The modified Claus process is commonly used in oil refining and gas processing to recover sulfur and destroy contaminants formed in upstreamprocessing. In oil refining, in addition to the typicalmodified Claus plant feed of H2S and CO2, NH3, CS2, and COS are also often present or formed. These contaminants pose a risk of poisoning the catalyst beds and plugging off downstream equipment, as well decreasing the overall achievable sulfur recovery. In this paper, the parameters that may affect adjusting the temperature of furnace and converters will be discussed. These process parameters are important in designing a new Claus sulfur recovery plant. For this purpose, a typical sulfur recovery unit is analyzed and the main process temperatures are achieved.