Journal of the Society of Powder Technology, Japan
Online ISSN : 1883-7239
Print ISSN : 0386-6157
ISSN-L : 0386-6157
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Volume 20, Issue 4
Displaying 1-7 of 7 articles from this issue
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  • Simulation of Moving Granular-Bed Type Heat Exchanger
    Tadayuki MINOURA, Shunichi MIZUKAMI, Takayoshi ASAMI, Hiroyuki KOHAMA
    1983 Volume 20 Issue 4 Pages 185-193
    Published: April 10, 1983
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.20.185
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    A simulation of the moving granular-bed type heat exchanger, in which heat is transferred from the hot gas through granular materials and heat pipes to the cold gas, has been performed. A numerical simulation model was made by dividing each part of the heat exchanger in to small elements, and each heat balance was calculated using the finite difference method. The heat transfer coefficients and effective thermal conductivies of the granular-bed in each part of the heat exchanger were estimated from a general theory, while the heat transfer coefficient between the granular-bed and heat-pipes was determined from the experiment.
    The steady characteristic of the heat exchanger from the calculations was compared with the data obtained from the experiment. The calculation results coincided well with the experimental results.
    The method of modelling and simulation was confirmed to be accurately applicable to the estimation of the performance of the heat exchanger using granules as heat transferring media and heat pipes.
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  • The Properties of II-CaSO4 Obtained by Flash-Calcination
    Hirobumi TANAKA, Kiyohiko UCHIDA, Yasumichi KANESAKI
    1983 Volume 20 Issue 4 Pages 194-202
    Published: April 10, 1983
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.20.194
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    This paper is concerned with a process of manufacturing II-CaSO4 from powdered gypsum (CaSO4·2H2O) and the properties of the products obtained from the process.
    Apart from fluorogypsum (II-CaSO4) formed as by-product in the industrial manufacture of hydrofluoric acid, II-CaSO4 is usually produced by calcining (at 600-800°C) in a rotary kiln or shaft kiln, which consumes a larger amount of heat energy.
    In order to manufacture II-CaSO4 at lower cost, the authors have developed a new technique of manufacturing II-CaSO4 which calcines powdered gypsum (CaSO4·2H2O) instantly by dispersing it into an atmosphere of high temperature gas including flames.
    The main characteristics of this technique are as follows:
    (1) Time for calcining is a few seconds.
    (2) Heat for calcining is below half of those of the old techniques.
    (3) II-CaSO4 can be produced even at 250°C which is below the conversion temperature, from III-β-CaSO4 to II-CaSO4, obtained by DTA.
    The properties of the products calcined at 250, 600 and 800°C, such as pore size distribution, heat of hydration and micro-structures of hydrated bodies were investigated.
    On the basis of these results, it has been proven that the hydration reaction of each product proceeds under the same mechanism. The rate of heat evolution depends upon their micropore distribution and size of crystallite which are characterized by the calcining temperatures.
    Using this new calcining technique, consequently, various types of II-CaSO4 can be obtained only by changing the calcining temperature.
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  • Behaviour of a Single Particle and Classification in Rotating Tilted Liquid Column
    Kouzaburo UEDA, Kotaro SHIRANE, Ichiro AOKI
    1983 Volume 20 Issue 4 Pages 202-210
    Published: April 10, 1983
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.20.202
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    A new method for the classification and separation of fine particles; rotating column (RTC) is analysed. In the theoretical calculation, the motion of a particle in the RTC is solved numerically taking account of the rotation of the particle in addition to the drag of the fluid under the condition of creeping flow.
    The calculated particle trajectories and the effective range of the terminal velocity for the separation on the RTC are varified by comparison with the experimental observations. The influence of the apparatus parameters on the separation power of the RTC, tilted angle, revolution speed, column diameter and apex angle of the conical column, are investigated, and then the optimal combination of the paramters is searched for.
    The existence of the fluid flow in the axial direction is found to improve the separation power of the RTC It would be feasible to operate the RTC continuously by flowing fluid in the axial direction.
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  • Atomization of Slurries Due to Pneumatic Nozzles
    Noriyuki YAMADA, Hideharu HIROSUE, Hiroshi IHARA, Takashi MURAYAMA
    1983 Volume 20 Issue 4 Pages 211-217
    Published: April 10, 1983
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.20.211
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    DL powder, which is called a driftless powder and has a particle size of 10 to 46μm, is being produced in practice by pulverizing and classifying mineral particles such as roseki, talc, limestone and so on. The authors are trying to reutilize the powders less than 10μm, which is a by-product in producing DL powder, by means of a spray drying method.
    This paper deals with the flow characteristics and atomization of slurries composed of water, polyvinyl alcohol (PVA) and clays, such as roseki and talc. The conclusions are summarized as follows:
    1. PVA, added as a binder for products, effectively dispersed roseki and talc in the slurries. The apparent vicosity of the slurries at 50% mass concentration, showed the lowest value at an about 1% PVA solution.
    2. The mass median diameter of slurry droplets could be estimated by Kim-Marshall's equation applicable to Newtonian fluids. In the calculation of the equation, the apparent viscosity of the slurries at the shear rate of 300s-1 was used in place of the vicosity of Newtonian fluids.
    3. The size distribution of droplets approximated to the logarithmic normal distribution and the geometric standard deviation, one of the parameters in the distribution, was connected with the mass median diameter.
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  • Viscosity of Clay Slurries
    Noriyuki YAMADA
    1983 Volume 20 Issue 4 Pages 218-220
    Published: April 10, 1983
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.20.218
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  • [title in Japanese]
    Tomio MIYAZAKI, Yasuo SHOJI
    1983 Volume 20 Issue 4 Pages 221-232
    Published: April 10, 1983
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.20.221
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  • [title in Japanese]
    Fumio SAITO
    1983 Volume 20 Issue 4 Pages 233-235
    Published: April 10, 1983
    Released on J-STAGE: April 30, 2010
    DOIhttps://doi.org/10.4164/sptj.20.233
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