PURPOSE: To control the coloration of product sulfuric acid to a specified chromaticity by obtaining the chromaticity of a sulfuric acid sample sampled from a pipeline on the outlet side of a removal tower, and automatically adjusting the amt. of a decolorant to be added corresponding to the obtained chromaticity at the final stage of sulfuric acid production.
CONSTITUTION: The concd. sulfuric acid produced in a sulfuric acid producing facility is introduced into the removal tower 1, brought into contact with the air blown in by a fan 9 to remove the contained gaseous sulfur dioxide, and then sent to a product sulfuric acid tank through a pipeline 11. In this case, a branch pipe 10 is provided on midway of the pipeline 11, a sulfuric acid sample is intermittently sampled by a sampler 3, and the amt. of the decolorant to be consumed before the oxidation- reduction potential reaches a reference value is measured by an automatic titrator 4. The chromaticity is obtained by a computing element 5 from the measured value, an appropriate amt. of the decolorant is given to a decolorant feeder 8 in accordance with the obtained chromaticity, the deodorant 7 is added to the sulfuric acid in the removal tower 1 to decolor the sulfuric acid, and a colorless and transparent sulfuric acid is produced.
MANABE YASUNORI
KODA FUMIHIKO
