Sulfuric acid Plinke process

Pauling-Plinke A process for concentrating and purifying waste sulfuric acid by distillation and addition of nitric acid. It was obsolete by 1994. 

PERCOS A process for removing sulfur dioxide from waste gases by scmbbing with aqueous hydrogen peroxide. The product is a commercial grade of 30 to 60 percent sulfuric acid. Developed by Adolph Plinke Sohne and Degussa. 

Plinke process In this process sulfuric acid is distilled at atmospheric pressure with indirect heating by natural gas and oil combustion (combustion chamber temperature 800 to 1100°C). This process is predominantly used in Europe. The to be concentrated waste acid is fed in at the top of the distillation column into boiling 96% sulfuric acid at atmospheric pressure and 320°C in a cast iron boiler. Water is expelled at the column head leaving a 96% acid. By adding nitric acid, which is mainly reduced to nitrogen, organic impurities can be removed oxidatively. 

Drum concentrators Concentrations up to 93% acid are attained by direct contact with furnace gases. The purification effect is less than in the Plinke process. The sulfuric acid to be concentrated flows through a number of brick-lined chambers, which are connected in a cascade, in which furnace gases at 600°C flow in countercurrent to the acid and become saturated with water vapor. 

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