A NEW METHOD TO DETERMINE THE MINIMUM BUBBLING VELOCITY IN FINE POWDER AERATIONS BY USING EXPERIMENTALLY MEASURED ELASTIC DEFORMATION COEFFICIENT

摘要

The standard emulsion phase of fine powders under the bubble-free aerated condition, which occurred at gas velocity (U) ranged between minimum fluidization (U_(mf)) and minimum bubbling (U_(mb)), had been defined at ambient and high temperature as the 'homogeneously aerated expanded (HAE) emulsion phase' (1). Basic powder rheological parameters such as mean elastic deformation coefficient (Y), tensile strength (σ_f), and viscosity (μ) had also been defined in previous papers, so that the characterization of fine powder flow properties became possible (1,2). In this paper Y values were measured in small increment of powder strains within the range of the standard HAE emulsion phase. Based on the new interpretation of the Y data, a new definition of bubble (fracture) formation was proposed in this paper to modify the concept of 'minimum bubbling point'.