Basic design of an ORC demonstrator system for implementation in an Iron & Steel plant through the DECAGONE project

Abstract

Waste heat recovery (WHR) technologies offer great opportunities for improving energy efficiency and reducing CO2 emissions for energy intensive industrial processes. The DECAGONE project is developing an innovative ORC-based WHR system to be demonstrated in an iron & steel plant located in the Czech Republic. The design of the ORC system considers the practical site-specific conditions and limitations, such as variations in heat source conditions, heat sink availability, and size and space limitations for the ORC components. Various cycle configurations are compared with a thermodynamic optimization model for maximizing the net power output subject to the process constraints, including (1) recuperative vs. non-recuperative designs, (2) air vs. water as heat sink and (3) direct vs. indirect evaporation. The recuperative cycle with indirect evaporation and direct air condensation is deemed the most suitable solution for the project site conditions. The results provide recommendations for performance improvement and indications for performance subject to practical plant operating conditions, such as large range of temperature and flow rate of waste heat source. Analyses in this work provide the basis for detailed component design and decision processes towards finalizing the design of the demonstrator.