回转式空气预热器积灰分层监测方法研究

Study on Layered Fouling Monitoring Method of Rotary Air Preheater

为了便于研究多层回转式空气预热器运行时不同结构参数和工况参数对内部积灰特性的影响,并解决内部积灰难以分层监测的问题,基于有限差分法建立了用于分层监测积灰程度的数学模型,同时以某电厂的三分仓回转式空气预热器为研究对象分析了其合理性。结果表明:随各层实测温度由341℃、241℃、104℃逐步提高至367℃、303℃、130℃时,清洁系数均由1减小至0.1,表明传热削弱逐渐加剧;相应地,与清洁状态下的出口温度偏差由0.8%、2.6%、2.8%提升至7.8%、26.1%、25.2%,表明当某层积灰加重时,其进出口温差减小,也说明传热能力被削弱;该模型适用于任意数目分仓与分层的回转式空气预热器,并可在2 s内完成一次计算,如果忽略电厂数据传输延迟,则该模型实现了空气预热器积灰情况的实时监测。

In order to facilitate the study on the effects of different structure parameters and working conditions on the fouling characteristics in multi-layer rotary air preheaters,and solve the difficult monitoring problem of layered fouling in preheater,a mathematical model for layered fouling monitoring of ash accumulation was established based on the finite difference method.Meanwhile,the rationality of the model was analyzed by a certain rotary air preheater with three sectors.Results show that as the measured temperature of each layer increases from 341℃,241℃and 104℃to 367℃,303℃and 130℃,the clean factors decrease from 1 to 0.1,which indicates that the weakening of heat transfer is gradually aggravated.Accordingly,the deviation of the outlet temperature from the clean state increases from 0.8%,2.6%,2.8%to 7.8%,26.1%,25.2%.These data reflect that when fouling in a certain layer becomes more severe,the temperature difference between inlets and outlets decreases,indicating that the heat transfer capacity of the heat storage element is weakened.The proposed model has a great adaptability and can be applied to rotary air preheaters with any numbers of sectors and layers.A calculation can be completed within 2 s.If the data transmission delay of the power plant is ignored,the layered and real-time fouling monitoring of rotary air preheaters will be realized through the model.