Rotary characteristics

However, rotary furnaces tend to produce more exhaust gas and fumes, require more skill fill manipulation, and are more labor intensive. Also, the slags produced in the rotary furnaces, soda or fayaUte [13918-37-1] slags, normally do not pass the toxic characteristic leach procedure (TCLP) test and pose a disposal problem. 

Rota.ry Lobe Pumps. Rotary lobe pumps are similar to gear pumps in principle. These pumps have an added advantage of noncontacting metal parts by use of external gears, which reduces the wear, but adds complexity. Low wear and improved shear characteristics make these pumps apphcable to the food industry, where cleanliness and absence of contamination are required. These pumps produce a strong pulsing flow that must be addressed. 

From the viewpoint of accommodation to the filter-supporting structure, some cloths cannot be used, even though the filtering characteristics are excellent. For rotary drum filters, for example, the cloth is pressed onto the drum by the caulking method, which uses cords that pass over the drum. In this case, the closely woven cloths manufactured from monofilament polyethylene or polypropylene fiber are less desirable than more flexible cloths of polyfilament fibers or staple cloths. 

Figure 12-112. Performance characteristics for a typical single-stage rotary helical rotor compressor, using matching helical rotors. (Used by permission Fairbanks, Morse, Co. for earlier editions. [Company no longer exists producing compressors, 1998, per research information.])...

The reciprocating and rotary positive displacement pumps primary characteristic is that they have a nearly direct relationship between the motion of the pumping... 

This type of compressor is classified as a constant volume, variable-pressure machine that is quite similar to the vane-type rotary in general characteristics. Both have a built-in compression ratio. 

For natural gas service, five types of compressors are typically used, that is, diaphragm, piston, rotary, screw, and turbo compressors. The characteristics of each type of compressors are a function of throughput and pressure, as shown in Figure 10.22 [6]. Currently, piston (or reciprocating) and rotary compressors are used to compress hydrogen that are similar to those used for natural gas, with modifications of design and materials. 

Condensation of vapours must be avoided since it causes a deterioration of the oil water vapour condense at 234 torr at 70°C, which is the typical working temperature of the pump. To avoid condensation, most pumps have a ballast valve in the high-pressure stage. After the gas has been closed off from the inlet, some gas is bled in through the ballast valve. This causes the discharge valve to open sooner, with a reduction of the compression ratio. Rotary piston pumps have similar characteristics. 

A system of cascaded booster pumps has the characteristics of a medium-size rotary vane pump but does not present the drawback of the back-streaming. For this reason, it finds application in cryogenics, for example, for the circulation of the He mixture in dilution refrigerators. 

For the most part, positive displacement pumps can be classified either as rotary pumps or as reciprocating pumps. However, pumps do exist which exhibit some of the characteristics of both types. 

As with spherical particles the Peclet number is of great importance in describing the transitions in rheological behaviour. In order for the applied flow field to overcome the diffusive motion and shear thinning to be observed a Peclet number exceeding unity is required. However, we can define both rotational and translational Peclet numbers, depending upon which of the diffusive modes we consider most important to the flow we initiate. The most rapid diffusion is the rotational component and it is this that must be overcome in order to initiate flow. We can define this in terms of a diffusive timescale relative to the applied shear rate. The characteristic Maxwell time for rotary diffusion is... 

Specific Rotation A polarized light when passed through an optically active substance, each molecule of it encountered by the light beam rotates the plane of polarization by a constant amount characteristic of the substance. Consequently, a measure of the rotary power of the individual molecule, irrespective of the two parameters, namely the path length and the concentration, is achieved by converting the measured rotation into a specific rotation by the help of the following expressions ... 

Figure 16.21. Characteristic rotary atomisers (a) Sharp-edge flat disc (b) Bowl (c) Vaned disc (d) Air-blast...

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