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电容层析成像技术是一种有效的气力输送过程监测手段。由于物料种类变化或物性变化引起的两相流混合介电常数变化,会导致测量结果的误差,需要对新流动介质重新标定。标定过程中,一般要将电容层析成像传感器拆下,置于空管和满管2种状态下标定,获得空满管电容。该文提出一种气力输送电容层析成像在线标定方式。建立电容传感器模型,并通过有限元仿真的方式分析了电容模型的误差。通过对被测物料的采样,获得物料的介电常数,根据预先标定好的电容-介电常数关系计算出当前介电常数下的传感器的满管电容值。该方法无需拆卸传感器,不干扰气力输送过程。
Capacitance tomography is an effective means of pneumatic conveying process monitoring. Due to changes in material types or changes in physical properties caused by changes in the mixing dielectric constant of two-phase flow will lead to errors in the measurement results, the need for a new mobile medium recalibration. Calibration process, the general will capacitive tomography sensor removed, placed in empty tube and full tube calibration under two conditions, to obtain empty full tube capacitance. This paper presents a pneumatic transfer capacitance tomography on-line calibration method. The capacitive sensor model is established, and the error of the capacitance model is analyzed by finite element simulation. By sampling the material under test, the dielectric constant of the material is obtained, and the full-cap capacitance of the sensor under the current dielectric constant is calculated according to the pre-calibrated capacitance-dielectric constant relationship. This method eliminates the need to disassemble the sensor and does not interfere with the pneumatic conveying process.