脉冲进料流化床电化学反应器电位波动信号分析

Analysis of Potential Fluctuation Signal in Fluidized Bed Electrochemical Reactor with Pulse Feed

以铁氰化钾体系Fe3+/Fe2+为研究对象,导电石墨颗粒为工作电极,采用自制复合探针测定了液固流化床电化学反应器床层颗粒电位和溶液电位波动信号,并进行了功率谱及概率分布密度分析。分析结果表明,在二电极可逆慢反应体系中,颗粒电位与溶液电位信号的波动幅度比较接近且相对均匀,未出现低频大幅波动信号,过电位(颗粒电位与溶液电位之差)信号的波动幅度相对较小;在初始流化状态以及膨胀率为15%时出现多个幅值较大的波动主频,主要频率分布小于10 Hz且波动主频与脉冲进料频率相吻合,过电位功率谱图的波动幅值均较小并接近于白噪声。电位波动与进料方式有关,采用脉冲蠕动方式进料可使床层过电位分布均匀。

The potential fluctuation signals of particles and electrolyte in a liquid-solid fluidized bed electrochemical reactor （FBER） with pulse feed for [K3Fe（CN）6]/[-K4Fe（CN）6] reaction system were measured by the composite probe. Experiments were performed on beds of conductive graphite particles undergoing reduction of ferricyanide in alkaline solution of 1.0 mol/L NaOH. The analysis methods of signals included power spectral density （PSD）, probability distribution density and variance. It was observed that particle potential and electrolyte potential had approximate fluctuation extent, without the fluctuation manner of low frequency but high amplitude. The fluctuation extent of overpotential （the difference between particles potential and electrolyte potential） was relatively low. At incipient fluidization and at around 15% bed expansion, the potential fluctuation for both the particles and electrolyte became remarkable. The primary frequency distribution was below 10 Hz and it was consistent with the pulse feed frequency. The fluctuation extent of overpotential PSD was small and near the ＂white＂ noise. The fluctuation of potential is related to feed method and the uniform overpotential distribution is obtained with pulse feed.