Thermodynamic Comparison of the Steam Ejectors Integrated at Different Locations in Cogeneration Systems

Shifei Zhao (), Chunlan Wang, Fan Duan and Ze Tian
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Shifei Zhao: School of Energy and Power Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, China
Chunlan Wang: School of Energy and Power Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, China
Fan Duan: School of Energy and Power Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, China
Ze Tian: School of Energy and Power Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, China

Energies, 2024, vol. 17, issue 11, 1-18

Abstract: Under the challenge of global energy transition, coal-fired cogeneration systems are undergoing a technical revolution towards enhanced efficiency, heating capacity, and flexibility. In this paper, four schemes using a steam ejector integrated into a cogeneration system are designed. Considering operational safety, integrated locations are selected at the front and back of high- and medium-pressure turbines. Subsequently, the thermodynamic and operational characteristics under both design and off-design conditions are analyzed based on a model built in EBSILON Professional. Finally, a sensitivity analysis of the heating process is conducted. The results show that the integration of steam ejectors can increase the waste heat recovery ratio of exhaust steam by 18.42–45.61% under design conditions. The largest waste heat recovery ratio is obtained in System 4, resulting in the power generation efficiency ( η g ) and gross energy utilization efficiency ( η p ) of 81.95% and 65.53%, respectively. Meanwhile, the steam ejector can expand the power-load regulation range of the cogeneration system, and System 4 has the lowest lower power limit among all the systems. The η p values of Systems 1–4 reach extreme values at different mixed steam pressures of the ejector. Increasing the pinch point temperature difference reduces the power load η g and η p of Systems 1–4. The results provide technical solutions for improving the heating capacity and efficient and flexible operation of cogeneration systems.

Keywords: waste heat recovery; cogeneration system; steam ejector; thermodynamic performance; sensitivity analysis (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2024
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