黏性颗粒失流态化过程的实验研究

Experimental Study on Process of Cohesive Particle Defluidization

采用低温黏结的聚乙烯颗粒,在二维半热态内循环流化床实验台上模拟黏性颗粒高温失流态化过程,并对失流态化过程进行了规律性总结,对其床压信号进行了时域分析与频域分析.实验结果表明:从颗粒正常流化到失流态化可分为熔融、分层、成核、成团和死床5个阶段.时域分析中,压力变化可反映出床内失流态化发生的大致时间,标准偏差的变化先于均值的变化;频域分析中,频谱图上主频的变化明显于均值的变化,为防止床内出现失流态化提供了可能;通过对比不同测点的频谱图,可反映出床内最早出现失流态化的位置.

The low-fusion-temperature polyethylene particles were used to simulate the process of high- temperature defluidization in a two-dimensional semi-thermal circulating fluidized bed. The process of defluidization can be divided into five stages, including fusion, layering, nucleation, agglomeration and shutdown. The time-domain analysis shows that pressure changes can reflect the approximate time of the oc currence of defluidization and the changes of standard deviation preceding the changes of average value. The frequency domain analysis shows that the changes of dominant frequency in spectrogram are more obvious than that of ayerage value, which makes it possible to prevent defluidization. By comparing the spectrogram of different measuring points, the earliest position of the defluidization can be obtained.