还原区焦炭黏附在线测量及黏附模型

Online Deposition Measurement and Char-Slag Transition Model in the Reduction Zone

采用焦炭黏附重量在线测量实验平台,对分级燃烧还原区中含有不同比例未燃尽碳的焦炭黏附进行了研究。实验结果表明,黏附速率取决于未燃尽碳含量,可分为三个区域。Ⅰ区未燃尽碳含量低于下临界值(UBC_L),黏附特性可由灰分性质计算;Ⅲ区未燃尽碳含量高于上临界值(UBC_U),黏附受炭骨架控制,黏附速率很小。Ⅱ区介于UBC_L~UBC_U,黏附特性受炭骨架和灰分性质共同控制。提出了一种焦炭黏附模型并应用于CFD模拟,预测结果与实验数据吻合良好。

Char deposition experiment with various fraction of unburnt carbon in the reduction zone of pulverized coal staged combustion is performed by using an electric-heated down-firing furnace(E-DFF)and a deposition probe with online thermogravimetric measurement.Experimental results show that the deposition rate depends on the unburnt carbon content and can be divided into three zones.The unburnt carbon content in zone Ⅰ is lower than the lower critical value(UBCL),and the deposition characteristics can be calculated from the ash properties;the unburnt carbon content in zone Ⅲ is higher than the upper critical value(UBCu),and the deposition is controlled by the carbon skeleton,and the deposition rate is very small.Zone Ⅱ is between UBCL~UBCu,and the deposition properties are controlled by the carbon skeleton and ash properties.A char deposition model is proposed and applied to CFD simulation,and the prediction results are in good agreement with the experimental data.