A Disjunctive Programming Approach for Optimizing Carbon, Hydrogen, and Oxygen Symbiosis Networks

Recently, the synthesis of carbon–hydrogen–oxygen symbiosis networks (CHOSYNs) has been proposed for the multi-scale integration of process industries that deal mainly with hydrocarbons while enabling chemical reactions, separation, heating/cooling, pressurization/depressurization, and allocation of the participating streams and species. Because of the complexity of the design problem, there is a need for efficient optimization approaches to solve the problem. In this paper, two optimization approaches are presented based on disjunctive programming. Several objective functions are used to target resource conservation (e.g., minimum fresh usage and minimum waste discharge) and economics (e.g., minimum cost, maximum profit). The optimization formulations include the tracking of species and streams, the potential installation of industrial facilities to carry out chemical conversions and other tasks, and the allocation of streams from sources to sinks via newly added interceptors. The first approach is a two-stage mathematical programming method. In the first stage, an optimization model based on atomic balances is used to determine the targets for fresh resources and discharges of the system. In the second stage, a disjunctive optimization model with an economic objective is employed to determine the configuration and allocation of the network considering existing and new industrial plants involved in the eco-industrial plant. The second approach is a simultaneous method based on a disjunctive optimization model to determine the targets and network configuration. A case study is presented to show the applicability of the proposed approaches.