Study On The Cold State Experiment And CFD Simulation Of Bubbling Fluidized Bed Of Synthesize Si₃N₄

The silicon nitride materials have some characteristic, for example: high intensity, wearable, small distensibility, small density, etc. Besides, the silicon nitride materials also have some merits of corrosion-resistant, oxidation-resistant, and good aseismatic. The silicon nitride material has a amplitude market. For form a high quality and low cost's product line, there have a produce mode of continuum. The consecutive and high temperature fluidized bed is one of the most future technique to produce the high a phase silicon nitride.Aimed at this technique, we design the bubbling fluidized bed in cold state and build the experiment flow. Especially we made optimize design to the distributor. On this basic, study the fluidized characteristic, and emphases to study three different rate and mode of the hole in different flux. The cold state study indicate that the different rate and mode of the hole has the different influence to the resistance, the perfect hole rate is 0.47%, use the slanting hole the flow state is better than use the straight hole, and we can see that the perfect flux is 50m /h~60m /h.Since CFD (Computational Fluid Dynamics) technique has been attached great importance as a new technique and has been greatly developed. By now, it can be used to solve some problems involved in a fluidized bed, such as multi-phase flow, heat transfer and combustion of pulverized coal, etc. Aim at experiment setting that we study, use the CFD technique to establish a equality model, by the compute parameter's setting to analyse the compute result: to the silicon powder's gas and solid fluidized bed, used the multiple-phase model is in reason; in the whole bed, the gas phase, the thin powder and the thick powder have the perfect distribute state at 60m3/h; use the mode of slanting hole can decrease the "dead flow" and "chimb flow", gained the perfect flow state.