Applied Chemical Engineering

Low-grade heat utilization for combined cycle power plants using organic rankine cycle

Igor Maksimov

Department of Innovative Technologies for High-Tech Industries, National Research University "Moscow Power Engineering Institute”, Moscow, 111250, Russia

Roman Zuikin

Department of Innovative Technologies for High-Tech Industries, National Research University "Moscow Power Engineering Institute”, Moscow, 111250, Russia

Nikita Bonadykov

Department of Innovative Technologies for High-Tech Industries, National Research University "Moscow Power Engineering Institute”, Moscow, 111250, Russia

Valeria Zhikhareva

Department of Innovative Technologies for High-Tech Industries, National Research University "Moscow Power Engineering Institute”, Moscow, 111250, Russia

Polina Golosova

Department of Innovative Technologies for High-Tech Industries, National Research University "Moscow Power Engineering Institute”, Moscow, 111250, Russia

DOI: https://doi.org/10.59429/ace.v7i4.5564

---

Abstract

This paper presents a comprehensive thermodynamic analysis of trinary power plants, focusing on the efficiency of Organic Rankine Cycle (ORC) configurations and regenerative heating methods. Despite advancements in nuclear and renewable energy, fossil fuels still dominate electricity generation, necessitating improved efficiency in existing power plants. The study reveals that low-pressure mixing-type heaters provide higher efficiency compared to surface heaters, with net efficiencies of 0.099%, 0.227%, and 0.425% at deaerator pressures of 0.12, 0.3, and 0.7 MPa, respectively. The analysis highlights the impact of feedwater temperature on the thermal efficiency of steam turbine units (STUs), noting that while optimal feedwater temperatures enhance efficiency, they can reduce STU capacity. The study identifies configurations for regenerative heating that optimize exhaust gas temperatures, facilitating additional electricity production through a low-boiling working fluid in the ORC. The findings indicate that R245fa refrigerant is optimal for ORC without recuperative heater, achieving maximum net power at a feedwater temperature of 115°C. For ORC with a recuperative heater, R236ea is preferred for temperatures between 115°C and 154.5°C, while R245fa is optimal for higher temperatures. The results also demonstrate that trinary power plants with recuperators achieve greater efficiency and net capacity compared to double-circuit systems, with notable improvements in thermal efficiency attributed to effective regeneration schemes. This research underscores the potential for optimizing existing domestic power units to enhance their efficiency and performance without significant financial or technical burden, thereby contributing to more sustainable energy generation.

---

References

[1]. IEA Electricity 2024 - Analysis and forecast up to 2026 - 2024

[2]. Guyol N.B. The World Electric Power Industry - Univ of California Press, 2023. - 560 pp.

[3]. Morimoto K., Matsumura Y., Iijima T., Wakazono S., Kataoka M., Yuri M. Validation Results of 1650°C Class JAC Gas Turbine at T-point 2 Demonstration Plant. — 2021. — Vol. 58. - No. 1. - P. 12.

[4]. Jansohn P. Modern Gas Turbine Systems: High Efficiency, Low Emission, Fuel Flexible Power Generation. Modern Gas Turbine Systems - Elsevier, 2013. - 849 pp.

[5]. Boyce M.P. Gas Turbine Engineering Handbook. — 2nd ed. - Boston, MA: Gulf Professional Publ, 2002. - 799 p.

[6]. Kindra V., Rogalev N., Osipov S., Zlyvko O., Naumov V. Research and development of triple energy cycles // Inventions. - 2022. - Vol. 7. — No. 3. — P. 56. 7. Kindra V.O. et al. Trinary energy cycles for highly efficient production of electricity from fossil fuels // New in Russian electric power industry. 2022. No. 4. P. 7–25 .

[7]. Choudhary N.K., Hankari G., Karmakar S. Waste heat recovery using organic Rankine cycle from pulverized pressurized combined cycle power plant // Transactions of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy. — 2024.

[8]. Macchi E., Astolfi M. Organic Rankine cycle (ORC) power systems: technologies and applications. - Woodhead Publishing, 2016.

[9]. Comparative analysis of supercritical CO2–ORC combined cycle for gas turbine waste heat recovery based on multi-objective optimization // Applied Thermal Engineering. — 2024. — Vol. 236. - P. 121776.

[10]. Antanenkova, I.S. and Vetrenko, A.A. (2020). Thermodynamic analysis of the cycle efficiency of the utilization units for gas transmission systems. Journal of Physics Conference Series, 1565(1), pp.012034–012034.doi:https://doi.org/10.1088/1742-6596/1565/1/012034.

[11]. Bălănescu D.-T., Homutescu V.-M. Performance analysis of a gas turbo combined cycle power plant with waste heat recovery in Organic Rankine Cycle // Procedia Manufacturing. — 2019. — Vol. 32. - P. 520-528.

[12]. Kindra V., Rogalev N., Rogalev A., Naumov V., Sabanova E. Thermodynamic optimization of low-temperature cycles for thermal power engineering // New in Russian electric power engineering Founders: Information agency "Energo-press". - No. 5. - P. 6-30.

[13]. Naumov V., Osipov S., Zlivko O., Kindra V. UTILIZATION OF LOW-POTENTIAL HEAT IN THE BRIGHTON AND RANKINE CARBON DIOXIDE CYCLES // Energy Saving - Theory and Practice. - 2022. - P. 19-25.

[14]. Welcome to CoolProp - CoolProp 6.6.0 documentation. - URL: http://www.coolprop.org/ (accessed 2024-10-31).