固定床鼓泡反应器的流型与压降的瞬态表征

Transient Characterizations of Flow Pattern and Pressure Drop in a Fixed-Bed Bubble-Column Reactor

采用高采集频率的差压传感器及A/D转换器,对固定床鼓泡反应器的瞬时压降数据进行了采集,建立了反应器内的流型识别方法,并通过电容层析成像仪(ECT)对不同流型的气含率的瞬态特征进行了研究。结果表明:不同流型内压降信号的波形、概率密度分布及功率谱密度分布特点差异显著,瞬态气含率亦存在不同特点;随着气液相流速的增加,床层压降梯度逐渐上升;根据实验数据修正的Larachi关联式及Khan和Varma关联式可较好地预测中等塔径(D=280 mm)的固定床鼓泡反应器的摩擦压降,均方根偏差分别为18.0%与14.5%。

A differential pressure sensor and an A/D converter with high frequency were employed to collect transient pressure drop data in a fixed-bed bubble-column reactor.Methods were established to identify the flow patterns in the reactor.The ECT（electrical capacitance tomography）system was employed to investigate transient characteristics of gas holdup in different flow regimes.The waveforms,probability density distributions and power spectrum density distributions of pressure drops are significantly different in various flow regimes.So do transient gas holdups.The bed pressure drop gradient increases with the increase of gas and liquid flow rates.Comparison between experimental data and estimation shows that the revised Larachi＇s relationship and Khan and Varma＇s relationship can be used to predict frictional pressure drops in fixed-bed bubble-column reactors of medium diameter（280 mm） with an averaged deviation of 18.0% and 14.5%,respectively.