Diameter surface equivalent

For example, surface equivalent diameter diameter of monosized spherical particles which feature the same specific surface as the particulate mass to be characterized. 

Figure 71 shows some of the results as a function of the mean particle size Xq and Xi Xq is the surface equivalent diameter and Xi is the maximum of the diameter distribution density (see Section 3.1.1.1). The diagonal lines represent the maximally transferable tensile strength calculated according to equation (4) using a = 6 and a = 8. 

To achieve growth, the individual mass of adhering particles must be small and their surface large. This is equivalent to the requirement that the size of agglomerating particles must be small. Typically, the surface equivalent diameter (see Section... 

In contrast to tumble/growth agglomeration, which requires a feed with a surface equivalent diameter of less than a few hundred micrometers (see Section 7.1), as well as excellent dispersion and aeration, pressure agglomeration tolerates a wide particle size distribution. The maximum allowable particle size increases with increasing pressure, and aeration of the feed prior to agglomeration must be avoided by all means. As mentioned repeatedly (see for example Section 8.1) and also discussed below, air in the feed must be removed from the compaction area during densification. 

Growth/tumble agglomeration happens in a similar fashion to natural agglomeration. Because the particles to be agglomerated are larger (surface equivalent diameter 10 < Xq < 200 (tm [B.97]), the particle-to-particle adhesion must be enhanced by binders and the collision probability must be increased by providing a high particle con-... 

Since for the evaluation of the influence of particle size, only a single parameter can be considered, the surface equivalent diameter, x, of a particulate feed is used (Chapter 5, [B.48, B.75, B.97]). Typically, this diameter should be in a range below 100-200 pm. 

The previously mentioned representative surface equivalent diameter, x, is calculated from the specific surface area (m /g) of a bulk poivder. Therefore, it takes into account the respective surfaces of all particle sizes. Since the mass decreases ivith the third poiver of diameter but the surface area only ivith its square, the specific surface area of smaller particles has a relatively larger influence on the surface equivalent diameter. This means that the requirement of < 200 pm can be reached ivhile some of the particles in the feed are much larger, for example up to 1 mm in diameter. The model in Fig. 10.3 shoivs that, if a sufficient quantity of fine particles is available, a matrix-like structure forms around larger pieces, ivhich may also consist... 

Since industrial plants process large amounts of solids, the forces required to transport these masses and to cause the turbulent, stochastic movement of individual particles, nuclei, and agglomerates are much bigger than those experienced in the smaller developmental systems. Therefore, it is not unusual that additional and/or more effective binder(s) is (are) required or the feed size must be adjusted to feature a smaller surface equivalent diameter of the fresh input, possibly combined with modified recycle properties, such as smaller size obtained by a suitable mill to be installed in the return loop. 

A better characterization of a particulate feed for tumble/growth agglomeration is by the surface equivalent diameter,, which would directly indicate changes in the fines content (e.g., shift to a smaller size if more fines are present). In addition, it is recom-... 

The representative particle size most appropriate to describe the agglomeration process is the surface equivalent diameter, (Table 2.5), because porosity is surface dependant. As described in Chapter 2, such diameter is the size of a spherical particle which, if the powder consisted of only these particles, would have the same specific surface area as the actual sample. When determining the specific surface area, methods must be chosen at only measure the outer particle surface excluding the accessible irmer surface due to open particle porosity. One of these recommended methods is permeability, also discuss in Chapter 2. 

Bingchen Zhu et al obtained the surface equivalent diameter d g = 1.92 mm, and the shape coefficient is 0.487 for ammonia s3mthesis catalyst A301 with size of 3.3-4.7 mm. 

The volume equivalent diameter is the diameter of a sphere with the same volume as the actual particle s. The surface equivalent diameter is the diameter of a sphere with the same surface area as the actual particle. The surface/volume diameter is the diameter of a particle with the same surface-to-volume ratio as the actual particle. 

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