Electric Power ›› 2021, Vol. 54 ›› Issue (6): 104-110.DOI: 10.11930/j.issn.1004-9649.202101041

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Analysis on Thermal Peak Shaving and Economic Performance of Gas-Fired Unit

LIU Jiale, MA Suxia, MA Honghe, ZHANG Lifang   

  1. College of Electrical and Power Engineering, Taiyuan University of Technology, Taiyuan 030024, China
  • Received:2021-01-08 Revised:2021-04-02 Published:2021-06-05
  • Supported by:
    This work is supported by the National Key Research and Development Program of China (The Key Technologies for Clean & High-Efficient Combustion of Low Calorific Coal and Resource Utilization and Flexible Generating, No.2020YFB0606300)

Abstract: Generally, low-pressure cylinder transformation with no-load heating are implemented in many cogeneration units to ensure heat supply in winter season. In this paper, in order to study the no-load heating performance of low-pressure cylinder under limited natural gas supply and different back pressures, by taking a gas-steam combined cycle unit as the study object, the safe regulation range of no-load heating is determined based on the calculation of the minimum steam intake of low-pressure cylinder under different back pressures. Moreover, an exergy analysis model is established for the energy system including heat supply, low-pressure cylinder power, cold source losses and the power consumption of auxiliary equipment to comprehensively evaluate the heating economy of low-pressure cylinder under no-load operating conditions. The results show that the reduction of back pressure is beneficial to the improvement of the maximum heating output and thermal peak shaving capacity of the unit under low power loads. At the same time, the energy system of low pressure cylinder can also achieve higher exergy efficiency.

Key words: gas-fired thermoelectric unit, no-load operation of low-pressure cylinder, minimum steam flow, thermal peak shaving, heating economy, exergy efficiency, direct air-cooling