Application: The WSA process (Wet gas Sulfuric Acid) treats all types of sulfur-containing gases such as amine and Rectisol regenerator offgas, SWS gas and Claus plant tail gas in refineries, gas treatment plants, petrochemicals and coke chemicals plants. The WSA process can also be applied for SOx removal and regeneration of spent sulfuric acid.
Sulfur, in any form, is efficiently recovered as concentrated commercial-quality sulfuric acid.
Description: Feed gas is combusted and cooled to approximately 420°C in a waste heat boiler. The gas then enters the SO2 converter containing one or several beds of SO2 oxidation catalyst to convert SO2 to SO3. The gas is cooled in a gas cooler whereby SO3 hydrates to H2SO4 (gas), which is finally condensed as concentrated sulfuric acid (typically 98% w/w).
The WSA condenser is cooled by ambient air, and heated air may be used as combustion air in the incinerator for increased thermal efficiency. The heat released by incineration and SO2 oxidation is recovered as steam. The process operates without removing water from the gas. Therefore, the number of equipment items is minimized, and no liquid waste is formed. Cleaned process gas leaving the WSA condenser is sent to stack without further treatment.
The WSA process is characterized by:
• More than 99% recovery of sulfur as commercial-grade sulfuric acid
• No generation of waste solids or wastewater
• No consumption of absorbents or auxiliary chemicals
• Efficient heat recovery ensuring economical operation
• Simple and fully automated operation adapting to variations in feed gas flow and composition.
Licensor: Haldor Topsøe A/S.