Particle Characterization, Present State and possible Future Trends

Abstract

The investigations of single and combined properties of particles or of particulate matter still belongs to the most important areas of present research and practical applications of Particle Characterization. Methods to measure single particle properties, as for instance particle size, shape, composition and velocity, are of much higher sophistication than before and they still aim at improved accuracy and higher resolution. There still is a considerable lack of understanding, and lack of theoretical interpretation and of experimental evidence of the differences seen in the correlation of different equivalent diameters, obtained when analysing the same irregularly shaped particle, or a distribution of particles, using different physical principles. Furthermore, there still is a lack of understanding of the influence of shape on the results obtained with optical methods using diffraction, light scattering etc., thus asking for more information with respect to the transferability of results from one physical principle to another. The measurement of combined particle properties comprises the simultaneous measurement of, for instance, size, velocity and concentration, which is of particular importance in the comprehensive description of multiphase flow systems. Those instruments which are in working order are highly complicated, not easy to use and to handle and they are in most cases special adaptations for a limited range of the variables to be analysed. There is also growing interest in the evaluation of socalled property functions. Particle Characterization will remain for quite a number of years just as exciting as it has been in the past. If industrial demand enforces the use of on-line inskumentation it might even become more interesting.QVCH Verlagsgesellschaft mbH, D-6940 Weinheim, 1986

Measurement of bubble and pellet size distributions: past and current image analysis technology

“…On-line analysis should reduce and not increase the laboratory workload [19]. There has been a perceivable trend towards computer-controlled chemical operating plants [47], and most recently process analytical technology (PAT), in part based on online sensors, is being applied to many processes [93].…”

“…Overdilution increases the number of objects detected, while under-dilution causes overlaid objects; optimal dilution is the lowest dilution that enabled the maximum percentage of recognition [5]. As the overall variance of analysis is composed of the sum of individual variances of each step, a 10% sampling error is large compared with a 1% standard error in size analysis [47]. Errors also exist when the sensor is placed next to the glass window of a tank (applicable primarily to small-scale laboratory apparatus) which can affect measurements due to its curvature, although this error is smaller than the sampling error.…”

Particle Size Analysis and Characterization of a Classification Process

“…The reason for this must partly be attributed to the fact that in particle size analysis every possible physical principle has been used to determine these distributions. For several reasons, the results are generally not the same [3]. One of the main problems still encountered with most methods in use is their unknown absolute accuracy.…”

“…49) A 2 coarse particles in the feed material (Eq. 50) A 3 fine particles in the coarse fraction (Eq. 51) A 4 coarse particles in the coarse fraction (Eq.…”

“…expected value E M Ecart of Mayer [22], [ mass flow rate of the feed material m 1 mass flow rate of the fine fractioṅ m 2 mass flow rate of the coarse fraction n spread parameter of the RRSB function n number of intervals q density distribution q 0 number density distribution q 0 density distribution of the feed material q 1 density distribution of the fine fraction q 2 density distribution of the coarse fraction Q cumulative distribution Q 0 cumulative distribution of the feed material Q 1 cumulative distribution of the fine fraction Q 2 cumulative distribution of the coarse fraction Q 3 mass …”