(58f) Optimization of Direct Recycle Networks Considering Property, Mass, and Thermal Effects

Abstract: Direct recycle strategies are used to reduce the consumption of fresh raw materials and waste discharged by any process. These strategies lead to conservation of resources, reduction of negative environmental impact, and enhancement of sustainability. There is a growing need to develop systematic and cost-effective design strategies in order to achieve this goal. Traditionally, most of the previous research efforts in the area of designing direct-recycle networks have considered the chemical composition as the basis for major constraints for direct recycle. However, there are many design problems that are not component based, but they are property based (e.g., pH, density, viscosity, COD, BOD, toxicity). Additionally, thermal constraints (e.g., stream temperature) may be required to identify acceptable recycles. In this work, we introduce a novel approach to the design of recycle networks while accounting for mass, thermal, and property constraints. This methodology is unique because it solves mass and property integration simultaneously, while observing thermal constraints and considering their impact on mass and property integration. An optimization formulation is developed to embed all potential configurations of interest and to model the mass, thermal, and property characteristics of the targeted streams and units. Solution strategies are developed to identify stream allocation and targets for minimum fresh usage and waste discharge. A case study will be presented to illustrate the concept of the proposed approach, its computational aspects, and its future extensions.