1000MW超超临界机单顺阀无扰切换的技术分析及应用

单阀控制和顺序阀控制切换的目的是为了提高机组的经济性,实质是通过喷嘴的节流配汽(单阀控制)和喷嘴配汽(顺序阀控制)的切换,解决变负荷过程中均匀加热与部分负荷经济性的矛盾。某电厂在投产后,单阀控制和顺序阀控制切换过程中,负荷、压力波动较大,文章仔细分析了不能无扰切换的原因,较详细介绍了单阀方式和顺序阀方式的切换设计原理。通过DEH汽轮机阀门流量特性试验,调整阀门跟踪流量修正曲线,优化DEH汽轮机阀门流量特性,现实单阀和顺序控制方式下蒸汽流量基本不变,利用MSC-CCS协调闭环控制来进一步减小单顺阀切换时引起的机组功率、压力波动,流量曲线和逻辑优化后,单顺阀切换过程中负荷、压力平稳,实现单阀和顺序阀相互无扰切换,保证机组安全稳定地运行,基本达到了满意的结果。

Analysis and Application of Single and Sequence Valve Switching of 1 000 MW Ultra Supercritical Unit without Disturbing Balance

The switching of single valve and sequence valve is designed to improve the unit＇ s economical efficiency. It is essentially to solve the contradictions between uniform heating and partial load efficiency at variable load condi- tions by switching of the nozzle throttle steam distribution （ single valve control） and nozzle steam distribution （ se- quence valve control）. After the production of a power plant, there were load and pressure fluctuation during the switching of single valve and sequence valve. This article analyzed the reason for switching failure and introduced the design principle for switching of single valve and sequence valve. DEH valve flow characteristics test was made to ad- just DEH valve flux curve,to optimize DEH valve flow characteristics and to achieve constant steam flow in both sin- gle valve mode and sequence valve mode. MSC-CCS closed loop control was applied to minimize the fluctuation in power and pressure caused by switching. After optimization of flow curve and related logics, smooth switching of sin- gle and sequence valve was achieved that ensured the safe operation of the units. The results are satisfactory.