Optimal Design Of Water-Using Networks With Multiple Contaminants

Water resource plays an important role in process industries and it is one of key factors of sustainable development. The scarcity of water resource and the severity of environmental Pollution draw close attention of society to the research on the optimal design of water-using network. Process Integration techniques provide a systematic approach for the research on optimizing design for water-using network. On the basis of analyzing the methods of water-using network integration presented in the literature, this paper does further research on the design of water-using network with multiple contaminants, and new design methods are also developed. The main contents are listed as follows:Firstly, based on the concept of the concentration potentials of demand and source streams, a heuristic procedure is proposed to design water-using networks with multiple contaminants. The concentration potential of a demand stream reflects the possibility of the stream to reuse the source streams, and the concentration-potential of a source stream reflects the possibility of the stream to be reused by the demand streams. The method of calculating concentration potentials in the literature is improved to develop a simple approach to solve the design problem for the water-using networks with multiple contaminants involving reuse of source streams to demand streams. The processes should be performed in ascending order of CPDs. The results show that the method proposed can give excellent designs whose freshwater consumptions are very close to the target values.Secondly, On the basis of NNA presented by Prakash and Shenoy and the calculation method of concentration potentials presented above, a design method for water-using networks with multiple contaminants involving multiple resources is proposed. The fact that both the optimize design and the flowsheet of the network can be obtained simultaneously during the calculation of the target(s) is proved by examples Thirdly, the concept of concentration potentials is incorporated with mathematical programming to design the water-using networks with multiple contaminants. The performing order of water-using processes should be determined by their CPDs. A mathematical model is established with boundary conditions for the water-using unit. The model can be solved by non-linear mathematical programming.