Experimental results for gas-solid separations in a 102 mm diameter conventional cyclone operated with air heated to temperatures between 300 K and 2 000 K, are presented. Overall and fractional collection efficiencies were measured for alumina and silica having particle sizes of 100% less than 44 pm and mass median diameters of 5.0 and 10.0 pm respectively. Inlet velocities ranged from three to 42 rn/s and inlet dust loads were between 0.3 and 235 g/mi. The dust load had a strong intluence on the collection efficiency and the loading effect was stronger at high temperatures.On presente des resultats experimentaux pour les separations gaz-solides dans un cyclone conventionnel de 102 mni de diarnktre fonctionnant B I'air chauffe B des temperatures comprises entre 300 et 2 000 K. Les efficacitks de recuperation fractionnelle et globale ont t t C mesurees pour des alumines et des silices ayant des tailles de particules h 100% inferieures a 44 pm et des diametres moyens massiques de 5,O et 10.0 pm, respectivement. Les vitesses d'entree varient entre 3 et 42 rn/s et les charges de poussieres d'entree entre 0,3 et 235 g/m'. La charge de poussikres a une grande influence sur I'efficacitC de rCcupCration et I'effet de charge est plus grand h temperatures ClevCes.

Measurements of the arc velocity and of the erosion rate are reported for a copper cathode. The 100 A arc, burning in nitrogen, is driven by a magnetic field B, varying from 5.1 to 171.0 mT, between concentric copper electrodes having an inter-electrode gap of 4 mm. The arc velocity varied with B0.60 throughout the range investigated. The erosion rates dropped from 9.0 to 1.0 mu g C-1 as the arc velocity was increased from 15 to 135 m s-1.

No abstract

Erosion measurements on a copper cathode are reported. The 100 A arc, driven by a magnetic field, runs continuously for up to 30 min between two concentric cylindrical electrodes. Argon-nitrogen gas mixtures in various proportions are blown through the electrode gap. The erosion rate in argon is drastically reduced by the addition of only 1% nitrogen and is further reduced as the nitrogen content increases in the gas mixtures. The decrease in erosion rate is found to be correlated to an increase in arc velocity.

Experimental results are presented for a study of gas and particle flows in a 102 mm diameter conventional cyclone operated at temperatures between 300 and 2000 K. Inlet gas velocities ranged from 3 to 42 m/s. Particle deposition patterns and the measurements of local pressures were used to determine the flow patterns and velocity profiles within the cyclone. A “Reynolds Number” has been defined based on the mean inlet velocity and the hydraulic diameter of the annulus between the cyclone wall and the gas outlet duct. An empirical equation was derived to correlate the ratio of the wall tangential velocity to the mean inlet velocity with this Reynolds Number.

No abstract

Doped cerium oxide (CeO 2 ) based electrolytes are attractive alternative materials to replace the existing yttria-stabilized zirconia (YSZ) used as electrolyte for SOFC (solid oxide fuel cells). Cerium oxide electrolytes offer a similar performance to YSZ electrolytes at a lower cell operating temperature (∼600-800 • C), therefore reducing thermal stresses and solid state reactions among the cell components.Doped Ce 1−x Me x O 2−x/2 (Me = Gd, Sm or Y) fine powders were synthesized from nitrate salts dissolved in water using a radio frequency inductively coupled plasma reactor. It was demonstrated that the relative concentrations of Ce and dopants fed in the solutions were retained in the synthesized powders. The products were all nano-crystalline with the basic crystal structure of CeO 2 and the crystal size of the products was essentially independent of the dopant used. The particle size distributions obtained were multimodal and in most cases trimodal. The results obtained differ from a previously reported mechanism of particle synthesis from liquid precursors.

No abstract