Decarbonisation Technology - February 2025 Issue

exhaust heat to generate carbon-free electricity while simultaneously replacing the overhead condenser, used in the typical layout of the chemical plant. This dual functionality makes the system both efficient and cost-effective. The ORC is fully integrated with the customer’s process but does not interfere with chemical manufacturing operations, ensuring no impact on PET production capacity or rates, even during start-up and shutdown phases. The electricity generated by the ORC plant is employed for internal consumption, meeting 20% of the factory’s energy needs. The plant has been operating since October 2023. It is estimated to contribute to an annual CO₂ emissions reduction of approximately 20,000 tons, also avoiding the consumption of 8,500 tons of oil equivalent per year by replacing electricity from fossil fuels. The plant underwent a technical evaluation by an external committee of academicians from the Chinese Academy of Engineering and senior engineers from independent engineering companies. The evaluation highlighted an impressive thermoelectric efficiency of 11.22% and an isentropic turbine efficiency of 88.69%. Return on investment An ORC waste heat recovery system installation in the industrial sector has a typical payback time of four to eight years depending on variables such as the electrical output of the ORC required, the plant configuration, the selling price of electricity and others. Incentives like carbon credits and additional premiums for saved CO₂ emissions can further shorten this period. For the Sanfame project, the waste heat recovery system demonstrates an advantageous payback time, expected in three years. Conclusion Waste heat recovery systems are proven solutions for reducing the environmental impact and energy costs of energy-intensive industries. By decreasing reliance on fossil fuels, these systems also significantly cut carbon emissions, covering up to 30% of industrial energy needs. VIEW REFERENCES Sara Milanesi s.milanesi@exergy.it

for quick and simple maintenance without fluid draining. • Reduced rotation speeds, compatible with direct coupling to a generator. Case study: Sanfame ORC waste heat recovery project Jiangyin Xingjia New Material Co., part of the Sanfame Group, active in the chemical industry and polyester chemical fibre production, sought a low-carbon technology solution for a new greenfield polyethylene terephthalate (PET) manufacturing site of two production lines, each with a capacity of 750,000 tons per year. Sanfame selected Exergy’s ORC technology to achieve its sustainability goals. The plant comprises two ORC units, each rated at 2.9 MWe, for a total installed power of 5.8 MWe (see Figure 5 ). These units recover heat at 102°C from saturated polyester steam at the top of the stripping column and from the non-condensable gas (NCG) stream generated by the production process. This installation represents the highest power generation capacity ORC technology applied to the polyester industry. The process steam flow and NCG are directed to the heat exchangers of the ORC system, which transfer the heat from the primary source to the organic working fluid of the ORC cycle. As the organic fluid heats up, it vaporises and passes through Exergy’s high-efficiency ROT turbine, generating electricity. The solution designed by Exergy provides a dual advantage: the ORC system repurposes Figure 5 Overview of Exergy’s ORC waste heat recovery installation at Sanfame’s chemical plant