Fe_3O_4、Fe_2O_3对燃煤飞灰比电阻和击穿场强的影响

Effect of Fe_3O_4 and Fe_2O_3 on the specific resistivity and the field strength of electrical breakdown for coal fired fly ash

利用从国内不同燃煤电厂采集的飞灰作为本底灰样，采用试剂添加、磁选分离和高温煅烧等多种方法分别制备Ｆｅ_２Ｏ_３、Ｆｅ_３Ｏ_４含量不等的试样，进而对这些试样的比电阻和击穿场强进行实验研究。研究结果表明，Ｆｅ_２Ｏ_３和Ｆｅ_３Ｏ_４对飞灰的电导性质的影响规律明显不同：Ｆｅ_３Ｏ_４含量提高４％，可使飞灰的比电阻降低约１个数量级，并使霜些飞灰在０．５ｋＶ／ｃｍ场强下产生电击穿；Ｆｅ_２Ｏ_３的比电阻和击穿场强大大高于Ｆｅ_３Ｏ_４，对飞灰的影响不大。实验结果为研究电除尘器收尘极板上飞灰对收尘机理的影响，和飞灰比电阻数学模型的建立提供了依据。

he fly ash collected from coal fired power plants in various regions was used as the background ash. The samples that various contents of Fe3O4and Fe2O4 in them were prepared by the methods of adding reagents,magnetic dressing and high temperature calcination respectively, and then the specific resistivity and the field strength of electrical breakdown for the samples were determined. The results show that Fe3O4. and Fe2O3 have markedly different lawr for the electrical transmision of fly ash,with Fe3O4 increased by 4 % ,the specific resistivity of fly ash reduced about one magnitude level,the field strength of breakdown reduced by several times and some fly ashes even broken down at 0.5kV/cm. The specific resistivity and the field strength of electrical breakdown for Fe2O3 are greatly higher than Fe3O4 The experimental results have offered the basis for studying the effect of dust at the collecting electrode of ESP on the dust collection,and for establishing the mathematical model of the specific resistivity for fly ash.