HELP NEEDED with CHOOSING THE RIGHT SEAL for a rotating furnace

[maqadir]

I am a mechanical engineering student and have a desin project application question.
In the picture, as you can see, the working tube, is a glass cylindrical tube, mounted onto main body of the furnace using a motor that rotates the tube at certain RPM.
This is an open ended tube, and the blue holes on the end of the tube, show, where the seal, that i need to select should be mounted, onto the ends A,B of the tube, with ideally 2 holes in it for feeding of the material, that goes into the tube. Hence the seal needs to seal the ends, and be rotary so that the outer layer of the seal rotates with the tube, while the middle, which should have 2 ideal holes in it, stay stationary, so materilas that are to be added to the furnace tube can be fed through easily. for the process:
Tungsten Oxide, Wo3+H2S-----> WS2 (Tungsten+H20)

The two holes at end B, show one hole to let the gas product out in the gas chamber which sucks it away, and the other hole to collect the powdered material in a base, or likewise. These two holes will have pipes, or otherwise likewise material connected for feeding purposes.
Any one know what such seals are called, and where they can be found or bought??
thanks , would be great help!

 

[turbo]

You may be able to use seals made of compressed graphite. These are sold as "pump packing" to seal pump shafts. I'm pretty sure Garlock has them.

 

[maqadir]

You may be able to use seals made of compressed graphite. These are sold as "pump packing" to seal pump shafts. I'm pretty sure Garlock has them.

Thankyou for your reply, however, wot do i do about the 2 holes needed for feeding?

 

[FredGarvin]

So the blue tubes remain stationary and the glass tube rotates? The seal needs to be between the blue tubes and the rotating glass tube? Am I understanding you correctly?

Also, you need to specify the speed of rotation, the ID of the glass tube and the expected temperature the seal will see.

 

[maqadir]

So the blue tubes remain stationary and the glass tube rotates? The seal needs to be between the blue tubes and the rotating glass tube? Am I understanding you correctly?

Also, you need to specify the speed of rotation, the ID of the glass tube and the expected temperature the seal will see.

Umm, you misunderstood me there, the blue dots, does not mean a separate tube, the glass tube rotates yes, and it is hollow, the blue dots on the diagram, is where i need the seal to fit, ( i.e at the hollow end of the glass tube) and the blue dots describe, the holes that should be in the seal to allow feeding of the material into the glass tube (its a gas and powder ) so that a reaction can be obtained in the glass tube. For this reasons, the blue dots, which is essential the seal, should remain stationary. The blue dots, are just my requirments of a whole in a seal, that allows material to be fed into the rotating tube, that's all
Its controlled by a electric motor, supplied by a.c current alternator, so the RPM, is not going to be very high, maybe 60-100 rpm, while temperatures in furnace will conduct the glass tube to be working at 200 odd degrees celcius.

So in summary, i need

a seal, to seal the hollow ends of the tube that is drawn
blue dots indicate, that the sea i fit onto both ends, remains stationary, while the tube rotates and has holes for as said earlier feeding of the metrial

I hope this helps explain what the seal is required for,
Thanks a lot for your reply

 

[coreyh]

Wow, confusing problem... Good job mentioning temperature, which is pretty much the most important consideration when it comes to seals. 200C is pretty reasonable for high temperature plastics, so you should have lots of options.

I'm still a bit confused about the two blue dots. So these are inlets for material on one side and outlets on the other side? If this is the case, can you make a small manifold, say out of stainless steel, which has two fittings on it for supplying material and have the seal on the outer rim of the glass tube? This would simplify things significantly! A great company for high temp seals is:
http://www.tss.trelleborg.com/com/www/en/homepage.jsp
I would suggest to write them a request with a less confusing diagram;)

hope this helps!

 

[maqadir]

The blue dots , forget about them
Just consider a normal rotary seal. Now in this type os seal, only the outer part rotates, and the inner part stays stationary right?
Now, the stationary part of this seal, needs to have 2 holes ( which are the 2 blue dots) that are required for feeding.
Thanks for the website though, its just that i have no idea what to do about the holes.

 

[coreyh]

Sounds like you need more than just a seal, but rather a mechanical part which holds the seal and also provides holes for feeding in material and supports the tube/furnace.

Usually a seal is just a single part, like an 0-ring for example, which is inserted into a groove cut into a fixed part. The rotating part then inserts into the fixed part and the seal is compressed between the two surfaces. Check out this link for a few nice diagrams:

http://www.azom.com/details.asp?ArticleID=504

I would recommend doing some google searching and trying to find a similar problem to yours and see how it was solved.

Good luck!

 

[andy taylor]

if your looking fora vacuum /rotary seal.. there is also the possibility of choosinga feroofluidic seal and or a magnetic driven feed . eliminating any machining