Vacuum screw-type

Screw-type rotary lobe blower, 390-391 Vacuum relief, 435... 

A limitation of vacuum pyrolysis technology is heat transfer. Previous studies have shown that the rate of heat transfer is essentially the rate limiting step for pyrolysis reactions [2]. Conventional pyrolysis reactors such as multiple hearth furnaces, rotary kilns and screw type reactors exhibit overall heat transfer coefficients ranging from 10 to 60 [3], depending on the type of feedstock handled. The low thermal... 

In the past, environmental problems associated with the commonly used pump fluids, namely water and oil, have led to the development of dry vacuum pumps that compress without contact. Rotary lobe and screw-type vacuum pumps (Fig. 5 and 6) are the types most commonly used for industrial applications. 

Figure 5.23 Screw type vacuum pump Sihidry. (With permission from Sterling SIHI GmbH, Itzehoe, Germany.) Shown is the service concept for easy cleaning of screw rotors. Main components water cooled housing, two vertical screw rotors (internally cooled), driven by two electronic synchronized motors, gas flow top-down.

Break-seals (Fig. 9.31) are commonly used on sealed reaction and storage tubes because this type of seal allows recovery of volatile materials. The type illustrated in Fig. 9.31a may be opened in an apparatus which contains an off-center arm which may be rotated to break the small tube (Fig. 9.32a). Among the many variants of this design of tube opener, one by Mahler and Velmey is constructed from a /4-in. stainless-steel needle valve which is drilled out to receive the break-seal so that the valve stem may be screwed down on the small tube (Fig. 9.32b).59 The break-seal and vacuum system are connected to this... 

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