English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Gas-sparged vessels agitated by mechanically rotating impellers are apparatuses widely used mainly to enhance the gas-liquid mass transfer in industrial chemical process productions. For gas-liquid contacting operations handling liquids of low viscosity, baffled vessels with unidirectionally rotating, relatively small sized turbine type impellers are generally adopted and the impeller is rotated at higher rates. In such a conventional agitation vessel, there are problems which must be considered (Bruijn et al., 1974; Tanaka and Ueda, 1975; Warmoeskerken and Smith, 1985; Nienow, 1990; Takahashi, 1994): 1) occurrence of a zone of insufficient mixing behind the baffles and possible adhesion of a scale to the baffles and the need to clean them periodically; 2) formation of large gas-filled cavities behind the impeller blades, producing a considerable decrease of the impeller power consumption closely related to characteristics on gas-liquid contact, i.e., mass transfer; 3) restriction in the range of gassing rate in order to avoid phenomena such as flooding of the impeller by gas bubbles, etc. Neglecting these problems may result in a reduced performance of conventional agitation vessels. Review of the literatures for the conventional agitation vessel reveals that a considerable amount of work was carried out to improve existing type apparatuses. However, a gas-liquid agitation vessel which is almost free of the above-mentioned problems seems not to have hitherto been available. Therefore, there is a need to develop a new type apparatus, namely, an unbaffled vessel which provides better gas-liquid contact and which may be used over a wide range of gassing rates. As mentioned above, in conventional agitation vessels, baffles are generally attached to the vessel wall to avoid the formation of a purely rotational liquid flow, resulting in an undeveloped vertical liquid flow. In contrast, if a rotation of an impeller and a flow produced by the impeller are allowed to alternate periodically its direction, a sufficient mixing of liquid phase would be expected in an unbaffled vessel without having anxiety about the problems encountered with conventional agitation vessels. We developed an agitator of a forward-reverse rotating shaft whose unsteady rotation proceeds while alternating periodically its direction at a constant angle (Yoshida et al., 1996). Additionally,

Gas-Liquid Mass Transfer in an Unbaffled Vessel Agitated by Unsteadily Forward-Reverse Rotating Multiple Impellers