外露管式熔盐吸热器动静态特性研究

Study on dynamic and static performance of external tubular molten salt receiver

以某50 MW塔式光热发电项目外露管式熔盐吸热器为研究对象,进行了建模,通过理想条件下的动静态仿真和实际气象条件下的模拟,给出吸热器特性参数的动静态响应曲线,提出了吸热器出口盐温控制的改进方法,分析了其在实际气象条件下的运行特点,总结了以下规律:吸热器表面最高温度、温度梯度、散热功率与太阳法向直射辐照度的变化基本呈正比关系;效率随太阳法向直射辐照度增大而升高但斜率逐渐减小;风速主要影响对流散热功率;太阳法向直射辐照度扰动下吸热器出口熔盐温度、表面最高温度、散热功率的过渡过程响应时间较吸热管轴向温度梯度更长,效率在瞬间突变后会重新逐渐回复到接近扰动前的水平;流量阶跃下降对吸热器性能影响更大。利用吸热器特性参数与太阳法向直射辐照度和熔盐流量三者间的定量关系可改进运行中的熔盐流量调整策略。

A 50 MW external tubular molten salt receiver model is developed for simulating the dynamic and static performance of the receiver in ideal conditions and actual meteorological conditions. The response curve is given to show that the maximum surface temperature, temperature gradient, and heat dissipation power of the receiver are basically proportional to the changes in direct normal irradiance(abbreviated as DNI);the efficiency grows with increase in direct normal irradiance, and the slope, however, decreases;wind speed mainly affects convection heat dissipation power;in the presence of direct normal irradiance step disturbance, the response time of the molten salt outlet temperature, the maximum surface temperature and the heat dissipation power of the receiver is longer than that of the receiver tube axial temperature gradient, and gradually the efficiency returns approximately to the level before a sudden change;flow step down have a greater impact on the receiver performance. Using the quantitative relationship between the characteristic parameters of the heat sink and the direct solar irradiance and molten salt flux can improve the molten salt flux adjustment strategy in operation.