TWO-ROTOR

FIG. 10-55 Two- rotor screw pump. Courtesy ofWan en Quimhy Tump Co. )... 

Figure 4-8. The two rotor profiles of helical screw compressors.

Straight-lobe compressors, or blowers, as they are commonly called are low-pressure machines. The feature unique to these compressors is that the machines do not compress the gas internally as do most of the other rotaries. The straight-lobe compressor uses two rotors that intermesh as they rotate (see Figure 1-7). The rotors are timed by a set of gears. The lobe shape is either an involute or cyclodial form. A rotor may have either two or three lobes. As the rotors turn and pass the inlet port, a volume of gas is trapped and carried between the lobes and the outer... 

Figure 11-21D. Helical rotors refrigerant compressors. (1) Cutaway of a 100-ton intermediate compressor. The intermediate Helirotor compressor has only three moving parts the two rotor assemblies and the capacity controlling slide valve. The general purpose Helirotor compressor has only four moving parts two rotor assemblies, the variable unloader valve, and the step unloader valve. Unlike reciprocating compressors, the Trane Helirotor compressor has no pistons, connecting rods, suction and discharge valves, or mechanical oil pump.

Screw compressors have two rotors with interlocking lobes and act as positive-displacement compressors (see Figure 44.11). This type of compressor is designed for baseload, or steady state, operation and is subject to extreme instability should either the inlet or discharge conditions change. Two helical gears mounted on the outboard ends of the male and female shafts synchronize the two rotor lobes. 

Screw compressors use both Babbitt and rolling-element bearings. Because of the thrust created by process instability and the normal dynamics of the two rotors, all screw compressors use heavy-duty thmst bearings. In most cases, they are located on the outboard end of the two rotors, but some designs place them on the inboard end. The actual location of the thmst bearings must be known and used as a primary measurement-point location. 

When balancing a keyed-shaft rotor, one half of the key s weight is assumed part of the shaft s male portion. The other half is considered part of the female portion that is coupled to it. However, when the two rotor parts are sent to a balancing shop for re-balancing, the actual key is rarely included. As a result, the balance operator usually guesses at the key s length, makes up a half key, and then balances the part. (Note A half key is of full-key length, but only half-key depth.)... 

Basically two rotor types are applied in the internal mixer The tangential rotor type and the intermeshing rotor type. The latter one interferes with the adjacent rotor and turns at the same rotor speed compulsory. In the drop door or through the side plates a thermocouple is mounted to record the temperature of the mbber. 

Kobe Steel reported two rotor developments. The first development is an improvement of the four flight rotor by extending the long rotor wing until four times the short rotor wing (see Figure 35.23). As for the ST rotor it can be mn in an even speed or with friction. The performance improvement can... 

The VIC mixer is an intermeshing mixer in which the distance between the two rotors can be varied during mixing. Power input can be controlled better, it is said." During masterbatch mixing the interclearance section between the two rotors can be maximal. After material intake and incorporation, the interclearance section can be reduced by reducing the distance between the two rotor axes, which leads to better dispersion performance. 

A machine for the incorporation of compounding ingredients into rubber or similar materials. Two rotors revolve in an enclosed chamber (see Open Mill). It is provided with a hopper for feeding the materials and a sliding or drop-door for discharge of the batch. 

In this case, the most efficient recoupling is obtained by adjusting the rf field strength to half the spinning frequency and selecting the m = 1 terms leading to the effective DQ Hamiltonian over two rotor periods... 

A Roots vacuum pump (see Fig. 2.17) Is a rotary positive-displacement type of pump where two symmetrically-shaped Impellers rotate Inside the pump casing past each other In close proximity. The two rotors have a aoss... 

FIG. 10-33 Two-rotor screw pump. (Courtesy of Warren Quimby Pump Co.)... 

Figure 3 Pulse sequences for the different CT-REDOR versions for two rotor cycles (A) MAS spin-echo reference experiment (B) CT-VPP-REDOR with the pulse position fpp of the /-spin dephasing pulses stepped from 0 to Tp and (C) CT-VPD-REDOR with the pulse width fpp of the /-spin dephasing pulses stepped from 0 to In.

Even with this unequal distribution there may be little effect on yield of distillate from a substantially fresh water feed hence the high output of the still from distilled water feed. With sea water, 3 to 4% NaCl equivalent, the average or effective boiling point elevation becomes unequal on the two rotors. Thus if a 50% cut is secured and the lower rotor receives twice the feed of the upper, the average residue concentrate of 7% brine from 3.5% feed could be an actual 10% from the upper periphery and 5% from the lower, supposing equal rates of distillation. Actually because of -the different elevations of boiling point (1.1° and 1.8° F.) the rate of evaporation from the upper rotor decreases while that from the lower rotor increases but less than proportionally because of the added thickness of the feed layer. Later experiments at Columbus on the No. 4 machine suggest that this situation existed in the No. 5 still. 

From microwave studies V3 was found to be 1.2 kJ/mol, i. e. about 1/10 of the V3 term, in agreement with results obtained theoretically207. This indicates that the interaction of the two rotors must be small in the propane case, though it is difficult to draw any general conclusion from this example. 

Most of these machines are based on two adjacent screws, but some, like the continuous mixers, have a different geometry, which is better defined as consisting of two rotors. 

Fig. 10.6 The single-stage FCM. (a) Size 15 FCM with chamber opened and rotated hydraulically (b) top view of staged apex twin rotors and the axial zones for carrying out the solids feed handling and the melting and mixing elementary steps (c) cross-sectional view of two rotor orientations, tip-to-tip (cx) and tip-to-flat (c2). [Reprinted by permission from E. L. Canedo and L. N. Valsamis, Farrel Continuous Mixer Systems for Plastics Compounding, in Plastics Compounding—Equipment and Processing, D. B. Todd, Ed., Hanser, Munich, 1998.]...

The TSMEE in the M-M mixing mode was used with three kneading blocks of 5/45/42 forwarding elements. Experiments were conducted at two melt temperatures, 180° and 140°C, and two rotor speeds, 60 and 120 rpm. The results and conclusions that emerged from the study are discussed in the following subsections. 

Due to the existence of the out-of-piane wagging, the two rotors are not equivalent anymore by simple superposition. They appear to be, however, equivalent by reflection in a plane perpendicular to the molecular plane dividing the molecule in two equal moeities. 

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