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

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.