Thermal Efficiency of Vacuum Drying in a Vibro-fluidized Bed

振動流動層を用いた新しい形の真空乾燥法の開発を試みた。本研究ではその予備試験として,真空乾燥における最も重要な問題である装置の熱効率について考察を加えた。実験には2種類の試料を用いた。一つはイオン交換樹脂球(Amberlite,IR-120B)であり,他の一つはおから(卯の花)である。

層に空気を吹き込まず,真空状態にしても層を適当な振動強度で振動させれば,層内の材料は移動,混合した。それ故,そのような真空下であっても,層全体にわたり均一含水率で乾燥を行うことができた。ヒーターに加えた熱量はまだ非常に少ない範囲であるが,得られた熱効率はほぼ100%であった。振動強度が一定の場合には,ヒーターに加える熱量が増加するにつれて熱効率は減少した。

本研究の結果,振動流動層を用いた真空乾燥の可能性が認められた。

We tried to develop a new system for vacuum drying by using a vibro-fluidized bed. The thermal efficiency of the apparatus which is the most important factor of the vacuum drying was investigated in this paper. Two kinds of samples were examined. One was ion exchange resin particle (Amberlite, IR-120B), and the other was okara.

When the bed was vibrated under suitable vibrational intensities, the materials in the bed were circulated and mixed even though the air was not flowed into the bed, and the bed was in vacuum state. Thus, the drying processes were able to be carried out at uniform bed moisture content even in such conditions.

The thermal efficiencies obtained were nearly equal to 100 % for both samples under suitable conditions of vibration, although the heat energies supplied to the heater were very low. When the vibrational intensities were constant, the thermal efficiencies decreased as the heat energies supplied to the heater increased. As a result of this study, the possibility of the vacuum drying in a vibro-fluidized bed was recognized.