气固流化床中声发射和结块定位

利用声发射检测技术，结合能量分析，实现了气固流化床内黏壁结块（静结块）的实时监控.通过单颗粒撞击有机玻璃板实验，建立了聚乙烯颗粒撞击有机玻璃的声波衰减方程，确定了声波的有效传播距离.通过150 mm冷模装置实验，分别考察了黏壁结块前后聚乙烯颗粒碰撞壁面产生声发射信号能量的轴向及周向变化，获得了气固流化床黏壁结块定位的判据，即以正常流化时声能量分布为基准，当实时监控的声能量轴向分布出现异常的低谷时，低谷所在的区间减去声波有效传播距离所得的区间为黏壁结块的轴向位置；而当声能量周向分布失去整体对称性、平均能量明显减小、标准偏差显著增大时，黏壁结块产生，而声能量小于平均值、且绝对相对误差明显大于正常流化的连续区域即为黏壁结块的周向位置

Acoustic emission and agglomeration location in gas-solid fluidized bed

Real time detection of agglomeration on the wall of fluidized bed reactors was implemented using the acoustic emission technique to analyze acoustic energy changes.The attenuation law of the acoustic wave for polyethylene particles and the effective distance was presented according to the experiment of single particle colliding to the glass plate.Acoustic signals of particles along the axis and round of the exterior surface with or without agglomeration adhering to the inner surface were investigated in the gas-solid fluidized bed with 150 mm in diameter.The energy distribution under normal condition was taken as a norm to determine the agglomeration location based on energy analysis.When the real time energy distribution performs abnormal low ebb,the zone difference of acoustic effective distance and low ebb corresponds to the axial location of agglomeration;while the radial energy distribution is anisomerous,the average energy is less and the standard difference is larger,the agglomeration takes place and the continuous zone having lower average energy and larger relative error is the radial position of agglomeration.