Chemical process opportunities for vibrated powders 3. Provisional design for an experimental sidewards flying bed

At a scale suitable for laboratory experimentation, a provisional mechanical design illustrates a concept for a “sidewards flying bed” (SFB), a layer of particulate matter held upon the inner wall of a cylinder that rotates at varying speed. Acting upon the layer are centrifugal and tangential forces whose patterns of variation create time intervals during which the latter is the greater. During such intervals, the layer is postulated to respond by “flying sidewards.” In a laboratory SFB set-up, experiments can elucidate a new area of non-steady-state soil mechanics, with outcomes bearing upon a full-scale SFB's chemical processing potential. An important question is, what will be the delay in the SFB layer's taking flight after the moment tangential force just begins to exceed centrifugal? For the SFB design to be successful, this delay should be significantly shorter than a time interval during which the tangential force dominates.If experiments were to show this not to be so, a “what-then?” might be to install several stationary rakes near the cylinder's inner wall, parallel to its axis. Loosening the particulate layer as the cylinder turns, these should advance the timing of the layer's flight.Achieving adequate flight in an experimental SFB could point to a design at a commercial scale capable of promoting rapid local mixing — more rapid than that afforded by conventional vibrated or fluid beds. Such should become a strong candidate for applications requiring rapid heating of hydrocarbonaceous matter followed by quick separation of vapor product and carbonaceous residue (e.g., flash pyrolysis of coal or oil-shale). The SFB's competencies should include ability to treat moieties of especially large size (e.g., for producing a smokeless solid fuel from coal, for heat-treating a metal part or a polymer, for flash-cooking foodstuffs without oil, for drying large particulates); ability to treat highly heterogeneous matter (e.g., for burning or gasifying comminuted biomass or solid wastes); and ability to promote excellent heat transfer between SFB and stationary surfaces embedded therein (e.g., in an air-cooled SFB steam-condenser).

If “soil failure" were to occur during an interval after tangential acceleration overtakes centrifugal acceleration holding a powder layer against the inside wall of a cylinder rotating at variable speed, the “sidewards flying bed" so created can afford rapid powder mixing, capability for flash heating, ability to process moieties of large size, and other advantages. A provisional test set-up is proposed.Figure optionsDownload as PowerPoint slide