加热器端差对机组热经济性影响的通用计算模型

GENERAL CALCULATION MODEL ON THE INFLUENCE OF TERMINAL TEMPERATURE DIFFERENCE ON HEAT ECONOMY OF UNIT

准确而快速地评价各级加热器端差的运行热经济性,对热力系统的设计、运行和检修具有十分重要的意义。文中以热力系统的热平衡方程、汽轮机功率方程和锅炉吸热量方程为基础,采用了将上述基本方程两端分别对加热器出口水焓求偏导的方法,并针对不同型式的加热器,找出了公式的规律性,得到了分析加热器端差运行热经济性的通用计算模型。推导过程中,定义了端差等效焓降和端差等效吸热量系数两个重要的概念。计算实例表明:该模型具有计算结果准确、使用方便简捷、通用性强等特点,尤其适用于机组运行经济性在线监测系统。

Evaluating exactly and fast heat economy of unit caused by heater terminal temperature difference is significant meaning for the design, operation and repair of thermodynamic system. The method adopted is based on heat balance equation, turbine power equation, boiler absorbed heat equation of thermodynamic system. Take the partial derivative of outlet water enthalpy on both sides of the above equations, the law of the formulas can be found. So, for different heater type, the general calculation model on the influence of heater terminal temperature difference on heat economy of unit is derived in the paper. Two important conceptions, which are called as terminal temperature difference equivalent enthalpy drops and terminal temperature difference equivalent absorbed heat coefficient, are defined in the paper. The model discussed in the paper is proved to be possessed of the character of accurate, simple and more universal. Especially, it is suitable for on-line monitoring system of heat economy of unit.