节流配汽超超临界汽轮机调门特性与经济运行

Valve Characteristics and Economic Operation for Steam Distribution Mode of Ultra-supercritical Steam Turbine1

汽轮机主蒸汽流量是机组性能指标计算的关键参数之一,采用现有调门模型对其计算面临建模繁琐、模型复杂和计算过程参数难以获取等问题。针对有效面积变化的汽轮机高压调门,提出用椭圆公式对其建模,并用公开文献试验数据对其进行验证。结合阀门模型,以某660 MW节流配汽型超超临界汽轮机组为研究对象,对该机组进行变工况计算,研究不同负荷的不同运行策略下,高压缸效率和机组经济性的变化情况。结果表明,椭圆公式能够表现调门变工况特性,该方法建模过程简单,计算方便,在调门工作区域内计算精度高。机组高压缸效率随着高压调门开度的减小而减小,纯滑压运行方式下热耗率最低,但考虑到电网调频要求,建议机组变工况运行时调门开度控制在30%～45%为宜。所推荐的宽范围变工况运行策略在调门调节裕量满足电网调频的要求下,能够提高机组的经济性和深度调峰能力。研究结果可为同类型机组的运行优化策略提供参考。

The main steam flow rate is one of the key parameters in performance calculation of steam turbine unit. The use of existing steam turbine high pressure governing valve models to calculate the main steam flow rate poses problems such as exhausting modeling, model complexity, and difficulty in obtaining parameters of the calculation process. The valve with variable effective flow area is modeled by elliptic equations and tested with open literature experimental data. Method a calculation model for the off-design performance of a 660 MW ultra supercritical steam turbine unit with steam distribution combined the valve model. Then this unit model is used to explore the efficiency of HP cylinder and the unit’s economic under different loads with different operation strategies. Analysis shows that the characteristics which the ellipse equations reflected are consistent with the literature experimental data and this method is simple in computation, high accuracy in work area. The efficiency of the HP cylinder of the unit decreases as the opening degree of the steam turbine high pressure governing valve decreases. The unit heat rate is the lowest when adopting the sliding pressure operation and the valve in 30%-45% opening should be recommended for operation when taking into account the request of frequency adjustment of electric network. The proposed operation strategies can improve the units’ economic performance and enhanced the ability of in depth peak load cycling at the request of frequency adjustment of electric network. It provides reference for the operation strategy of similar units.