一、前言随着电力工业的发展及国民经济对电力需要的增长,电网的峰谷差日益增大,不仅要求大型火电机组有较好的经济性,而且还要求这些机组具有一定的调峰能力。原有国产200兆瓦机组系六十年代设计的超高压三缸三排汽机组,投产后是各电网中主力机组。但是由于其设计年代较早,机组热耗值较高,运行灵活性差,难于满足当前节能和调峰的需要。为此水利电力部和机械工业部等有关单位近两年来都积极进行200兆瓦汽轮机的改型工作。大功率 I. INTRODUCTION With the development of the power industry and the growth of power demand in the national economy, the peak-to-valley difference of the power grid is increasing day by day, not only requiring large-scale thermal power units to have better economy, but also requiring these units to have some peaking capability . The original domestic 200 MW unit is a super high pressure three cylinder three-row steam turbine designed in the 1960s. After its operation, it is the main power unit in each power grid. However, due to its earlier design, higher unit heat consumption and poor operation flexibility, it is difficult to meet the current needs of energy conservation and peak regulation. For this reason, the Ministry of Water Conservancy and Electric Power and the Ministry of Machinery Industry and other relevant units have actively carried out the retrofitting of 200-MW steam turbines in the past two years. High Power