The change in acidity of the ZSM-5 zeolite was investigated after it was treated with water vapour, and its capability on ammonia adsorption was also studied after having adsorbed water vapour. The effect of water vapour on products distribution was studied during catalytic cracking of naphtha, the changes in the adsorption ability and catalytic performance of the ZSM-5 zeolite was investigated after the catalyst was loaded with phosphorus species. These results all indicated that water vapour could reduce the acid strength and acid density of ZSM-5 zeolite and affect the capability of ZSM-5 on adsorption of gases, therefore the activated energy contributed by the ZSM-5 zeolite to the catalytic cracking reaction would be low to prevent the feedstock from deepened catalytic cracking and coke formation.
A novel method, based on acoustic emission (AE) techniques, for detecting agglomeration in fluidized beds is presented. Particle size characteristics are determined based on the principle that AE signals with different frequency band energies are emitted when particles of different sizes impact an internal wall. By applying chaotic analysis to the AE signals, the malfunction coefficients are well defined. Agglomeration in the fluidized bed can then be detected by the sudden variation of malfunction coefficients. AE signals were investigated in a laboratory scale heated fluidized bed and an industrial polyethylene fluidized bed. Experimental data showed that the malfunction coefficients increased with the growth of agglomeration. The results indicated that agglomeration in fluidized beds can be predicted and diagnosed effectively and precisely using AE techniques based on chaotic analysis.
