Multiobjective optimization of industrial water networks with contaminants

摘要

This paper presents a multiobjective MILP formulation for optimizing industrial waterrnnetworks. By expressing balance equations in terms of partial mass flows instead ofrntotal mass flows and concentrations, and because the contaminant mass flow (ppm) isrnvery small compared to the water mass flow (T.h~(-1)), the problem becomes linear. Therninteger variables are related to the interconnections into the network. The biobjectivernoptimization of the fresh water flow rate at the network entrance and the water flow raternat regeneration unit inlets, parameterized by the number of interconnections, is carriedrnout according to a lexicographic procedure. A monocontaminant network involving tenrnprocesses and one regeneration unit illustrates the approach. Even if the results arernspecific, the methodology guide can be applied to a large panel of networks. On the onernhand, this example shows that the Pareto front is a straight line where each point is arnfeasible solution, when the number of connections is maximal (120). On the other hand,rnthe Pareto front is reduced with the number of connections (11) and constituted byrnisolated points located mainly on a straight line with the same slope as for 120rnconnections, but no feasible solution exists between these points.