Flow regime identification in a novel circulating-turbulent fluidized bed

• Flow behavior in C-TFB was a novel regime on the micro-level.
• Wavelet analysis was utilized to analyze the flow dynamics.
• Wavelet energy was obtained as unique features of flow regimes.
• Flow regimes were recognized by fuzzy system identification method.
• The C-TFB optimizes flow dynamics and gas–solid contact efficiency.

Whether flow dynamics in a novel circulating-turbulent fluidized bed (C-TFB) belongs to a new flow regime or just a transition state is controversial. In order to resolve this confusion, transient fluctuation signal processing and wavelet analysis have been used to identify the flow regimes in five specially designed flow systems, which have been proven to be effective tools to extract detailed information of flow features in different flow regimes. Furthermore, the fuzzy system identification method, which was used to process wavelet energy data of various scales obtained by wavelet analysis, was employed to make a quantitative distinction among the flow regimes. The results showed that the flow regime in the C-TFB is a novel flow regime, which is different from traditional flow regimes such as bubbling, turbulent, fast fluidization (FF) and dense suspension up-flow (DSU) regimes. The new regime has some unique characteristics including intensive gas–solids interaction, high gas–solids contact efficiency, two peaks of probability density distribution (PDD) curves in the center of the fluidized bed, broader spectrum of solids holdup for PDD curves, a decreasing extent of gas–solids separation extent and unique radial detail wavelet energy percentage profiles. Quantitative analysis by the fuzzy system identification method further confirmed that the flow behavior in the C-TFB can be described as a novel flow regime.

The gas–solids flow dynamics especially flow regime in a circulating-turbulent fluidized bed (C-TFB) compared with other traditional flow regime were studied. Traditional original signal processing and novel wavelet analysis method were utilized to identify different flow regimes. Fuzzy system recognition method combined with wavelet analysis results were employed to judge whether flow regime in the C-TFB was a novel flow regime.Figure optionsDownload as PowerPoint slide