Hoss emptied the retort after run #5 to examine the alumina nozzle that I mentioned at the beginning of this thread. At this point, we had about 1.5 hours of run-time on this nozzle.
We were disappointed to see that approximately 1 inch of the nozzle was missing.
Unfortunately, I was not there when he opened and emptied the retort.
However, he said that he found something very curious.
Rather than finding the broken end of the the alumina pipe as one might expect, he only found a small pile of fine white powder where it should have been.
This makes me think that the alumina itself was eroded and broken down by some high temp corrosion process.
Here is what the nozzle looks like now:
The good news is that we have about 5 inches of the alumina nozzle remaining (most of it is stuffed back inside the steel nipple and coupling. So, in theory, we can merely draw it out a little bit as it erodes.
However, at this rate of consumption, I would say that alumina pipe is not a viable option since it is fairly expensive (I think I gave around $30 to $40 for the pipe).