Mixer-blender, double-cone

Carefully identify at least 10 sampling locations in the blender to represent potential areas of poor blending. For example, in tumbling blenders (such as V-blenders, double cones, or drum mixers), samples should be selected from at least two depths along the axis of the blender. For convective blenders (such as a ribbon blender), a special effort should be made to implement uniform volumetric sampling to include the corners and discharge area (at least 20 locations are recommended to adequately validate convective blenders). 

FIGURE 13.4 Tumbler mixers (a) double-cone mixer (b) twin-shell blender. (Data from McCabe, W., and J. C. Smith, Unit Operations of Chemical Engineering, 2nd edn., McGraw-Hill, New York, 1967, 851-859.)... 

Sohd—sohd blending can be accompHshed by a number of techniques. Some of the most common iaclude mechanical agitatioa which iacludes devices such as ribboa Headers, impellers, paddle mixers, orbiting screws, etc a rotary fixed container which iacludes twia-sheU (Vee) and double-cone blenders and fluidization, ia which air is used to Head some fine powders. 

Double-Cone Mixer. This term may be applied to the " Twin-Shell laboratory blenders... 

Figure 10.15. Some mixers and blenders for powders and pastes, (a) Ribbon blender for powders, (b) Flow pattern in a double cone blender rotating on a horizontal axis, (c) Twin shell (Vee-type) agglomerate breaking and liquid injection are shown on the broken line, (d) Twin rotor available with jacket and hollow screws for heat transfer, (e) Batch muller. (f) Twin mullers operated continuously, (g) Double-arm mixer and kneader (Baker-Perkins Inc.), (h) Some types of blades for the double-arm kneader (Baker—Perkins Irtc.).

Industrial equipment. Rotating-shell mixers or tumbling mixers are shown in Fig. 3. Drum-type, cubical-shaped, double-cone, and twin-shell blenders with their axis of rotation horizontal to the center of the drum on its axis increase crossflow and improve the mixing action. Cubical and polyhedron-shaped... 

FIG. 21-157 Examples of low-shear mixers used in granulation, (a) Ribbon blender (h) planetary mixer (c) orbiting screw mixer (d) sigma blender (e) double-cone blender with baffles (/) v blender with breaker bar. (See also Solids Mixing. ) [( ) and (d), Chirkot and Propst, in Parikh (ed.). Handbook of Pharmaceutical Granulation Technology, Taylor 6- Francis, 2005.]... 

The two components (W and C) must be blended thoroughly prior to carburization. This is done in different types of equipment, like V or double cone blenders, mixing ball mills, or high-energy mixers. An even blend is of importance because, during carburization, carbon atoms can only move via diffusion or as methane molecules over very short distances. Pelletizing or compacting enhances diffusion and increases the furnace capacity. 

Other low shear mixers use double or slanted cone and V-shaped vessels. Fig. 7.25 depicts schematically these always batch operating blenders which rotate about a horizontal axis. The lines and arrows in the sketches try to explain the particle paths that cause mixing. In Fig. 7.26 photographs of typical equipment are presented. 

Fig. 11.13 Photograph of different tumble/growth agglomeration work modules that are attached to the all purpose drive stand of Fig. 11.12. (a) disc or pan agglomerator (b) coating pan (c) bowl blender (d) planetary bowl blender (e) double cone blender (f) cube mixer (g) high shear mixer (h) pug mill/kneader (courtesy Erweka, Heusenstamm, Germany).

For the first group the following types of dryers are generally used convective (tray, band, fluid bed, flash dryers, and their modifications) or contact (vacuum dryers such as double-cone dryer-blender, conical dryer with rotating helical mixer, paddle dryer). Pastelike materials are dried in tray dryers, band dryers equipped with extruding devices, and spin-flash dryers. Finally, thin pastes can be dried in spray dryers or on fluid beds or spouted beds of inert particles. Small amounts of solutions and suspensions are generally freeze-dried, especially if the product is thermolabile. 

Conical Dryer with Screw Mixer The conical dryer with screw mixer is similar in principle to the double-cone dryer-blender although the vessel is stationary and solids are mixed by epicyclic screw mixer (Figure 33.13). For pressures from 25 to 150 mbar and wall temperatures from 40°C to 60°C, Simon [6] reports evaporation rates of water up to 10 kg/h m. Units up to 5 m are commercially available. The dryer has no dead spaces and is easy to clean. 

Figure 5.2 Low-intensity mixer designs (a) double-cone blender (b) twin-shell ( V ) blender (c) conical screw mixer (d) conical screw mixer...

Y mixer Double cone Ribbon blender Fluidized mixer Nauta mixer... 

---