Site-wide process integration for low grade heat recovery

Abstract

Large quantities of unrecovered low-grade heat are wasted across the process industry. Wide range of technologies and design options for recovering low grade heat are available, including heat pumps, organic Rankine cycle (ORC), energy recovery from gas turbine exhaust, absorption refrigeration, and boiler feed water heating. However, it is not straightforward to identify the most appropriate technology to be implemented, due to complex design interactions inside energy systems in process industry. Process integration of technologies using low-grade heat in the context of a process site has been considered. Simulation model for heat recovery processes has been developed to evaluate techno-economic performance of each technology and to assess the impact of quality and quantity of available low-grade heat sources on the site. Site-wide potential for the utilization of low grade heat has been evaluated with site analysis tool, and the integration of design options for using low-grade energy are systematically screened and compared in a holistic manner. A case study has been carried out to demonstrate the applicability of design methodology proposed in this work and significant benefits of using an integrated approach when implementing low-grade energy upgrading and/or recovery in the context of industrial application.