Improved particle image velocimetry measurements in gas-particle flows with a dense wall layer

This work concerns particle image velocimetry (PIV) measurements with a high-speed camera in a circulating fluidized bed (CFB). Because of the nature of the gas-particle flow in the riser of the CFB a dense wall layer of particles is observed when the superficial gas velocity is increased beyond a certain limit. This dense wall layer reduced the quality of the measurements. A mask is developed which improves the quality of the PIV measurements. Furthermore, it increases the range of superficial gas velocities for which the measurements can be obtained in the CFB system. The improved PIV measurement is verified via laser Doppler anemometry measurements. The results are of interest for measurements of dense wall-layer flows.