基于声发射信号频率位移的催化剂积炭量检测

MEASUREMENT OF THE AMOUNT OF COKE DEPOSIT ON CATALYST BASED ON ACOUSTIC EMISSION FREQUENCY SHIFT

基于气-固流化床内催化剂颗粒运动碰撞反应器壁面产生声发射信号的机理,借助多次扫描累加及平滑消噪等处理手段,结合功率谱分析,获得了代表催化剂颗粒运动的特征信号频率。同时,基于特征信号频率随结焦催化剂的不同积炭量的规律性变化,建立了声发射测量结焦催化剂积炭量的预测模型,即C(i)=aΔf(i)+b,其中Δf(i)为反应器i高度声发射信号功率谱特征峰的频率位移,a和b为拟合参数。在不同表观气速下和不同探头高度处,该模型均能预测催化剂积炭量,且预测值与实际值的平均相对误差(AARD)小于8.12%。由此,获得了一种快捷灵敏、安全环保的非侵入式结焦催化剂积炭量检测技术,能够实现流化床内结焦催化剂积炭量的实时在线监控。

The characteristic frequency of acoustic emission（AE） in a fluidized bed with respect to the behavior of catalyst particles movement was obtained by analyzing the power spectrum after denoising based on the mechanism of interaction between particles and the internal wall of the fluidized bed.A model to predict the amount of coke deposit on catalyst was established to describe the correlation between the characteristic frequency of AE signals from the particles-wall collisions and coke deposit.The corresponding relationship could be expressed as C（i）=aDf（i）＋b,in which Df（i） was the frequency shift of characteristic peak at height i of the fluidized bed,and a and b were the fitting parameters.Experimental results in a cold mode fluidized bed showed that this model was useful to measure the amount of coke deposit on catalyst at different superficial gas velocity and different sensor height.The average absolute relative deviation（AARD） was below 8.12% when the predicted amount of coke deposit was compared with the true one.Therefore,it could be concluded that the model could meet the requirements of online measurement of the amount of coke deposit on catalyst in fluidized beds.