Speed Requirement

An alternative type of downhole mud motor is the mud turbine, (multistage axial flow turbine) which directly drives the bit. The tool consists of an upper section containing the turbine blades and lower section with bearings. As mud is pumped through the upper section the blades are turned. Turbines are designed to rotate at higher speed than the displacement motor. The higher rotation speed requires diamond or composite bits. 

The seam closure on a folding carton is typicahy made using a latex, poly(vinyl acetate), vinyl acetate copolymer, or hot-melt adhesive (27). The choice of adhesive depends on a number of factors, including the nature of any coating used on the package and the production speeds required. 

At the fan-tip speeds required for economical performance, a large amount of noise is produced. The predominant source of noise is vortex shedding at the traihug edge of the fan blade. Noise control of aircooled exchangers is required oy the Occupational Safety and Health... 

Rake-speed requirements depend on the type of solids entering the thickener. Peripheral speed ranges used are, for slow-setthng sohds, 3 to 8 m/min (10 to 25 rt/min) for fast-setthng solids, 8 to 12 iTi/min (25 to 40 ft/min) and for coarse sohds or crystalline materials, 12 to 30 iTi/min (40 to 100 ft/min). 

Since the performance of an induction motor can be varied by altering the rotor parameters, a slip-ring motor, through its rotor circuit, can be made to suit any specific torque and speed requirement. 

Such a control is good for machines that are required to operate at low speeds with a high accuracy. Now the phasor /, in terms of /, , is varied according to the speed required. Figure 6.2 now changes to Figure 6.8, which is a marked improvement on the earlier characteristics. The torque variation with speed is now almost constant, except at very low speeds. The reason for poor torque at low speeds is the method of speed variation which is. still based on Vlf. Now a motor s mathematical model is used... 

Empirical energy functions can fulfill the demands required by computational studies of biochemical and biophysical systems. The mathematical equations in empirical energy functions include relatively simple terms to describe the physical interactions that dictate the structure and dynamic properties of biological molecules. In addition, empirical force fields use atomistic models, in which atoms are the smallest particles in the system rather than the electrons and nuclei used in quantum mechanics. These two simplifications allow for the computational speed required to perform the required number of energy calculations on biomolecules in their environments to be attained, and, more important, via the use of properly optimized parameters in the mathematical models the required chemical accuracy can be achieved. The use of empirical energy functions was initially applied to small organic molecules, where it was referred to as molecular mechanics [4], and more recently to biological systems [2,3]. 

High speeds require relatively lightweight gear elements. All case-hardening procedures produce distortion—to keep this distortion to a minimum, nitriding is the preferred hardening method. This method is employed after all machinery operations are complete and no further corrections are to be made to the tooth geometry. 

Most of the drivers used with the sliding vane compressor are electric motors. Variable speed operation is possible within the limits of vane speed requirements. The vanes must travel fast enough to seal against the cylinder wall but not so fast that they cause excessive wear. For the smaller units, under 100 hp, V-belts are widely used. Direct connection to a motor, however, is possible for most compressors and is used through out the size range. 

Reeently, Corpstein et al. [43] found that high-effieieney impellers provide the same levels of solids suspension at redueed eapital and operating eosts. They introdueed the term just-suspended for the most eommonly eneountered level of liquid solid agitation. This oeeurs when none of the solid partieles remains stationary on the bottom of the vessel for longer than 1-2 see. They developed a eorrelation of the speed required to aehieve just-suspended eonditions as ... 

In addition to improving safety during transportation by optimizing the mode, route, physical conditions, and container design, the way the shipment is handled should be examined to see if safety can be improved. For example, one company tested to determine the speed required for the tines of the forklift trucks used at its terminal to penetrate its shipping containers. They installed governors on the forklift trucks to limit the speed below the speed required for penetration. They also specified blunt tine ends for the forklifts. 

Within the elastic regime, the conservation relations for shock profiles can be directly applied to the loading pulse, and for most solids, positive curvature to the stress volume will lead to the increase in shock speed required to propagate a shock. The resulting stress-volume relations determined for elastic solids can be used to determine higher-order elastic constants. The division between the elastic and elastic-plastic regimes is ideally marked by the Hugoniot elastic limit of the solid. 

The minimum stirrer speed required to just suspend the partiele. v, A js, may be ealeulated by the semi-empirieal equation due to Zweitering (1958)... 

Slow speed requires high degree of vibration and pulsation suppression. Vane-Type Rotary Compressors... 

Most mixers are driven by electric motons, or in some cases by mechanical turbines, with gears ratioed to give the proper performance speed of the impeller. A variable or 2-speed driver or gear system often proves worth the extra cost, since it is difficult to predict the exact speed requirements for some new installations. This is particu-... 

Figure 5-33. Scaled-up horsepower/speed requirement for an agitator system is readily related to industrial equipment. By permission, Rautzen, R. R., ef a/., Chem. Engr., Oct. 25,1976, p. 119 [32].

Torque, horsepower, and speed requirements demanded in drives for most machines can be met with one of four designs of squirrel-cage polyphase induction motors, Each design offers a different combination of torque, speed, and current characteristics to meet the operating requirements of various industrial applications. 

Using these relationships, the sheave rotational speeds can be determined. However, obtaining the other component speeds requires a bit more effort. The rotational speed of the belt cannot directly be determined using the information presented so far. To calculate belt rotational speed (rpm), the linear belt speed must first be determined by finding the linear speed (in/min) of the sheave at its... 

Pump power requirements increase with the cube of the speed, so doubling the speed requires eight times the power. 

Finally, i should be noted that the calculation of the power requirement requires a knowledge of the impeller speed which is necessary to blend the contents of a tank in a given time, or of the impeller speed required to achieve a given mass transfer rate in a gas-liquid system. A full understanding of the mass transfer/mixing mechanism is not yet available, and therefore the selection of the optimum operating speed remains primarily a matter of experience. Before concluding this section, it is appropriate to indicate typical power consumptions in kW/m3 of liquid for various duties, and these are shown in Table 7.2. 

The presence of a gas in the suspension results in an increase of the stirrer speed required to establish the state of complete suspension. The propeller usually requires a higher speed than the turbine. Furthermore, a critical volume gas flow exists above which drastic sedimentation of particles occurs. Hence, homogenisation of the suspension requires an increase of the rotational speed and/or a decrease of the gas flow rate. The hydrodynamics of suspensions with a solid fraction exceeding 0.25-0.3 becomes very complex because such suspensions behave like non-Newtonian liquids. This produces problems in the scale-up of operations. Hydrodynamics, gas hold-up, mass-transfer coefficients, etc. have been widely studied and many correlations can be found in literature (see e.g. Shah, 1991). 

Turbulence is required for the flame front to accelerate to the speeds required for a VCE otherwise, a flash fire will result. This turbulence is typically formed by the interaction between the flame front and obstacles such as process structures or equipment. Turbulence also results from material released explosively or via pressure jets. The blast effects produced by VCEs can vary greatly and are strongly dependent on flame speed. In most cases, the mode of flame propagation is deflagration. Under extraordinary conditions, a detonation with more severe blast effects might occur. In the absence of turbulence, under laminar or near-laminar conditions, flame speeds are too low to produce significant blast overpressure. In such a case, the cloud will merely bum as a flash fire. 

NOTE Each Change in Pump Speed requires calculating a new correction factor. 

Connectors hide complex collaborations. The stream of payment orders from Payment Control probably requires a buffer along with a signaling mechanism to tell the receiving component to pick up the orders. The stream of invoices from Purchasing follows the same pattern. The continous update of the Meter s value from the Motor s speed requires a change-notification message other values transmitted in that example need the same message. 

A full marathon (42.2 km), for a normal person, run at whatever speed, requires the oxidation of about 700 g of glycogen - about 5 g/min for elite runners. However, since only about 500 g can be stored in liver plus muscle, another fuel must contribute. This is fatty acid, derived from tria-... 

The Lawrence Berkeley Laboratory and other groups were unable to confirm the spontaneous-fission reaction of Ku-260, so the Dubna groups discovery was disputed. The Berkeley equipment was unable to accelerate neon ions to the speeds required to produce Ku-260, and thus they tried a different reaction in a new automated rapid chemistry apparatus that identified and confirmed new isotopes of heavy metals. The procedure involved bombarding the element californium-239 with a mixture of the isotopes carbon-12 and carbon-13 ions, as follows ... 

The effective pumping speed required to evacuate a vessel or to carry out a process inside a vacuum system will correspond to the inlet speed of a particular pump (or the pump system) only if the pump is joined directly to the vessel or system. Practically speaking, this is possible only in rare situations. It is almost always necessary to include an intermediate piping system comprising valves, separators, cold traps and the like. All this... 

A typical pump selection chart such as shown in Fig. 10-46 calculates the specific speed for a given flow, head, and speed requirements. Based on the calculated specific speed, the optimal pump design is indicated. 

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