关键词: 燃气热电机组, 低压缸空载, 最小进汽量, 热调峰, 供热经济性, 㶲效率, 直接空冷

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