Freeze Concentration with Ice-Lining in a Crystallizer of Agitated Vessel

Mechanical energy dissipation was investigated in a cylindrical, flat bottomed vessel with four radial baffles and the pitched blade turbine impeller of varied size. This study was based upon the experimental data on the hydrodynamics of the turbulent flow of water in an agitated vessel. They were gained by means of the three-holes Pitot tube technique for three impeller-to-vessel diameter ratio d/D = 1/3, 1/4 and 1/5. The experimental results obtained for two levels below and two levels above the impeller were used in the present study. Radial profiles of the mean velocity components, static and total pressures were presented for one of the levels. Local contribution to the axial transport of the agitated charge and energy was presented. Using the assumption of the axial symmetry of the flow field the volumetric flow rates were determined for the four horizontal cross-sections. Regions of positive and negative values of the total pressure of the liquid were indicated. Energy dissipation rates in various regions of the agitated vessel were estimated in the range from 0.2 to 6.0 of the average value for the whole vessel. Hydraulic impeller efficiency amounting to about 68% was obtained. The mechanical energy transferred by the impellers is dissipated in the following ways: 54% in the space below the impeller, 32% in the impeller region, 14% in the remaining part of the agitated liquid.

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Freeze concentration of dilute aqueous solution

BUNSEKI KAGAKU ◽

10.2116/bunsekikagaku.17.354 ◽

1968 ◽

Vol 17 (3) ◽

pp. 354-355 ◽

Cited By ~ 1

Author(s):

Atsushi MIZUIKE ◽

Shigeki KANO

Keyword(s):

Aqueous Solution ◽

Freeze Concentration ◽

Dilute Aqueous Solution

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Advances in Cryochemistry: Mechanisms, Reactions and Applications

Molecules ◽

10.3390/molecules26030750 ◽

2021 ◽

Vol 26 (3) ◽

pp. 750

Author(s):

Lu-Yan An ◽

Zhen Dai ◽

Bin Di ◽

Li-Li Xu

Keyword(s):

Low Temperature ◽

Chemical Reactions ◽

Common Sense ◽

Reaction Rate ◽

Concentration Effect ◽

Biological Products ◽

Freeze Concentration ◽

New Strategy ◽

The 1960S

It is counterintuitive that chemical reactions can be accelerated by freezing, but this amazing phenomenon was discovered as early as the 1960s. In frozen systems, the increase in reaction rate is caused by various mechanisms and the freeze concentration effect is the main reason for the observed acceleration. Some accelerated reactions have great application value in the chemistry synthesis and environmental fields; at the same time, certain reactions accelerated at low temperature during the storage of food, medicine, and biological products should cause concern. The study of reactions accelerated by freezing will overturn common sense and provide a new strategy for researchers in the chemistry field. In this review, we mainly introduce various mechanisms for accelerating reactions induced by freezing and summarize a variety of accelerated cryochemical reactions and their applications.

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