Pressure characterization study in the jet influence zone of riser based on HHT analysis

By large-scale cold mold experiments, pressure pulsation signals within the jet influence zone of riser reactor are processed by using Hilbert-Huang analysis (HHT) in this study. Effects of different jet forms and operating conditions on the intrinsic mode function (IMF) energy and Hilbert-Huang spectrum are compared. Results show that the IMF energy and Hilbert-Huang spectrum of pressure pulsation signals show significant differences under the influence of upward and downward jets. Moreover, the change of jet velocity will also lead to significant changes in IMF energy and Hilbert-Huang spectrum. Among them, energy values and energy proportions corresponding to high-frequency pressure pulsations show a good correlation with the jet velocity. On this basis, energy value and energy proportion data in the high frequency range of the original pressure signal are clustered and analyzed by using the K-means clustering algorithm. Based on clustering results, the jet influence zone of riser can be defined into three regions. From partitioning results, it is found that the introduction of downward inclined jets could effectively improve the gas-solid mixing in the feed injection zone of riser.