Application of Exergy Concept to Deodorization Process Using Soil Cover

Abstract

Exergy of air including odorous gas components was considered in order to decide the optimum air flow rate for filtering odorous gas components by soil cover. Filtering odorous gas components gives a comfortable feeling to man. It means that the purer air has a higher quality for human life and the cleanliness of the air is related to the exergy which shows the degree of quality of every kind of energy. From the above view point, the author defined the exergy of air under deodorization process regarding the raw air exhausted from stock farming as being at the standard condition. The difference between the exergy of pure air and that of raw air expresses difference in quality, and this difference is related to the odor intensity of the raw air. From the results of an NH₃-air system for example, there seemed to be a non-linear relation between the exergy of air containing odorous gas components and its odor intensity. The overall efficiency of the deodorization process ε was shown to be a product of exergy efficiency η and the effectiveness of soil bed use as a medium for deodorization ζ. Based on the overall efficiency of the deodorization process, the optimum flow rate of raw air was estimated to be proportional to the rate of deodorization for the NH₃ filtering process. On the other hand, the optimum flow rate of raw air seemed to depend on the reaction rate constant k_B and the overall mass transfer coefficient Ka for the H₂S filtering process.