Kazuhiko Nishi

総合学術電子ジャーナルサイト「J-STAGE」－国内で発行された学術論文全文を読むことのできる、日本最大級の総合電子ジャーナルプラットフォームです。

Effects of the feed location on crystal growth and agglomeration using a model of a classified bed type crystallizer were examined. Semi-batch crystallization tests were examined with a feed from one of various feed locations. The particle size distribution and the number of the product particles were measured. From the results of the investigations, it was concluded that a feed positioned inside the slurry phase of the crystallizer affects the crystal growth and agglomeration phenomena, though the knowledge about phenomena of fine crystals is inadequate. Positioning the feed within the slurry phase increases the crystal growth rate slightly at the bottom of the slurry phase, as well as the agglomeration of the seed crystals, by increasing the degree of supersaturation at the inlet to the crystallizer. However, when the feed is positioned in the upper part of the slurry phase, the feed interferes with the agglomeration by reducing the concentration of the mother solution. It was thought that we can control the size of the crystals that form in the crystallizer by moving the location of the feed to a point within the slurry phase.

Mixing is one of the most fundamental operations in chemical engineering. Stirred tanks are widely used in the manufacture of such materials as chemicals, paints, inks, electronics materials, ceramics, foods, pharmaceuticals and cosmetics. Suitable mixing is indispensable to the purpose achievement of a process. Eccentric mixing, in which an impeller installed at eccentric position in a vessel, is one of the traditional methods of promoting mixing. An asymmetrical flow which occurs in vessel is complicated, and it promotes mixing, distribution, and mass transfer. In this study, a new mixing method which eccentric mixing using a large type impeller which attracts attention in recent years is shown. The high performance of a large impeller can be combined with the advantages of an eccentric impeller by using the impeller at an eccentric position. The power consumption and mixing time for MAXBLEND, which is a type of large impeller, were investigated. The power consumption, P, and mixing time, θ_M, were measured under various eccentric conditions. The relation between the power number (N_p) and Reynolds number (Re) and that between the dimensionless mixing time (nθ_M) and Re were investigated. When eccentric mixing is used industrially, we should be concerned about the horizontal load to a agitating shaft. The large oscillating horizontal load causes serious problems, such as the falling off of the impeller or the breakage of the motor, mechanical seal or gearbox. It is, therefore, important to understand the relation between these values and the impeller rotational speed when designing the mixing equipment and determining the operating conditions. In this study, the torque and horizontal load were measured in eccentric mixing under various eccentric conditions. The averages of both, the torque and the horizontal load, and their standard deviations, corresponding to the amplitude of fluctuation, were shown. Doi: 10.12777/ijse.5.2.73-80 [How to cite this article: Nishi, K., Enya, N., Sonoda, K., Misumi, R., Kaminoyama, M. (2013). Potential of an asymmetrical agitation in industrial mixing. International Journal of Science and Engineering , 5(2),73-80. Doi: 10.12777/ijse.5.2.73-80]