Smelter Acid Plant—Replacement Hot Gas Exchanger Case Study

Sulfuric acid plants attached to copper smelters often experience high SO₂ gas concentrations entering the first converter pass, resulting in very high outlet gas temperatures. The hot gas exchanger downstream of the first pass is therefore a critical piece of equipment and may be routinely exposed to gas temperatures in excess of 650 °C (1,200 °F). The combined effects of hot gas corrosion and the potential for excessive thermal stress on the tubes make for one of the most severe service cases seen in sulfuric acid plants. NORAM has been engaged to design and supply a replacement hot gas exchanger for Rio Tinto Kennecott’s large copper smelter acid plant in Utah, the design of which is a useful case study in general strategies to mitigate the deleterious effects of high temperatures on gas-to-gas heat exchangers. In addition to general solutions, the design process also highlights the usefulness of more advanced techniques, such as computational fluid dynamics, in identifying and remedying issues unique to a particular heat exchanger, or other acid plant equipment.