A sulfuric-acid process with near-zero SO2 gas emissions

Abstract  A sulfuric-acid process has been developed that is able to handle low and variable SO2 concentrations with practically zero SO2 emissions (less than 3 ppm). The plant comprises two stages—a single-bed converter contact plant and a modified tower plant. Acids of 95–98% and/or oleum with up to 32% free SO3 can be produced in the first stage. Off-gas of the first stage is piped to the second stage, where the SO2 is converted to near nontracability while producing 76% strong acid. It is then returned to the contact plant to produce stronger acid or oleum. This process does not generate any additional disposable waste.