Sulfuric acid (H2SO4) is among the most important industrial chemicals, with large-scale uses in several industry sectors, such as basic chemicals, fertilizers, petroleum refining, metals, explosives, detergents and plastics. H2SO4 is broadly used in different concentrations and grades. Major applications include its use as a dehydrating agent, catalyst, reactant in chemical processes, solvent and absorbent.
The following paragraphs describe a double-contact process for sulfuric acid production (Figure 1) in which elemental sulfur is the source of sulfur dioxide (SO2). SO2 can also be obtained from several sulfur-bearing raw materials, including spent H2SO4 and smelter off-gases.
Sulfur burning. Elemental sulfur (in molten form) and dried air are fed into a combustion furnace, in which the sulfur is burned to produce SO2. The proportion of airflow relative to sulfur feedrate is controlled so that a sufficient concentration of oxygen is maintained in...