Measurement of solids circulation rates with optical techniques in circulating beds and comparison to pressure drop methods

Conference Dates

May 22-27, 2016


The number of applications employing circulating fluidized beds has increased considerably over the last years following the important development of chemical looping technologies for power generation (combustion) or fuel conversion (reforming) with inherent CO2 capture. The performance of these reactors is strongly determined by the amount of solids transferred from one reactor to the other, commonly referred to as the Solids Circulation Rate (SCR). The solids inventory, particle characteristics and gas velocities strongly influence the SCR. The determination of the SCR has been carried out using invasive and non-invasive measurement techniques. The direct measurement through solids collection in the loop seal is the most applied technique, but this technique requires opening of the loop seals and thus may be expensive, whereas other methods suffer from large inaccuracies. There is yet no optimal technique available that combines good accuracy with reasonable costs, as recently also discussed by Alghamdi et al. (1).

In this work, a pseudo 2D internally circulating fluidized bed (Figure 1) has been built to explore the potential of optical techniques like Particle Image Velocimetry (PIV) combined with Digital Image Analysis (DIA) for non-invasive, whole-field measurements. Moreover, the setup allows for the measurement of the pressure drop (fluctuations) along the riser and the collection of particles circulating from one reactor to the other, so that the three different measurement techniques can be compared.

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