额定功率下抽汽压损对机组热经济性的影响

Influence of Extraction Steam Pressure Loss on Thermal Economy of Unit Under the Condition of Constant Power Output

基于热力系统矩阵热平衡方程,建立了机组在额定功率运行时抽汽压损变化对其热经济性影响的数学模型.数学模型与热耗变换系数有关,在该模型中考虑了辅助汽水系统的影响,并对热力系统中加热器的不同型式和连接方式进行了讨论.运用该模型计算了某600 MW机组在额定功率下,各级抽汽压损增大5%时对机组热经济性的影响,其结果与热平衡法计算的结果一致.通过数值拟合,给出了该机组抽汽压损变化对热经济性影响的特性曲线,它表明抽汽压损越大,机组的热经济性越低.

A mathematic model for the influence of extraction steam pressure loss on thermal economy of the unit was established based on the matrix thermal balance equation of the thermodynamic system. The mathematic model has the relationship with the heat rate transformation coefficient. The influence of unit＇s steam-water auxiliary system was considered in the model. The discussions about the different types of heaters in the thermodynamic system are performed. The change of thermal economy was calculated when each stage＇s extraction steam pressure loss increase 5 % for one 600 MW unit under constant power output by using of this model. The results were consistent with that by thermal balance method. The characteristic curves for the influence of each stage＇s extraction steam pressure loss variation on the unit＇s thermal economy were presented by curve fitting. It indicates that, the larger extraction steam pressure loss is, the lower unit＇s thermal economy is.