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直接空冷凝汽器在高空中受环境风的影响,容易出现热风回流和倒灌等问题,影响机组的安全与经济运行,为此提出了空冷岛地下进风方式。以某600 MW直接空冷机组为例,建立空冷岛地下进风的物理模型,利用Fluent软件,采用Simple算法和标准k-ε模型,对采用两风道地下进风布置方式的空冷岛周围空气流场和温度场进行数值模拟;计算了地上、地下进风的空冷岛通风量,分析了在主导风向下风速对直接空冷凝汽器换热效率及压力的影响。计算结果表明:在有环境风的条件下,空冷岛地下进风方式的凝汽器工作性能优于地上进风,在任何风速下都没有出现热风回流和倒灌;在同等条件下,当环境风速大于4 m/s时,地下进风的通风量较地上进风大,换热效率较地上进风高,当风速超过8 m/s后,凝汽器压力比地上进风低7~11 kPa。
Direct air-cooled condenser in the air by the impact of the environment, prone to hot air backflow and backflow and other issues that affect the safety and economic operation of the unit, air-cooled island for this proposed underground approach. Taking a 600 MW direct air-cooled unit as an example, a physical model of ground air entering the air-cooled island was established. By using the FLUENT software and Simple algorithm and standard k-ε model, the air flow around the air-cooled island Field and temperature field are simulated. The ventilation rate of air-cooling island above and below ground is calculated. The effect of wind speed on the heat transfer efficiency and pressure of direct air-cooled condenser under the prevailing wind direction is analyzed. The calculation results show that under the conditions of ambient wind, the working performance of the condenser with air-in-ground approach is better than that of the ground air, and no hot air backflow and backflow occur at any wind speed. Under the same conditions, when the ambient wind speed When the air velocity exceeds 8 m / s, the condenser pressure is 7 ~ 11 kPa lower than that of the ground air when the air velocity is higher than 4 m / s. .