Availability analysis of waste -water recovery systems

The objective is to evaluate the energetic and entropic characteristics of the components of waste-water recovery systems that can be used in varying applications such as enclosed life support systems or industrial waste-water treatment processes. Techniques and methods that are used to evaluate these characteristics have been developed to model and analyze these systems.;Availability analysis and pinch analysis are used to study the behavior of these systems in order to increase the efficiency of useful energy utilization, and therefore reduce the energy consumption and utilities loads. The availability analysis method, which is a combined first law and second law analysis method, can locate the irreversibility of the system components. The irreversibility of the components may be reduced and entropically optimal systems may be designed using availability analysis. Pinch analysis is an easy and effective method to analyze and optimize heat exchanger networks. The pinch analysis results for the heat exchanger network are used by the availability analysis to evaluate the entire system behavior. The integrated method will be more effective than either of these two methods.;A generic model is established for treating waste-water containing solids, organic and inorganic contaminants using vapor compression distillation and gas-phase oxidation reactions. Solids and non-volatile species are removed by vapor compression distillation. Volatile organic and inorganic contaminants are destroyed by chemical oxidation reactions in the vapor phase. Because of the diversity of waste-water, it is unrealistic to list all possible contaminants in the waste-water stream. A simplified waste-water stream containing water, methanol, ammonia and sodium chloride is used in this study. Methanol represents the volatile organic species in waste-water, ammonia represents inorganic contaminants, while sodium chloride represents dissolved solids.;Material and energy balances as well as the values of lost work and the second law efficiency of the components of this model under various operating conditions are computed and evaluated. The irreversibility of the components may be reduced and entropically optimal systems may be designed. The limiting relationships between contaminant level and energy consumption are obtained based on the results of the analysis.