Characteristics of an ice wash column was investigated under non-washing condition. Ice crystalsproduced by the second refrigerant freezing method were used in this experiment.
The hydraulic piston bed (HPB) formed in the wash column showed a zigzag upward movementby the effect of the wall friction. The average velocity was in proportion to the pressure drop ofthe solution flowing in the driving section, but this relation was remarkably changed by thesaturation of the residual solution in the washing section. Under the higher pressure drop, theaverage porosity of the bed in the driving section was nearly the same as that of the top bed inthe washing section, but under the lower pressure drop, the former was a little larger than thelatter, while those values of the porosity were distributed in the range of ±10% in the relationwith the pressure drop. Therefore, the HPB was considered to consist of the bed in which theporosity was not uniform, and especially it was considered to consist of a compressible one underthe lower pressure drop.
Under the non-washing condition, it may be assumed that the saturation of the residual solutionof the top bed just equalled to the unit when the HPB moves upward with the maximum allowancevelocity. From the relation between the average velocity of the HPB and the saturation of theresidual solution of the top bed, it was found that both the maximum allowace velocities of the HPB were about 24cm/min and 30cm/min, respectively, when the porosity of the top bed was 0.4 and 0.5
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