Heat supply is effective to improve the overall efficiency and reduce the coal consumption rate in air-cooled power plants. A key issue about design optimization of cogeneration system is to determine the optimal values of the designed primary network water supply temperature,based on the performance variation of overrall system resulting from the temperature of supply water in the primary network. The heat transfer efficiency and energy consumption were analyzed for different design parameters,i. e. heating load and primary side water supply temperature. The heating characteristics under off-design conditions were discussed with the mechanism modeling and Ebsilon platform. Results showed that design value of primary side water supply temperature had significant effect on system heat transfer efficiency and energy consumption. The variation of coal rate was 4.56g/kW·h due to the change of primary side water supply temperature.%高背压供热模式是提高能源利用率、降低火力发电煤耗的有效途径,从全局角度研究一次网设计供水温度取值对热电联产系统的影响、确定热网供水温度最佳设计值是热电联产系统参数设计的核心问题.本文利用热网变工况模型及Ebsilon软件仿真,以某310MW直接空冷高背压供热机组与热网组成的热电联产系统为研究对象,分析了设计参数(供热负荷、一次网供水温度)不同时整个供热周期内系统能源转化效率及能耗水平.结果表明:一次网设计供水温度取值不同时,系统周期供电煤耗极差可达4.56g/kW·h;供热负荷设计值较低时,系统周期净供电功率在一次网设计供水温度取中间某值时存在最大值;供热负荷设计值较高时,随一次网设计供水温度增加,系统周期净供电功率不断增加.
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