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Mixing in multiple‐impeller stirred tank reactors with boiling liquids
Author(s) -
Dohi Naoki,
Matsuda Yukimasa,
Itano Norihiro,
Shimizu Kazuhiro,
Wa Kimio Mineka,
Wase Yoshinorika
Publication year - 1999
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450770502
Subject(s) - impeller , boiling , mixing (physics) , materials science , power consumption , thermodynamics , power (physics) , physics , quantum mechanics
Mixing in a boil‐off mechanically stirred tank reactor with multiple impellers was examined. Power consumption and gas hold‐up were measured in boiling water in a 0.2 m i.d. stirred tank reactor with three four‐pitched blade downflow disk turbines. Vapour was generated from both the immersed ring heater and the impellers. At low vapour generation rates, vapour was mainly generated from the impellers rather than from the heater, whereas nucleation occurred at the heater instead of the impeller at higher vapour generation rates. The mechanical power consumption decreased due to vapour generation. The change in boiling‐to‐non‐boiling mechanical power ratio with varying impeller rotational speed and boiling rate was complicated and not monotonous except at higher impeller speeds and boiling rates. The gas hold‐ups increased with increasing vapour generation rate but were rather small as compared to those in cold gas dispersing systems. Empirical correlations for power consumption and gas hold‐up in boiling liquids were developed using the present experimental data.