Koichi Iinoya

The capillary binding force of a liquid bridge

Abstract Capillary binding forces caused by liquid bridges between a solid body and a liquid surface, or between two solid bodies, are experimentally measured. Based on the results, a new method for analytical estimation of the binding force is proposed and the interrelations among various similar methods so far proposed are discussed. Next the validity of the circular approximation for the meridian curve of the bridge surface is quantitatively examined and the conditions required for use of this approximation are clearly stated. Then for the cases where this approximation is allowable, some characteristcis of a very small bridge: binding force, pressure deficiency and vapor pressure of the liquid etc. are discussed. Finally a method to improve the circular approximation is suggested.

Electrification of gas—solid suspensions flowing in steel and insulating-coated pipes

Abstract Electrification of gas—solid suspensions flowing in steel and insulating-coated pipes are experimentally studied. It is found that the currents generated on insulating-coated pipes are higher than the currents generated on a steel pipe and the sign of the currents follows a kind of tribo-electric series. The currents are proportional to powder flow rate, proportional to mean air velocity to the power 1.4–1.9, and inversely proportional to the mean particle diameter. It seems that the currents are proportional to the pipe diameter. The effects of a bend and powder feeding inlet are also studied.

New Estimation Method of Particle Size Distribution by Anisokinetic Sampling.

固気二相流中の粒径分布の測定は, 粉体プロセスの性能管理, 排煙中の粒子状物質の性状評価などにおいて, 極めて重要な操作である.従来の測定法では, 等速吸引によりサンプリングを行い, その後, 複雑な分級器を用いて粒径分布が計測されていた.本論文は, 非等速吸引による濃度測定誤差が粒子径によって異なることを粒径分布測定に利用する技術について検討したものである.非等速吸引の際の流速比 (主流流速の吸引流速に対する比率) が, 測定濃度と直線関係を持つことから容易に真濃度が求められ, また当然, 流速比は濃度比 (測定濃度の真濃度に対する比率) とも直線関係を持ち, その傾きは粒径分布によって異なる.本技術は, この概念を粒径分布測定に応用したもので, フライアッシュ, 灯油燃焼ばいじんなどについて測定した結果, 従来法と良い一致を示し, 十分な測定精度を有していることが明らかになった.

PRESENT STATUS OF POWDER TECHNOLOGY EDUCATIONAL PROGRAMS AND RESEARCHES IN JAPAN

(Abstract) Tables to indicate the present status of powder technology educational programs in Japan are presented on the basis of a questionnaire style investigation by the Society of Powder Technology, Japan. Research activities in universities and research institutes are also included in the tables. The activities of both the Society of Powder Technology and the Association of Powder Process Industry and Engineering in Japan are also introduced by explaining their organizations and annual events.

State of equilibrium between dust pile and jet flow in slit nozzle impactor

Abstract The shape of the dust pile equilibrated on a collection plate with a two-dimensional impinging jet flow is studied experimentally and analytically in relation to re-entrainment in a cascade impactor. Consequently, it becomes clear that the shape of the equilibrated dust pile may be expressed as a function of the dimensionless number B , which represents the ratio of the weight of piled dust per characteristic volume of the nozzle to the momentum of fluid jet per unit time, and of the effective angle of internal friction of the dust. A maximum weight and volume of the dust pile for an impactor can be estimated by use of the value of B , calculated from the operating conditions. When an impactor is used for the separation of small quantity of a precious dust, the maximum weight and volume of the dust pile are the critical value.

On the Economically Optimal Design of Air Filter

エアフィルタの年間経費式をファンの固定費と動力費, エアフィルタの固定費, およびろ材費から構成した。特に自動交換形で部分交換運転によるろ材寿命の増加を考慮してろ材費を求めた。2～3の典型的なろ材を想定して, それぞれの場合について年間経費を最小にする最適ろ過風速, および最適運転圧損 (パネル形では最終圧損, 自動交換形では標準運転圧損) を毬々の処理風量と粉塵濃度に対して求めた。なお2～3のメーカーやユーザーに間い合わせ, 現在の実用的な定数値を計算に使用した。さらに近似精度のよい最適解を解析的に求めた。それを使って各パラメータの最適解に対する影響を論じた。その結果, 最適操作条件は処理ガス風量には余り影響を受けないが, 粉塵濃度に大きく影響されること, さらに, ろ材の圧損特性によって著しく影響されることなどがわかった。自動交換形での部分交換運転の経済的効果は, たかだか2割程度の年間経費の低減であることがわかった。

On the Characteristics of a Table Feeder

テーブルフィーダの静的および動的特性に関して検討した。その結果, 静特性は堆積粉体層の形状を考慮することにより, 広い操作範囲で精度よく推定できること, また定量性を向上させるためには, スクレーパをテーブルの同心円に接する方向に挿入すべきであることがわかった。一方, スクレーパ位置を操作量とするステップ応答には, 粉体の種類によって微分動作的応答と比例動作的応答があり, これらはいずれも理論的に説明できた。

On Critical Cut Size of Particle Separator

The particle diameter at 50% partial collection efficiency is usually used as critical cut size to evaluate a particle separator. However, such assumption is not adequate for exact estimation of the overall collection efficiency, because the latter depends on the inlet particle size distribution too.The theoretical correlations between overall collection efficiency and equilibrium (real) cut size are herein derived, assuming the Rosin-Rammler or the logarithmic normal distribution for the inlet particle size. The ratio of the equilibrium and an arbitrary cut size is also calculated for any R-R distribution, assuming an equation of partial collection efficiency. As an example, this calculation method is applied to the measurement of size distribution of monodisperse aerosol by a two-stage cascade impacter.

Measurement and Control of the Solid-Gas Mixture Ratio in Two-Phase Flow

Automatic control technique does not seem to be applied very much to the field of solid particle handlings, because no adequate device is available to measure and to manipulate the flow rate of solid particles.According to previous report, the solid-gas mixture ratio can be calculated using the two pressure differences of a two phase flowmeter. In this paper, therefore, a specific servo-computer is employed “on line” for this purpose.The mixture ratio is continuously measured within the accuracy of ±5% and successfully contr olled using an electromagnetic vibrating feeder as the manipulating device. In the mixture ratio control, an upside weir should be attached to the feeder trough to get wider manipulating range. The inverse response appears in the mixture ratio by the difference of dynamic characteristics between high and low pressure side s of a transmitter. Therefore, particular attention should be paid to select a transmitter in order t o get a quick and stable response.