汽轮机轴封系统是火电厂热力系统的重要组成部分,轴封系统漏汽的大小对机组的热经济性有直接的影响.基于热经济状态方程,利用矩阵分析的思路,根据轴封系统漏汽的来源不同,分别建立了定功率条件下高压缸漏汽和中低压缸漏汽对机组热经济性影响的定量数学模型.利用微分理论,得出了轴封蒸汽流量变化时主蒸汽流量和轴封漏汽量的依变关系.以某300 MW火电机组为例,针对其典型工况,分别计算高压缸漏汽和中低压缸漏汽变化对机组热经济性的影响.结果表明:高压缸轴封漏汽对机组热经济性影响较大. Steam turbine shaft sealing system is an important part of the thermal power plant thermal power system, the size of the leakage of shaft seal system has a direct impact on the thermal economy of the unit.Based on the thermal economic equation of state, using the idea of ​​matrix analysis, , The quantitative mathematical models of the influence of leakage of high-pressure cylinder and medium-low pressure cylinder on thermal economy of generating units under constant power are established respectively.Using differential theory, the relationship between main steam flow and shaft According to the typical working conditions of a 300 MW unit, the influence of leakage of high pressure cylinder and low and medium pressure cylinder on the thermal economy of the unit is calculated respectively.The results show that the high pressure cylinder Shaft leakage steam thermal economy of greater impact.