Chaos Characteristics Research Of Wind Caps Pressure Signals In Bubbling Fluidized Bed

At present, the study on pressure signals of fluidized bed is based on the state that the pressure measuring points are installed in the furnace walls. The disadvantage is that pressure measuring points may be worn and jammed. And when fluidized bed is to the large-scale development, with the increase of the furnace volume, the layout of pressure measuring points will produce some problems in quantity and position. At the same time, it can also affect the accuracy of the measured value. According to the problems, we arrange the pressure measuring points on the walls at the entrance of the wind chamber hood when setting up the bubbling fluidized-bed test bench. Also, the measurement of pressure value can be changed from gas-solid two-phase to gas phase. As a result, the accuracy of the measurement is improved.In this thesis, we analysis the pressure fluctuations time sequence measured from bubbling fluidized bed using chaos theory. In data collection process, we collect not only real signals, but also the noise signals. So we must remove the noise signals from original signals before processing the pressure fluctuation signals. After analysis and comparison, db2wavelet method is a kind of good method in removing the noise signals from original signals.When we analysis pressure signal using chaos theory, the first thing must be done is reconstructing the phase space. In the phase space reconstruction process, we must choose the reconstruct parameters. This paper uses the autocorrelation function method to determine reconstruction parameter time delay τ. Through the comparative study, we found that the time delay when the autocorrelation function is0.1is the best delay time. Studying the chaos characteristics of correlation dimension of pressure fluctuations time sequence in fluidized bed, we found that correlation dimension is not an integer value. So we know that fluidized bed system is chaotic system. In view of the analysis of pressure fluctuation signals in different experimental conditions, we draw the conclusion that static bed high and superficial gas velocity have influence on pressure signals from wind caps.In addition, we also studied characteristics parameter Lyapunov index. The study found that Lyapunov index of pressure fluctuations time sequence in fluidized bed is positive. And this also showed the fluidized bed system is chaotic system. In view of the analysis of pressure fluctuation signals in different experimental conditions, we draw the conclusion that static bed high and superficial gas velocity have influence on the fluidized state in fluidized bed. We analysis chaos characteristics of wind caps pressure signals in fluidized bed, and this enriches the signal analysis methods of wind caps pressure fluctuation signals. After in-depth research we found that wind caps pressure signals can be a very good reaction in the fluidized state. This is consistent with the conclusions draw from the situation that the pressure measuring points are installed in the furnace walls. The research provided theory basis for actual application, at the same time, created a condition for engineering application of on-line monitoring system based on the wind caps pressure signals of fluidized bed.