In one plant, odorous emissions were observed for several years near a drum dryer line used for volatilizing an organic solvent from a reaction mixture. Although two dryer-product lines existed, the odors were observed only near one line.
The analysis and field testing indicated that the chemical compounds causing the odors were produced in upstream unit operations due to the hydrolysis of a chemical additive used in the process. The hydrolysis products were stripped out of the solution by the process solvent and appeared as odorous fumes at the dryer. Conditions for hydrolysis were favorable at upstream locations because of temperature and acidity conditions and the residence time available in the process. Also, the water for the hydrolysis was provided by another water-based chemical additive used in the dryer line that had the odor problem.
Because the cause of the odorous emission was the process chemistry, the plant had to evaluate ways to minimize hydrolysis and the resulting formation of odorous products. Ventilation modifications to mitigate the odor levels would not be a long-term solution to the odor problem.
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