Refining of heavy crudes and to an even greater degree, stiffening of the environmental requirements for the sulfur content in petroleum products and sulfur compounds in gaseous emissions into the atmosphere make the problem of process and technical improvement in active elemental sulfur production units (ESU) in oil refineries very pressing. These units are in the first 10 of the 30 environmentally most hazardous basic processes in refining of hydrocarbon feedstock [1].