On-Line Multi-Frequency Electrical Resistance Tomography (mfERT) Device for Crystalline Phase Imaging in High-Temperature Molten Oxide

An on-line multi-frequency electrical resistance tomography (mfERT) device with a melt-resistive sensor and noise reduction hardware has been proposed for crystalline phase imaging in high-temperature molten oxide. The melt-resistive sensor consists of eight electrodes made of platinum-rhodium (Pt-20mass%Rh) alloy covered by non-conductive aluminum oxide (Al(2)O(3)) to prevent an electrical short. The noise reduction hardware has been designed by two approaches: (1) total harmonic distortion (THD) for the robust multiplexer, and (2) a current injection frequency pair: low [Formula: see text] and high [Formula: see text] , for thermal noise compensation. THD is determined by a percentage evaluation of k-th harmonic distortions of ZnO at [Formula: see text].1~10,000 Hz. The [Formula: see text] and [Formula: see text] are determined by the thermal noise behavior estimation at different temperatures. At [Formula: see text] 00 Hz, the THD percentage is relatively high and fluctuates; otherwise, THD dramatically declines, nearly reaching zero. At the determined [Formula: see text] 10,000 Hz and [Formula: see text] 1,000,000 Hz, thermal noise is significantly compensated. The on-line mfERT was tested in the experiments of a non-conductive Al(2)O(3) rod dipped into conductive molten zinc-borate (60ZnO-40B(2)O(3)) at 1000~1200 [Formula: see text] C. As a result, the on-line mfERT is able to reconstruct the Al(2)O(3) rod inclusion images in the high-temperature fields with low error, [Formula: see text] = 5.99%, at 1000 [Formula: see text] C, and an average error [Formula: see text] = 9.2%.