Abstract
Power consumption in a baffled agitated vessel with pitched wire-gauze blade impeller is measured over a wide range of Reynolds number in turbulent flow region, where the power consumption decreases with decreasing the wire-gauze blade angle. The power consumption without aeration is well correlated with the baffled condition parameter (BW/D)nb0.8. The rotational speed to occur the gross circulation of gas NR increased with the decrease of a blade angle θ for the upflow condition. In the operating conditions of the gross circulation flow of the gas back into the impeller (N > NR) and the turbulent flow (Red > 200), the power consumption under aeration at the standard baffled condition Npg is correlated with the modified equation by the blade angle θ, which was reduced to the power correlation for the wire-gauze impeller (θ = π/2). In the range of the rotational speed of N > NR the power number under aeration is almost independent of the impeller position and the liquid flow direction through the impeller.
The measured gas-liquid mass transfer volumetric coefficient for the pitched wire-gauze blade impeller kLa coincides well with the correlation of kLa for the wire-gauze impeller in lower viscosity liquid, whereas the former is smaller than the latter in higher viscosity liquid because of the lost of the wire-gauze blade effect.
