摘要:

AbstractParticle Technology is a broad and multidisciplinary subject of great importance but diffuse in definition. In this paper a view is presented of the underlying science and its technological applications. In particular a structured subject is dependent upon characterization techniques from which predictions can be made. In this paper the interrelationship between macroscopic and microscopic characterization is discussed. The standardisation and development of the microscopic techniques, particle analysis, is identified as the key to the development of the whole subject.

ISSN:0934-0866    

DOI:10.1002/ppsc.19840010101

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractIn the application and the development of on‐line methods for particle size analysis one has to distinguish three principally different problem areas:aallocation and preparation of a representative sample,banalysis of the sample,cevaluation of the results.Methods and problems connected with these areas will be discussed in this paper. Some of the methods available for rapid response analysis of particle size distributions mark the beginning of a new era of particle size analysis. One has to recognize however that a uniform solution of the problems of on‐line particle size analysis is extremely difficult if not impossible to find. The boundary conditions vary to such an extent that similar methods or combinations of methods can rarely be used in different cases. Since instrument manufacturers will in most cases not be able to adopt their instruments to different industrial applications, specialists will have to solve the problem. One has to recognize, however, that not all of the steps described in this paper have been investigated to an extent which renders possible appropriate solutions. There is still room for improvem

ISSN:0934-0866    

DOI:10.1002/ppsc.19840010102

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractMandelbrothas extended the concept of classical dimensional description of physical systems to include fractional values which describe the ruggedness of a structure. Thus if one has a dimension of 1.2 one knows that one is dealing with a line which fills space more efficiently than a line which has dimension of 1.1. A mathematical curve which exhibits ideal fractal structure has the same appearance when viewed at any level of scrutiny.Kayeand co‐workers applied the concept of fractal mathematics to the description of the boundaries of fineparticle profiles. As demonstrated in this communication a natural fractal boundary in contrast with an ideal fractal can exhibit different fractal structures over different ranges of scrutiny. As a consequence one should always report the scale of scrutiny employed when examining the fractal structure of natural boundaries. Data is presented demonstrating the fractal/euclidean boundary structure manifest by aluminum shot fineparticles examined at various levels of scrutiny. The relationship between fractal descriptors of fineparticle boundaries and the Fourier analysis of geometric signature waveforms for describing the structure of fineparticles is explored. Data presented by Flook on the physical significance of the various co‐efficients of a Fourier analysis of a signature waveform is correlated with the fractal description of the ruggedness of a prof

ISSN:0934-0866    

DOI:10.1002/ppsc.19840010103

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractFor some time studies have been made relating the values obtained from simple shape description to bulk powder properties. More recently the detailed mathematical description of particle outline has become possible and quite powerful techniques have been developed. These techniques may be used for the regeneration by computer of the shape and, more importantly, for studies relating shape to individual particle behaviour and to bulk powder properties. Quite inadequate attention has been directed to the task of obtaining from the laboratory sample of the bulk powder a representative sample of shapes without bias. In this communication the considerations to be included in the sampling procedure are reviewed and a possible solution to the problems posed is presented.

ISSN:0934-0866    

DOI:10.1002/ppsc.19840010104

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractThe currently used methods of sample preparation are examined and found to be unsatisfactory in case of counting methods for particle size analysis. It is the purpose of this paper to review the results of investigations of two different measuring principles (light extinction and electrical resistance change) by use of the same signal handling equipment. The commonly used techniques and units are compared with regard to the resulting density distributions of particle size below 0.25 mm. The final conclusions including recommendations to the use of ultrasonic treatment and to improvements of the sampling and the sample‐feeding units are valid for all counting method

ISSN:0934-0866    

DOI:10.1002/ppsc.19840010105

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractMost existing theories of the response of electrical sensing zone particle size analysers, for instance of the type Coulter Counter®, predict that a significant deviation from sizing linearity will occur at and above some 40% of the aperture diameter. Practical experience, at least for the only test models available ‐ latex spheres ‐ shows that this is not the case in practice. Linear particle response up to 80% of the aperture diameter has been established, confirming the prediction recently made byScarlettin a new response th

ISSN:0934-0866    

DOI:10.1002/ppsc.19840010106

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractIterative numerical analysis methods, similar to those used for ray tracing in electron and ion guns, have been employed to calculate the electrical potential distribution in the vicinity of the orifice of an electrical sensing zone (esz) instrument. In particular, the electrical potential across the mouth of the orifice is considered and the effects of numerically bevelling the sharp peripheral edge are demonstrated.The results support the empirical equation:\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm d}\phi {\rm /d}x \sim 1 + \alpha '\{(r/R)/(1 - r/R)\} ^{\beta '} $$\end{document}for the axial component of the potential gradient, dϕ/dx, at the mouth of the orifice expressed as a function of the radial distance,r, from the centre of the orifice of radiusR; α′ and β′ are empirical constants. This equation was derived from previously reported experimental data on relative shifts and heights of artefact peaks apparent on the coarse side of size distributions measured via the esz method on a series of latex copo

ISSN:0934-0866    

DOI:10.1002/ppsc.19840010107

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractThree general types of commercial particle sizing instruments have been tested with redispersed fly ash and devolatilised coal char in the size range 0.5 to 5 μm. Results are compared with volume‐equivalent diameters obtained by Coulter Counter. Single‐particle light‐scattering counters are found to oversize fly ash, primarily because of the irregular particle shape, but generally to undersize the strongly absorbing char particles. The Malvern sizer, based on Fraunhofer diffraction analysis, grossly oversizes fly ash dispersed in water, probably because most of the particles are too small for the Fraunhofer approximation to be valid; results for carbon char are closer to the expected values, although results for particles dispersed in air and in water show some disagreement. The Aerodynamic Particle Sizer undersizes irregular particles substantially, probably because of increased drag resulting from the irregular shape and tumbling motion of these par

ISSN:0934-0866    

DOI:10.1002/ppsc.19840010108

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractWhen performing particle size analysis by scattered light, coincidences in the measuring volume of optical particle counters not only cause too small a particle concentration to be measured, but also a size distribution to be obtained which is systematically shifted towards coarser particle sizes. It is pointed out in this paper how this shift can be precalculated when the true distribution is given. The results show under which conditions a correction of the measured distribution is indispensable.

ISSN:0934-0866    

DOI:10.1002/ppsc.19840010109

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractIt has been shown that the projected area of a rotating fineparticle can be used to construct a signature waveform which is descriptive of some aspects of the three‐dimensional morphology of a fineparticle. If the fineparticle is rotated systematically about two mutually independent axes, through two sets of 90 degrees rotations, the signature waveform can be related to the surface area of the convex hull. It could be that the convex hull of a fineparticle is related to its fluid dynamic behaviour and its ability to modify the effective viscosity of a fluid in its suspension. This type of significance of different types of Cauchy signature waveforms are discussed. The concept of three‐dimensional signature waveforms is extended to cover the structural shape waveform and the fractal waveforms which, respectively, describe the spatial structure and the ruggedness of a fineparticle profile. The possible utilization of all three types of waveforms to describe in a complete manner the three‐dimensional structure of a rugged fineparticle is disc

ISSN:0934-0866    

DOI:10.1002/ppsc.19840010110

出版商:WILEY‐VCH Verlag GmbH    

年代:1984

数据来源: WILEY