2 replies to this topic

[kougon]

Hi, I am working on a continuous run Carbon nanotube plant. The nanotubes are about 1 nanometer in diameter and have a length of between 1-100um. They should be removed continuously from the system. I brainstormed several ideas but seem to have hit a roadblock. I'd appreciate suggestions for a commercially available system that can meet our needs. (About 300-800grams of particulate matter per day is the designed capacity).

In simpler terms this is a problem of purifying a gas by continuously removing the particulate matter which could be higher than 300g per day. And this particulate must be removed continuously from the system with ideally zero loss of gas.


Designs considered and shelved so far.

Filter paper/cloth/mesh: This cannot be a continuous process as we will need to turn off the reactor as soon as the filter clogs; this(turning off) is not allowed.

Cyclone Filter: We are using Carbon Monoxide and a Cyclone needs a counter current of monoxide. We can't figure out how we can remove the particulate matter continuously with zero gas leak.

Electrostatic Precipitator: I'm not sure if the nanotubes will be electrostatically charged under a field. It's an unexplored territory and we need to have a backup if this fails.

Trickle Bed filter: A trickle bed with tiny gravel and water could catch hold of and remove the nanotubes but once wet they become useless for some applications. Nanotubes are hydrophobic by the way and do not dissolve in any solution except for Super acids (Sulfonic acid).

[fra.telli]

I suggest:

Removing action will be continuos, discharging phase, not (batch).

carbon composites can be charged.
I think I'll use two electrostatic precipitators (ESP) - one spare to the other.
you can even consider using acid solution for washing the captured particulate. (making it a Wet ESP) In this case, electrodes can be made of graphite (as the grounding system). for iternal casing, consider resin composites.
You'll need to switch to the spare ESP while/after washing the first one. on the top of the ESP (even inside the ESP) you can install a high performance mesh with a washing system on the lower face (washing cicle shall occur together with ESP washing, of course). Drying the wet WESP can be done with dedicated gas or partially/toatally circulating gas coming from the other WESP.
I'm not sure if you can use water as washing liquid: in fact, liquid is used just to remove solid particles that adhere to the collecting surface (that I'm imaging as tubular, but can be planar surfaces - in this case washing wont be siutable): it's a mechanical action, it doesn't need to be more than this. I'm wondering if you will accept having a water saturated gas downwards the WESP... Moreover, in case of nanotubes-in-liquid, you'll need a second stage for separate solids from liquid sol (but beeing idrophobic, maybe will help).

I suggest to contact a specialised supplier with references in acid areosol/fine carbon powder abatement.

If you want to explore the mesh alternative, consider that, in any case, you'll need to wash the mesh (once a our/day/or what else) in order to remove particulate but the efficiency will depend on the available dP - and again, you have to solve the "second stage" problem of separating solids from liquid.

[fra.telli]

I beg your pardon, kougon.
I've realized now that maybe you need a small scale system... a little bit more than a lab system, far smaller than a full industrial scale system.
Anyway: two ESP, manually wagged to remove the partriculate. Once you have put offline the "full" ESP, purged with N2 (or any other cheap gas that wont react with nanotubes - air?), a skilled operator can manually remove particulate and/or wash the ESP.

A doubt: can sparkling ruins nanotubes (I don't think so, but I don't have any evidence)?

bye

Edited by fra.telli, 12 April 2011 - 03:46 AM.