Extrusion cylindrical channel

Many commercial ceramic membranes nowadays come in the form of a monolith consisting of multiple, straight channels parallel to the axis of the cylindrical structure (Figure 3.6). The surfaces of the open channels are deposited with permselective membranes and possibly one or more intermediate support layers. The porous suppon of these multi-channel structures are produced by extrusion of ceramic pastes described above with a channel diameter of a few millimeters. Their lengths are somewhat limited by the size of the furnaces used to dry, calcine and sinter them and also by such practical considerations as the total compact weights to be supported during heat ueatment and the risk of distortion in the middle section. It should be noted that this type of honeycomb... 

All features depend on the application and the feed properties. Capacities, although strongly influenced by the material as well as the pellet size and shape, may be as low as a few hundred kg/h and, on the high end, exceed 80 t/h. As visible from the dies shown in Fig. 8.50, most of the extrusion channels in pellet mills are cylindrical bores however, as depicted in the center of this Fig. (8.50), square openings (and others) are provided for specific applications (for example, the manufacturing of catalyst carriers). As a typical product of pellet mills, Fig. 8.56 presents some cylindrical animal feed pellets. 

---