某电厂温排水三维扩散特征物理模型研究及分析

Research and Analysis on 3D Diffusion Characteristic of Thermal Discharge in Power Plant by Physical Model

温排水研究是电厂排水环境影响评价和海域使用评估的重要前提。受排水量、排水结构设计及受纳水体动力条件等影响,温排水三维热力扩散特征较为复杂,规律性不强,是电厂温排水研究的难点。以某"近取远深排"布置滨海电厂为例,采用物理模型试验手段,结合排水口多点多层温升实时监测数据,研究电厂排水三维热扩散特性。以大范围温排物理试验为基础,根据平面二维数值模拟成果,并结合电厂排水头部局部布置,在排水口表层2℃温升包络范围内,布置10条测温垂线,每条垂线设4个测温点。通过生潮系统及测温系统,监测不同工况下各测点温升值,插值并绘制三维垂向温升分布图,分析电厂排水口垂向温升分布及扩散特征。分析表明,就本项目温排水条件,高温升水团被约束在排水口附近较小区域内;温排垂向扩散呈椭榄或烛焰形态;底部高温升扩散受水平海流影响较小;温排水上浮过程中,高温升水团快速减小,低温升水团范围逐渐扩大。研究可为类似电厂排水三维热力扩散分析提供参考。

Thermal drainage research is an important prerequisite for the drainage environmental impact assessment and the evaluation of sea area utilization for power plants. With the influence of the drainage amount, drainage structure design and the dynamic conditions of adjacent water, the 3D thermal diffusion characteristics are so complex and irregularity, which is difficult problem in thermal drainage research. Taking a coastal power plant with a near water intake and far-deep drainage design as an example, the physical model test method is established to study the 3D thermal diffusion characteristics of the power plant by using the real-time monitoring data of multi-point and multi-layer temperature rise of the drain. On the basis of the large range physical model test and the plane 2D numerical simulation study results, according to the drainage layout of the power plant, 10 temperature measuring plumbs are arranged in the envelope range of the 2℃ temperature rise, and 4 temperature measuring points are set at each plumb. Through the tide generating system and temperature measuring system, the temperature rise in different conditions are monitored, and the 3D vertical temperature rise distribution is interpolated and plotted, and the vertical temperature rise distribution and diffusion characteristics are analyzed. The result shows that, for the drainage condition of this power plant, the high temperature rise mass is confined to the smaller area near the drain. The vertical diffusion appears ellipsoid or candle flame shape. The diffusion of high temperature rise at the bottom is less affected by the horizontal sea current. The area of high temperature rise decreased rapidly but the range of low temperature rise increases gradually with the floatation of the drain. The research can provide a reference for the 3D thermal diffusivity analysis of similar power plants.