(118g) Wide Spanned Minimum Spouting Velocity Correlations Based on a New Quantitative Measurement and Identification Procedure

The minimum spouting velocity, Ums, corresponds to the minimum gas velocity needed to maintain the spouting condition in the gas-solid spouted bed. Ums plays an important role in dimensionless analysis of the hydrodynamics of spouted beds and their design and operation. Although there are many correlations predicting Ums, most of them are based on particles with density lower than or around 3,000 kg/m3. Our research on the hydrodynamics of nuclear fuel particles involves solid particles where the density spreads from 1,000 to 6,000kg/m3.

Previous minimum spouting velocity studies identified Ums by carefully observing particle movement on the bed surface visually. We introduce a new quantitative evaluation technique to measure Ums. The advent of HMIs (Human-Machine-Interfaces) that allow easy and accurate adjustment of process inputs and measurement of process outputs with real-time analysis and plots played a role in developing the quantitative methodology. It is similar to the method utilized in quantitatively defining the minimum fluidized velocity, Umf. The gas velocity is first increased to get a full spouting condition. Then the gas velocity is lowered in small steps and the corresponding ÄP across the bed initially decreases. At U=Ums, Δ P(gas pressure drop ) reaches its minimum value, then Δ P increases sharply as gas velocity is lowered below Ums. The HMI (Human-Machine-Interface) allows the approximate value of Ums to be determined. Then a second determination of Ums is made with the gas flow rate decreased accurately in small increments with no undershoot in the gas flow rate. Generally multiple experiments are made for Ums and they have a small standard deviation.

The experimental matrix for ZrO2 and HfO2, surrogates for nuclear fuel particles, are included. A correlation for the parameters covered by the experimental matrix is presented. The identification procedure is used to identify Ums for a range of other particles.