应用于汽轮机灵活运行的电加热系统实验与数值模拟研究

Experimental and Numerical Investigations on Electric Heating System applied to Flexible Operation of Steam Turbine

为了研究不同加热功率下汽轮机开机预热所需的时间以及停机保温所需的加热功率,开展了实验及数值模拟研究。首先,为了验证数值模拟方案的有效性,针对某汽轮机控制阀门的缩比模型进行电加热实验和传热数值模拟。实验利用52个热电偶历时100 h记录了电加热过程中阀门各个位置的温度变化情况,然后利用有限元分析方法对该过程进行仿真,发现模拟与实验结果吻合良好。基于阀门研究结果,同样采用有限元分析方法预测了电加热系统对某100 MW汽轮机高压部分(蒸汽关闭)的开机预热和停机保温的灵活运行效果。研究表明:对于开机预热工况,当加热系统的功率为发电功率的0.014%,0.041%和0.083%时,开机预热所需时间分别为51.4,19.5和12.1 h;对于停机保温工况,仅需以发电功率的0.011%对高压真机进行保温,则可以让其维持在阈值温度,极大提高其运行的灵活性。

In order to explore the time required for start-up pre-heating and the heating power required for shutdown warm-keeping under different heating power,the experiments and numerical simulations were carried out.Firstly,to verify the effectiveness of the numerical simulation scheme,the electric heating experiment and heat transfer simulation were carried out for the scaled model of a certain steam turbine control valve.In the experiment,52 thermocouples were used to record the temperature changes of different positions of the valve during the electric heating process lasting 100 hours.Then,the process was simulated by finite element analysis.It was found that the simulation was in good agreement with the experimental results.Based on the valve research results,the flexible operation effect of electric heating system on preheating and warm-keeping condition of a 100 MW high pressure steam turbine(steam shut-down)was predicted numerically by finite element analysis.The research results show that for pre-heating condition,when the heating power is 0.014%,0.041%and 0.083%of the generating power,the start-up pre-heating time is 51.4 hours,19.5 hours and 12.1 hours respectively.For warm-keeping condition,only 0.011%of generating power is needed to keep the high pressure turbine at the threshold temperature,which greatly improves the flexibility of operation.