[关键词]
[摘要]
针对锅炉内典型烟气-金属-蒸汽换热器的动态换热过程,采用单一变量控制法,分析受热面对质量流量阶跃的动态响应时间,并建立锅炉动态模型,在不同边界条件发生阶跃变化时,计算各受热面的动态响应特性。结果表明:动态响应时间随并联管长度及壁厚尺寸的增加而增加;随入口工质温度、热负荷以及质量流速的增加而缩短。在质量流量发生-10%阶跃扰动时,省煤器对扰动的响应速度最慢,响应时间约220 s;水冷壁低温段及水平低温再热器次之,高温受热面(如末级过热器、末级再热器等)响应速度最快,响应时间约10 s,为提高机组变负荷灵活性,缩短锅炉对负荷响应时间,可通过旁路部分响应速率慢的受热面来实现。
[Key word]
[Abstract]
Based on the dynamic heat transfer process of typical flue gas-metal-steam heat exchanger in boiler,the single-variable control method was adopted to analyze the heat surface′s dynamic response time to mass flow steps.The results show that the dynamic response time increases as the length of connecting surface and wall thickness increase,but decreases as the inlet working fluid temperature,heat load,and mass flow rate increase.Meanwhile,by establishing a practical boiler dynamic model,the dynamic response characteristics of each heating surface were calculated when step changes occur under different boundary conditions.The results indicate that when a 10% step disturbance occurs in the mass flow,the response speed of the economizer to disturbance is the slowest with a response time of 220 seconds at a maximum/(220 s),followed by low temperature section of water cold wall and horizontal low temperature reheater.However,the response speed of high temperature heating surfaces (such as last stage superheater,last stage reheater,etc.) to disturbance is the fastest with a response time of 10 seconds/(10 s).To improve the variable-loading flexibility of the units and shorten the response time of the boiler to the load,bypassing the heating surface with slow response speed is an effective approach.
[中图分类号]
TK224
[基金项目]
中国华能集团公司总部科技项目(HNKJ17-H13)