Study of Fluidization Behavior Transition from Geldart B to A Induced by High Temperature Using Electrical Capacitance Tomography

The transition of the fluidization behavior of GeldartB particlesto that of A particles induced by temperature change was investigatedby a developed high-temperature electrical capacitance tomography(ECT) sensor. Silica particles with a Sauter mean diameter of 237 mu m and density of 2650 kg/m(3), typically Geldart Bparticles under ambient conditions, were fluidized in a column of5.5 cm from 20 to 600 degrees C. With the increase in temperature, ECTmeasurements showed a decrease in minimum bubbling velocity (U (mb)), no bed expansion characteristic in thehomogeneous fluidization regime, an absence of multiple-bubbles regime,and a larger bubble size. The pressure drop against superficial gasvelocity curves at elevated temperatures confirmed homogeneous fluidizationbetween the minimum fluidization velocity (U (mf)) and U (mb). Our analysis demonstratesthat cohesive interparticle forces, which increase linearly with temperature,are responsible for the fluidization behavior transition of the silicaparticles.

Automated summary

This study investigated the transition of fluidization behavior from Geldart B particles to A particles induced by temperature change using a developed high-temperature electrical capacitance tomography (ECT) sensor. Silica particles with a Sauter mean diameter of 237 μm and density of 2650 kg/m^3, typically Geldart B particles under ambient conditions, were fluidized in a 5.5 cm column from 20 to 600 degrees C. The ECT measurements showed that with increasing temperature, there was a decrease in minimum bubbling velocity (U(mb)), no bed expansion characteristic in the homogeneous fluidization regime, an absence of multiple-bubbles regime, and a larger bubble size. The pressure drop against superficial gas velocity curves at elevated temperatures confirmed homogeneous fluidization between the minimum fluidization velocity (U(mf)) and U(mb). Our analysis demonstrated that cohesive interparticle forces, which increase linearly with temperature, are responsible for the fluidization behavior transition of the silica particles.