不同制焦条件下煤焦的介电特性研究

Experimental study on dielectric properties of coal chars under different char-making conditions

选用3种不同煤阶的煤分别制成800~1 200℃温度下的煤焦试样,通过同轴探头法测试煤焦的介电特性参数,考察测量频率、制焦温度、煤种对介电特性的影响。结果表明：煤焦的复介电常数实部、虚部、介质损耗角正切均随频率的增加而减小,随制焦温度的升高而增大;低频时测试频率和制焦温度对煤焦介电特性影响较大,频率升高影响作用减弱;不同煤种生成的煤焦介电特性差异明显,无烟煤煤焦的介电性能参数最大,烟煤煤焦的介电性能参数最小。

Three kinds of rank coals were selected to prepare coal chars at temperatures ranging from 8 00℃ to 1200℃. The coaxial probe method was applied to detect the dielectric properties parameters of the coal chars. The effects of measuring frequency,preparation temperature and coal type on the chars＂ die- lectric property were investigated. The results show that, the real part, imaginary part of the complex per- mittivity and dielectric loss tangent of coal chars all decreased with the increasing frequency while increased with the elevated temperature. The measuring frequency and preparing temperature had great effect on the chars＂ dielectric properties at low frequencies, and the effect gradually weakened at high frequencies. The di- electric properties of chars prepared by different coals varied dramatically. The anthracite coal char had the maximum dielectric oarameter while the bituminous coal char had the minimum.