TWIN-SHAFT

Rotating drums, disks, and to a lesser extent, cones are used in continuous large-scale balling of iron ores (E3). A pelletizing disk of industrial type is shown in Fig. 1. Fertilizers are granulated in twin-shaft pug mills, drums,... 

Fig. 8.3 Schematic representation of the List twin shaft co-rotating continuous mechanical and thermal processor. [Courtesy of the List Corporation.]...

Fig. 7.34 Photograph of a double trough (twin shafted) pug mill (courtesy FEECO International, Green Bay, Wl, USA).

The first mixer was an annular container with a spiked rotor for rubber compounding [Hancock, 1823]. The calender/two roll mill was patented by Chaffe in 1836 and manufactured by Parrel Co. A counter rotating twin shaft internal mixer with elliptical rotating discs or sigma-blades was developed by the end of the last century [Freyburger, 1876 Pfleiderer, 1880]. The first hand-operated extruder was a ram press, used for forming NR or GP, then later NC. 

Before introduction of the intensive internal mixers, the mixing was accomplished on open mills — a slow, dirty process requiring skilled operators. An efficient, counter rotating twin shaft internal mixer with elhptical rotating discs was... 

N. Rauber et al., Designing lime kiln plants with the aid of a process simulation model for a VALEC twin-shaft kiln , Zement Kalk Gips 9, 1988, 428-433 (English 11, 1988, 253-256). 

There are basically two gas turbine driving methods, known as single-shaft and two (or twin) shaft drives. In a single-shaft gas turbine, all the rotating elements share a common shaft. The common elements are the air compressor, the compressor turbine and the power turbine. The power turbine drives the generator. 

For extrusion of very wide, flat clay ribbons the twin-shaft auger extruder was reintroduced in 1994 in the field of structural clay products, whereas co-rotating screw-extruders are used since the late 1970s in advanced ceramic for the production of honeycombs. 

Flow laminations, laminations caused by inner gliding surfaces, and cutting laminations, all can be distinguished to varying degrees in the extrusion of plastic bodies, independent of the extrusion method employed, e.g. piston extrusion presses, single-shaft extruders, twin-shaft extrusion machines or rotory-type extruders. 

FIGURE 43.13 Various designs of indirect dryers (a) rotaplate indirect dryer (Courtesy of Stord) (b) kneading and self-cleaning disc dryer—twin shafts (Courtesy of LIST) (c) the Porcupine processor (Courtesy of The Bethlehem Corporation) (d) K.-S. Nara paddle and paddle dryer. (Courtesy of Komline-Sanderson.)... 

Single-shaft type and twin-shaft type... 

The aforementioned problems have been examined by performing outline designs of two cases of heat outputs 450 MWt and 1200 kWt. In the case of the heat output 450 MWt, the efficiency difference in the compressor between the twin-shaft system and the single-shaft system is 1 to 1.5% and the efficiency difference in the turbine is around 0.5% and the efficiency improvement and the compact design are possible, but the benefit of the tw in-shaft system is small in terms of the shaft system vibration. 

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