Sulfuric Acid | Wet gas Sulfuric Acid (WSA)

The WSA process is a wet gas catalytic process. The concentrated sulfuric acid is produced by condensation from a wet process gas. Drying of the process gas prior to treatment in a WSA plant, therefore, becomes superfluous, hence generation of wastewater and loss of sulfur are avoided. The purpose of the first step in the process is to produce an SO₂ gas at the operating temperature of the oxidation catalyst in the SO₂ converter. If the sulfur in the feed is SO₂, only a simple preheating is required. Other sulfurous feeds are oxidized to SO₂ by combustion and then cooled to the optimum catalytic conversion temperature in a waste heat boiler. The excess heat from this operation is recovered as steam. The catalytic conversion of SO₂ to SO₃ takes place in one or more catalyst beds. Reaction heat is recovered between the catalyst beds by superheating of steam. After the last conversion step, the gas is cooled and the SO₃ reacts with water vapor to form gas-phase sulfuric acid. The process gas is finally cooled by a countercurrent flow of air in the proprietary WSA condenser. Clean gas exits at the top of the WSA condenser and the sulfuric acid is collected in the bottom section from where it is cooled and sent to storage. Hot air generated in the WSA condenser may be used as preheated combustion air to ensure optimal energy efficiency.