Identification of the flow structure of dense phase in a gas-solid fluidized bed reactor in bubbling fluidization regime with Geldart B + A particles

Abstract

Gas-solid fluidized bed in the bubbling fluidization regime is extensively used in various industrial applications involving thermochemical conversion. The gas–solid suspension can be separated into bubble phase, emulsion phase and intermediate phase (mid-phase). Among them, intermediate phase plays a very important role in enhancing gas–solid contact and reaction performance, but there is a lack of its effective identification method. In this study, a descriptive statistical method including the indexes of standard deviation, skewness and kurtosis is proposed to identify the intermediate zone, and the solids holdup boundary thresholds of mid-phase and dense phase can be effectively determined at different conditions. The local solids-holdup in the intermediate phase is found to range from 0.2 to 0.3, and the local volume proportion varies between 0.1 and 0.2. Detailed insights into the intermediate phase structure in a bubbling fluidized bed reactor of Geldart B + A particles are revealed for the design and operation purposes.