Investigation on the Performance of Volatile Distributors with Different Configurations under Different Fluidization Regimes

The uniform horizontal distribution of volatiles over the cross section of a fluidized bed with the purpose to obtain good contact between volatiles and bed materials is a key issue to improve the gas conversion in the fuel reactor of chemical looping combustion of solid fuels. The effectiveness of the volatile distributor (VD) concept on the lateral distribution of volatiles in a fluidized bed has been investigated under different operational conditions using a cold-flow model. Furthermore, the performance of the VD has been examined using different configurations of the holes used to distribute the volatiles. The fluidization regimes, i.e., single bubble regime, with only one large bubble formed at a time at the bottom bed, exploding bubble regime, with irregular bubbles containing more particles, and multiple bubble regime, with many small bubbles formed and distributed in the bed, are determined by visual observation of the bottom riser and analysis of the pressure fluctuations, including frequency analysis. The VDs with uneven hole arrangements, which have less distribution holes at the simulated volatile inlet side and a larger open area far from the inlet, provide a more even horizontal distribution of volatiles compared to the VD with equally distributed holes. A larger simulated volatile flow and less open area of the VD increase the pressure drop over the distribution holes and improve the horizontal distribution. In general, the VD gives a more uniform distribution of the volatiles under the exploding bubble regime and better distribution in the single bubble regime compared to the multiple bubble regime. However, the bottom leakage, i.e., the volatile leakage from the bottom of the VD, should be considered, especially in the single bubble regime.