基于能级匹配的高参数供热方案研究

Research on high-parameter heating scheme of unit based on energy level matching

热电联产是煤炭高效利用的重要手段,其中供热源参数的选择对热力循环经济性有重要影响。以亚临界300MW机组为研究对象,针对高参数(压力4.0MPa且温度400℃及以上)供热温度和压力参数匹配困难的问题,采用热力学分析和变工况分析方法,得出热力循环压力和温度变化的规律,找出供热参数无法直接匹配的根本原因,提出“分级匹配,梯级利用”的高参数供热方法。在理论分析基础上,结合电厂系统的特征,提出了主蒸汽混温方案、烟气源再热方案和蒸汽源再热方案共三种供热方案,对方案的适用性和热经济性进行比较分析,结果表明:(1)适用性方面,三种方案均可行,能满足高参数供热需求;(2)热经济性方面,主蒸汽混温方案不符合能量梯级利用原则,热经济性差;(3)烟气源再热技术和蒸汽源再热方案在高参数供热量为167t/h工况下,热电联产供电煤耗比主汽混温方案降低4.65g/(kW·h)。研究结果对解决高参数供热参数匹配困难问题具有参考价值。

Cogeneration system is an important means of efficient utilization of coal,in which the selection of heating source parameters has an important impact on the economy of thermal cycle.The subcritical 300MW unit as the research object,aiming at the problem that it is difficult to match the heating temperature and pressure parameters with high parameters(pressure 4.0MPa and temperature 400℃and above).The thermodynamic analysis and variable condition analysis methods are used to obtain the law of the pressure and temperature change of the thermal cycle.The fundamental reason why the heating parameters cannot be directly matched is found out.The high parameter heating method of"graded matching and cascade utilization"has been proposed.On the basis of theoretical analysis,combined with the characteristics of the power plant system,three heating schemes of main steam mixed temperature scheme,flue gas source reheat scheme and steam source reheat scheme are proposed.The applicability and thermal economy of the schemes are compared and analyzed.The results show that(1)in terms of applicability,the three schemes are feasible and can meet the demand of high parameter heating.(2)In terms of thermal economy,the main steam mixing scheme does not conform to the principle of energy cascade utilization,and the thermal economy is poor.(3)Under the condition of 167t/h high parameter heating capacity,the coal consumption of cogeneration power supply is 4.65g/kwh lower than that of the main steam mixed temperature scheme.The research results have reference value for solving the problem of difficult matching of high parameter heating parameters..