Abstract: An air-cooled cyclone coal combustor comprises a horizontally disposed shell, provided with a non-sacrificial refractory liner. The liner is surrounded by an array of air-cooling tubes, the tubes serving both to cool the liner and to physically support and reinforce it. Air cooling in the manner disclosed facilities precise control of the thickness and flow of slag on internal walls of the combustor, so as to avoid reevolution from the slag of the sulfur pollutants. Pulverized coal fuel and a pulverized sulfur sorbent (limestone or the like), as well as primary and secondary combustion air, are introduced into the chamber at an end wall. The cooling air, heated regeneratively in the cooling tubes, provides the secondary air, and is introduced in the chamber in helical flow, at a radius outwardly from the radius at which the solids and primary combustion air are introduced into the chamber. A thermally insulated nozzle provides an outlet for combustion gases.