Experimental Comparison Of Hydrodynamics Measurement Methods In Different Gas-Solid Fluidization Regimes

The measurement of hydrodynamics parameters in fluidized beds has always been a hot topic.In the measurement of particle concentration in fluidized beds,optical fiber probes and differential pressure sensors are used most widely.The former is an invasive probe,the latter is a non-invasive type.In this study,two different types of optical fiber probes were used,namely Labasys-100 particle concentration velocity measurement instrument of Swiss’ s MSE Meili AG company and PC-6M particle concentration measurement instrument developed by Chinese Academy of Sciences Process.The particle concentration results of two typical fluid states(fast bed and bubbling bed)are systematically compared with the differential pressure sensor in order to quantitatively evaluate the measurement effect of the three instruments in different fluid states.Furthermore,Labasys-100 was used to measure the particle velocities in the two flow regimes,and the reliability and applicability of the measurement results in different fluid state were analyzed.Finally,based on the preliminary research on the mechanical characteristics of the internal components in the fluidized bed,a new instrument for measuring the flow characteristics in the fluidized bed was proposed and designed.It was designed to reflect the fluidization using the stress signals measured on the blades.The specific fluidization characteristics in the bed,such as the frequency and size of the bubbles or particle clusters,and other characteristic parameters,have been preliminarily verified in this study.By comparing the particle concentration measurement results of the three instruments,it is found that in the dense phase bed,the particle concentration measurement result of Labasys-100 is close to the measurement result of the pressure difference method,while the particle concentration measurement result of PC-6M is somewhat lower for differential pressure method.In the dilute phase bed,the particle concentration measurement results of the differential pressure method are larger than those of the Labasys-100 and PC-6M,while the results of the Labasys-100 and PC-6M are close.In terms of data repeatability measurement,Labasys-100 has the smallest relative standard deviation(RSD)of data repeatability in the dilute phase bed and dense phase bed compared to PC-6M and the differential pressure method,while the differential pressure method is located at the side wall Measurements have the largest relative standard deviation(RSD)of data repeatability.Labasys-100’s particle velocity measurement results under two different flow states show that in the fast bed,the distribution of particle velocity and correlation coefficient is relatively concentrated,and the standard deviation is also small,while the distribution in the dense phase bed is very dispersed,the standard deviation Larger.By selecting different cross-correlation coefficients to calculate the particle velocity,it is found that the fast bed is almost unaffected,while the dense phase bed is more affected.Therefore,the measurement results of Labasys-100 in the fast bed are more reliable and more applicable,but the measurement data in the dense phase bed is of poor quality and poor applicability.In the preliminary experimental verification of the measurement principle of the new instrument,it was found that the instrument can clearly distinguish the bubbles in the dense-phase fluidized bed,and the relationship between the strain signal and the bubble chord length in the two-dimensional bed is obtained by using small cantilever blade It is found that the instrument can determine the chord length or size of the bubble to a certain extent through the change of the strain signal under certain operating conditions with fewer bubbles.