Application of electrical resistance tomography in bubble columns for volume fraction measurement

Bubble columns have been widely used in chemical and pharmacy industries for its simplicity and efficiency. In bubble column, air distribution depends on various factors, e.g. sieve plate pattern, air and liquid volumes, temperatures, which in turn determines the efficiency of the reaction. Real-time measurement of air volume fraction distribution is of significant importance for process control and further optimization of the reactor. Therefore, great attentions have been paid to this problem in recent studies. Generally, conventional methods, e.g. differential pressure and conductivity probe method, can only obtain a lumped parameter or local information. Hence, electrical resistance tomography technique has been introduced to provide real-time measurement of air volume fraction distribution within its sensing region. With a dual-plane sensor, the electrical resistance tomography system could generate cross-sectional images as well as flow velocity map. Moreover, both global and local information of the flow can be obtained by data/image post-processing. Experimental results show that test results from electrical resistance tomography are in good accordance with those from conventional methods, i.e. only 5% deviation.