Experimental procedure particle size distribution

Despite these potential problems, remarkably little work has been published on particle degradation in pneumatic conveying systems. That may be explained by experimental problems that are even much more serious than with fluidized beds. According to the different problems mentioned above, there are more individual measurement techniques and assessment procedures required than with fluidized bed attrition. Usually, the assessment is restricted to the comparison of the particle size distribution before and after conveying. Moreover, there is no steady-state attrition that could be measured. It is only possible to measure an integrated value, which... 

In addition to the patent literature available on the production of BR in the gas-phase there is some scientific literature which mainly refers to the modeling of reaction kinetics. Details on the experimental procedure for the determination of the macroscopic kinetics of the Nd-mediated gas-phase polymerization of BD in a stirred-tank reactor are reported [568,569]. Special emphasis is given to video microscopy of individual supported catalyst particles, individual particle growth and particle size distribution (PSD). These studies reveal that individual particles differ in polymerization activity [536,537,570,571]. Reactor performance and PSD are modeled on the... 

The aim of this paper is to describe the experimental and numerical techniques that, when combined, provide a procedure that enables full particle-size distribution studies of sub-micrometer emulsion systems. We then present distribution results for several oil/water emulsions to demonstrate the ability of these techniques to monitor the effect of processing variables (such as surfactant concentration) on the final emulsion. Finally, we discuss some of the problems of converting the intensity weighted distribution to a mass weighted distribution and suggest methods for minimizing or eliminating some of these problems. 

Related Calculations. This procedure can be used to calculate average sizes, moments, surface area, and mass of solids per volume of slurry for any known particle size distribution. The method can also be used for dry-solids distributions, say, from grinding operations. See Example 10.7 for an example of a situation in which the size distribution is based on an experimental sample rather than on a known size-distribution function. 

The development of the experimental procedure then involves the preparation of standard mixtures to prepare a calibration curve, with due care paid to corrections for particle size distribution, background, illuminated volume of sample and preferred orientation. A typical calibration run is shown in Fig. 4.25. Determinations on a series of similar spiked mixtures leads to the calibration curve in Fig. 4.26. Analysis of the resulting data led to the determination of a minimum quantifiable limit of 5 per cent, a working range of 5-50 per cent Form B and an RDS of 16 per cent. The method... 

In early instruments, the detectors consisted of a series of half rings [143,144] (Figure 10.8) so that a matrix equation developed. Sliepcevich and co-workers [145,146] inverted this equation to obtain the particle size distribution. The equation was solved by assuming the distribution fitted a standard equation and carrying out an iteration to obtain the best fit. A matrix inversion was not possible due to the large dynamic range of the coefficients and experimental noise that could give rise to non-physical results. An inversion procedure that overcame these problems was developed by Philips [147] and Twomey [148] that eliminated the need to assume a shape for the distribution curve. 

The procedure above is particularly usefiil for preparing supported noble metal (NM Pd, Pt, Rh) catalysts. T ugh obviously sensitive to the support surik e area, metal loading, and the specific experimental protocol, this procedure, at the laboratory scale, often leads to well dispersed metal systems with relatively narrow metal particle size distributions (97,117,183,235). 

In relation to limit tests, the general trend will therefore be soft precipitates give a precipitate of a relative small particle size distribution regardless of the experimental procedures used and will not change in time. The particle size distribution of a hard precipitate depends on sample handling and might display crystal growth. 

There are examples in the literature of fitting parameters to single particle models in both aggregation and breakage processes until an experimentally measured equilibrium particle size distribution is closely matched by the solution to the population balance equation. The rationality of such a procedure is much in question, as it is clearly not sensitive to the time scales of breakage and aggregation. 

Figure 7 Changes in the particle size distribution of a FCC catalyst material that was subjected to cyclone attrition. (Zenz and Kelleher, 1980.) The respective experimental procedure is described in Sec. 5.3.

Experimental methods presented in the literature may prove of value in combustion studies of both solid and liquid suspensions. Such suspensions include the common liquid spray. Uniform droplets can be produced by aerosol generators, spinning disks, vibrating capillary tubes, and other techniques. Mechanical, physicochemical, optical, and electrical means are available for determination of droplet size and distribution. The size distribution, aggregation, and electrical properties of suspended particles are discussed as well as their flow and metering characteristics. The study of continuous fuel sprays includes both analytical and experimental procedures. Rayleigh s work on liquid jet breakup is reviewed and its subsequent verification and limitations are shown. 

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