固废流化床异型颗粒与床料共流化特性

Co-fluidization of irregular particles with bed material in solid waste fluidized bed

建立了截面0.2 m×0.2 m、高1.2 m的固体废弃物流化床冷态实验装置,选取4种形状、尺寸和密度差异较大的异型颗粒模拟固体废弃物,床料为粒径0.18 mm的石英砂.采用压力信号和快速CCD图像分析相结合的方法,重点考察了不同种类和比例的异型颗粒与床料共流化时的压降特征、流动结构和最小流化速度,并提出了该体系最小流化速度的新关联式.结果表明,异型颗粒与床料共流化时,升速压降曲线波动大且易低估最小流化速度,而降速压降曲线较为平滑,类似纯床料流化,可用于确定最小流化速度;最小流化速度随异型颗粒体积比和特征密度的增大而增大,与静止床高变化无关.关联式的预测值与实验结果及国内外其他一些研究者的实验值吻合得较好,平均相对误差为14.7%,可适合于多种类异型颗粒与床料共流化体系.

Co-fluidization characteristics of irregular particles with bed material have been investiga- ted. Experimental were carried out in a solid waste fluidized bed with a cross section of 0. 2 m x 0. 2 m and a height of 1.2 m. Four particles with different sharps, sizes and densities were used as simu- lative solid waste, and silica sand was employed as fluidization medium. The pressure drop, flow pattern and minimum fluidization velocity （ Umf ） under different operating condition were tested through pressure signal and fluidization images. Correlation for predicting the Umf was also devel- oped. The results show that with mixture of irregular property particles and bed material, the pres- sure curve measured with increasing flow rate is remarkably fluctuant and always results in underesti- mation of Umf value. While like fluidization of pure regular particles, the pressure curve with decrea- sing flow rate is smooth and reasonable to determine the value of Umf. Besides, Umf is found to be increased with the increasing of volume proportion and effective particle diameter density, but it is not affected by the change of static bed height. Comparisons show that predicted Umf by the present correlation corresponds well to the experimental data and those in literatures. It is found that the cor- relation can satisfactorily predict Umf in fluidizing of irregular particles with bed material with a mean relative error of 14. 7%.