热电联产机组工业供汽优化控制机理研究

Study on optimal control mechanism of industrial steam supply for cogeneration units

针对热电联产机组工业供汽引起能耗大幅升高,导致电厂热经济性下降的问题,以某310 MW机组为研究对象,进行EBSILON平台建模模拟和真机试验研究,计算冷段再热蒸汽抽汽(冷再)和热段再热蒸汽抽汽(热再)2种汽源、2.0 MPa/2.5 MPa/3.0 MPa 3种抽汽参数、不同负荷下机组运行状态,分析(火用)损耗特性、能耗临界特性等,得到了工业供汽优化控制机理。结果表明:冷再和热再汽源下,机组热耗率存在差异;工业供汽存在一条能耗临界特性曲线,该曲线对机组经济运行意义重大。只有当机组在该曲线右侧区域工况运行时,工业供汽工况热耗率才小于相同电负荷纯凝工况机组热耗率,工业供汽对降低能耗水平有益,机组热经济性提高;机组在曲线左侧运行时,工业供汽工况热耗率大于纯凝。建议热电厂工业供汽改造时,合理规划各机组间工业供汽流量及汽源参数。

The energy consumption of cogeneration unit is greatly increased due to industrial steam supply,which leads to the decline of thermal economy of power plant.In this study,a 310 MW unit is selected as the research object.Method of software simulation and experiment are used.The EBSILON software is used to model and simulate the operating conditions of the unit under two steam extraction sources,three extraction pressures,and different electrical loads respectively.The exergy loss and energy consumption critical characteristics of industrial steam supply are analyzed.The results show that,the heat consumption of the unit is different under the steam source of cold reheating and hot reheating industrial steam supply.There is a critical characteristic curve of energy consumption for industrial steam supply.This curve is of great significance to the economic operation of the unit.Only when the unit operates on the right area of the curve,the unit heat consumption of the industrial steam supply condition is less than that of the pure condensing condition,and the industrial steam supply is beneficial to reduce the energy consumption level and improve the thermal economy of the unit.When the unit operates on the left area of the curve,the heat consumption under industrial steam supply condition is greater than that of pure condensation condition.It is suggested that the industrial steam supply flow and steam source parameters between units should be reasonably planned during the transformation of industrial steam supply in thermal power plant.