Returning again unto our first ways and so retracing our paths, let's get back to the retort type apparatus. This seems more likely to get built, and to have fewer places to go wrong.
The retort arm descends at a steep angle to its bend, a reinforced elbow joint resting on, or cast into, a block. This block might have provisions for moderate auxiliary heating, if it is thought to be necessary. From the elbow stretches a long pipe of large diameter (put your fist in it) which descends at a shallow angle into a trough of water until its far end is just submerged.
You do not want to have the end of your condenser pipe in deep water. You want to show minimal back pressure to any impulse pressure. Burning solids have granulations and hot spots, they burn sometimes irregularly. Since you can't tell how strong a pressure wave might bee, you don't want to trap it. You want to let it go. You want it to bubble out and flare freely in the air, as far may bee from your main apparatus, and from human noses. So put the end of the pipe in shallow water, not in deep water.
I have also changed my opinion about the water temperature. I no longer think ice water would be ideal starting coolant for this reaction. You don't want to end up with solid phosphorus in your pipe, in fact you want it liquid all the time it is in your pipe, so it will all flow out into the water. A phosphorus blockage is one of the prime things you want to avoid. Using these considerations, I might want to put warm water in my trough to start with. Steamy warm, maybe 50 or 60 degrees, to make sure that condenser pipe holds runny liquid phosphorus with no tendency to congeal. Again, though, as the reaction progressed, I might wash out the old water with new cooler water, at a flow rate which does not threaten to splash out any phosphorus.
The main differences I see now, with the way I pictured it at first, is the use of the elbow block, and starting with warm water not ice water. Plus the decision, that if anything pushes too hard, to let it go. You are polluting a bit, as anything that bubbles from the end of the pipe gets carried away by the breeze into the natural environment, but if you can ensure people and large mammals are not in the way, you cause no mortal harm. This way I think we can run, still a dangerous run, but I think we've worked the suicidal aspects out of it.
turning science fact into <<science fiction>>