Pellet bulk density

Calculate the feeding screw throughput rate capacity assuming plug-flow and LDPE pellet bulk density of 0.45 g/cc. The geometrical variables of the feeder screw are barrel diameter, Dj = 1.66 in screw root diameter, /.L 0.325 in and lead,... 

Stmcture is usually measured by a void volume test such as the absorption of dibutyl phthalate (DBPA) (15), or by bulk density measurements of the carbon black under compression. In order to eliminate the effects of pelletizing conditions the DBPA test has been modified to use a sample that has been precompressed at a pressure of 165 MPa (24,000 psi) and then broken up four successive times (24M4) (16). This procedure causes some aggregate breakdown and is claimed to more closely approximate the actual breakdown that occurs duting mbber mixing. 

One of the most important material-handling techniques in the chemical industry is the movement of material suspended in a stream of air over horizontal and vertical distances ranging from a few to several hundred feet. Materials ranging from fine powders through 6.35-mm (lA-in) pellets and bulk densities of 16 to more than 3200 kg/m (1 to more than 200 Ib/ft ) can be handled. A large, capable manufacturing... 

The reactor volume is calculated from Mj and the bulk density of the catalyst material, (-r ) depends not only on composition and temperature, but also on the nature and size of the catalyst pellets and the flow velocity of the mixture. In a heterogeneous reaction where a solid catalyst is used, the reactor load is often determined by the term space velocity, SV. This is defined as the volumetric flow at the inlet of the reactor divided by the reaction volume (or the total mass of catalyst), that is... 

The particle density and bulk density of AN particulates (prills, granules, pellets) are reflected in the density of the cast Minol II prepd. The highest Minol 11 density is attained thru use of... 

The catalyst consists of 3-mm pellets that pack to a bulk density of 1350 kg/m and = 0.5. Mercury porosimetry has found 7 ore = 5nm. The feed mixture to a differential reactor consisted of 5mol% SO2 and 95mol% air. The following initial rate data were obtained at atmospheric pressure ... 

Typical results of the dry pelletizing process when a charge of carbon black and its plus 52-mesh seeds is tumbled in a drum (12) are shown in Figs. 31 and 32. Initially, the seeds grow in size rapidly by snowballing. The dip in the bulk density of the seeds (Fig. 32) suggests that the deposited layers are quite porous in the beginning but get compacted in due course to... 

Fig. 32. Bulk densities of seed and intermediate granules and fines as a function of the pelletizing time. [From Israel and Ventakeswarlu (12).]...

Continuous SSP plants are characterized by longer residence times and larger product hold-ups compared to the melt phase. This is due to the lower processing temperatures and the lower bulk density of the pellets compared to the melt. At today s standard bottle grade capacities of ca. 300 t/d, the typical plant hold-up is approximately 2501, which equates to around 300 m3 of product volume at a bulk density of 800kg/m3. Because the plants make use of gravity flow through the equipment they tend to be very tall - up to 50 m at 300 t/d. 

The bulk density of the flakes is typically between 250 and 450kg/m3. Compared to pellets, with a typical bulk density of between 750 and 850kg/m3, this has a negative effect on equipment sizing and product handling. Further comminuting the PET flakes increases the bulk density and improves product uniformity, but also creates additional product loss to dust. 

As shown in Fig. 4.1, resin feedstocks have a considerable level of interparticle space that is occupied by air. This level of space and thus the bulk density of the feedstock depend on the temperature, pressure, pellet (or powder) shape, resin type, and the level and shape of the recycle material. For a specific resin feedstock, the bulk density Increases with both temperature and the applied pressure. Understanding the compaction behavior of a resin feedstock is essential for both screw design and numerical simulation of the solids-conveying and melting processes. Screw channels must be able to accommodate the change in the bulk density to mitigate the entrainment of air and the decomposition of resin at the root of the screw. Typically, screw channels are set by using an acceptable compression ratio and compression rate for the resin. These parameters will be discussed in Section 6.1. 

Amorphous HIPS resin pellets compact very little in the temperature range of 25 °C to about 75 °C, a temperature that is about 25 °C below Tg, as shown in Fig. 4.5. The HIPS resin compacts to a much higher degree for temperatures of 25 °C below Tg up to Tg. Like the LDPE resin, the bulk density at 25 °C and zero pressure was measured using the cell shown in Fig. 4.2 at 0.62 g/cmL At temperatures 25 °C below the Tg (100 °C), the bulk modulus of the resin is relatively high, and thus the pellets do not deform easily under pressure. At higher temperatures, how... 

Figure 4.4 Bulk density as a function of temperature and pressure for an LORE resin in the pellet form. This is the same LORE resin used in the solids-conveying studies of Section 5.3.2...

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