Abstract: Multi-sensor integration including electrostatic sensor,pressure sensor and capacitance tomography system(ECT)were used to investigate the flow behavior of dense phase pneumatic conveying of coal powder under various operating conditions(transportation pressure difference,carrier gas and moisture content).Statistics and fractal method were applied to extracting the Hurst of electrostatic fluctuation signal and the variance of differential pressure signal.Experimental results showed that when CO₂ was used as carrier gas,the complexity of micro-movement of individual particle increased with increasing total transportation pressure difference and the interaction between gas and particles was more intensified under pressure difference of 0.75 MPa.However,the macro-motion state of the coal particles kept stable.The increase of coal moisture content resulted in higher complexity of micro-motion of individual particle,and yet had no influence on the stability of macro-motion state of the whole coal particles.When N₂ was used as carrier gas,coal average concentration over the cross section of the pipeline fluctuated obviously and the macro-motion state of the whole coal particles was unstable.But the micro- motion of individual coal particle was similar to that with carrier gas of CO₂.

Key words: electrostatic sensor, electrostatic capacitance tomography, gas-solids two-phase flow, fractal method

摘要： 在加压密相气力输送煤粉实验装置上,结合静电、压力传感器与电容层析成像系统(ECT)3种方法,利用统计学和分形方法研究了不同操作条件(总输送压差、输送载气和煤粉含水率等)下密相气固两相流动力学行为。结果表明:输送载气为CO₂时,颗粒相微观运动剧烈程度随总输送压差(0.3~1 MPa)的增大而增大,气流和颗粒相之间的相互作用在总输送压差0.75 MPa下最强烈,但煤粉宏观整体的流动保持稳定;煤粉含水率增加对宏观流动稳定性没有影响,但水分增加使颗粒相的微观运动剧烈性减小;载气为N₂时,管道截面煤粉的平均浓度及分布变化明显,宏观流动状态不稳定,但颗粒相的微观运动剧烈程度与载气为CO₂时的变化规律一致。

关键词: 静电传感器, 电容层析成像, 气固两相流, 分形