燃煤机组烟气余热回收系统影响因素分析与优化

摘要

Generally,the exhaust gas temperature in domestic coal-fired units is relatively high.Aiming at solving this problem,the flue gas waste heat recovery technology was proposed to carry out technical trans-formation for the unit.By introducing the concept of"relative efficiency",the"relative efficiency" thermo-dynamic calculation model was established.Moreover,considering the "relative efficiency" and economic benefits as a comprehensive index,the influence of such key factors as flue gas parameters,condensate pa-rameters and heat exchanger's structural parameters on overall performance of the flue gas waste heat re-covery system was investigated.On the premise of ensuring the unit safety operation,the corrosion resist-ance,performances of the system like the wear resistance and ash deposition resistance should be consid-ered to optimize the system by regulating the parameters mentioned above.Taking a 600 MW unit as the example,the calculation results show that,after the optimization,the equipment mass of the system de-creased by 3.9%,the relative efficiency increased by 4.4%.%针对国内燃煤机组排烟温度普遍偏高问题，提出采用烟气余热回收技术对系统进行改造.通过引入“相对效益”的概念，建立“相对效益”热力计算模型，并以“相对效益”和经济效益作为综合指标，分析了烟气参数、凝结水参数、换热器结构参数对烟气余热回收系统整体水平的影响规律.在保证机组安全运行的前提下，应结合系统防腐、防磨、防积灰特性，通过调整上述参数对烟气余热回收系统进行优化.对某600 MW 机组的实际计算结果表明，系统优化后比优化前的设备质量减少了3．9％，相对效益提高了4．4％.