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Energy conservation in the petrochemical sector holds the key to its financial viability. The pervasive application of Heat Exchanger Networks (HEN) exemplifies the industry's efforts in heat recovery. Yet, despite its widespread adoption, an alarming quantum of low-grade heat remains squandered, underscoring the potential for augmenting energy savings through more effective utilization of this heat. Recognizing the pivotal role of the synergistic interaction between the process and the heat recovery system in maximizing energy retrieval, an innovative approach is proposed. This methodology initially entailed the development of a process model and an enhanced heat recovery system, the latter embodying the integration of an organic Rankine cycle (ORC) with HEN. Subsequently, a strategic diagnostic was proposed to incorporate these sub-systems into a cohesive, optimisation framework. Following this, an array of energy, exergy, and economic analyses were conducted to appraise the system's performance. The findings suggest a considerable improvement in heat recovery and an amplification in ORC efficiency from a mere 7.64%–11.38%. The enhanced heat recovery further translated into a reduced need for cold utility, thereby minimizing cooler deployment. Given the substantial exergy destruction associated with coolers, their lesser usage bolstered the system's exergy efficiency. Moreover, the optimised ORC manifested in heightened net power generation, consequently elevating electricity revenues. Despite a nominal surge in equipment costs, the aggregate profit witnessed a substantial hike from 165.19 M$/year to 178.79 M$/year. The proposed system substanitally improved thermodynamic and economic performance. This study offers valuable guidance for the design and operation of petrochemical industries, serving as a roadmap to energy conservation and enhanced profitability. • A new simultaneous optimisation framework proposed. • Interactions between process and heat recovery system considered. • Stream classification strategy applied to connect the ANN and MINLP models. • Process operating conditions and layouts of HEN optimised. • Energy, exergy and economic analyses used to evaluate system performance. [ABSTRACT FROM AUTHOR]

Thermochemical energy storage offers a cost-effective and efficient approach for storing thermal energy at high temperature (∼1100 °C) for concentrated solar power and large-scale long duration energy storage. SrCO 3 is a potential candidate as a thermal energy storage material due to its high energy density of 205 kJ/mol of CO 2 during reversible CO 2 release and absorption. However, it loses cyclic capacity rapidly due to sintering. This study determined that the cyclic capacity of SrCO 3 was enhanced by the addition of either reactive SrTiO 3 or inert SrZrO 3 , where the molar ratios of SrCO 3 to SrZrO 3 were varied from 1:0.125 to 1:1. Thermogravimetric analysis over 15 CO 2 sorption cycles demonstrated that both materials retained ∼80 % of their maximum cyclic capacity on the milligram scale. Repeated measurements using gram scale samples revealed a decrease in maximum capacity to 11 % using a sample of SrCO 3 – 0.5 SrZrO 3 over 53 cycles, while the use of SrTiO 3 additives allowed for the retention of 80 % maximum capacity over 55 cycles. These findings highlight the potential of reactive additives in enhancing the performance of thermochemical energy storage systems, while providing valuable insights for the development of cost-effective materials. [Display omitted] • SrCO 3 is a cost-effective thermochemical energy storage material. • TGA shows both SrZrO 3 and SrTiO 3 additives increase cyclic capacity up to ∼80 %. • SrTiO 3 reduces sintering whereas SrZrO 3 does not prevent sintering. [ABSTRACT FROM AUTHOR]