Someone on here did something similar a while back, but I don’t remember who, and I don’t think we really found out if it worked or not. I’m thinking “tuyere-less charcoal gasifier” or something.
I recall that they removed the valve stem from a moderate sized propane tank, cut a door in the bottom of the tank, pounded a wooden dowel into/through the valve stem bung, turned the entire thing upside-down, and poured in an inch or 2 thick layer of refractory into the bottom (formerly the top of the tank) around the dowel.
Once everything is set, the dowel was removed, leaving a hole in the refractory, much like a magma vent under a volcano.
I found the link (super easy) Tuyere-less charcoal gassers it looks like it was @Jeff who made this, and luckily he’s still around here, unlike a few too many creative souls.