to the glare of the lamps, can be stained near-black with mixed Fe/Co/Ni/Mn oxides.

Put your sample in its container - boat or crucible, that onto/into the support, that into the pyrex tube. Pump the tube down, turn on the HBF, then the quartz heaters.

The region at the image focus of the heaters can be raised to nearly the temperature of the heaters' filaments, depending on heat losses. As the radiative loss is mostly 'seeing' the filaments, conduction losses and absorbtion by the pyrex tube will likely be the controlling element.

The pyrex will be absorbing the longer IR. The larger the tube, the less heating per unit area of the pyrex tube there is. The air blast needs to carry away that absorbed heat.

Or you could just use what I suggested earlier for the containg, Mo heating elements in the container, or maybe induction.