Application of Water Source Diagram for Multiple Sources and Multiple Contaminants Processes

摘要

The minimization of the use of water source and, therefore, the reduction of effluent generation, has been an increasing concern in the chemical industry. Because of that, heuristical algorithms have been developed trying to supply systemic approach to the mass transfer network optimization's problem. The main objective of these heuristical algorithms is to get a mass transfer network [1], where contaminants of rich streams are transferred to other poor streams, in an optimized structure of linked mass transfer operations. This optimization is measured in terms of pure or low concentration water source consumption, in relation to a structure in which only these sources are used. In this network, the streams have a maximum inlet and outlet concentrations to be respected, which characterizes mathematical restrictions in an optimization context. These restrictions make the best solution attainment difficult. A distinguished method to attainment mass transfer networks is the Water Source Diagram (WSD). This method uses hand calculations being, particularly, a useful tool for processes engineers. From WSD, it is possible to consider a variety of situations as reuse, multiple water sources, loss of water throughout the process, outflow restrictions, regeneration and recycle [2]. The WSD has resulted satisfactory solutions for the single contaminant case [2]. For the multi-contaminant one, a similar approach increased of the mass transfer ratio concept has been proposal. This approach was used in some simple cases [2], revealing it satisfactory. However, its application is still necessary in complex cases to prove the method's robustness and efficiency. The aim of the present work is to apply the Water Sources Diagram methodology, as well as a proposal variation, in multiples contaminants and multiple water sources problems, to compare its results with more complex approaches presented in literature. As a base case it was used the solution proposed by Jin-Kuk Kim [3] to the problem proposed by Alva-Argaez[4]. The results obtained from WSD methodology was about 1% higher than base case in terms of mass flow used and about 5% in terms of costs. Considering the difference in complexity between the methodology used in the base case and the one presented in this study, we can concluded that WSD generate satisfactory results with less work, becoming very useful to problems that requires fast solutions and as a initial estimation in more complex ones.