燃煤火电机组直接空冷凝汽器运行时，环境风速、环境温度等对三角腔内空气与热蒸气的对流换热均有重要影响，从而影响机组运行稳定性。通过三维流场模拟方法，以某600 MW机组单列/单个空冷单元为例，研究了典型环境参数下的空冷凝汽器换热性能，提出了一种在三角腔内加装夹角可调的“羽翼型”实心/多孔导流板的流场优化技术方法。结果表明：单列凝汽器受环境风效应影响，空气进口方向第1个位置的空冷凝汽器平均空气流量受环境风速影响最大；当环境风速从3 m/s增加到9 m/s时，单列（8个空冷单元组成）空冷凝汽器平均空气流量下降约590 kg/s,说明高风速会增大三角腔内空气扰动不利换热，采用凝汽器三角腔体内加装实心板/多孔板的方式对流动涡旋整流效果明显；进而通过调节2片导流板夹角至240°，三角腔内静压平均提升了153 Pa，可有效缓解冬季换热管束底部冻结现象。该类加装导流装置的直接空冷凝汽器适用环境工况范围相对较广，有利于在实际工程中实现高温防阻、低温防冻、运行稳定的作用。

In coal-fired power plants,the ambience wind speed and ambient temperature play an important role in determining the convective heat transfer between the cooling air and hot steam in the triangular cavity of the direct air-cooled condenser. Thus affecting the operational stability of the unit. In this paper,taking 600 MW unit single row/single air-cooled unit as an example,the performance of the direct air-cooled condenser was investigated by means of three-dimensional CFD under varied ambience conditions. Moreover,a novel "wing-type" solid/porous deflect plate with the adjustable angle in the triangular cavity to optimize the flow field of the condenser was proposed. The simulated results indicate that:the single row condenser is affected by the ambient wind effect,and the average air flow rate of the air condenser at the first position in the air inlet direction is most affected by the environmental wind speed. When the environmental wind speed increases from 3 m/s to 9 m/s,the average air flow rate of single column (consisting of 8 air cooling units) air condenser decreases by about 590 kg/s,indicating that the air disturbance increase and the heat transfer is unfavorable in the triangular cavity with high wind speed. The method of adding solid plate/porous plate in the condenser triangle cavity has obvious rectifying effect on the flow vortex generated in adverse environment. Besides,by adjusting the angle of the two plates to 240°,the static pressure in the triangular cavity has increased by 153 Pa on average,which can effectively alleviate the freezing phenomenon at the bottom of heat exchange tubes in the winter. This kind of direct air condenser with diversion device is suitable for a wide range of environmental conditions,which is beneficial to realize the functions of high temperature resistance prevention,low temperature anti-freezing and stable operation in practical engineering.

0 引言

1 直接空冷凝汽器物理模型与计算方法

   1.1 物理模型及网格划分

   1.2 计算方法及边界

   1.3 网格无关性及模型有效性验证

2 凝汽器对流换热性能分析

   2.1 环境风速对凝汽器换热性能影响

   2.2 环境温度对凝汽器换热性能影响

   2.3 腔内板间夹角对凝汽器换热性能影响

3 结论