Like probably most everyone I've wanted an Ursutz burner. Trying to do that in the bottom of a furnace with a corbel or orifice plate has me wanting to build another furnace. When I first started on foundry work I read where several people claimed you always want to build a better furnace. I didn't understand it then but I do now. I believe an internal disc would approach flame temperature and be subject to failure. Refractory hot face with a cold side keeps sucking heat out of the hot face and thus cools it allowing it to survive. The disc internally to the furnace would have little cooling and would suffer much higher temperatures. Maybe someone will try it.