燃气锅炉排放的烟气中含有大量的水蒸气，因排烟温度未能降到露点以下而无法有效回收水蒸气的冷凝潜热。本文采用压缩式热泵与低温空预器相结合的方式深度回收燃气锅炉烟气余热，主要研究了在不同过量空气系数下供热回水流量和供热回水温度对排烟温度、余热回收效率、热泵机组制热性能系数及水蒸气冷凝率的影响。研究结果表明：在过量空气系数为1、供热回水流量为80 t/h条件下，热泵可将供热回水温度从50.0 ℃提升至65.1 ℃，其制热性能系数为4.25；空气进、出低温空预器的温度分别为-3.8 ℃和33.0 ℃，流量为15 360 m3/h时，排烟温度从90 ℃降至20 ℃，烟气余热回收效率达到14.8%；以29 MW的燃气锅炉为研究对象，按供热面积为5.2×105m2，供暖151天计算，烟气中回收的冷凝水量为8 000 t，占锅炉补水量的54.1%；该余热回收系统的投资回收期为2.1年，压缩式热泵烟气余热回收系统节能效果显著。

The flue gas emitted by the gas boiler contains a large amount of water vapor, and the condensation latent heat of water vapor cannot be effectively recovered due to the failure of the exhaust gas temperature to fall below the dew point. In this paper, the compressed heat pump combined with low temperature air preheater is used to recover the flue gas waste heat of gas boiler in depth. The effects of heating return water flow rate and heating return water temperature on flue gas temperature, waste heat recovery efficiency, heating performance coefficient of heat pump unit and condensation rate of water vapor under different excess air coefficients are mainly studied. The results show that when the excess air coefficient is 1 and the return water flow rate is 80 t/h, the heat pump can increase the return water temperature from 50 ℃ to 65.1 ℃, and the heating performance coefficient is 4.25; when the air inlet and outlet temperatures of the low-temperature air preheater are -3.8 ℃ and 33.0 ℃ respectively, and the flow rate is 15 360 m3/h, the exhaust temperature drops from 90 ℃ to 20 ℃, and the flue gas waste heat recovery efficiency reaches 14.8%; for a 29 MW gas boiler with a heating area of 5.2×105 m2 and 151 days of heating, the amount of condensate recovered from flue gas is 8 000 tons, accounting for 54.1% of the boiler water replenishment rate; the payback period for this waste heat recovery system is 2.1 years. The flue gas waste heat recovery system of compressed heat pump has a significant energy saving effect.

TK11+5

国家自然科学基金项目（51806093）；兰州市城关区科技计划项目（2021JSCX0046）；甘肃省教育厅产业支撑计划项目（2021CYZC27）