Design Of Water Networks Involving Two Regeneration Units

With the development of society,the water requirement increases significantly. Water pollution is becoming more and more serious. As an important technique for freshwater saving and wastewater emissions reducing, water network integration attracts growing attention. Compared to the water-using network involving reuse/recycle only, when the regeneration units is introduced in a water network, both freshwater consumption and wastewater discharge can be reduced significantly. In this thesis, we research the design of water networks involving two regeneration units mainly.Chapter One: The research background and the main contents are briefly discussed,and a brief review of the design methods of water networks are displayed.Chapter Two: In this chapter, we discuss two models of regeneration units, and give a brief introduction to the connection structures of the regeneration units, series and parallel connection. The design procedure includes the following steps:(1) estimating the initial regeneration concentration of two regeneration units,(2) allocating source streams to demand streams,(3) obtaining the regeneration concentrations after an iteration,(4)checking the convergence by comparing the two adjacent regeneration concentrations.Chapter Three: In this chapter, by using the iterative method in the literature, a detail design process is given to design the network involving one regeneration unit, and it is the basis of Chapter Four.Chapter Four: By using the concepts of concentration potential and the iterative method, a detail procedure is given to design a water network of multiple contaminants involving two regeneration units. In order to start the iterative calculation, the initial concentrations of the regeneration streams are estimated for both series connection and parallel connection. Allocating source streams to demand streams, identifying the performing order and the concepts of concentration potentials are used as numerical indicator. When an iteration is completed, the concentrations of regeneration streams are calculated based on concentration potential values of the source streams.Chapter Five: A new graphic method is proposed. One of the literature method of the literature graphic methods is that they cannot deal with the networks in which the regeneration concentration is higher than the concentration of the demand which is justhigher than the freshwater. In the proposed method, the processes are divided into three groups: the processes using freshwater only; the processes using both freshwater and regenerated water, and the other processes. The relationships between these groups are analyzed, and a new graphic method is proposed based on the above analysis. The proposed method can be used to identify the regeneration water target for the network in which the regeneration concentration is higher than the concentration of the demand which is just higher than the freshwater.