Statistical validation of a non-isokinetic solids sampler for low-flux CFBs using Geldart C particles

Accurate determination of the solid flux in circulating fluidized beds (CFBs), particularly low-flux systems (< 8 kg.m −2 .s −1 ), is challenging. This study validates a non-isokinetic solid sampling technique for low-flux dry and semi-dry flue gas desulfurization (FGD) CFBs, where conventional isokinetic and non-invasive methods, such as radioactive particle tracking and electrical capacitance volume tomography (ECVT), encounter limitations. This study presents an experimental and statistical analysis that quantifies the influence of suction velocity on solid flux measurements in low-flux CFB systems, using Geldart Group C particles to validate the non-isokinetic sampling technique. It focuses on environments under varying flow velocity conditions. Bland-Altman plots, Kruskal-Wallis test, and one-way ANOVA were used to determine the statistical significance of the difference in measurements obtained at different probe suction velocities. It was found that solids flux measurements taken in a riser with an average superficial gas velocity of 3.8 m.s −1 at probe suction velocities of 2 m.s −1 , 3.8 m.s −1 , 5 m.s −1 , and 8 m.s −1 exhibit comparable solids flux distributions. The maximum bias between the measurements obtained at these varying suction velocities was 0.06, and the p -value obtained from the one-way ANOVA test was 0.96, indicating that there was no statistical difference between the measurements taken at different suction velocities. These findings substantiate the reliability of the non-isokinetic sampling method for solid flux measurements in low-flux CFBs and contribute to the future characterization of flow patterns in such systems. The results suggest that the bias escalates with the rise in the solid flux load within the system, although additional investigation is needed to validate this preliminary observation. • A custom-built non-isokinetic sampler was validated for measuring solids flux in low-flux FGD-CFB risers operating below 8 kg·m −2 ·s −1 . • Statistical analysis (Bland-Altman, Kruskal-Wallis, ANOVA) confirmed probe suction velocity (2–8 m·s −1 ) has negligible effect on flux measurements. • Results support the use of non-isokinetic sampling in Geldart C particle systems where conventional methods are limited.