Advanced Development of a Pressurized Ash Agglomerating Fluidized-Bed Coal Gasification System. Cold Flow Scaleup Facility (CFSF) Experimental Results: 16-Inch Air Tube Test, FY-1982

摘要

Preliminary experimental results of the cold flow scaleup facility (CFSF) using an 8-inch/16-inch diameter concentric jet nozzle are summarized. Data on bubble diameter, bubble frequency, bubble velocity, jet half angle, and jet penetration depth obtained through frame-by-frame analysis of motion pictures are reported. These data were compared, with different degrees of success, with correlations in available literature. The results indicated that correlations based on dimensional analysis and data from small units alone could introduce large errors during scaleup. Experimental data from the CFSF showed substantial gas leaks from the bubble to the emulsion phase during bubble formation, particularly when the bed is less than minimally fluidized. A correlation model developed on the basis of this mechanism closely matched the experimental bubble diameter. The experimentally observed bubble frequency was determined to be a factor of 3 to 5 lower than that calculated from the Davidson and Harrison model, which assumed no net gas interchange between the bubble and the emulsion phase. This discrepancy was attributed to the extensive bubble coalescence above the jet nozzle and the assumption that no gas leaks from the bubble phase. Pitot tube data are also reported. The pitot tube apparently sensed not only the gas momentum but also the solid particle momentum. Assumptions on particle velocity and voidage distribution in the jet permit the calculation of velocity profiles from the pitot tube data. Dissipation of the maximum velocity at the jet axis could be correlated with the simple power law decay similar to a homogeneous jet. Preliminary analysis of tracer gas concentration profiles indicated that the gas mixing in the bed was due primarily to convection. Diffusion has a negligible contribution. Gas recirculation between the jet and the emulsion phase may exist at the region close to the jet nozzle. 31 references, 30 figures, 16 tables. (ERA citation 10:012045)