Modeling and Economic Assessment of Organic Rankine Cycle Integration into an Inter-Plant Heat Exchanger Network

Abstract

Establishing energy-based industrial symbiosis networks (EISNs) through inter-plant heat integration is a collaborative energy efficiency initiative to reduce industrial energy consumption. Its benefits can be improved by incorporating an organic Rankine cycle (ORC) into an inter-plant heat exchanger network (HEN) to generate electricity from waste heat. In this study, a novel nonlinear programming (NLP) model is formulated for inter-plant HEN-ORC integration optimization. This model reduces the combinatorial complexity of conventional mixed-integer nonlinear programming (MINLP) models and improves the accuracy of total EISN cost computation by using chemical engineering plant cost indices (CEPCIs) to adjust capital cost values to a common time based on the year when the cost correlations have been derived. Furthermore, this study also proposes a Shapley value-based methodology to ascertain whether joining in inter-plant HEN-ORC integration would be economically advantageous for each prospective participant. The model and methodology have been applied to two case studies to demonstrate their effectiveness in generating practicable insights. Results show that the difference in the process stream supply temperatures of the heat source and sink plants can influence the economic viability of inter-plant heat integration. Furthermore, the results show that installing an ORC plant into an inter-plant HEN can increase the EISN’s economic viability, with the magnitude of the hot utility prices and the difference between them greatly influencing the economic benefits of the heat sink plants’ participation. Overall, the proposed model and methodology have been demonstrated to yield realistic insights on the cost-effectiveness of inter-plant HEN-ORC integration.

Keywords: heat integration, industrial symbiosis, mathematical programming, waste heat recovery, organic Rankine cycle, Shapley value