In the present report, the weight control of the hopper was discussed by using a microcomputer as the controller and using sand as granules, due to its good flowability.
For the control algorithm, the so-called “Finite Time Settling Control (F. T. S. C.)” method was used and for the control action, two actions are considered; namely, integral and proportional actions which are inserted into the main loop, respectively. Applying the above F. T. S. C. algorithm, it is usually necessary for all the state variables to be fed back to the set point, but this time, only the weight of the hopper as the control variable was weasured, and the remaining variables were estimated by an “observer” which is realized within the microcomputer by the soft-ware program.
The following results were obtained:
1) The suitable index of controllability was obtained from the responses thrrough the step change of the weight and the external disturbance to the system.
2) The results of he computer simulation and the experimental wave form show good agreement and this fact shows that the simulation is useful for estimating the dynamic states of fhe granules inside the hooper.
3) Applying the F. T. S. C. method, it is more suitable to use P-action than I-action in the main loop for the following reasons.
a) The undesired influence of the saturation characteristics coming from the motion of the actuator is less for P-action than for I-action.
b) The response wave form of P-action is more stable than for I-action both for the step change of the set point value and the external disturbance.
c) In P-action, it was confirmed that there is no “off-set” in the response wave form for the external disturbance, despite of the fact that “off-set” remains for the step change of the set point value.

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The dry grinding mechanisms of a laboratory hammer mill with an internal classifier were investigated by using three kinds of cokes and pitch which are byproducts in the manufacture of petroleum. Progress of the comminution of the byproducts in the mill was analyzed on the basis of the grinding rate equation.
The experimental results are summarized as follows: 1) The quantity ratio of fine powder to daughter fragments produced from the screen mill was larger than that produced from a ball mill. This may be thought to be due to the higher impact speed of the grinding media of the mill to the ground material. 2) The grinding rate equation was expressed under the stationary state grinding condition by the mass balance equation which is composed of the breakage parameter, selection parameter and specific rate of separation. 3) The value of the breakage parameter was increased with increase of the feed size of the ground material. On the other hand, the values of selection parameter, the specific rate of separation and grinding efficiency were increased with increase of the feed rate. 4) The addition of a small amount of carbon black to the pitch in the mill increased the values of the selection parameter, the specific rate of separation, the capacity of the mill, and it improved the grinding efficiency remarkably. Therefore, carbon black is expected to be a useful Bringing aid for the comminution of ground materials like the pitch even by the use of the hammer screen mill.

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Deposition of unipolarly charged aerosol particles flowing through parallel plates has been investigated both theoretically and experimentally. The equation of motion for the particles was solved numerically in consideration of the coulombic force, image force, particle-inertia force, and fluid-velocity profile. Then the deposition efficiency was calculated based on the limiting trajectories of the particles
It was found that the calculated deposition efficiency, assuming a laminar flow, was a little smaller than the corresponding analytical solution obtained for the plug flow distribution. It was also found that the effect of the image force and particle-inertia force was negligible in the experimental range. The experimental deposition efficiencies for charged fly-ash particles were well explained in so far as the actual velocity distributions were taken into consideration.

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In a previous paper, it was shown that electro-charged water, which was injected in parallel to the gas flow, could help point the way forward improvement in venturi scrubber performance. However, it had a wholesome on the throat gas velocity below 40m/sec. The present paper examines the effect of electro-charged water, which is injected through a glass tube placed in the center of the throat, on collection efficiency. Calcium carbonate is used for the test dust. The results are summarized as follows: (1) Collection efficiency is 95-98% for 20-30kV charged water. Throat gas velocity is as high as 45-65m/sec. Additionally, this system is applicable to the small liquid-gas ratio 0.03(l/Nm³). (2) Collection efficiency is independent of water conductivity in the range of 10²-10³(μmho/cm) and of water surface tension more than about 40(dyne/cm). Fortunately, ordinary water has conductivity and surface tension with in this range.

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