Characterization of gas fluidization regimes using pressure fluctuations

Systematic Study of Pressure Fluctuation in the Riser of a Dual Inter-Connected Circulating Fluidized Bed: Using Single and Binary Particle Species

This study systematically investigates the pressure fluctuation in the riser of a dual interconnected circulating fluidized bed (CFB) representing a 10 kWth cold-flow model (CFM) of a chemical-looping combustion (CLC) system. Specifically, a single-species system (SSS) and a binary-mixtures system (BMS) of particles with different sizes and densities were utilized. The pressure fluctuation was analyzed using the fast Fourier transform (FFT) method. The effect of introducing a second particle, changing the inventory, composition (i.e., 5, 10 to 20 wt.%), particle size ratio, and fluidization velocity were investigated. For typical SSS experiments, the results were similar to those scarcely reported in the literature, where the pressure fluctuation intensity was influenced by varying the initial operating conditions. The pressure fluctuations of BMS were investigated in detail and compared with those obtained from SSS experiments. BMS exhibited different behaviour; it had intense pressure fluctuation in the air reactor and in the riser when compared to SSS experiments. The standard deviation (SD) of the pressure fluctuation was found to be influenced by the fluidization regime and initial operating conditions, while the power spectrum density (PSD) values were more sensitive to the presence of the particles with the higher terminal velocity in the binary mixture.

A study on fluidized bed combustion characteristics of corncob in three different combustion modes

This paper presents results obtained from corncob combustion in a pilot scale vortexing fluidized bed combustor (VFBC). Three combustion modes including direct combustion, staged combustion and flue gas recirculation (FGR) combustion were employed, and their combustion and pollutant emission characteristics were studied. In addition, the effects of combustion fraction and bed temperature on pollutant emission characteristics were investigated. The experimental results show that the combustion fractions vary with different combustion modes, resulting in different CO and NO emission characteristics. Staged and FGR combustions can reduce the NO emission concentration. Under similar working condition, NO concentration decreases by 30% in FGR mode, while 15% in staged mode compared with direct mode.