一种利用压强脉动信号测取鼓泡床中气含率的新方法

A Novel Approach for Measuring Gas Holdup through Pressure Fluctuation Signals in Bubble Columns

实验测定了不同操作条件下反应器内的压强脉动时序信号.提出了一种求取鼓泡床中气含率的新方法,即根据压强脉动信号功率谱图上的主频确定小波主尺度,并对该尺度上的细节信号的间歇行为进行了分析;在局部间歇性分析(LocalIntermittencyMeasurement,LIM)曲线上选取合适的阈值后,对不同径向位置上的局部气含率进行估计,进而得到反应器截面上的平均气含率值.根据本工作的LIM分析方法计算得到的气含率与压降法实测气含率相一致,这也表明反应器内气泡是导致鼓泡流中压强脉动的主要因素.

The time series of fluctuating pressure signals under different experimental conditions were measured by a pressure transducer, and a novel method for measuring gas holdup in bubble column was proposed, namely, the local gas holdup was estimated by resorting to local intermittency measurement （LIM） method and multi-resolution analysis of the time series of fluctuating pressure signals. Firstly, the dominant wavelet scale was determined, which corresponds to the major frequency of power spectral density function （PSDF） of pressure fluctuating signals. Then, signals corresponding to this scale were selected for an intermittent behavior analysis. Consequently, by choosing a proper threshold value on the LIM profile of the major scale detail signal, the gas hold-up was estimated at six radial locations and hence the area average gas hold-up was obtained. A comparison of the gas hold-up values obtained by means of the present LIM analysis and the conventional pressure drop method showed a good agreement, indicating that the larger fluctuations in the column could be attributed to the bubble motions.