热电联产机组热电解耦技术对比分析

Comparison and analysis of heat-power decoupling technologies for CHP units

增加热电联产机组运行的灵活性可以提高可再生能源利用率,减小“弃风”和“弃光”率,然而对于灵活性改造技术的对比分析研究相对较少。本文基于Ebsilon建立了600MW案例机组的热力学模型,采用Matlab调用模拟数据构建了该机组的能耗模型。基于此模型对比分析了热泵、电锅炉、蓄热罐及采用汽轮机本体改造等热电解耦技术对机组供热可行域及可行域内机组热力性能的影响规律。研究结果表明,采用热电解耦技术可以扩大机组的供热可行域,当机组热负荷为500MW时,采用热电解耦技术后,机组最小调峰能力由大到小排列为:电锅炉>低压缸光轴运行>低压缸零出力>压缩式热泵>蓄热罐。但电锅炉的能量利用率与㶲效率在所有热电解耦技术中最低。综合对比分析,在热电联产机组中采用压缩式热泵或热泵与蓄热罐耦合运行是一种节能的热电解耦方式。

Increasing the flexibility of combined heat and power(CHP)unit operation can improve the utilization rate of renewable energy and reduce the"abandoned wind energy"and"abandoned solar energy".However,there have been few comparison and analysis studies of the flexible modification techniques.In this paper,Ebsilon software was used to establish thermodynamic model of a 600MW unit,and an associated energy consumption model was established by passing simulation results to a Matlab routine.The influence of heat-power decoupling technologies,such as heat pump,electric boiler,heat storage tank,and steam turbine retrofit technologies on the operation feasible region and thermodynamic performance within the operation feasible region was analyzed using thermodynamic and energy consumption models.The results showed that the heat-power decoupling technologies can expand the operation feasible region of the unit.When heat load of the unit was 500MW,minimum peaking capability of the unit can be ranked from the largest to the smallest after using the heat-power decoupling technologies:electric boiler>bladeless shaft operation of low pressure cylinder>low pressure cylinder near zero output>compression heat pump>heat storage tank.However,energy and exergy efficiency of electric boiler were the lowest among all heat-power decoupling technologies.After analysis,it is an energy-saving decoupling way to use compression heat pump or compression heat pump coupled with heat storage tank in CHP units.