抽汽压损对机组热经济性影响的通用计算模型

经过严格的数学推导，证明了抽汽压损对热经济性的影响等同于抽汽压损引起的加热器出口水焓和疏水焓变化对热经济性影响的线性叠加。根据热力系统热经济性分析的基本方程，针对不同型式的加热器，计算了疏水焓对汽轮机作功量和锅炉吸热量的影响。得出了分析疏水焓变化对热经济性影响的通用计算模型。结合已建立的加热器出口水焓对热经济性影响的通用计算模型，推导了抽汽压损对机组热经济性影响的通用计算模型。该模型具有通用性强，适于程序化的特点。算例验证了该方法的正确性。

A General Model for Calculating the Influence of Steam Extraction Pressure Loss on a Unit's Thermal Efficiency

By strict mathematical deduction,it is being proven that the influence of steam extraction pressure loss on a unit's thermal efficiency is equivalent to the linear superposed effects on efficiency,caused by relevant heaters' out flowing feed and drain water enthalpy variation.Using the basic equations of thermal efficiency analysis,the influence of drain water's enthalpy on work done by the turbine and on the heat absorbed by the boiler are calculated for various types of heaters,obtaining herewith the general calculation model for analyzing the influence of drain water enthalpy variations on thermal efficiency.Combined with the general model on hand for calculating the effect of a heater's outlet water enthalpy on thermal efficiency,a general model for calculating the influence of steam extraction pressure loss on a units' thermal efficiency is derived.This model is universal and suitable for programming.Calculated examples prove the correctness of the method.Figs 2,table 1 and refs 7.