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Waste heat accounts for up to 70% of input energy in industrial processes which enunciates the importance of energy recovery measures to improve efficiency and reduce excessive energy consumption. A portion of the energy can be recovered within the process, while the rest is rejected to the environment as unavoidable [1] waste; therefore, providing a large opportunity for organic Rankine cycle (ORC)s which are capable of producing electricity from heat at medium-low temperatures. These cycles are often regarded as one of the best waste heat recovery measures but industrial applications are still limited due to the lack of comprehensive methodologies for their integration with processes. As such, this work proposes a novel and comprehensive superstructure optimization methodology for ORC integration including architectural features such as turbine-bleeding, reheating, and transcritical cycles. Additional developments include a novel dynamic linearization technique for supercritical and near-critical streams and calculation of heat transfer coefficients. The optimization problem is solved using a bi-level approach including fluid selection, operating condition determination and equipment sizing and is applied to a literature case study. The results exhibit that interactions between these elements are complex and therefore underline the necessity of such methods to explore the optimal integration of ORCs with industrial processes. [ABSTRACT FROM AUTHOR]

Efficient consumption of energy and material resources, including water, is the primary focus for process industries to reduce their environmental impact. The Conference of Parties in Paris (COP21) highlighted the prominent role of industrial energy efficiency in combating climate change by reducing greenhouse gas emissions. Consumption of energy and material resources, especially water, are strongly interconnected and, therefore, must be treated simultaneously using a holistic approach to identify optimal solutions for efficient processing. Such approaches must consider energy and water recovery within a comprehensive process integration framework which includes options such as organic Rankine cycles for electricity generation from low–medium-temperature heat. This work addresses the importance of holistic approaches by proposing a methodology for simultaneous consideration of heat, mass, and power in industrial processes. The methodology is applied to a kraft pulp mill. In doing so, freshwater consumption is reduced by more than 60%, while net power output is increased by a factor of up to six (from 3.2 MW to between 10–26 MW). The results show that interactions among these elements are complex and therefore underline the necessity of such comprehensive methods to explore their optimal integration with industrial processes. The potential applications of this work are vast, extending from total site resource integration to addressing synergies in the context of industrial symbiosis. [ABSTRACT FROM AUTHOR]