The total pressure drop across the fluidized bed\({P}_{\text{total},\ V}\), as shown in Figure 1, includes pressure drop of both preheating section and distributor, which was measured by a differential pressure transducer through the pressure port pointing downward. Each time the pressure drop data were recorded continuously at a sampling rate of 125 Hz and for a duration of 80 seconds. Before an experiment, dried and filtered air was first supplied to the empty bed. By changing the flow rate, the pressure drop across the empty bed was obtained at various superficial gas velocities. Then, for a given superficial gas velocity, the pressure drop was derived by subtracting the pressure drop across the empty bed from the total pressure drop across the bed:
\({P}_{\text{fluidized}\ \text{bed},\ V}={P}_{\text{total},\ V}-{P}_{\text{empty},\ V}\ \)(1)
The high-temperature ECT sensor consists of 8 electrodes. The center of the ECT sensor is located at a horizontal plane, 185 mm above the distributor. The main parameters of the ECT sensor are given in Table 2. It can work up to 800°C. The detailed design was reported in our previous publication.23
Table 2. Parameters of high-temperature ECT sensor