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Two experimental slurry bubble column facilities comprising of 10.8 and 30.5 ern diameter columns and appropriate for conducting hydrodynamic and heat transfer studies arc described. The average and local gas holdup data are reported for the air-water system as a function of air velocity. The holdups for th" three phases are also reported for the air-water-glass beads system over a range of air velocity values.. The air holdup data are compared with the predictions of some of the commonly used correlations. The heat transfer coefficient for a 19 mm diameter cylindrical probe and the two-and three-phase dispersions are measured as a function of air velocity. Most of these hydrodynamic and heat transfer data correspond to the churn turbulent regime and the values obtained on the two columns differ appreciably from each other under similar operating conditions. This fact indicates that the scaleup of slurry bubble columns could be quite difficult on the basis of data obtained on the bench and pilot-plant scale units. The continuing data from these facilities on different systems will shed more light in the future on this important aspect which is crucial to the commercialization of indirect coal liquefaction technology.

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Air-holdup and heat transfer coefficient data are reported for the air-water and air-water-sand system as a function of air velocity in the temperature range 297-343 K as measured in a 0.305 m diameter bubble column operating in semi-batch mode and equipped with either a five-or seven-tube bundle. A 65 p n average size sand powder is used at concentrations of 5 and 10 mass percent in the slurry. Available correlations of gas holdup and heat transfer coefficients are examined on the basis of these data. These are found inappropriate and inadequate for representing these experimental data. Gas holdup data are well represented by an approach based on Nicklin's (1962) work, and heat transfer data are adequately represented by a simple semi-empirical expression. Accurate experimental data on additional systems are needed to develop a reliable heat transfer theory particularly for process representation at temperatures higher than ambient. ~~~~ ~ ..~ ~~On presente des donntes sur la rktention d'air et le coefficient de transfert de chaleur pour les systemes air-eau et air-eau-sable en fonction de la vitesse de I'air B des temperatures comprises entre 297 et 343 K telles qu'elles ont @ t i mesurees dans une colonne de 0,305 m de diambtre fonctionnant en mode semi-discontinu et munie d'un faisceau de cinq ou sept tuyaux. Du sable trbs fin d'un diambtre moyen de 65 gm a CtC utilisC i des concentrations de 5 zt 10 pour cent en masse dans la suspension. Des corrklations existantes sur la rCtention du gaz et le coefficient de transfert de chaleur ont Ctt examintes a partir de ces donntes. On a trouvt qu'elles Ctaient inappropriCes et inadCquates pour reprtsenter les donnCes exPCrimentales. II est possible de bien repisenter les donnCes de rCtention de gaz en utilisant une mCthode s'appuyant sur le travail de Nicklin (1962); les donnees sur le transfert de chaleur sont quant 1 elles bien representees par une expression semi-einpirique simple. Des donnCes experimentales prCcises sur d'autres systems sont nkcessaires pour mettre au point une theorie du transfert de chaleur fiable, en particulier pour la representation des proctdCs i des tempkratures plus ClevCes que la tempCrature ambiante.

The bubble size distributions are measured for the air‐water system as a function of air velocity at room temperature in two bubble columns. High speed cinephotography and fiber optic probe techniques are used to measure the bubble size. Our limited measurements suggest that the bubble size may be independent of gas velocity in the range 3.6 to 9.2 cm/s and may be dependent on column diameter with smaller bubbles for narrower columns. The bubble size appears to be smaller at the column wall than at distances away from the wall.