循環回路式ジェット粉砕機の解析

抄録

In the previous report, we gave an account of the analysis of the mechanism of jet-pulverization observed in a small-scale experimental jet-pulverizing apparatus, and derived some assumptions, of which the proposed relation between mill-power (H) and mill-capacity (G) had the most important meaning. We proposed there the following equation:
G∝H^σ
in which σ_??_2.5}(1)
This equation shows that the jet pulverizer becomes more efficient as the mill-power increases. With most mills of other types, value of σ, which shall be called a coefficient of the size effect of pulverizer, is about 1.21.5.
In order to confirm this relation and other assumptions, we conducted some experiments with a laboratory-scale jet-pulverizer of practical use (Jet-O-Mizer 202 with 30HP compressor), and the results are given here to make clear the effects of variable factors, such as nozzle pressure, feeding rate of raw materials and diam. of nozzle, etc. on the rate of grinding.
This type of jet-pulverizer has a ring-shaped circular tube through which the mixture of air and particle circulates continuously, while some part of the mixture is taken out and sent to the collector successively.
The number of circulation, which was inversely proportional to the feeding rate was found to be one of the most important factors in this pulverization. The grinding action was strongest in the jet-stream, and it was negligibly weak on the surface of the mill wall. (Cf. Fig. 7.)
From these and other assumptions previously proposed, we derived Eq. 5.
X=100KA_N1P_N1+100(1-KA_N1P_N1)[1-(1-KA_N2P_N2)^2N] (5)
as a fundamental equation for calculating the capacity of the circulating type jet-pulverizer.
By comparing the capacity of this type of mill with that of the above-mentioned small-scale experimental apparatus (2HP) and of Jet-O-Mizer 808 (250HP), we substantiated the results of our experiment.
Data on Jet-O-Mizer shown in the information by Fluid-Energy Equipment and Processing Co. also verify Eq. 5. (Cf. Fig. 10.)
We had assumed, in the previous report that when mill-power became larger, the mechanism of breakage would change from surface grinding to bulk crushing and that the constant for the degree of surface grinding (n) would become small. The results of this experiment shown in Table 4 also verify this assumption.