Compressor twin-screw

As compression occurs concurrently in both halves of the compressor, radial forces are oppositely directed, resulting in negligible net-radial loads on the rotor bearings (uuhke twin screw compressors), but there are some loads on the star wheel shafts. 

Figure 4.15 Twin-screw compressor. (Courtesy of Stal Refrigeration AB)...

Capacity reduction of the twin-screw compressor is effected by a sliding block covering part of the barrel wall, which permits gas to... 

The provision of a separate oil cooler will reduce condenser load by the amount of heat lost to the oil and removed in the oil cooler. This is of special note with twin-screw compressors, where a high proportion of the compressor energy is taken away in the oil. This proportion varies with the exact method of oil cooling, and figures should be obtained from the compressor manufacturer for a particular application. 

Figure 28.4 Flow chart of the Hunan University process. 1 twin screw feeder 2 fluidized-bed reactor 3 catalyst feeder 4 cyclone separator 5 catalytic reforming column 6 rectifying tower 7 condenser 8 compressor 9 reactivation reactor...

Figure 8.2 View into an Opcon Auto rotor Twin-screw compressor providing oil-free air for use In pressurised fuel cell systems (photograph courtesy of Opcon).

Other companies developing compressors for fuel cells are Vairex, who offer vane compressors, and Opcon, who have twin-screw compressors in their portfolio (see Figure 8.2). 

Figure 9.2 (a) Typical centrifugal air compressor rotor and (b) model of twin screw Lysholm compressor. 

The oil separation, cooling and filtering for a twin-screwcompressor adds to the complexity of an otherwise simple machine. Some commercial screw compressors are available which have the oilhandling circuit built into the assembly, with a small loss of overall efficiency. 

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